diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c9b568f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.pyc
+*.swp
diff --git a/generator/google/__init__.py b/generator/google/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/generator/google/__init__.py
diff --git a/generator/google/protobuf/__init__.py b/generator/google/protobuf/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/generator/google/protobuf/__init__.py
diff --git a/generator/google/protobuf/compiler/__init__.py b/generator/google/protobuf/compiler/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/generator/google/protobuf/compiler/__init__.py
diff --git a/generator/google/protobuf/compiler/plugin_pb2.py b/generator/google/protobuf/compiler/plugin_pb2.py
new file mode 100644
index 0000000..77cc07a
--- /dev/null
+++ b/generator/google/protobuf/compiler/plugin_pb2.py
@@ -0,0 +1,166 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/protobuf/compiler/plugin.proto
+
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+
+import google.protobuf.descriptor_pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/protobuf/compiler/plugin.proto',
+  package='google.protobuf.compiler',
+  serialized_pb='\n%google/protobuf/compiler/plugin.proto\x12\x18google.protobuf.compiler\x1a google/protobuf/descriptor.proto\"}\n\x14\x43odeGeneratorRequest\x12\x18\n\x10\x66ile_to_generate\x18\x01 \x03(\t\x12\x11\n\tparameter\x18\x02 \x01(\t\x12\x38\n\nproto_file\x18\x0f \x03(\x0b\x32$.google.protobuf.FileDescriptorProto\"\xaa\x01\n\x15\x43odeGeneratorResponse\x12\r\n\x05\x65rror\x18\x01 \x01(\t\x12\x42\n\x04\x66ile\x18\x0f \x03(\x0b\x32\x34.google.protobuf.compiler.CodeGeneratorResponse.File\x1a>\n\x04\x46ile\x12\x0c\n\x04name\x18\x01 \x01(\t\x12\x17\n\x0finsertion_point\x18\x02 \x01(\t\x12\x0f\n\x07\x63ontent\x18\x0f \x01(\tB,\n\x1c\x63om.google.protobuf.compilerB\x0cPluginProtos')
+
+
+
+
+_CODEGENERATORREQUEST = _descriptor.Descriptor(
+  name='CodeGeneratorRequest',
+  full_name='google.protobuf.compiler.CodeGeneratorRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='file_to_generate', full_name='google.protobuf.compiler.CodeGeneratorRequest.file_to_generate', index=0,
+      number=1, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='parameter', full_name='google.protobuf.compiler.CodeGeneratorRequest.parameter', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='proto_file', full_name='google.protobuf.compiler.CodeGeneratorRequest.proto_file', index=2,
+      number=15, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=101,
+  serialized_end=226,
+)
+
+
+_CODEGENERATORRESPONSE_FILE = _descriptor.Descriptor(
+  name='File',
+  full_name='google.protobuf.compiler.CodeGeneratorResponse.File',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.compiler.CodeGeneratorResponse.File.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='insertion_point', full_name='google.protobuf.compiler.CodeGeneratorResponse.File.insertion_point', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='content', full_name='google.protobuf.compiler.CodeGeneratorResponse.File.content', index=2,
+      number=15, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=337,
+  serialized_end=399,
+)
+
+_CODEGENERATORRESPONSE = _descriptor.Descriptor(
+  name='CodeGeneratorResponse',
+  full_name='google.protobuf.compiler.CodeGeneratorResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='error', full_name='google.protobuf.compiler.CodeGeneratorResponse.error', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='file', full_name='google.protobuf.compiler.CodeGeneratorResponse.file', index=1,
+      number=15, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[_CODEGENERATORRESPONSE_FILE, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=229,
+  serialized_end=399,
+)
+
+_CODEGENERATORREQUEST.fields_by_name['proto_file'].message_type = google.protobuf.descriptor_pb2._FILEDESCRIPTORPROTO
+_CODEGENERATORRESPONSE_FILE.containing_type = _CODEGENERATORRESPONSE;
+_CODEGENERATORRESPONSE.fields_by_name['file'].message_type = _CODEGENERATORRESPONSE_FILE
+DESCRIPTOR.message_types_by_name['CodeGeneratorRequest'] = _CODEGENERATORREQUEST
+DESCRIPTOR.message_types_by_name['CodeGeneratorResponse'] = _CODEGENERATORRESPONSE
+
+class CodeGeneratorRequest(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _CODEGENERATORREQUEST
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorRequest)
+
+class CodeGeneratorResponse(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+
+  class File(_message.Message):
+    __metaclass__ = _reflection.GeneratedProtocolMessageType
+    DESCRIPTOR = _CODEGENERATORRESPONSE_FILE
+
+    # @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorResponse.File)
+  DESCRIPTOR = _CODEGENERATORRESPONSE
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.compiler.CodeGeneratorResponse)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), '\n\034com.google.protobuf.compilerB\014PluginProtos')
+# @@protoc_insertion_point(module_scope)
diff --git a/generator/google/protobuf/descriptor.py b/generator/google/protobuf/descriptor.py
new file mode 100644
index 0000000..eb13eda
--- /dev/null
+++ b/generator/google/protobuf/descriptor.py
@@ -0,0 +1,713 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Descriptors essentially contain exactly the information found in a .proto
+file, in types that make this information accessible in Python.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+
+from google.protobuf.internal import api_implementation
+
+
+if api_implementation.Type() == 'cpp':
+  if api_implementation.Version() == 2:
+    from google.protobuf.internal.cpp import _message
+  else:
+    from google.protobuf.internal import cpp_message
+
+
+class Error(Exception):
+  """Base error for this module."""
+
+
+class TypeTransformationError(Error):
+  """Error transforming between python proto type and corresponding C++ type."""
+
+
+class DescriptorBase(object):
+
+  """Descriptors base class.
+
+  This class is the base of all descriptor classes. It provides common options
+  related functionaility.
+
+  Attributes:
+    has_options:  True if the descriptor has non-default options.  Usually it
+        is not necessary to read this -- just call GetOptions() which will
+        happily return the default instance.  However, it's sometimes useful
+        for efficiency, and also useful inside the protobuf implementation to
+        avoid some bootstrapping issues.
+  """
+
+  def __init__(self, options, options_class_name):
+    """Initialize the descriptor given its options message and the name of the
+    class of the options message. The name of the class is required in case
+    the options message is None and has to be created.
+    """
+    self._options = options
+    self._options_class_name = options_class_name
+
+    # Does this descriptor have non-default options?
+    self.has_options = options is not None
+
+  def _SetOptions(self, options, options_class_name):
+    """Sets the descriptor's options
+
+    This function is used in generated proto2 files to update descriptor
+    options. It must not be used outside proto2.
+    """
+    self._options = options
+    self._options_class_name = options_class_name
+
+    # Does this descriptor have non-default options?
+    self.has_options = options is not None
+
+  def GetOptions(self):
+    """Retrieves descriptor options.
+
+    This method returns the options set or creates the default options for the
+    descriptor.
+    """
+    if self._options:
+      return self._options
+    from google.protobuf import descriptor_pb2
+    try:
+      options_class = getattr(descriptor_pb2, self._options_class_name)
+    except AttributeError:
+      raise RuntimeError('Unknown options class name %s!' %
+                         (self._options_class_name))
+    self._options = options_class()
+    return self._options
+
+
+class _NestedDescriptorBase(DescriptorBase):
+  """Common class for descriptors that can be nested."""
+
+  def __init__(self, options, options_class_name, name, full_name,
+               file, containing_type, serialized_start=None,
+               serialized_end=None):
+    """Constructor.
+
+    Args:
+      options: Protocol message options or None
+        to use default message options.
+      options_class_name: (str) The class name of the above options.
+
+      name: (str) Name of this protocol message type.
+      full_name: (str) Fully-qualified name of this protocol message type,
+        which will include protocol "package" name and the name of any
+        enclosing types.
+      file: (FileDescriptor) Reference to file info.
+      containing_type: if provided, this is a nested descriptor, with this
+        descriptor as parent, otherwise None.
+      serialized_start: The start index (inclusive) in block in the
+        file.serialized_pb that describes this descriptor.
+      serialized_end: The end index (exclusive) in block in the
+        file.serialized_pb that describes this descriptor.
+    """
+    super(_NestedDescriptorBase, self).__init__(
+        options, options_class_name)
+
+    self.name = name
+    # TODO(falk): Add function to calculate full_name instead of having it in
+    #             memory?
+    self.full_name = full_name
+    self.file = file
+    self.containing_type = containing_type
+
+    self._serialized_start = serialized_start
+    self._serialized_end = serialized_end
+
+  def GetTopLevelContainingType(self):
+    """Returns the root if this is a nested type, or itself if its the root."""
+    desc = self
+    while desc.containing_type is not None:
+      desc = desc.containing_type
+    return desc
+
+  def CopyToProto(self, proto):
+    """Copies this to the matching proto in descriptor_pb2.
+
+    Args:
+      proto: An empty proto instance from descriptor_pb2.
+
+    Raises:
+      Error: If self couldnt be serialized, due to to few constructor arguments.
+    """
+    if (self.file is not None and
+        self._serialized_start is not None and
+        self._serialized_end is not None):
+      proto.ParseFromString(self.file.serialized_pb[
+          self._serialized_start:self._serialized_end])
+    else:
+      raise Error('Descriptor does not contain serialization.')
+
+
+class Descriptor(_NestedDescriptorBase):
+
+  """Descriptor for a protocol message type.
+
+  A Descriptor instance has the following attributes:
+
+    name: (str) Name of this protocol message type.
+    full_name: (str) Fully-qualified name of this protocol message type,
+      which will include protocol "package" name and the name of any
+      enclosing types.
+
+    containing_type: (Descriptor) Reference to the descriptor of the
+      type containing us, or None if this is top-level.
+
+    fields: (list of FieldDescriptors) Field descriptors for all
+      fields in this type.
+    fields_by_number: (dict int -> FieldDescriptor) Same FieldDescriptor
+      objects as in |fields|, but indexed by "number" attribute in each
+      FieldDescriptor.
+    fields_by_name: (dict str -> FieldDescriptor) Same FieldDescriptor
+      objects as in |fields|, but indexed by "name" attribute in each
+      FieldDescriptor.
+
+    nested_types: (list of Descriptors) Descriptor references
+      for all protocol message types nested within this one.
+    nested_types_by_name: (dict str -> Descriptor) Same Descriptor
+      objects as in |nested_types|, but indexed by "name" attribute
+      in each Descriptor.
+
+    enum_types: (list of EnumDescriptors) EnumDescriptor references
+      for all enums contained within this type.
+    enum_types_by_name: (dict str ->EnumDescriptor) Same EnumDescriptor
+      objects as in |enum_types|, but indexed by "name" attribute
+      in each EnumDescriptor.
+    enum_values_by_name: (dict str -> EnumValueDescriptor) Dict mapping
+      from enum value name to EnumValueDescriptor for that value.
+
+    extensions: (list of FieldDescriptor) All extensions defined directly
+      within this message type (NOT within a nested type).
+    extensions_by_name: (dict, string -> FieldDescriptor) Same FieldDescriptor
+      objects as |extensions|, but indexed by "name" attribute of each
+      FieldDescriptor.
+
+    is_extendable:  Does this type define any extension ranges?
+
+    options: (descriptor_pb2.MessageOptions) Protocol message options or None
+      to use default message options.
+
+    file: (FileDescriptor) Reference to file descriptor.
+  """
+
+  def __init__(self, name, full_name, filename, containing_type, fields,
+               nested_types, enum_types, extensions, options=None,
+               is_extendable=True, extension_ranges=None, file=None,
+               serialized_start=None, serialized_end=None):
+    """Arguments to __init__() are as described in the description
+    of Descriptor fields above.
+
+    Note that filename is an obsolete argument, that is not used anymore.
+    Please use file.name to access this as an attribute.
+    """
+    super(Descriptor, self).__init__(
+        options, 'MessageOptions', name, full_name, file,
+        containing_type, serialized_start=serialized_start,
+        serialized_end=serialized_start)
+
+    # We have fields in addition to fields_by_name and fields_by_number,
+    # so that:
+    #   1. Clients can index fields by "order in which they're listed."
+    #   2. Clients can easily iterate over all fields with the terse
+    #      syntax: for f in descriptor.fields: ...
+    self.fields = fields
+    for field in self.fields:
+      field.containing_type = self
+    self.fields_by_number = dict((f.number, f) for f in fields)
+    self.fields_by_name = dict((f.name, f) for f in fields)
+
+    self.nested_types = nested_types
+    self.nested_types_by_name = dict((t.name, t) for t in nested_types)
+
+    self.enum_types = enum_types
+    for enum_type in self.enum_types:
+      enum_type.containing_type = self
+    self.enum_types_by_name = dict((t.name, t) for t in enum_types)
+    self.enum_values_by_name = dict(
+        (v.name, v) for t in enum_types for v in t.values)
+
+    self.extensions = extensions
+    for extension in self.extensions:
+      extension.extension_scope = self
+    self.extensions_by_name = dict((f.name, f) for f in extensions)
+    self.is_extendable = is_extendable
+    self.extension_ranges = extension_ranges
+
+    self._serialized_start = serialized_start
+    self._serialized_end = serialized_end
+
+  def EnumValueName(self, enum, value):
+    """Returns the string name of an enum value.
+
+    This is just a small helper method to simplify a common operation.
+
+    Args:
+      enum: string name of the Enum.
+      value: int, value of the enum.
+
+    Returns:
+      string name of the enum value.
+
+    Raises:
+      KeyError if either the Enum doesn't exist or the value is not a valid
+        value for the enum.
+    """
+    return self.enum_types_by_name[enum].values_by_number[value].name
+
+  def CopyToProto(self, proto):
+    """Copies this to a descriptor_pb2.DescriptorProto.
+
+    Args:
+      proto: An empty descriptor_pb2.DescriptorProto.
+    """
+    # This function is overriden to give a better doc comment.
+    super(Descriptor, self).CopyToProto(proto)
+
+
+# TODO(robinson): We should have aggressive checking here,
+# for example:
+#   * If you specify a repeated field, you should not be allowed
+#     to specify a default value.
+#   * [Other examples here as needed].
+#
+# TODO(robinson): for this and other *Descriptor classes, we
+# might also want to lock things down aggressively (e.g.,
+# prevent clients from setting the attributes).  Having
+# stronger invariants here in general will reduce the number
+# of runtime checks we must do in reflection.py...
+class FieldDescriptor(DescriptorBase):
+
+  """Descriptor for a single field in a .proto file.
+
+  A FieldDescriptor instance has the following attributes:
+
+    name: (str) Name of this field, exactly as it appears in .proto.
+    full_name: (str) Name of this field, including containing scope.  This is
+      particularly relevant for extensions.
+    index: (int) Dense, 0-indexed index giving the order that this
+      field textually appears within its message in the .proto file.
+    number: (int) Tag number declared for this field in the .proto file.
+
+    type: (One of the TYPE_* constants below) Declared type.
+    cpp_type: (One of the CPPTYPE_* constants below) C++ type used to
+      represent this field.
+
+    label: (One of the LABEL_* constants below) Tells whether this
+      field is optional, required, or repeated.
+    has_default_value: (bool) True if this field has a default value defined,
+      otherwise false.
+    default_value: (Varies) Default value of this field.  Only
+      meaningful for non-repeated scalar fields.  Repeated fields
+      should always set this to [], and non-repeated composite
+      fields should always set this to None.
+
+    containing_type: (Descriptor) Descriptor of the protocol message
+      type that contains this field.  Set by the Descriptor constructor
+      if we're passed into one.
+      Somewhat confusingly, for extension fields, this is the
+      descriptor of the EXTENDED message, not the descriptor
+      of the message containing this field.  (See is_extension and
+      extension_scope below).
+    message_type: (Descriptor) If a composite field, a descriptor
+      of the message type contained in this field.  Otherwise, this is None.
+    enum_type: (EnumDescriptor) If this field contains an enum, a
+      descriptor of that enum.  Otherwise, this is None.
+
+    is_extension: True iff this describes an extension field.
+    extension_scope: (Descriptor) Only meaningful if is_extension is True.
+      Gives the message that immediately contains this extension field.
+      Will be None iff we're a top-level (file-level) extension field.
+
+    options: (descriptor_pb2.FieldOptions) Protocol message field options or
+      None to use default field options.
+  """
+
+  # Must be consistent with C++ FieldDescriptor::Type enum in
+  # descriptor.h.
+  #
+  # TODO(robinson): Find a way to eliminate this repetition.
+  TYPE_DOUBLE         = 1
+  TYPE_FLOAT          = 2
+  TYPE_INT64          = 3
+  TYPE_UINT64         = 4
+  TYPE_INT32          = 5
+  TYPE_FIXED64        = 6
+  TYPE_FIXED32        = 7
+  TYPE_BOOL           = 8
+  TYPE_STRING         = 9
+  TYPE_GROUP          = 10
+  TYPE_MESSAGE        = 11
+  TYPE_BYTES          = 12
+  TYPE_UINT32         = 13
+  TYPE_ENUM           = 14
+  TYPE_SFIXED32       = 15
+  TYPE_SFIXED64       = 16
+  TYPE_SINT32         = 17
+  TYPE_SINT64         = 18
+  MAX_TYPE            = 18
+
+  # Must be consistent with C++ FieldDescriptor::CppType enum in
+  # descriptor.h.
+  #
+  # TODO(robinson): Find a way to eliminate this repetition.
+  CPPTYPE_INT32       = 1
+  CPPTYPE_INT64       = 2
+  CPPTYPE_UINT32      = 3
+  CPPTYPE_UINT64      = 4
+  CPPTYPE_DOUBLE      = 5
+  CPPTYPE_FLOAT       = 6
+  CPPTYPE_BOOL        = 7
+  CPPTYPE_ENUM        = 8
+  CPPTYPE_STRING      = 9
+  CPPTYPE_MESSAGE     = 10
+  MAX_CPPTYPE         = 10
+
+  _PYTHON_TO_CPP_PROTO_TYPE_MAP = {
+      TYPE_DOUBLE: CPPTYPE_DOUBLE,
+      TYPE_FLOAT: CPPTYPE_FLOAT,
+      TYPE_ENUM: CPPTYPE_ENUM,
+      TYPE_INT64: CPPTYPE_INT64,
+      TYPE_SINT64: CPPTYPE_INT64,
+      TYPE_SFIXED64: CPPTYPE_INT64,
+      TYPE_UINT64: CPPTYPE_UINT64,
+      TYPE_FIXED64: CPPTYPE_UINT64,
+      TYPE_INT32: CPPTYPE_INT32,
+      TYPE_SFIXED32: CPPTYPE_INT32,
+      TYPE_SINT32: CPPTYPE_INT32,
+      TYPE_UINT32: CPPTYPE_UINT32,
+      TYPE_FIXED32: CPPTYPE_UINT32,
+      TYPE_BYTES: CPPTYPE_STRING,
+      TYPE_STRING: CPPTYPE_STRING,
+      TYPE_BOOL: CPPTYPE_BOOL,
+      TYPE_MESSAGE: CPPTYPE_MESSAGE,
+      TYPE_GROUP: CPPTYPE_MESSAGE
+      }
+
+  # Must be consistent with C++ FieldDescriptor::Label enum in
+  # descriptor.h.
+  #
+  # TODO(robinson): Find a way to eliminate this repetition.
+  LABEL_OPTIONAL      = 1
+  LABEL_REQUIRED      = 2
+  LABEL_REPEATED      = 3
+  MAX_LABEL           = 3
+
+  def __init__(self, name, full_name, index, number, type, cpp_type, label,
+               default_value, message_type, enum_type, containing_type,
+               is_extension, extension_scope, options=None,
+               has_default_value=True):
+    """The arguments are as described in the description of FieldDescriptor
+    attributes above.
+
+    Note that containing_type may be None, and may be set later if necessary
+    (to deal with circular references between message types, for example).
+    Likewise for extension_scope.
+    """
+    super(FieldDescriptor, self).__init__(options, 'FieldOptions')
+    self.name = name
+    self.full_name = full_name
+    self.index = index
+    self.number = number
+    self.type = type
+    self.cpp_type = cpp_type
+    self.label = label
+    self.has_default_value = has_default_value
+    self.default_value = default_value
+    self.containing_type = containing_type
+    self.message_type = message_type
+    self.enum_type = enum_type
+    self.is_extension = is_extension
+    self.extension_scope = extension_scope
+    if api_implementation.Type() == 'cpp':
+      if is_extension:
+        if api_implementation.Version() == 2:
+          self._cdescriptor = _message.GetExtensionDescriptor(full_name)
+        else:
+          self._cdescriptor = cpp_message.GetExtensionDescriptor(full_name)
+      else:
+        if api_implementation.Version() == 2:
+          self._cdescriptor = _message.GetFieldDescriptor(full_name)
+        else:
+          self._cdescriptor = cpp_message.GetFieldDescriptor(full_name)
+    else:
+      self._cdescriptor = None
+
+  @staticmethod
+  def ProtoTypeToCppProtoType(proto_type):
+    """Converts from a Python proto type to a C++ Proto Type.
+
+    The Python ProtocolBuffer classes specify both the 'Python' datatype and the
+    'C++' datatype - and they're not the same. This helper method should
+    translate from one to another.
+
+    Args:
+      proto_type: the Python proto type (descriptor.FieldDescriptor.TYPE_*)
+    Returns:
+      descriptor.FieldDescriptor.CPPTYPE_*, the C++ type.
+    Raises:
+      TypeTransformationError: when the Python proto type isn't known.
+    """
+    try:
+      return FieldDescriptor._PYTHON_TO_CPP_PROTO_TYPE_MAP[proto_type]
+    except KeyError:
+      raise TypeTransformationError('Unknown proto_type: %s' % proto_type)
+
+
+class EnumDescriptor(_NestedDescriptorBase):
+
+  """Descriptor for an enum defined in a .proto file.
+
+  An EnumDescriptor instance has the following attributes:
+
+    name: (str) Name of the enum type.
+    full_name: (str) Full name of the type, including package name
+      and any enclosing type(s).
+
+    values: (list of EnumValueDescriptors) List of the values
+      in this enum.
+    values_by_name: (dict str -> EnumValueDescriptor) Same as |values|,
+      but indexed by the "name" field of each EnumValueDescriptor.
+    values_by_number: (dict int -> EnumValueDescriptor) Same as |values|,
+      but indexed by the "number" field of each EnumValueDescriptor.
+    containing_type: (Descriptor) Descriptor of the immediate containing
+      type of this enum, or None if this is an enum defined at the
+      top level in a .proto file.  Set by Descriptor's constructor
+      if we're passed into one.
+    file: (FileDescriptor) Reference to file descriptor.
+    options: (descriptor_pb2.EnumOptions) Enum options message or
+      None to use default enum options.
+  """
+
+  def __init__(self, name, full_name, filename, values,
+               containing_type=None, options=None, file=None,
+               serialized_start=None, serialized_end=None):
+    """Arguments are as described in the attribute description above.
+
+    Note that filename is an obsolete argument, that is not used anymore.
+    Please use file.name to access this as an attribute.
+    """
+    super(EnumDescriptor, self).__init__(
+        options, 'EnumOptions', name, full_name, file,
+        containing_type, serialized_start=serialized_start,
+        serialized_end=serialized_start)
+
+    self.values = values
+    for value in self.values:
+      value.type = self
+    self.values_by_name = dict((v.name, v) for v in values)
+    self.values_by_number = dict((v.number, v) for v in values)
+
+    self._serialized_start = serialized_start
+    self._serialized_end = serialized_end
+
+  def CopyToProto(self, proto):
+    """Copies this to a descriptor_pb2.EnumDescriptorProto.
+
+    Args:
+      proto: An empty descriptor_pb2.EnumDescriptorProto.
+    """
+    # This function is overriden to give a better doc comment.
+    super(EnumDescriptor, self).CopyToProto(proto)
+
+
+class EnumValueDescriptor(DescriptorBase):
+
+  """Descriptor for a single value within an enum.
+
+    name: (str) Name of this value.
+    index: (int) Dense, 0-indexed index giving the order that this
+      value appears textually within its enum in the .proto file.
+    number: (int) Actual number assigned to this enum value.
+    type: (EnumDescriptor) EnumDescriptor to which this value
+      belongs.  Set by EnumDescriptor's constructor if we're
+      passed into one.
+    options: (descriptor_pb2.EnumValueOptions) Enum value options message or
+      None to use default enum value options options.
+  """
+
+  def __init__(self, name, index, number, type=None, options=None):
+    """Arguments are as described in the attribute description above."""
+    super(EnumValueDescriptor, self).__init__(options, 'EnumValueOptions')
+    self.name = name
+    self.index = index
+    self.number = number
+    self.type = type
+
+
+class ServiceDescriptor(_NestedDescriptorBase):
+
+  """Descriptor for a service.
+
+    name: (str) Name of the service.
+    full_name: (str) Full name of the service, including package name.
+    index: (int) 0-indexed index giving the order that this services
+      definition appears withing the .proto file.
+    methods: (list of MethodDescriptor) List of methods provided by this
+      service.
+    options: (descriptor_pb2.ServiceOptions) Service options message or
+      None to use default service options.
+    file: (FileDescriptor) Reference to file info.
+  """
+
+  def __init__(self, name, full_name, index, methods, options=None, file=None,
+               serialized_start=None, serialized_end=None):
+    super(ServiceDescriptor, self).__init__(
+        options, 'ServiceOptions', name, full_name, file,
+        None, serialized_start=serialized_start,
+        serialized_end=serialized_end)
+    self.index = index
+    self.methods = methods
+    # Set the containing service for each method in this service.
+    for method in self.methods:
+      method.containing_service = self
+
+  def FindMethodByName(self, name):
+    """Searches for the specified method, and returns its descriptor."""
+    for method in self.methods:
+      if name == method.name:
+        return method
+    return None
+
+  def CopyToProto(self, proto):
+    """Copies this to a descriptor_pb2.ServiceDescriptorProto.
+
+    Args:
+      proto: An empty descriptor_pb2.ServiceDescriptorProto.
+    """
+    # This function is overriden to give a better doc comment.
+    super(ServiceDescriptor, self).CopyToProto(proto)
+
+
+class MethodDescriptor(DescriptorBase):
+
+  """Descriptor for a method in a service.
+
+  name: (str) Name of the method within the service.
+  full_name: (str) Full name of method.
+  index: (int) 0-indexed index of the method inside the service.
+  containing_service: (ServiceDescriptor) The service that contains this
+    method.
+  input_type: The descriptor of the message that this method accepts.
+  output_type: The descriptor of the message that this method returns.
+  options: (descriptor_pb2.MethodOptions) Method options message or
+    None to use default method options.
+  """
+
+  def __init__(self, name, full_name, index, containing_service,
+               input_type, output_type, options=None):
+    """The arguments are as described in the description of MethodDescriptor
+    attributes above.
+
+    Note that containing_service may be None, and may be set later if necessary.
+    """
+    super(MethodDescriptor, self).__init__(options, 'MethodOptions')
+    self.name = name
+    self.full_name = full_name
+    self.index = index
+    self.containing_service = containing_service
+    self.input_type = input_type
+    self.output_type = output_type
+
+
+class FileDescriptor(DescriptorBase):
+  """Descriptor for a file. Mimics the descriptor_pb2.FileDescriptorProto.
+
+  name: name of file, relative to root of source tree.
+  package: name of the package
+  serialized_pb: (str) Byte string of serialized
+    descriptor_pb2.FileDescriptorProto.
+  """
+
+  def __init__(self, name, package, options=None, serialized_pb=None):
+    """Constructor."""
+    super(FileDescriptor, self).__init__(options, 'FileOptions')
+
+    self.message_types_by_name = {}
+    self.name = name
+    self.package = package
+    self.serialized_pb = serialized_pb
+    if (api_implementation.Type() == 'cpp' and
+        self.serialized_pb is not None):
+      if api_implementation.Version() == 2:
+        _message.BuildFile(self.serialized_pb)
+      else:
+        cpp_message.BuildFile(self.serialized_pb)
+
+  def CopyToProto(self, proto):
+    """Copies this to a descriptor_pb2.FileDescriptorProto.
+
+    Args:
+      proto: An empty descriptor_pb2.FileDescriptorProto.
+    """
+    proto.ParseFromString(self.serialized_pb)
+
+
+def _ParseOptions(message, string):
+  """Parses serialized options.
+
+  This helper function is used to parse serialized options in generated
+  proto2 files. It must not be used outside proto2.
+  """
+  message.ParseFromString(string)
+  return message
+
+
+def MakeDescriptor(desc_proto, package=''):
+  """Make a protobuf Descriptor given a DescriptorProto protobuf.
+
+  Args:
+    desc_proto: The descriptor_pb2.DescriptorProto protobuf message.
+    package: Optional package name for the new message Descriptor (string).
+
+  Returns:
+    A Descriptor for protobuf messages.
+  """
+  full_message_name = [desc_proto.name]
+  if package: full_message_name.insert(0, package)
+  fields = []
+  for field_proto in desc_proto.field:
+    full_name = '.'.join(full_message_name + [field_proto.name])
+    field = FieldDescriptor(
+        field_proto.name, full_name, field_proto.number - 1,
+        field_proto.number, field_proto.type,
+        FieldDescriptor.ProtoTypeToCppProtoType(field_proto.type),
+        field_proto.label, None, None, None, None, False, None,
+        has_default_value=False)
+    fields.append(field)
+
+  desc_name = '.'.join(full_message_name)
+  return Descriptor(desc_proto.name, desc_name, None, None, fields,
+                    [], [], [])
diff --git a/generator/google/protobuf/descriptor_database.py b/generator/google/protobuf/descriptor_database.py
new file mode 100644
index 0000000..8665d3c
--- /dev/null
+++ b/generator/google/protobuf/descriptor_database.py
@@ -0,0 +1,120 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides a container for DescriptorProtos."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+
+class DescriptorDatabase(object):
+  """A container accepting FileDescriptorProtos and maps DescriptorProtos."""
+
+  def __init__(self):
+    self._file_desc_protos_by_file = {}
+    self._file_desc_protos_by_symbol = {}
+
+  def Add(self, file_desc_proto):
+    """Adds the FileDescriptorProto and its types to this database.
+
+    Args:
+      file_desc_proto: The FileDescriptorProto to add.
+    """
+
+    self._file_desc_protos_by_file[file_desc_proto.name] = file_desc_proto
+    package = file_desc_proto.package
+    for message in file_desc_proto.message_type:
+      self._file_desc_protos_by_symbol.update(
+          (name, file_desc_proto) for name in _ExtractSymbols(message, package))
+    for enum in file_desc_proto.enum_type:
+      self._file_desc_protos_by_symbol[
+          '.'.join((package, enum.name))] = file_desc_proto
+
+  def FindFileByName(self, name):
+    """Finds the file descriptor proto by file name.
+
+    Typically the file name is a relative path ending to a .proto file. The
+    proto with the given name will have to have been added to this database
+    using the Add method or else an error will be raised.
+
+    Args:
+      name: The file name to find.
+
+    Returns:
+      The file descriptor proto matching the name.
+
+    Raises:
+      KeyError if no file by the given name was added.
+    """
+
+    return self._file_desc_protos_by_file[name]
+
+  def FindFileContainingSymbol(self, symbol):
+    """Finds the file descriptor proto containing the specified symbol.
+
+    The symbol should be a fully qualified name including the file descriptor's
+    package and any containing messages. Some examples:
+
+    'some.package.name.Message'
+    'some.package.name.Message.NestedEnum'
+
+    The file descriptor proto containing the specified symbol must be added to
+    this database using the Add method or else an error will be raised.
+
+    Args:
+      symbol: The fully qualified symbol name.
+
+    Returns:
+      The file descriptor proto containing the symbol.
+
+    Raises:
+      KeyError if no file contains the specified symbol.
+    """
+
+    return self._file_desc_protos_by_symbol[symbol]
+
+
+def _ExtractSymbols(desc_proto, package):
+  """Pulls out all the symbols from a descriptor proto.
+
+  Args:
+    desc_proto: The proto to extract symbols from.
+    package: The package containing the descriptor type.
+
+  Yields:
+    The fully qualified name found in the descriptor.
+  """
+
+  message_name = '.'.join((package, desc_proto.name))
+  yield message_name
+  for nested_type in desc_proto.nested_type:
+    for symbol in _ExtractSymbols(nested_type, message_name):
+      yield symbol
+    for enum_type in desc_proto.enum_type:
+      yield '.'.join((message_name, enum_type.name))
diff --git a/generator/google/protobuf/descriptor_pb2.py b/generator/google/protobuf/descriptor_pb2.py
new file mode 100644
index 0000000..20b2d94
--- /dev/null
+++ b/generator/google/protobuf/descriptor_pb2.py
@@ -0,0 +1,1346 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/protobuf/descriptor.proto
+
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+# @@protoc_insertion_point(imports)
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/protobuf/descriptor.proto',
+  package='google.protobuf',
+  serialized_pb='\n google/protobuf/descriptor.proto\x12\x0fgoogle.protobuf\"G\n\x11\x46ileDescriptorSet\x12\x32\n\x04\x66ile\x18\x01 \x03(\x0b\x32$.google.protobuf.FileDescriptorProto\"\xcb\x03\n\x13\x46ileDescriptorProto\x12\x0c\n\x04name\x18\x01 \x01(\t\x12\x0f\n\x07package\x18\x02 \x01(\t\x12\x12\n\ndependency\x18\x03 \x03(\t\x12\x19\n\x11public_dependency\x18\n \x03(\x05\x12\x17\n\x0fweak_dependency\x18\x0b \x03(\x05\x12\x36\n\x0cmessage_type\x18\x04 \x03(\x0b\x32 .google.protobuf.DescriptorProto\x12\x37\n\tenum_type\x18\x05 \x03(\x0b\x32$.google.protobuf.EnumDescriptorProto\x12\x38\n\x07service\x18\x06 \x03(\x0b\x32\'.google.protobuf.ServiceDescriptorProto\x12\x38\n\textension\x18\x07 \x03(\x0b\x32%.google.protobuf.FieldDescriptorProto\x12-\n\x07options\x18\x08 \x01(\x0b\x32\x1c.google.protobuf.FileOptions\x12\x39\n\x10source_code_info\x18\t \x01(\x0b\x32\x1f.google.protobuf.SourceCodeInfo\"\xa9\x03\n\x0f\x44\x65scriptorProto\x12\x0c\n\x04name\x18\x01 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+      type=None),
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
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+      options=None,
+      type=None),
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+  serialized_start=1298,
+  serialized_end=1608,
+)
+
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+  full_name='google.protobuf.FieldDescriptorProto.Label',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='LABEL_REQUIRED', index=1, number=2,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='LABEL_REPEATED', index=2, number=3,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=1610,
+  serialized_end=1677,
+)
+
+_FILEOPTIONS_OPTIMIZEMODE = _descriptor.EnumDescriptor(
+  name='OptimizeMode',
+  full_name='google.protobuf.FileOptions.OptimizeMode',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
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+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='CODE_SIZE', index=1, number=2,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='LITE_RUNTIME', index=2, number=3,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=2629,
+  serialized_end=2687,
+)
+
+_FIELDOPTIONS_CTYPE = _descriptor.EnumDescriptor(
+  name='CType',
+  full_name='google.protobuf.FieldOptions.CType',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='STRING', index=0, number=0,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='CORD', index=1, number=1,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='STRING_PIECE', index=2, number=2,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=3148,
+  serialized_end=3195,
+)
+
+
+_FILEDESCRIPTORSET = _descriptor.Descriptor(
+  name='FileDescriptorSet',
+  full_name='google.protobuf.FileDescriptorSet',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
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+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
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+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
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+  nested_types=[],
+  enum_types=[
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+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=53,
+  serialized_end=124,
+)
+
+
+_FILEDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='FileDescriptorProto',
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+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
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+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
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+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=3, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=10, type=5, cpp_type=1, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=11, type=5, cpp_type=1, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=4, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=5, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='service', full_name='google.protobuf.FileDescriptorProto.service', index=7,
+      number=6, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='extension', full_name='google.protobuf.FileDescriptorProto.extension', index=8,
+      number=7, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.FileDescriptorProto.options', index=9,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=9, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
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+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=127,
+  serialized_end=586,
+)
+
+
+_DESCRIPTORPROTO_EXTENSIONRANGE = _descriptor.Descriptor(
+  name='ExtensionRange',
+  full_name='google.protobuf.DescriptorProto.ExtensionRange',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
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+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='end', full_name='google.protobuf.DescriptorProto.ExtensionRange.end', index=1,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+  extensions=[
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+  enum_types=[
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+  options=None,
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+  extension_ranges=[],
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+  serialized_end=1014,
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+
+_DESCRIPTORPROTO = _descriptor.Descriptor(
+  name='DescriptorProto',
+  full_name='google.protobuf.DescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
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+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
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+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=6, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=3, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=4, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=5, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=7, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
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+  nested_types=[_DESCRIPTORPROTO_EXTENSIONRANGE, ],
+  enum_types=[
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+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=589,
+  serialized_end=1014,
+)
+
+
+_FIELDDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='FieldDescriptorProto',
+  full_name='google.protobuf.FieldDescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
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+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
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+      number=3, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=4, type=14, cpp_type=8, label=1,
+      has_default_value=False, default_value=1,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
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+      has_default_value=False, default_value=1,
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+      is_extension=False, extension_scope=None,
+      options=None),
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+      has_default_value=False, default_value=unicode("", "utf-8"),
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+      is_extension=False, extension_scope=None,
+      options=None),
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+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
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+      options=None),
+    _descriptor.FieldDescriptor(
+      name='default_value', full_name='google.protobuf.FieldDescriptorProto.default_value', index=6,
+      number=7, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.FieldDescriptorProto.options', index=7,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _FIELDDESCRIPTORPROTO_TYPE,
+    _FIELDDESCRIPTORPROTO_LABEL,
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=1017,
+  serialized_end=1677,
+)
+
+
+_ENUMDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='EnumDescriptorProto',
+  full_name='google.protobuf.EnumDescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.EnumDescriptorProto.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='value', full_name='google.protobuf.EnumDescriptorProto.value', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.EnumDescriptorProto.options', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=1680,
+  serialized_end=1820,
+)
+
+
+_ENUMVALUEDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='EnumValueDescriptorProto',
+  full_name='google.protobuf.EnumValueDescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.EnumValueDescriptorProto.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='number', full_name='google.protobuf.EnumValueDescriptorProto.number', index=1,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.EnumValueDescriptorProto.options', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=1822,
+  serialized_end=1930,
+)
+
+
+_SERVICEDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='ServiceDescriptorProto',
+  full_name='google.protobuf.ServiceDescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.ServiceDescriptorProto.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='method', full_name='google.protobuf.ServiceDescriptorProto.method', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.ServiceDescriptorProto.options', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=1933,
+  serialized_end=2077,
+)
+
+
+_METHODDESCRIPTORPROTO = _descriptor.Descriptor(
+  name='MethodDescriptorProto',
+  full_name='google.protobuf.MethodDescriptorProto',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.MethodDescriptorProto.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='input_type', full_name='google.protobuf.MethodDescriptorProto.input_type', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='output_type', full_name='google.protobuf.MethodDescriptorProto.output_type', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='options', full_name='google.protobuf.MethodDescriptorProto.options', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=2079,
+  serialized_end=2206,
+)
+
+
+_FILEOPTIONS = _descriptor.Descriptor(
+  name='FileOptions',
+  full_name='google.protobuf.FileOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='java_package', full_name='google.protobuf.FileOptions.java_package', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='java_outer_classname', full_name='google.protobuf.FileOptions.java_outer_classname', index=1,
+      number=8, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='java_multiple_files', full_name='google.protobuf.FileOptions.java_multiple_files', index=2,
+      number=10, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='java_generate_equals_and_hash', full_name='google.protobuf.FileOptions.java_generate_equals_and_hash', index=3,
+      number=20, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='optimize_for', full_name='google.protobuf.FileOptions.optimize_for', index=4,
+      number=9, type=14, cpp_type=8, label=1,
+      has_default_value=True, default_value=1,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='go_package', full_name='google.protobuf.FileOptions.go_package', index=5,
+      number=11, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='cc_generic_services', full_name='google.protobuf.FileOptions.cc_generic_services', index=6,
+      number=16, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='java_generic_services', full_name='google.protobuf.FileOptions.java_generic_services', index=7,
+      number=17, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='py_generic_services', full_name='google.protobuf.FileOptions.py_generic_services', index=8,
+      number=18, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.FileOptions.uninterpreted_option', index=9,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _FILEOPTIONS_OPTIMIZEMODE,
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=2209,
+  serialized_end=2698,
+)
+
+
+_MESSAGEOPTIONS = _descriptor.Descriptor(
+  name='MessageOptions',
+  full_name='google.protobuf.MessageOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='message_set_wire_format', full_name='google.protobuf.MessageOptions.message_set_wire_format', index=0,
+      number=1, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='no_standard_descriptor_accessor', full_name='google.protobuf.MessageOptions.no_standard_descriptor_accessor', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.MessageOptions.uninterpreted_option', index=2,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=2701,
+  serialized_end=2885,
+)
+
+
+_FIELDOPTIONS = _descriptor.Descriptor(
+  name='FieldOptions',
+  full_name='google.protobuf.FieldOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='ctype', full_name='google.protobuf.FieldOptions.ctype', index=0,
+      number=1, type=14, cpp_type=8, label=1,
+      has_default_value=True, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='packed', full_name='google.protobuf.FieldOptions.packed', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='lazy', full_name='google.protobuf.FieldOptions.lazy', index=2,
+      number=5, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='deprecated', full_name='google.protobuf.FieldOptions.deprecated', index=3,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='experimental_map_key', full_name='google.protobuf.FieldOptions.experimental_map_key', index=4,
+      number=9, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='weak', full_name='google.protobuf.FieldOptions.weak', index=5,
+      number=10, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.FieldOptions.uninterpreted_option', index=6,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _FIELDOPTIONS_CTYPE,
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=2888,
+  serialized_end=3206,
+)
+
+
+_ENUMOPTIONS = _descriptor.Descriptor(
+  name='EnumOptions',
+  full_name='google.protobuf.EnumOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='allow_alias', full_name='google.protobuf.EnumOptions.allow_alias', index=0,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=True, default_value=True,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.EnumOptions.uninterpreted_option', index=1,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=3208,
+  serialized_end=3328,
+)
+
+
+_ENUMVALUEOPTIONS = _descriptor.Descriptor(
+  name='EnumValueOptions',
+  full_name='google.protobuf.EnumValueOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.EnumValueOptions.uninterpreted_option', index=0,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=3330,
+  serialized_end=3428,
+)
+
+
+_SERVICEOPTIONS = _descriptor.Descriptor(
+  name='ServiceOptions',
+  full_name='google.protobuf.ServiceOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.ServiceOptions.uninterpreted_option', index=0,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=3430,
+  serialized_end=3526,
+)
+
+
+_METHODOPTIONS = _descriptor.Descriptor(
+  name='MethodOptions',
+  full_name='google.protobuf.MethodOptions',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='uninterpreted_option', full_name='google.protobuf.MethodOptions.uninterpreted_option', index=0,
+      number=999, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=True,
+  extension_ranges=[(1000, 536870912), ],
+  serialized_start=3528,
+  serialized_end=3623,
+)
+
+
+_UNINTERPRETEDOPTION_NAMEPART = _descriptor.Descriptor(
+  name='NamePart',
+  full_name='google.protobuf.UninterpretedOption.NamePart',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name_part', full_name='google.protobuf.UninterpretedOption.NamePart.name_part', index=0,
+      number=1, type=9, cpp_type=9, label=2,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='is_extension', full_name='google.protobuf.UninterpretedOption.NamePart.is_extension', index=1,
+      number=2, type=8, cpp_type=7, label=2,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=3861,
+  serialized_end=3912,
+)
+
+_UNINTERPRETEDOPTION = _descriptor.Descriptor(
+  name='UninterpretedOption',
+  full_name='google.protobuf.UninterpretedOption',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.protobuf.UninterpretedOption.name', index=0,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='identifier_value', full_name='google.protobuf.UninterpretedOption.identifier_value', index=1,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='positive_int_value', full_name='google.protobuf.UninterpretedOption.positive_int_value', index=2,
+      number=4, type=4, cpp_type=4, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='negative_int_value', full_name='google.protobuf.UninterpretedOption.negative_int_value', index=3,
+      number=5, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='double_value', full_name='google.protobuf.UninterpretedOption.double_value', index=4,
+      number=6, type=1, cpp_type=5, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='string_value', full_name='google.protobuf.UninterpretedOption.string_value', index=5,
+      number=7, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value="",
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='aggregate_value', full_name='google.protobuf.UninterpretedOption.aggregate_value', index=6,
+      number=8, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[_UNINTERPRETEDOPTION_NAMEPART, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=3626,
+  serialized_end=3912,
+)
+
+
+_SOURCECODEINFO_LOCATION = _descriptor.Descriptor(
+  name='Location',
+  full_name='google.protobuf.SourceCodeInfo.Location',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='path', full_name='google.protobuf.SourceCodeInfo.Location.path', index=0,
+      number=1, type=5, cpp_type=1, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='span', full_name='google.protobuf.SourceCodeInfo.Location.span', index=1,
+      number=2, type=5, cpp_type=1, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='leading_comments', full_name='google.protobuf.SourceCodeInfo.Location.leading_comments', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='trailing_comments', full_name='google.protobuf.SourceCodeInfo.Location.trailing_comments', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=unicode("", "utf-8"),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=3993,
+  serialized_end=4092,
+)
+
+_SOURCECODEINFO = _descriptor.Descriptor(
+  name='SourceCodeInfo',
+  full_name='google.protobuf.SourceCodeInfo',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='location', full_name='google.protobuf.SourceCodeInfo.location', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[_SOURCECODEINFO_LOCATION, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  serialized_start=3915,
+  serialized_end=4092,
+)
+
+_FILEDESCRIPTORSET.fields_by_name['file'].message_type = _FILEDESCRIPTORPROTO
+_FILEDESCRIPTORPROTO.fields_by_name['message_type'].message_type = _DESCRIPTORPROTO
+_FILEDESCRIPTORPROTO.fields_by_name['enum_type'].message_type = _ENUMDESCRIPTORPROTO
+_FILEDESCRIPTORPROTO.fields_by_name['service'].message_type = _SERVICEDESCRIPTORPROTO
+_FILEDESCRIPTORPROTO.fields_by_name['extension'].message_type = _FIELDDESCRIPTORPROTO
+_FILEDESCRIPTORPROTO.fields_by_name['options'].message_type = _FILEOPTIONS
+_FILEDESCRIPTORPROTO.fields_by_name['source_code_info'].message_type = _SOURCECODEINFO
+_DESCRIPTORPROTO_EXTENSIONRANGE.containing_type = _DESCRIPTORPROTO;
+_DESCRIPTORPROTO.fields_by_name['field'].message_type = _FIELDDESCRIPTORPROTO
+_DESCRIPTORPROTO.fields_by_name['extension'].message_type = _FIELDDESCRIPTORPROTO
+_DESCRIPTORPROTO.fields_by_name['nested_type'].message_type = _DESCRIPTORPROTO
+_DESCRIPTORPROTO.fields_by_name['enum_type'].message_type = _ENUMDESCRIPTORPROTO
+_DESCRIPTORPROTO.fields_by_name['extension_range'].message_type = _DESCRIPTORPROTO_EXTENSIONRANGE
+_DESCRIPTORPROTO.fields_by_name['options'].message_type = _MESSAGEOPTIONS
+_FIELDDESCRIPTORPROTO.fields_by_name['label'].enum_type = _FIELDDESCRIPTORPROTO_LABEL
+_FIELDDESCRIPTORPROTO.fields_by_name['type'].enum_type = _FIELDDESCRIPTORPROTO_TYPE
+_FIELDDESCRIPTORPROTO.fields_by_name['options'].message_type = _FIELDOPTIONS
+_FIELDDESCRIPTORPROTO_TYPE.containing_type = _FIELDDESCRIPTORPROTO;
+_FIELDDESCRIPTORPROTO_LABEL.containing_type = _FIELDDESCRIPTORPROTO;
+_ENUMDESCRIPTORPROTO.fields_by_name['value'].message_type = _ENUMVALUEDESCRIPTORPROTO
+_ENUMDESCRIPTORPROTO.fields_by_name['options'].message_type = _ENUMOPTIONS
+_ENUMVALUEDESCRIPTORPROTO.fields_by_name['options'].message_type = _ENUMVALUEOPTIONS
+_SERVICEDESCRIPTORPROTO.fields_by_name['method'].message_type = _METHODDESCRIPTORPROTO
+_SERVICEDESCRIPTORPROTO.fields_by_name['options'].message_type = _SERVICEOPTIONS
+_METHODDESCRIPTORPROTO.fields_by_name['options'].message_type = _METHODOPTIONS
+_FILEOPTIONS.fields_by_name['optimize_for'].enum_type = _FILEOPTIONS_OPTIMIZEMODE
+_FILEOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_FILEOPTIONS_OPTIMIZEMODE.containing_type = _FILEOPTIONS;
+_MESSAGEOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_FIELDOPTIONS.fields_by_name['ctype'].enum_type = _FIELDOPTIONS_CTYPE
+_FIELDOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_FIELDOPTIONS_CTYPE.containing_type = _FIELDOPTIONS;
+_ENUMOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_ENUMVALUEOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_SERVICEOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_METHODOPTIONS.fields_by_name['uninterpreted_option'].message_type = _UNINTERPRETEDOPTION
+_UNINTERPRETEDOPTION_NAMEPART.containing_type = _UNINTERPRETEDOPTION;
+_UNINTERPRETEDOPTION.fields_by_name['name'].message_type = _UNINTERPRETEDOPTION_NAMEPART
+_SOURCECODEINFO_LOCATION.containing_type = _SOURCECODEINFO;
+_SOURCECODEINFO.fields_by_name['location'].message_type = _SOURCECODEINFO_LOCATION
+DESCRIPTOR.message_types_by_name['FileDescriptorSet'] = _FILEDESCRIPTORSET
+DESCRIPTOR.message_types_by_name['FileDescriptorProto'] = _FILEDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['DescriptorProto'] = _DESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['FieldDescriptorProto'] = _FIELDDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['EnumDescriptorProto'] = _ENUMDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['EnumValueDescriptorProto'] = _ENUMVALUEDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['ServiceDescriptorProto'] = _SERVICEDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['MethodDescriptorProto'] = _METHODDESCRIPTORPROTO
+DESCRIPTOR.message_types_by_name['FileOptions'] = _FILEOPTIONS
+DESCRIPTOR.message_types_by_name['MessageOptions'] = _MESSAGEOPTIONS
+DESCRIPTOR.message_types_by_name['FieldOptions'] = _FIELDOPTIONS
+DESCRIPTOR.message_types_by_name['EnumOptions'] = _ENUMOPTIONS
+DESCRIPTOR.message_types_by_name['EnumValueOptions'] = _ENUMVALUEOPTIONS
+DESCRIPTOR.message_types_by_name['ServiceOptions'] = _SERVICEOPTIONS
+DESCRIPTOR.message_types_by_name['MethodOptions'] = _METHODOPTIONS
+DESCRIPTOR.message_types_by_name['UninterpretedOption'] = _UNINTERPRETEDOPTION
+DESCRIPTOR.message_types_by_name['SourceCodeInfo'] = _SOURCECODEINFO
+
+class FileDescriptorSet(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _FILEDESCRIPTORSET
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.FileDescriptorSet)
+
+class FileDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _FILEDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.FileDescriptorProto)
+
+class DescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+
+  class ExtensionRange(_message.Message):
+    __metaclass__ = _reflection.GeneratedProtocolMessageType
+    DESCRIPTOR = _DESCRIPTORPROTO_EXTENSIONRANGE
+
+    # @@protoc_insertion_point(class_scope:google.protobuf.DescriptorProto.ExtensionRange)
+  DESCRIPTOR = _DESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.DescriptorProto)
+
+class FieldDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _FIELDDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.FieldDescriptorProto)
+
+class EnumDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _ENUMDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.EnumDescriptorProto)
+
+class EnumValueDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _ENUMVALUEDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.EnumValueDescriptorProto)
+
+class ServiceDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _SERVICEDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.ServiceDescriptorProto)
+
+class MethodDescriptorProto(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _METHODDESCRIPTORPROTO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.MethodDescriptorProto)
+
+class FileOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _FILEOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.FileOptions)
+
+class MessageOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _MESSAGEOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.MessageOptions)
+
+class FieldOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _FIELDOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.FieldOptions)
+
+class EnumOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _ENUMOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.EnumOptions)
+
+class EnumValueOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _ENUMVALUEOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.EnumValueOptions)
+
+class ServiceOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _SERVICEOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.ServiceOptions)
+
+class MethodOptions(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+  DESCRIPTOR = _METHODOPTIONS
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.MethodOptions)
+
+class UninterpretedOption(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+
+  class NamePart(_message.Message):
+    __metaclass__ = _reflection.GeneratedProtocolMessageType
+    DESCRIPTOR = _UNINTERPRETEDOPTION_NAMEPART
+
+    # @@protoc_insertion_point(class_scope:google.protobuf.UninterpretedOption.NamePart)
+  DESCRIPTOR = _UNINTERPRETEDOPTION
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.UninterpretedOption)
+
+class SourceCodeInfo(_message.Message):
+  __metaclass__ = _reflection.GeneratedProtocolMessageType
+
+  class Location(_message.Message):
+    __metaclass__ = _reflection.GeneratedProtocolMessageType
+    DESCRIPTOR = _SOURCECODEINFO_LOCATION
+
+    # @@protoc_insertion_point(class_scope:google.protobuf.SourceCodeInfo.Location)
+  DESCRIPTOR = _SOURCECODEINFO
+
+  # @@protoc_insertion_point(class_scope:google.protobuf.SourceCodeInfo)
+
+
+# @@protoc_insertion_point(module_scope)
diff --git a/generator/google/protobuf/descriptor_pool.py b/generator/google/protobuf/descriptor_pool.py
new file mode 100644
index 0000000..8f1f445
--- /dev/null
+++ b/generator/google/protobuf/descriptor_pool.py
@@ -0,0 +1,527 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides DescriptorPool to use as a container for proto2 descriptors.
+
+The DescriptorPool is used in conjection with a DescriptorDatabase to maintain
+a collection of protocol buffer descriptors for use when dynamically creating
+message types at runtime.
+
+For most applications protocol buffers should be used via modules generated by
+the protocol buffer compiler tool. This should only be used when the type of
+protocol buffers used in an application or library cannot be predetermined.
+
+Below is a straightforward example on how to use this class:
+
+  pool = DescriptorPool()
+  file_descriptor_protos = [ ... ]
+  for file_descriptor_proto in file_descriptor_protos:
+    pool.Add(file_descriptor_proto)
+  my_message_descriptor = pool.FindMessageTypeByName('some.package.MessageType')
+
+The message descriptor can be used in conjunction with the message_factory
+module in order to create a protocol buffer class that can be encoded and
+decoded.
+"""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+from google.protobuf import descriptor_pb2
+from google.protobuf import descriptor
+from google.protobuf import descriptor_database
+
+
+class DescriptorPool(object):
+  """A collection of protobufs dynamically constructed by descriptor protos."""
+
+  def __init__(self, descriptor_db=None):
+    """Initializes a Pool of proto buffs.
+
+    The descriptor_db argument to the constructor is provided to allow
+    specialized file descriptor proto lookup code to be triggered on demand. An
+    example would be an implementation which will read and compile a file
+    specified in a call to FindFileByName() and not require the call to Add()
+    at all. Results from this database will be cached internally here as well.
+
+    Args:
+      descriptor_db: A secondary source of file descriptors.
+    """
+
+    self._internal_db = descriptor_database.DescriptorDatabase()
+    self._descriptor_db = descriptor_db
+    self._descriptors = {}
+    self._enum_descriptors = {}
+    self._file_descriptors = {}
+
+  def Add(self, file_desc_proto):
+    """Adds the FileDescriptorProto and its types to this pool.
+
+    Args:
+      file_desc_proto: The FileDescriptorProto to add.
+    """
+
+    self._internal_db.Add(file_desc_proto)
+
+  def FindFileByName(self, file_name):
+    """Gets a FileDescriptor by file name.
+
+    Args:
+      file_name: The path to the file to get a descriptor for.
+
+    Returns:
+      A FileDescriptor for the named file.
+
+    Raises:
+      KeyError: if the file can not be found in the pool.
+    """
+
+    try:
+      file_proto = self._internal_db.FindFileByName(file_name)
+    except KeyError as error:
+      if self._descriptor_db:
+        file_proto = self._descriptor_db.FindFileByName(file_name)
+      else:
+        raise error
+    if not file_proto:
+      raise KeyError('Cannot find a file named %s' % file_name)
+    return self._ConvertFileProtoToFileDescriptor(file_proto)
+
+  def FindFileContainingSymbol(self, symbol):
+    """Gets the FileDescriptor for the file containing the specified symbol.
+
+    Args:
+      symbol: The name of the symbol to search for.
+
+    Returns:
+      A FileDescriptor that contains the specified symbol.
+
+    Raises:
+      KeyError: if the file can not be found in the pool.
+    """
+
+    try:
+      file_proto = self._internal_db.FindFileContainingSymbol(symbol)
+    except KeyError as error:
+      if self._descriptor_db:
+        file_proto = self._descriptor_db.FindFileContainingSymbol(symbol)
+      else:
+        raise error
+    if not file_proto:
+      raise KeyError('Cannot find a file containing %s' % symbol)
+    return self._ConvertFileProtoToFileDescriptor(file_proto)
+
+  def FindMessageTypeByName(self, full_name):
+    """Loads the named descriptor from the pool.
+
+    Args:
+      full_name: The full name of the descriptor to load.
+
+    Returns:
+      The descriptor for the named type.
+    """
+
+    full_name = full_name.lstrip('.')  # fix inconsistent qualified name formats
+    if full_name not in self._descriptors:
+      self.FindFileContainingSymbol(full_name)
+    return self._descriptors[full_name]
+
+  def FindEnumTypeByName(self, full_name):
+    """Loads the named enum descriptor from the pool.
+
+    Args:
+      full_name: The full name of the enum descriptor to load.
+
+    Returns:
+      The enum descriptor for the named type.
+    """
+
+    full_name = full_name.lstrip('.')  # fix inconsistent qualified name formats
+    if full_name not in self._enum_descriptors:
+      self.FindFileContainingSymbol(full_name)
+    return self._enum_descriptors[full_name]
+
+  def _ConvertFileProtoToFileDescriptor(self, file_proto):
+    """Creates a FileDescriptor from a proto or returns a cached copy.
+
+    This method also has the side effect of loading all the symbols found in
+    the file into the appropriate dictionaries in the pool.
+
+    Args:
+      file_proto: The proto to convert.
+
+    Returns:
+      A FileDescriptor matching the passed in proto.
+    """
+
+    if file_proto.name not in self._file_descriptors:
+      file_descriptor = descriptor.FileDescriptor(
+          name=file_proto.name,
+          package=file_proto.package,
+          options=file_proto.options,
+          serialized_pb=file_proto.SerializeToString())
+      scope = {}
+      dependencies = list(self._GetDeps(file_proto))
+
+      for dependency in dependencies:
+        dep_desc = self.FindFileByName(dependency.name)
+        dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
+            dep_desc.serialized_pb)
+        package = '.' + dep_proto.package
+        package_prefix = package + '.'
+
+        def _strip_package(symbol):
+          if symbol.startswith(package_prefix):
+            return symbol[len(package_prefix):]
+          return symbol
+
+        symbols = list(self._ExtractSymbols(dep_proto.message_type, package))
+        scope.update(symbols)
+        scope.update((_strip_package(k), v) for k, v in symbols)
+
+        symbols = list(self._ExtractEnums(dep_proto.enum_type, package))
+        scope.update(symbols)
+        scope.update((_strip_package(k), v) for k, v in symbols)
+
+      for message_type in file_proto.message_type:
+        message_desc = self._ConvertMessageDescriptor(
+            message_type, file_proto.package, file_descriptor, scope)
+        file_descriptor.message_types_by_name[message_desc.name] = message_desc
+      for enum_type in file_proto.enum_type:
+        self._ConvertEnumDescriptor(enum_type, file_proto.package,
+                                    file_descriptor, None, scope)
+      for desc_proto in self._ExtractMessages(file_proto.message_type):
+        self._SetFieldTypes(desc_proto, scope)
+
+      for desc_proto in file_proto.message_type:
+        desc = scope[desc_proto.name]
+        file_descriptor.message_types_by_name[desc_proto.name] = desc
+      self.Add(file_proto)
+      self._file_descriptors[file_proto.name] = file_descriptor
+
+    return self._file_descriptors[file_proto.name]
+
+  def _ConvertMessageDescriptor(self, desc_proto, package=None, file_desc=None,
+                                scope=None):
+    """Adds the proto to the pool in the specified package.
+
+    Args:
+      desc_proto: The descriptor_pb2.DescriptorProto protobuf message.
+      package: The package the proto should be located in.
+      file_desc: The file containing this message.
+      scope: Dict mapping short and full symbols to message and enum types.
+
+    Returns:
+      The added descriptor.
+    """
+
+    if package:
+      desc_name = '.'.join((package, desc_proto.name))
+    else:
+      desc_name = desc_proto.name
+
+    if file_desc is None:
+      file_name = None
+    else:
+      file_name = file_desc.name
+
+    if scope is None:
+      scope = {}
+
+    nested = [
+        self._ConvertMessageDescriptor(nested, desc_name, file_desc, scope)
+        for nested in desc_proto.nested_type]
+    enums = [
+        self._ConvertEnumDescriptor(enum, desc_name, file_desc, None, scope)
+        for enum in desc_proto.enum_type]
+    fields = [self._MakeFieldDescriptor(field, desc_name, index)
+              for index, field in enumerate(desc_proto.field)]
+    extensions = [self._MakeFieldDescriptor(extension, desc_name, True)
+                  for index, extension in enumerate(desc_proto.extension)]
+    extension_ranges = [(r.start, r.end) for r in desc_proto.extension_range]
+    if extension_ranges:
+      is_extendable = True
+    else:
+      is_extendable = False
+    desc = descriptor.Descriptor(
+        name=desc_proto.name,
+        full_name=desc_name,
+        filename=file_name,
+        containing_type=None,
+        fields=fields,
+        nested_types=nested,
+        enum_types=enums,
+        extensions=extensions,
+        options=desc_proto.options,
+        is_extendable=is_extendable,
+        extension_ranges=extension_ranges,
+        file=file_desc,
+        serialized_start=None,
+        serialized_end=None)
+    for nested in desc.nested_types:
+      nested.containing_type = desc
+    for enum in desc.enum_types:
+      enum.containing_type = desc
+    scope[desc_proto.name] = desc
+    scope['.' + desc_name] = desc
+    self._descriptors[desc_name] = desc
+    return desc
+
+  def _ConvertEnumDescriptor(self, enum_proto, package=None, file_desc=None,
+                             containing_type=None, scope=None):
+    """Make a protobuf EnumDescriptor given an EnumDescriptorProto protobuf.
+
+    Args:
+      enum_proto: The descriptor_pb2.EnumDescriptorProto protobuf message.
+      package: Optional package name for the new message EnumDescriptor.
+      file_desc: The file containing the enum descriptor.
+      containing_type: The type containing this enum.
+      scope: Scope containing available types.
+
+    Returns:
+      The added descriptor
+    """
+
+    if package:
+      enum_name = '.'.join((package, enum_proto.name))
+    else:
+      enum_name = enum_proto.name
+
+    if file_desc is None:
+      file_name = None
+    else:
+      file_name = file_desc.name
+
+    values = [self._MakeEnumValueDescriptor(value, index)
+              for index, value in enumerate(enum_proto.value)]
+    desc = descriptor.EnumDescriptor(name=enum_proto.name,
+                                     full_name=enum_name,
+                                     filename=file_name,
+                                     file=file_desc,
+                                     values=values,
+                                     containing_type=containing_type,
+                                     options=enum_proto.options)
+    scope[enum_proto.name] = desc
+    scope['.%s' % enum_name] = desc
+    self._enum_descriptors[enum_name] = desc
+    return desc
+
+  def _MakeFieldDescriptor(self, field_proto, message_name, index,
+                           is_extension=False):
+    """Creates a field descriptor from a FieldDescriptorProto.
+
+    For message and enum type fields, this method will do a look up
+    in the pool for the appropriate descriptor for that type. If it
+    is unavailable, it will fall back to the _source function to
+    create it. If this type is still unavailable, construction will
+    fail.
+
+    Args:
+      field_proto: The proto describing the field.
+      message_name: The name of the containing message.
+      index: Index of the field
+      is_extension: Indication that this field is for an extension.
+
+    Returns:
+      An initialized FieldDescriptor object
+    """
+
+    if message_name:
+      full_name = '.'.join((message_name, field_proto.name))
+    else:
+      full_name = field_proto.name
+
+    return descriptor.FieldDescriptor(
+        name=field_proto.name,
+        full_name=full_name,
+        index=index,
+        number=field_proto.number,
+        type=field_proto.type,
+        cpp_type=None,
+        message_type=None,
+        enum_type=None,
+        containing_type=None,
+        label=field_proto.label,
+        has_default_value=False,
+        default_value=None,
+        is_extension=is_extension,
+        extension_scope=None,
+        options=field_proto.options)
+
+  def _SetFieldTypes(self, desc_proto, scope):
+    """Sets the field's type, cpp_type, message_type and enum_type.
+
+    Args:
+      desc_proto: The message descriptor to update.
+      scope: Enclosing scope of available types.
+    """
+
+    desc = scope[desc_proto.name]
+    for field_proto, field_desc in zip(desc_proto.field, desc.fields):
+      if field_proto.type_name:
+        type_name = field_proto.type_name
+        if type_name not in scope:
+          type_name = '.' + type_name
+        desc = scope[type_name]
+      else:
+        desc = None
+
+      if not field_proto.HasField('type'):
+        if isinstance(desc, descriptor.Descriptor):
+          field_proto.type = descriptor.FieldDescriptor.TYPE_MESSAGE
+        else:
+          field_proto.type = descriptor.FieldDescriptor.TYPE_ENUM
+
+      field_desc.cpp_type = descriptor.FieldDescriptor.ProtoTypeToCppProtoType(
+          field_proto.type)
+
+      if (field_proto.type == descriptor.FieldDescriptor.TYPE_MESSAGE
+          or field_proto.type == descriptor.FieldDescriptor.TYPE_GROUP):
+        field_desc.message_type = desc
+
+      if field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
+        field_desc.enum_type = desc
+
+      if field_proto.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+        field_desc.has_default = False
+        field_desc.default_value = []
+      elif field_proto.HasField('default_value'):
+        field_desc.has_default = True
+        if (field_proto.type == descriptor.FieldDescriptor.TYPE_DOUBLE or
+            field_proto.type == descriptor.FieldDescriptor.TYPE_FLOAT):
+          field_desc.default_value = float(field_proto.default_value)
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_STRING:
+          field_desc.default_value = field_proto.default_value
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_BOOL:
+          field_desc.default_value = field_proto.default_value.lower() == 'true'
+        elif field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
+          field_desc.default_value = field_desc.enum_type.values_by_name[
+              field_proto.default_value].index
+        else:
+          field_desc.default_value = int(field_proto.default_value)
+      else:
+        field_desc.has_default = False
+        field_desc.default_value = None
+
+      field_desc.type = field_proto.type
+
+    for nested_type in desc_proto.nested_type:
+      self._SetFieldTypes(nested_type, scope)
+
+  def _MakeEnumValueDescriptor(self, value_proto, index):
+    """Creates a enum value descriptor object from a enum value proto.
+
+    Args:
+      value_proto: The proto describing the enum value.
+      index: The index of the enum value.
+
+    Returns:
+      An initialized EnumValueDescriptor object.
+    """
+
+    return descriptor.EnumValueDescriptor(
+        name=value_proto.name,
+        index=index,
+        number=value_proto.number,
+        options=value_proto.options,
+        type=None)
+
+  def _ExtractSymbols(self, desc_protos, package):
+    """Pulls out all the symbols from descriptor protos.
+
+    Args:
+      desc_protos: The protos to extract symbols from.
+      package: The package containing the descriptor type.
+    Yields:
+      A two element tuple of the type name and descriptor object.
+    """
+
+    for desc_proto in desc_protos:
+      if package:
+        message_name = '.'.join((package, desc_proto.name))
+      else:
+        message_name = desc_proto.name
+      message_desc = self.FindMessageTypeByName(message_name)
+      yield (message_name, message_desc)
+      for symbol in self._ExtractSymbols(desc_proto.nested_type, message_name):
+        yield symbol
+      for symbol in self._ExtractEnums(desc_proto.enum_type, message_name):
+        yield symbol
+
+  def _ExtractEnums(self, enum_protos, package):
+    """Pulls out all the symbols from enum protos.
+
+    Args:
+      enum_protos: The protos to extract symbols from.
+      package: The package containing the enum type.
+
+    Yields:
+      A two element tuple of the type name and enum descriptor object.
+    """
+
+    for enum_proto in enum_protos:
+      if package:
+        enum_name = '.'.join((package, enum_proto.name))
+      else:
+        enum_name = enum_proto.name
+      enum_desc = self.FindEnumTypeByName(enum_name)
+      yield (enum_name, enum_desc)
+
+  def _ExtractMessages(self, desc_protos):
+    """Pulls out all the message protos from descriptos.
+
+    Args:
+      desc_protos: The protos to extract symbols from.
+
+    Yields:
+      Descriptor protos.
+    """
+
+    for desc_proto in desc_protos:
+      yield desc_proto
+      for message in self._ExtractMessages(desc_proto.nested_type):
+        yield message
+
+  def _GetDeps(self, file_proto):
+    """Recursively finds dependencies for file protos.
+
+    Args:
+      file_proto: The proto to get dependencies from.
+
+    Yields:
+      Each direct and indirect dependency.
+    """
+
+    for dependency in file_proto.dependency:
+      dep_desc = self.FindFileByName(dependency)
+      dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
+          dep_desc.serialized_pb)
+      yield dep_proto
+      for parent_dep in self._GetDeps(dep_proto):
+        yield parent_dep
diff --git a/generator/google/protobuf/internal/__init__.py b/generator/google/protobuf/internal/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/generator/google/protobuf/internal/__init__.py
diff --git a/generator/google/protobuf/internal/api_implementation.py b/generator/google/protobuf/internal/api_implementation.py
new file mode 100644
index 0000000..ce02a32
--- /dev/null
+++ b/generator/google/protobuf/internal/api_implementation.py
@@ -0,0 +1,87 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""
+This module is the central entity that determines which implementation of the
+API is used.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+import os
+# This environment variable can be used to switch to a certain implementation
+# of the Python API. Right now only 'python' and 'cpp' are valid values. Any
+# other value will be ignored.
+_implementation_type = os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION',
+                                 'python')
+
+
+if _implementation_type != 'python':
+  # For now, by default use the pure-Python implementation.
+  # The code below checks if the C extension is available and
+  # uses it if it is available.
+  _implementation_type = 'cpp'
+  ## Determine automatically which implementation to use.
+  #try:
+  #  from google.protobuf.internal import cpp_message
+  #  _implementation_type = 'cpp'
+  #except ImportError, e:
+  #  _implementation_type = 'python'
+
+
+# This environment variable can be used to switch between the two
+# 'cpp' implementations. Right now only 1 and 2 are valid values. Any
+# other value will be ignored.
+_implementation_version_str = os.getenv(
+    'PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION',
+    '1')
+
+
+if _implementation_version_str not in ('1', '2'):
+  raise ValueError(
+      "unsupported PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION: '" +
+      _implementation_version_str + "' (supported versions: 1, 2)"
+      )
+
+
+_implementation_version = int(_implementation_version_str)
+
+
+
+# Usage of this function is discouraged. Clients shouldn't care which
+# implementation of the API is in use. Note that there is no guarantee
+# that differences between APIs will be maintained.
+# Please don't use this function if possible.
+def Type():
+  return _implementation_type
+
+# See comment on 'Type' above.
+def Version():
+  return _implementation_version
diff --git a/generator/google/protobuf/internal/containers.py b/generator/google/protobuf/internal/containers.py
new file mode 100644
index 0000000..34b35f8
--- /dev/null
+++ b/generator/google/protobuf/internal/containers.py
@@ -0,0 +1,269 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Contains container classes to represent different protocol buffer types.
+
+This file defines container classes which represent categories of protocol
+buffer field types which need extra maintenance. Currently these categories
+are:
+  - Repeated scalar fields - These are all repeated fields which aren't
+    composite (e.g. they are of simple types like int32, string, etc).
+  - Repeated composite fields - Repeated fields which are composite. This
+    includes groups and nested messages.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+
+class BaseContainer(object):
+
+  """Base container class."""
+
+  # Minimizes memory usage and disallows assignment to other attributes.
+  __slots__ = ['_message_listener', '_values']
+
+  def __init__(self, message_listener):
+    """
+    Args:
+      message_listener: A MessageListener implementation.
+        The RepeatedScalarFieldContainer will call this object's
+        Modified() method when it is modified.
+    """
+    self._message_listener = message_listener
+    self._values = []
+
+  def __getitem__(self, key):
+    """Retrieves item by the specified key."""
+    return self._values[key]
+
+  def __len__(self):
+    """Returns the number of elements in the container."""
+    return len(self._values)
+
+  def __ne__(self, other):
+    """Checks if another instance isn't equal to this one."""
+    # The concrete classes should define __eq__.
+    return not self == other
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  def __repr__(self):
+    return repr(self._values)
+
+  def sort(self, *args, **kwargs):
+    # Continue to support the old sort_function keyword argument.
+    # This is expected to be a rare occurrence, so use LBYL to avoid
+    # the overhead of actually catching KeyError.
+    if 'sort_function' in kwargs:
+      kwargs['cmp'] = kwargs.pop('sort_function')
+    self._values.sort(*args, **kwargs)
+
+
+class RepeatedScalarFieldContainer(BaseContainer):
+
+  """Simple, type-checked, list-like container for holding repeated scalars."""
+
+  # Disallows assignment to other attributes.
+  __slots__ = ['_type_checker']
+
+  def __init__(self, message_listener, type_checker):
+    """
+    Args:
+      message_listener: A MessageListener implementation.
+        The RepeatedScalarFieldContainer will call this object's
+        Modified() method when it is modified.
+      type_checker: A type_checkers.ValueChecker instance to run on elements
+        inserted into this container.
+    """
+    super(RepeatedScalarFieldContainer, self).__init__(message_listener)
+    self._type_checker = type_checker
+
+  def append(self, value):
+    """Appends an item to the list. Similar to list.append()."""
+    self._type_checker.CheckValue(value)
+    self._values.append(value)
+    if not self._message_listener.dirty:
+      self._message_listener.Modified()
+
+  def insert(self, key, value):
+    """Inserts the item at the specified position. Similar to list.insert()."""
+    self._type_checker.CheckValue(value)
+    self._values.insert(key, value)
+    if not self._message_listener.dirty:
+      self._message_listener.Modified()
+
+  def extend(self, elem_seq):
+    """Extends by appending the given sequence. Similar to list.extend()."""
+    if not elem_seq:
+      return
+
+    new_values = []
+    for elem in elem_seq:
+      self._type_checker.CheckValue(elem)
+      new_values.append(elem)
+    self._values.extend(new_values)
+    self._message_listener.Modified()
+
+  def MergeFrom(self, other):
+    """Appends the contents of another repeated field of the same type to this
+    one. We do not check the types of the individual fields.
+    """
+    self._values.extend(other._values)
+    self._message_listener.Modified()
+
+  def remove(self, elem):
+    """Removes an item from the list. Similar to list.remove()."""
+    self._values.remove(elem)
+    self._message_listener.Modified()
+
+  def __setitem__(self, key, value):
+    """Sets the item on the specified position."""
+    self._type_checker.CheckValue(value)
+    self._values[key] = value
+    self._message_listener.Modified()
+
+  def __getslice__(self, start, stop):
+    """Retrieves the subset of items from between the specified indices."""
+    return self._values[start:stop]
+
+  def __setslice__(self, start, stop, values):
+    """Sets the subset of items from between the specified indices."""
+    new_values = []
+    for value in values:
+      self._type_checker.CheckValue(value)
+      new_values.append(value)
+    self._values[start:stop] = new_values
+    self._message_listener.Modified()
+
+  def __delitem__(self, key):
+    """Deletes the item at the specified position."""
+    del self._values[key]
+    self._message_listener.Modified()
+
+  def __delslice__(self, start, stop):
+    """Deletes the subset of items from between the specified indices."""
+    del self._values[start:stop]
+    self._message_listener.Modified()
+
+  def __eq__(self, other):
+    """Compares the current instance with another one."""
+    if self is other:
+      return True
+    # Special case for the same type which should be common and fast.
+    if isinstance(other, self.__class__):
+      return other._values == self._values
+    # We are presumably comparing against some other sequence type.
+    return other == self._values
+
+
+class RepeatedCompositeFieldContainer(BaseContainer):
+
+  """Simple, list-like container for holding repeated composite fields."""
+
+  # Disallows assignment to other attributes.
+  __slots__ = ['_message_descriptor']
+
+  def __init__(self, message_listener, message_descriptor):
+    """
+    Note that we pass in a descriptor instead of the generated directly,
+    since at the time we construct a _RepeatedCompositeFieldContainer we
+    haven't yet necessarily initialized the type that will be contained in the
+    container.
+
+    Args:
+      message_listener: A MessageListener implementation.
+        The RepeatedCompositeFieldContainer will call this object's
+        Modified() method when it is modified.
+      message_descriptor: A Descriptor instance describing the protocol type
+        that should be present in this container.  We'll use the
+        _concrete_class field of this descriptor when the client calls add().
+    """
+    super(RepeatedCompositeFieldContainer, self).__init__(message_listener)
+    self._message_descriptor = message_descriptor
+
+  def add(self, **kwargs):
+    """Adds a new element at the end of the list and returns it. Keyword
+    arguments may be used to initialize the element.
+    """
+    new_element = self._message_descriptor._concrete_class(**kwargs)
+    new_element._SetListener(self._message_listener)
+    self._values.append(new_element)
+    if not self._message_listener.dirty:
+      self._message_listener.Modified()
+    return new_element
+
+  def extend(self, elem_seq):
+    """Extends by appending the given sequence of elements of the same type
+    as this one, copying each individual message.
+    """
+    message_class = self._message_descriptor._concrete_class
+    listener = self._message_listener
+    values = self._values
+    for message in elem_seq:
+      new_element = message_class()
+      new_element._SetListener(listener)
+      new_element.MergeFrom(message)
+      values.append(new_element)
+    listener.Modified()
+
+  def MergeFrom(self, other):
+    """Appends the contents of another repeated field of the same type to this
+    one, copying each individual message.
+    """
+    self.extend(other._values)
+
+  def remove(self, elem):
+    """Removes an item from the list. Similar to list.remove()."""
+    self._values.remove(elem)
+    self._message_listener.Modified()
+
+  def __getslice__(self, start, stop):
+    """Retrieves the subset of items from between the specified indices."""
+    return self._values[start:stop]
+
+  def __delitem__(self, key):
+    """Deletes the item at the specified position."""
+    del self._values[key]
+    self._message_listener.Modified()
+
+  def __delslice__(self, start, stop):
+    """Deletes the subset of items from between the specified indices."""
+    del self._values[start:stop]
+    self._message_listener.Modified()
+
+  def __eq__(self, other):
+    """Compares the current instance with another one."""
+    if self is other:
+      return True
+    if not isinstance(other, self.__class__):
+      raise TypeError('Can only compare repeated composite fields against '
+                      'other repeated composite fields.')
+    return self._values == other._values
diff --git a/generator/google/protobuf/internal/decoder.py b/generator/google/protobuf/internal/decoder.py
new file mode 100644
index 0000000..cb6f572
--- /dev/null
+++ b/generator/google/protobuf/internal/decoder.py
@@ -0,0 +1,720 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Code for decoding protocol buffer primitives.
+
+This code is very similar to encoder.py -- read the docs for that module first.
+
+A "decoder" is a function with the signature:
+  Decode(buffer, pos, end, message, field_dict)
+The arguments are:
+  buffer:     The string containing the encoded message.
+  pos:        The current position in the string.
+  end:        The position in the string where the current message ends.  May be
+              less than len(buffer) if we're reading a sub-message.
+  message:    The message object into which we're parsing.
+  field_dict: message._fields (avoids a hashtable lookup).
+The decoder reads the field and stores it into field_dict, returning the new
+buffer position.  A decoder for a repeated field may proactively decode all of
+the elements of that field, if they appear consecutively.
+
+Note that decoders may throw any of the following:
+  IndexError:  Indicates a truncated message.
+  struct.error:  Unpacking of a fixed-width field failed.
+  message.DecodeError:  Other errors.
+
+Decoders are expected to raise an exception if they are called with pos > end.
+This allows callers to be lax about bounds checking:  it's fineto read past
+"end" as long as you are sure that someone else will notice and throw an
+exception later on.
+
+Something up the call stack is expected to catch IndexError and struct.error
+and convert them to message.DecodeError.
+
+Decoders are constructed using decoder constructors with the signature:
+  MakeDecoder(field_number, is_repeated, is_packed, key, new_default)
+The arguments are:
+  field_number:  The field number of the field we want to decode.
+  is_repeated:   Is the field a repeated field? (bool)
+  is_packed:     Is the field a packed field? (bool)
+  key:           The key to use when looking up the field within field_dict.
+                 (This is actually the FieldDescriptor but nothing in this
+                 file should depend on that.)
+  new_default:   A function which takes a message object as a parameter and
+                 returns a new instance of the default value for this field.
+                 (This is called for repeated fields and sub-messages, when an
+                 instance does not already exist.)
+
+As with encoders, we define a decoder constructor for every type of field.
+Then, for every field of every message class we construct an actual decoder.
+That decoder goes into a dict indexed by tag, so when we decode a message
+we repeatedly read a tag, look up the corresponding decoder, and invoke it.
+"""
+
+__author__ = 'kenton@google.com (Kenton Varda)'
+
+import struct
+from google.protobuf.internal import encoder
+from google.protobuf.internal import wire_format
+from google.protobuf import message
+
+
+# This will overflow and thus become IEEE-754 "infinity".  We would use
+# "float('inf')" but it doesn't work on Windows pre-Python-2.6.
+_POS_INF = 1e10000
+_NEG_INF = -_POS_INF
+_NAN = _POS_INF * 0
+
+
+# This is not for optimization, but rather to avoid conflicts with local
+# variables named "message".
+_DecodeError = message.DecodeError
+
+
+def _VarintDecoder(mask):
+  """Return an encoder for a basic varint value (does not include tag).
+
+  Decoded values will be bitwise-anded with the given mask before being
+  returned, e.g. to limit them to 32 bits.  The returned decoder does not
+  take the usual "end" parameter -- the caller is expected to do bounds checking
+  after the fact (often the caller can defer such checking until later).  The
+  decoder returns a (value, new_pos) pair.
+  """
+
+  local_ord = ord
+  def DecodeVarint(buffer, pos):
+    result = 0
+    shift = 0
+    while 1:
+      b = local_ord(buffer[pos])
+      result |= ((b & 0x7f) << shift)
+      pos += 1
+      if not (b & 0x80):
+        result &= mask
+        return (result, pos)
+      shift += 7
+      if shift >= 64:
+        raise _DecodeError('Too many bytes when decoding varint.')
+  return DecodeVarint
+
+
+def _SignedVarintDecoder(mask):
+  """Like _VarintDecoder() but decodes signed values."""
+
+  local_ord = ord
+  def DecodeVarint(buffer, pos):
+    result = 0
+    shift = 0
+    while 1:
+      b = local_ord(buffer[pos])
+      result |= ((b & 0x7f) << shift)
+      pos += 1
+      if not (b & 0x80):
+        if result > 0x7fffffffffffffff:
+          result -= (1 << 64)
+          result |= ~mask
+        else:
+          result &= mask
+        return (result, pos)
+      shift += 7
+      if shift >= 64:
+        raise _DecodeError('Too many bytes when decoding varint.')
+  return DecodeVarint
+
+
+_DecodeVarint = _VarintDecoder((1 << 64) - 1)
+_DecodeSignedVarint = _SignedVarintDecoder((1 << 64) - 1)
+
+# Use these versions for values which must be limited to 32 bits.
+_DecodeVarint32 = _VarintDecoder((1 << 32) - 1)
+_DecodeSignedVarint32 = _SignedVarintDecoder((1 << 32) - 1)
+
+
+def ReadTag(buffer, pos):
+  """Read a tag from the buffer, and return a (tag_bytes, new_pos) tuple.
+
+  We return the raw bytes of the tag rather than decoding them.  The raw
+  bytes can then be used to look up the proper decoder.  This effectively allows
+  us to trade some work that would be done in pure-python (decoding a varint)
+  for work that is done in C (searching for a byte string in a hash table).
+  In a low-level language it would be much cheaper to decode the varint and
+  use that, but not in Python.
+  """
+
+  start = pos
+  while ord(buffer[pos]) & 0x80:
+    pos += 1
+  pos += 1
+  return (buffer[start:pos], pos)
+
+
+# --------------------------------------------------------------------
+
+
+def _SimpleDecoder(wire_type, decode_value):
+  """Return a constructor for a decoder for fields of a particular type.
+
+  Args:
+      wire_type:  The field's wire type.
+      decode_value:  A function which decodes an individual value, e.g.
+        _DecodeVarint()
+  """
+
+  def SpecificDecoder(field_number, is_repeated, is_packed, key, new_default):
+    if is_packed:
+      local_DecodeVarint = _DecodeVarint
+      def DecodePackedField(buffer, pos, end, message, field_dict):
+        value = field_dict.get(key)
+        if value is None:
+          value = field_dict.setdefault(key, new_default(message))
+        (endpoint, pos) = local_DecodeVarint(buffer, pos)
+        endpoint += pos
+        if endpoint > end:
+          raise _DecodeError('Truncated message.')
+        while pos < endpoint:
+          (element, pos) = decode_value(buffer, pos)
+          value.append(element)
+        if pos > endpoint:
+          del value[-1]   # Discard corrupt value.
+          raise _DecodeError('Packed element was truncated.')
+        return pos
+      return DecodePackedField
+    elif is_repeated:
+      tag_bytes = encoder.TagBytes(field_number, wire_type)
+      tag_len = len(tag_bytes)
+      def DecodeRepeatedField(buffer, pos, end, message, field_dict):
+        value = field_dict.get(key)
+        if value is None:
+          value = field_dict.setdefault(key, new_default(message))
+        while 1:
+          (element, new_pos) = decode_value(buffer, pos)
+          value.append(element)
+          # Predict that the next tag is another copy of the same repeated
+          # field.
+          pos = new_pos + tag_len
+          if buffer[new_pos:pos] != tag_bytes or new_pos >= end:
+            # Prediction failed.  Return.
+            if new_pos > end:
+              raise _DecodeError('Truncated message.')
+            return new_pos
+      return DecodeRepeatedField
+    else:
+      def DecodeField(buffer, pos, end, message, field_dict):
+        (field_dict[key], pos) = decode_value(buffer, pos)
+        if pos > end:
+          del field_dict[key]  # Discard corrupt value.
+          raise _DecodeError('Truncated message.')
+        return pos
+      return DecodeField
+
+  return SpecificDecoder
+
+
+def _ModifiedDecoder(wire_type, decode_value, modify_value):
+  """Like SimpleDecoder but additionally invokes modify_value on every value
+  before storing it.  Usually modify_value is ZigZagDecode.
+  """
+
+  # Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but
+  # not enough to make a significant difference.
+
+  def InnerDecode(buffer, pos):
+    (result, new_pos) = decode_value(buffer, pos)
+    return (modify_value(result), new_pos)
+  return _SimpleDecoder(wire_type, InnerDecode)
+
+
+def _StructPackDecoder(wire_type, format):
+  """Return a constructor for a decoder for a fixed-width field.
+
+  Args:
+      wire_type:  The field's wire type.
+      format:  The format string to pass to struct.unpack().
+  """
+
+  value_size = struct.calcsize(format)
+  local_unpack = struct.unpack
+
+  # Reusing _SimpleDecoder is slightly slower than copying a bunch of code, but
+  # not enough to make a significant difference.
+
+  # Note that we expect someone up-stack to catch struct.error and convert
+  # it to _DecodeError -- this way we don't have to set up exception-
+  # handling blocks every time we parse one value.
+
+  def InnerDecode(buffer, pos):
+    new_pos = pos + value_size
+    result = local_unpack(format, buffer[pos:new_pos])[0]
+    return (result, new_pos)
+  return _SimpleDecoder(wire_type, InnerDecode)
+
+
+def _FloatDecoder():
+  """Returns a decoder for a float field.
+
+  This code works around a bug in struct.unpack for non-finite 32-bit
+  floating-point values.
+  """
+
+  local_unpack = struct.unpack
+
+  def InnerDecode(buffer, pos):
+    # We expect a 32-bit value in little-endian byte order.  Bit 1 is the sign
+    # bit, bits 2-9 represent the exponent, and bits 10-32 are the significand.
+    new_pos = pos + 4
+    float_bytes = buffer[pos:new_pos]
+
+    # If this value has all its exponent bits set, then it's non-finite.
+    # In Python 2.4, struct.unpack will convert it to a finite 64-bit value.
+    # To avoid that, we parse it specially.
+    if ((float_bytes[3] in '\x7F\xFF')
+        and (float_bytes[2] >= '\x80')):
+      # If at least one significand bit is set...
+      if float_bytes[0:3] != '\x00\x00\x80':
+        return (_NAN, new_pos)
+      # If sign bit is set...
+      if float_bytes[3] == '\xFF':
+        return (_NEG_INF, new_pos)
+      return (_POS_INF, new_pos)
+
+    # Note that we expect someone up-stack to catch struct.error and convert
+    # it to _DecodeError -- this way we don't have to set up exception-
+    # handling blocks every time we parse one value.
+    result = local_unpack('<f', float_bytes)[0]
+    return (result, new_pos)
+  return _SimpleDecoder(wire_format.WIRETYPE_FIXED32, InnerDecode)
+
+
+def _DoubleDecoder():
+  """Returns a decoder for a double field.
+
+  This code works around a bug in struct.unpack for not-a-number.
+  """
+
+  local_unpack = struct.unpack
+
+  def InnerDecode(buffer, pos):
+    # We expect a 64-bit value in little-endian byte order.  Bit 1 is the sign
+    # bit, bits 2-12 represent the exponent, and bits 13-64 are the significand.
+    new_pos = pos + 8
+    double_bytes = buffer[pos:new_pos]
+
+    # If this value has all its exponent bits set and at least one significand
+    # bit set, it's not a number.  In Python 2.4, struct.unpack will treat it
+    # as inf or -inf.  To avoid that, we treat it specially.
+    if ((double_bytes[7] in '\x7F\xFF')
+        and (double_bytes[6] >= '\xF0')
+        and (double_bytes[0:7] != '\x00\x00\x00\x00\x00\x00\xF0')):
+      return (_NAN, new_pos)
+
+    # Note that we expect someone up-stack to catch struct.error and convert
+    # it to _DecodeError -- this way we don't have to set up exception-
+    # handling blocks every time we parse one value.
+    result = local_unpack('<d', double_bytes)[0]
+    return (result, new_pos)
+  return _SimpleDecoder(wire_format.WIRETYPE_FIXED64, InnerDecode)
+
+
+# --------------------------------------------------------------------
+
+
+Int32Decoder = EnumDecoder = _SimpleDecoder(
+    wire_format.WIRETYPE_VARINT, _DecodeSignedVarint32)
+
+Int64Decoder = _SimpleDecoder(
+    wire_format.WIRETYPE_VARINT, _DecodeSignedVarint)
+
+UInt32Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint32)
+UInt64Decoder = _SimpleDecoder(wire_format.WIRETYPE_VARINT, _DecodeVarint)
+
+SInt32Decoder = _ModifiedDecoder(
+    wire_format.WIRETYPE_VARINT, _DecodeVarint32, wire_format.ZigZagDecode)
+SInt64Decoder = _ModifiedDecoder(
+    wire_format.WIRETYPE_VARINT, _DecodeVarint, wire_format.ZigZagDecode)
+
+# Note that Python conveniently guarantees that when using the '<' prefix on
+# formats, they will also have the same size across all platforms (as opposed
+# to without the prefix, where their sizes depend on the C compiler's basic
+# type sizes).
+Fixed32Decoder  = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<I')
+Fixed64Decoder  = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<Q')
+SFixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<i')
+SFixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<q')
+FloatDecoder = _FloatDecoder()
+DoubleDecoder = _DoubleDecoder()
+
+BoolDecoder = _ModifiedDecoder(
+    wire_format.WIRETYPE_VARINT, _DecodeVarint, bool)
+
+
+def StringDecoder(field_number, is_repeated, is_packed, key, new_default):
+  """Returns a decoder for a string field."""
+
+  local_DecodeVarint = _DecodeVarint
+  local_unicode = unicode
+
+  assert not is_packed
+  if is_repeated:
+    tag_bytes = encoder.TagBytes(field_number,
+                                 wire_format.WIRETYPE_LENGTH_DELIMITED)
+    tag_len = len(tag_bytes)
+    def DecodeRepeatedField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      while 1:
+        (size, pos) = local_DecodeVarint(buffer, pos)
+        new_pos = pos + size
+        if new_pos > end:
+          raise _DecodeError('Truncated string.')
+        value.append(local_unicode(buffer[pos:new_pos], 'utf-8'))
+        # Predict that the next tag is another copy of the same repeated field.
+        pos = new_pos + tag_len
+        if buffer[new_pos:pos] != tag_bytes or new_pos == end:
+          # Prediction failed.  Return.
+          return new_pos
+    return DecodeRepeatedField
+  else:
+    def DecodeField(buffer, pos, end, message, field_dict):
+      (size, pos) = local_DecodeVarint(buffer, pos)
+      new_pos = pos + size
+      if new_pos > end:
+        raise _DecodeError('Truncated string.')
+      field_dict[key] = local_unicode(buffer[pos:new_pos], 'utf-8')
+      return new_pos
+    return DecodeField
+
+
+def BytesDecoder(field_number, is_repeated, is_packed, key, new_default):
+  """Returns a decoder for a bytes field."""
+
+  local_DecodeVarint = _DecodeVarint
+
+  assert not is_packed
+  if is_repeated:
+    tag_bytes = encoder.TagBytes(field_number,
+                                 wire_format.WIRETYPE_LENGTH_DELIMITED)
+    tag_len = len(tag_bytes)
+    def DecodeRepeatedField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      while 1:
+        (size, pos) = local_DecodeVarint(buffer, pos)
+        new_pos = pos + size
+        if new_pos > end:
+          raise _DecodeError('Truncated string.')
+        value.append(buffer[pos:new_pos])
+        # Predict that the next tag is another copy of the same repeated field.
+        pos = new_pos + tag_len
+        if buffer[new_pos:pos] != tag_bytes or new_pos == end:
+          # Prediction failed.  Return.
+          return new_pos
+    return DecodeRepeatedField
+  else:
+    def DecodeField(buffer, pos, end, message, field_dict):
+      (size, pos) = local_DecodeVarint(buffer, pos)
+      new_pos = pos + size
+      if new_pos > end:
+        raise _DecodeError('Truncated string.')
+      field_dict[key] = buffer[pos:new_pos]
+      return new_pos
+    return DecodeField
+
+
+def GroupDecoder(field_number, is_repeated, is_packed, key, new_default):
+  """Returns a decoder for a group field."""
+
+  end_tag_bytes = encoder.TagBytes(field_number,
+                                   wire_format.WIRETYPE_END_GROUP)
+  end_tag_len = len(end_tag_bytes)
+
+  assert not is_packed
+  if is_repeated:
+    tag_bytes = encoder.TagBytes(field_number,
+                                 wire_format.WIRETYPE_START_GROUP)
+    tag_len = len(tag_bytes)
+    def DecodeRepeatedField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      while 1:
+        value = field_dict.get(key)
+        if value is None:
+          value = field_dict.setdefault(key, new_default(message))
+        # Read sub-message.
+        pos = value.add()._InternalParse(buffer, pos, end)
+        # Read end tag.
+        new_pos = pos+end_tag_len
+        if buffer[pos:new_pos] != end_tag_bytes or new_pos > end:
+          raise _DecodeError('Missing group end tag.')
+        # Predict that the next tag is another copy of the same repeated field.
+        pos = new_pos + tag_len
+        if buffer[new_pos:pos] != tag_bytes or new_pos == end:
+          # Prediction failed.  Return.
+          return new_pos
+    return DecodeRepeatedField
+  else:
+    def DecodeField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      # Read sub-message.
+      pos = value._InternalParse(buffer, pos, end)
+      # Read end tag.
+      new_pos = pos+end_tag_len
+      if buffer[pos:new_pos] != end_tag_bytes or new_pos > end:
+        raise _DecodeError('Missing group end tag.')
+      return new_pos
+    return DecodeField
+
+
+def MessageDecoder(field_number, is_repeated, is_packed, key, new_default):
+  """Returns a decoder for a message field."""
+
+  local_DecodeVarint = _DecodeVarint
+
+  assert not is_packed
+  if is_repeated:
+    tag_bytes = encoder.TagBytes(field_number,
+                                 wire_format.WIRETYPE_LENGTH_DELIMITED)
+    tag_len = len(tag_bytes)
+    def DecodeRepeatedField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      while 1:
+        value = field_dict.get(key)
+        if value is None:
+          value = field_dict.setdefault(key, new_default(message))
+        # Read length.
+        (size, pos) = local_DecodeVarint(buffer, pos)
+        new_pos = pos + size
+        if new_pos > end:
+          raise _DecodeError('Truncated message.')
+        # Read sub-message.
+        if value.add()._InternalParse(buffer, pos, new_pos) != new_pos:
+          # The only reason _InternalParse would return early is if it
+          # encountered an end-group tag.
+          raise _DecodeError('Unexpected end-group tag.')
+        # Predict that the next tag is another copy of the same repeated field.
+        pos = new_pos + tag_len
+        if buffer[new_pos:pos] != tag_bytes or new_pos == end:
+          # Prediction failed.  Return.
+          return new_pos
+    return DecodeRepeatedField
+  else:
+    def DecodeField(buffer, pos, end, message, field_dict):
+      value = field_dict.get(key)
+      if value is None:
+        value = field_dict.setdefault(key, new_default(message))
+      # Read length.
+      (size, pos) = local_DecodeVarint(buffer, pos)
+      new_pos = pos + size
+      if new_pos > end:
+        raise _DecodeError('Truncated message.')
+      # Read sub-message.
+      if value._InternalParse(buffer, pos, new_pos) != new_pos:
+        # The only reason _InternalParse would return early is if it encountered
+        # an end-group tag.
+        raise _DecodeError('Unexpected end-group tag.')
+      return new_pos
+    return DecodeField
+
+
+# --------------------------------------------------------------------
+
+MESSAGE_SET_ITEM_TAG = encoder.TagBytes(1, wire_format.WIRETYPE_START_GROUP)
+
+def MessageSetItemDecoder(extensions_by_number):
+  """Returns a decoder for a MessageSet item.
+
+  The parameter is the _extensions_by_number map for the message class.
+
+  The message set message looks like this:
+    message MessageSet {
+      repeated group Item = 1 {
+        required int32 type_id = 2;
+        required string message = 3;
+      }
+    }
+  """
+
+  type_id_tag_bytes = encoder.TagBytes(2, wire_format.WIRETYPE_VARINT)
+  message_tag_bytes = encoder.TagBytes(3, wire_format.WIRETYPE_LENGTH_DELIMITED)
+  item_end_tag_bytes = encoder.TagBytes(1, wire_format.WIRETYPE_END_GROUP)
+
+  local_ReadTag = ReadTag
+  local_DecodeVarint = _DecodeVarint
+  local_SkipField = SkipField
+
+  def DecodeItem(buffer, pos, end, message, field_dict):
+    message_set_item_start = pos
+    type_id = -1
+    message_start = -1
+    message_end = -1
+
+    # Technically, type_id and message can appear in any order, so we need
+    # a little loop here.
+    while 1:
+      (tag_bytes, pos) = local_ReadTag(buffer, pos)
+      if tag_bytes == type_id_tag_bytes:
+        (type_id, pos) = local_DecodeVarint(buffer, pos)
+      elif tag_bytes == message_tag_bytes:
+        (size, message_start) = local_DecodeVarint(buffer, pos)
+        pos = message_end = message_start + size
+      elif tag_bytes == item_end_tag_bytes:
+        break
+      else:
+        pos = SkipField(buffer, pos, end, tag_bytes)
+        if pos == -1:
+          raise _DecodeError('Missing group end tag.')
+
+    if pos > end:
+      raise _DecodeError('Truncated message.')
+
+    if type_id == -1:
+      raise _DecodeError('MessageSet item missing type_id.')
+    if message_start == -1:
+      raise _DecodeError('MessageSet item missing message.')
+
+    extension = extensions_by_number.get(type_id)
+    if extension is not None:
+      value = field_dict.get(extension)
+      if value is None:
+        value = field_dict.setdefault(
+            extension, extension.message_type._concrete_class())
+      if value._InternalParse(buffer, message_start,message_end) != message_end:
+        # The only reason _InternalParse would return early is if it encountered
+        # an end-group tag.
+        raise _DecodeError('Unexpected end-group tag.')
+    else:
+      if not message._unknown_fields:
+        message._unknown_fields = []
+      message._unknown_fields.append((MESSAGE_SET_ITEM_TAG,
+                                      buffer[message_set_item_start:pos]))
+
+    return pos
+
+  return DecodeItem
+
+# --------------------------------------------------------------------
+# Optimization is not as heavy here because calls to SkipField() are rare,
+# except for handling end-group tags.
+
+def _SkipVarint(buffer, pos, end):
+  """Skip a varint value.  Returns the new position."""
+
+  while ord(buffer[pos]) & 0x80:
+    pos += 1
+  pos += 1
+  if pos > end:
+    raise _DecodeError('Truncated message.')
+  return pos
+
+def _SkipFixed64(buffer, pos, end):
+  """Skip a fixed64 value.  Returns the new position."""
+
+  pos += 8
+  if pos > end:
+    raise _DecodeError('Truncated message.')
+  return pos
+
+def _SkipLengthDelimited(buffer, pos, end):
+  """Skip a length-delimited value.  Returns the new position."""
+
+  (size, pos) = _DecodeVarint(buffer, pos)
+  pos += size
+  if pos > end:
+    raise _DecodeError('Truncated message.')
+  return pos
+
+def _SkipGroup(buffer, pos, end):
+  """Skip sub-group.  Returns the new position."""
+
+  while 1:
+    (tag_bytes, pos) = ReadTag(buffer, pos)
+    new_pos = SkipField(buffer, pos, end, tag_bytes)
+    if new_pos == -1:
+      return pos
+    pos = new_pos
+
+def _EndGroup(buffer, pos, end):
+  """Skipping an END_GROUP tag returns -1 to tell the parent loop to break."""
+
+  return -1
+
+def _SkipFixed32(buffer, pos, end):
+  """Skip a fixed32 value.  Returns the new position."""
+
+  pos += 4
+  if pos > end:
+    raise _DecodeError('Truncated message.')
+  return pos
+
+def _RaiseInvalidWireType(buffer, pos, end):
+  """Skip function for unknown wire types.  Raises an exception."""
+
+  raise _DecodeError('Tag had invalid wire type.')
+
+def _FieldSkipper():
+  """Constructs the SkipField function."""
+
+  WIRETYPE_TO_SKIPPER = [
+      _SkipVarint,
+      _SkipFixed64,
+      _SkipLengthDelimited,
+      _SkipGroup,
+      _EndGroup,
+      _SkipFixed32,
+      _RaiseInvalidWireType,
+      _RaiseInvalidWireType,
+      ]
+
+  wiretype_mask = wire_format.TAG_TYPE_MASK
+  local_ord = ord
+
+  def SkipField(buffer, pos, end, tag_bytes):
+    """Skips a field with the specified tag.
+
+    |pos| should point to the byte immediately after the tag.
+
+    Returns:
+        The new position (after the tag value), or -1 if the tag is an end-group
+        tag (in which case the calling loop should break).
+    """
+
+    # The wire type is always in the first byte since varints are little-endian.
+    wire_type = local_ord(tag_bytes[0]) & wiretype_mask
+    return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end)
+
+  return SkipField
+
+SkipField = _FieldSkipper()
diff --git a/generator/google/protobuf/internal/encoder.py b/generator/google/protobuf/internal/encoder.py
new file mode 100644
index 0000000..777975e
--- /dev/null
+++ b/generator/google/protobuf/internal/encoder.py
@@ -0,0 +1,769 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Code for encoding protocol message primitives.
+
+Contains the logic for encoding every logical protocol field type
+into one of the 5 physical wire types.
+
+This code is designed to push the Python interpreter's performance to the
+limits.
+
+The basic idea is that at startup time, for every field (i.e. every
+FieldDescriptor) we construct two functions:  a "sizer" and an "encoder".  The
+sizer takes a value of this field's type and computes its byte size.  The
+encoder takes a writer function and a value.  It encodes the value into byte
+strings and invokes the writer function to write those strings.  Typically the
+writer function is the write() method of a cStringIO.
+
+We try to do as much work as possible when constructing the writer and the
+sizer rather than when calling them.  In particular:
+* We copy any needed global functions to local variables, so that we do not need
+  to do costly global table lookups at runtime.
+* Similarly, we try to do any attribute lookups at startup time if possible.
+* Every field's tag is encoded to bytes at startup, since it can't change at
+  runtime.
+* Whatever component of the field size we can compute at startup, we do.
+* We *avoid* sharing code if doing so would make the code slower and not sharing
+  does not burden us too much.  For example, encoders for repeated fields do
+  not just call the encoders for singular fields in a loop because this would
+  add an extra function call overhead for every loop iteration; instead, we
+  manually inline the single-value encoder into the loop.
+* If a Python function lacks a return statement, Python actually generates
+  instructions to pop the result of the last statement off the stack, push
+  None onto the stack, and then return that.  If we really don't care what
+  value is returned, then we can save two instructions by returning the
+  result of the last statement.  It looks funny but it helps.
+* We assume that type and bounds checking has happened at a higher level.
+"""
+
+__author__ = 'kenton@google.com (Kenton Varda)'
+
+import struct
+from google.protobuf.internal import wire_format
+
+
+# This will overflow and thus become IEEE-754 "infinity".  We would use
+# "float('inf')" but it doesn't work on Windows pre-Python-2.6.
+_POS_INF = 1e10000
+_NEG_INF = -_POS_INF
+
+
+def _VarintSize(value):
+  """Compute the size of a varint value."""
+  if value <= 0x7f: return 1
+  if value <= 0x3fff: return 2
+  if value <= 0x1fffff: return 3
+  if value <= 0xfffffff: return 4
+  if value <= 0x7ffffffff: return 5
+  if value <= 0x3ffffffffff: return 6
+  if value <= 0x1ffffffffffff: return 7
+  if value <= 0xffffffffffffff: return 8
+  if value <= 0x7fffffffffffffff: return 9
+  return 10
+
+
+def _SignedVarintSize(value):
+  """Compute the size of a signed varint value."""
+  if value < 0: return 10
+  if value <= 0x7f: return 1
+  if value <= 0x3fff: return 2
+  if value <= 0x1fffff: return 3
+  if value <= 0xfffffff: return 4
+  if value <= 0x7ffffffff: return 5
+  if value <= 0x3ffffffffff: return 6
+  if value <= 0x1ffffffffffff: return 7
+  if value <= 0xffffffffffffff: return 8
+  if value <= 0x7fffffffffffffff: return 9
+  return 10
+
+
+def _TagSize(field_number):
+  """Returns the number of bytes required to serialize a tag with this field
+  number."""
+  # Just pass in type 0, since the type won't affect the tag+type size.
+  return _VarintSize(wire_format.PackTag(field_number, 0))
+
+
+# --------------------------------------------------------------------
+# In this section we define some generic sizers.  Each of these functions
+# takes parameters specific to a particular field type, e.g. int32 or fixed64.
+# It returns another function which in turn takes parameters specific to a
+# particular field, e.g. the field number and whether it is repeated or packed.
+# Look at the next section to see how these are used.
+
+
+def _SimpleSizer(compute_value_size):
+  """A sizer which uses the function compute_value_size to compute the size of
+  each value.  Typically compute_value_size is _VarintSize."""
+
+  def SpecificSizer(field_number, is_repeated, is_packed):
+    tag_size = _TagSize(field_number)
+    if is_packed:
+      local_VarintSize = _VarintSize
+      def PackedFieldSize(value):
+        result = 0
+        for element in value:
+          result += compute_value_size(element)
+        return result + local_VarintSize(result) + tag_size
+      return PackedFieldSize
+    elif is_repeated:
+      def RepeatedFieldSize(value):
+        result = tag_size * len(value)
+        for element in value:
+          result += compute_value_size(element)
+        return result
+      return RepeatedFieldSize
+    else:
+      def FieldSize(value):
+        return tag_size + compute_value_size(value)
+      return FieldSize
+
+  return SpecificSizer
+
+
+def _ModifiedSizer(compute_value_size, modify_value):
+  """Like SimpleSizer, but modify_value is invoked on each value before it is
+  passed to compute_value_size.  modify_value is typically ZigZagEncode."""
+
+  def SpecificSizer(field_number, is_repeated, is_packed):
+    tag_size = _TagSize(field_number)
+    if is_packed:
+      local_VarintSize = _VarintSize
+      def PackedFieldSize(value):
+        result = 0
+        for element in value:
+          result += compute_value_size(modify_value(element))
+        return result + local_VarintSize(result) + tag_size
+      return PackedFieldSize
+    elif is_repeated:
+      def RepeatedFieldSize(value):
+        result = tag_size * len(value)
+        for element in value:
+          result += compute_value_size(modify_value(element))
+        return result
+      return RepeatedFieldSize
+    else:
+      def FieldSize(value):
+        return tag_size + compute_value_size(modify_value(value))
+      return FieldSize
+
+  return SpecificSizer
+
+
+def _FixedSizer(value_size):
+  """Like _SimpleSizer except for a fixed-size field.  The input is the size
+  of one value."""
+
+  def SpecificSizer(field_number, is_repeated, is_packed):
+    tag_size = _TagSize(field_number)
+    if is_packed:
+      local_VarintSize = _VarintSize
+      def PackedFieldSize(value):
+        result = len(value) * value_size
+        return result + local_VarintSize(result) + tag_size
+      return PackedFieldSize
+    elif is_repeated:
+      element_size = value_size + tag_size
+      def RepeatedFieldSize(value):
+        return len(value) * element_size
+      return RepeatedFieldSize
+    else:
+      field_size = value_size + tag_size
+      def FieldSize(value):
+        return field_size
+      return FieldSize
+
+  return SpecificSizer
+
+
+# ====================================================================
+# Here we declare a sizer constructor for each field type.  Each "sizer
+# constructor" is a function that takes (field_number, is_repeated, is_packed)
+# as parameters and returns a sizer, which in turn takes a field value as
+# a parameter and returns its encoded size.
+
+
+Int32Sizer = Int64Sizer = EnumSizer = _SimpleSizer(_SignedVarintSize)
+
+UInt32Sizer = UInt64Sizer = _SimpleSizer(_VarintSize)
+
+SInt32Sizer = SInt64Sizer = _ModifiedSizer(
+    _SignedVarintSize, wire_format.ZigZagEncode)
+
+Fixed32Sizer = SFixed32Sizer = FloatSizer  = _FixedSizer(4)
+Fixed64Sizer = SFixed64Sizer = DoubleSizer = _FixedSizer(8)
+
+BoolSizer = _FixedSizer(1)
+
+
+def StringSizer(field_number, is_repeated, is_packed):
+  """Returns a sizer for a string field."""
+
+  tag_size = _TagSize(field_number)
+  local_VarintSize = _VarintSize
+  local_len = len
+  assert not is_packed
+  if is_repeated:
+    def RepeatedFieldSize(value):
+      result = tag_size * len(value)
+      for element in value:
+        l = local_len(element.encode('utf-8'))
+        result += local_VarintSize(l) + l
+      return result
+    return RepeatedFieldSize
+  else:
+    def FieldSize(value):
+      l = local_len(value.encode('utf-8'))
+      return tag_size + local_VarintSize(l) + l
+    return FieldSize
+
+
+def BytesSizer(field_number, is_repeated, is_packed):
+  """Returns a sizer for a bytes field."""
+
+  tag_size = _TagSize(field_number)
+  local_VarintSize = _VarintSize
+  local_len = len
+  assert not is_packed
+  if is_repeated:
+    def RepeatedFieldSize(value):
+      result = tag_size * len(value)
+      for element in value:
+        l = local_len(element)
+        result += local_VarintSize(l) + l
+      return result
+    return RepeatedFieldSize
+  else:
+    def FieldSize(value):
+      l = local_len(value)
+      return tag_size + local_VarintSize(l) + l
+    return FieldSize
+
+
+def GroupSizer(field_number, is_repeated, is_packed):
+  """Returns a sizer for a group field."""
+
+  tag_size = _TagSize(field_number) * 2
+  assert not is_packed
+  if is_repeated:
+    def RepeatedFieldSize(value):
+      result = tag_size * len(value)
+      for element in value:
+        result += element.ByteSize()
+      return result
+    return RepeatedFieldSize
+  else:
+    def FieldSize(value):
+      return tag_size + value.ByteSize()
+    return FieldSize
+
+
+def MessageSizer(field_number, is_repeated, is_packed):
+  """Returns a sizer for a message field."""
+
+  tag_size = _TagSize(field_number)
+  local_VarintSize = _VarintSize
+  assert not is_packed
+  if is_repeated:
+    def RepeatedFieldSize(value):
+      result = tag_size * len(value)
+      for element in value:
+        l = element.ByteSize()
+        result += local_VarintSize(l) + l
+      return result
+    return RepeatedFieldSize
+  else:
+    def FieldSize(value):
+      l = value.ByteSize()
+      return tag_size + local_VarintSize(l) + l
+    return FieldSize
+
+
+# --------------------------------------------------------------------
+# MessageSet is special.
+
+
+def MessageSetItemSizer(field_number):
+  """Returns a sizer for extensions of MessageSet.
+
+  The message set message looks like this:
+    message MessageSet {
+      repeated group Item = 1 {
+        required int32 type_id = 2;
+        required string message = 3;
+      }
+    }
+  """
+  static_size = (_TagSize(1) * 2 + _TagSize(2) + _VarintSize(field_number) +
+                 _TagSize(3))
+  local_VarintSize = _VarintSize
+
+  def FieldSize(value):
+    l = value.ByteSize()
+    return static_size + local_VarintSize(l) + l
+
+  return FieldSize
+
+
+# ====================================================================
+# Encoders!
+
+
+def _VarintEncoder():
+  """Return an encoder for a basic varint value (does not include tag)."""
+
+  local_chr = chr
+  def EncodeVarint(write, value):
+    bits = value & 0x7f
+    value >>= 7
+    while value:
+      write(local_chr(0x80|bits))
+      bits = value & 0x7f
+      value >>= 7
+    return write(local_chr(bits))
+
+  return EncodeVarint
+
+
+def _SignedVarintEncoder():
+  """Return an encoder for a basic signed varint value (does not include
+  tag)."""
+
+  local_chr = chr
+  def EncodeSignedVarint(write, value):
+    if value < 0:
+      value += (1 << 64)
+    bits = value & 0x7f
+    value >>= 7
+    while value:
+      write(local_chr(0x80|bits))
+      bits = value & 0x7f
+      value >>= 7
+    return write(local_chr(bits))
+
+  return EncodeSignedVarint
+
+
+_EncodeVarint = _VarintEncoder()
+_EncodeSignedVarint = _SignedVarintEncoder()
+
+
+def _VarintBytes(value):
+  """Encode the given integer as a varint and return the bytes.  This is only
+  called at startup time so it doesn't need to be fast."""
+
+  pieces = []
+  _EncodeVarint(pieces.append, value)
+  return "".join(pieces)
+
+
+def TagBytes(field_number, wire_type):
+  """Encode the given tag and return the bytes.  Only called at startup."""
+
+  return _VarintBytes(wire_format.PackTag(field_number, wire_type))
+
+# --------------------------------------------------------------------
+# As with sizers (see above), we have a number of common encoder
+# implementations.
+
+
+def _SimpleEncoder(wire_type, encode_value, compute_value_size):
+  """Return a constructor for an encoder for fields of a particular type.
+
+  Args:
+      wire_type:  The field's wire type, for encoding tags.
+      encode_value:  A function which encodes an individual value, e.g.
+        _EncodeVarint().
+      compute_value_size:  A function which computes the size of an individual
+        value, e.g. _VarintSize().
+  """
+
+  def SpecificEncoder(field_number, is_repeated, is_packed):
+    if is_packed:
+      tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+      local_EncodeVarint = _EncodeVarint
+      def EncodePackedField(write, value):
+        write(tag_bytes)
+        size = 0
+        for element in value:
+          size += compute_value_size(element)
+        local_EncodeVarint(write, size)
+        for element in value:
+          encode_value(write, element)
+      return EncodePackedField
+    elif is_repeated:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeRepeatedField(write, value):
+        for element in value:
+          write(tag_bytes)
+          encode_value(write, element)
+      return EncodeRepeatedField
+    else:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeField(write, value):
+        write(tag_bytes)
+        return encode_value(write, value)
+      return EncodeField
+
+  return SpecificEncoder
+
+
+def _ModifiedEncoder(wire_type, encode_value, compute_value_size, modify_value):
+  """Like SimpleEncoder but additionally invokes modify_value on every value
+  before passing it to encode_value.  Usually modify_value is ZigZagEncode."""
+
+  def SpecificEncoder(field_number, is_repeated, is_packed):
+    if is_packed:
+      tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+      local_EncodeVarint = _EncodeVarint
+      def EncodePackedField(write, value):
+        write(tag_bytes)
+        size = 0
+        for element in value:
+          size += compute_value_size(modify_value(element))
+        local_EncodeVarint(write, size)
+        for element in value:
+          encode_value(write, modify_value(element))
+      return EncodePackedField
+    elif is_repeated:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeRepeatedField(write, value):
+        for element in value:
+          write(tag_bytes)
+          encode_value(write, modify_value(element))
+      return EncodeRepeatedField
+    else:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeField(write, value):
+        write(tag_bytes)
+        return encode_value(write, modify_value(value))
+      return EncodeField
+
+  return SpecificEncoder
+
+
+def _StructPackEncoder(wire_type, format):
+  """Return a constructor for an encoder for a fixed-width field.
+
+  Args:
+      wire_type:  The field's wire type, for encoding tags.
+      format:  The format string to pass to struct.pack().
+  """
+
+  value_size = struct.calcsize(format)
+
+  def SpecificEncoder(field_number, is_repeated, is_packed):
+    local_struct_pack = struct.pack
+    if is_packed:
+      tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+      local_EncodeVarint = _EncodeVarint
+      def EncodePackedField(write, value):
+        write(tag_bytes)
+        local_EncodeVarint(write, len(value) * value_size)
+        for element in value:
+          write(local_struct_pack(format, element))
+      return EncodePackedField
+    elif is_repeated:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeRepeatedField(write, value):
+        for element in value:
+          write(tag_bytes)
+          write(local_struct_pack(format, element))
+      return EncodeRepeatedField
+    else:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeField(write, value):
+        write(tag_bytes)
+        return write(local_struct_pack(format, value))
+      return EncodeField
+
+  return SpecificEncoder
+
+
+def _FloatingPointEncoder(wire_type, format):
+  """Return a constructor for an encoder for float fields.
+
+  This is like StructPackEncoder, but catches errors that may be due to
+  passing non-finite floating-point values to struct.pack, and makes a
+  second attempt to encode those values.
+
+  Args:
+      wire_type:  The field's wire type, for encoding tags.
+      format:  The format string to pass to struct.pack().
+  """
+
+  value_size = struct.calcsize(format)
+  if value_size == 4:
+    def EncodeNonFiniteOrRaise(write, value):
+      # Remember that the serialized form uses little-endian byte order.
+      if value == _POS_INF:
+        write('\x00\x00\x80\x7F')
+      elif value == _NEG_INF:
+        write('\x00\x00\x80\xFF')
+      elif value != value:           # NaN
+        write('\x00\x00\xC0\x7F')
+      else:
+        raise
+  elif value_size == 8:
+    def EncodeNonFiniteOrRaise(write, value):
+      if value == _POS_INF:
+        write('\x00\x00\x00\x00\x00\x00\xF0\x7F')
+      elif value == _NEG_INF:
+        write('\x00\x00\x00\x00\x00\x00\xF0\xFF')
+      elif value != value:                         # NaN
+        write('\x00\x00\x00\x00\x00\x00\xF8\x7F')
+      else:
+        raise
+  else:
+    raise ValueError('Can\'t encode floating-point values that are '
+                     '%d bytes long (only 4 or 8)' % value_size)
+
+  def SpecificEncoder(field_number, is_repeated, is_packed):
+    local_struct_pack = struct.pack
+    if is_packed:
+      tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+      local_EncodeVarint = _EncodeVarint
+      def EncodePackedField(write, value):
+        write(tag_bytes)
+        local_EncodeVarint(write, len(value) * value_size)
+        for element in value:
+          # This try/except block is going to be faster than any code that
+          # we could write to check whether element is finite.
+          try:
+            write(local_struct_pack(format, element))
+          except SystemError:
+            EncodeNonFiniteOrRaise(write, element)
+      return EncodePackedField
+    elif is_repeated:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeRepeatedField(write, value):
+        for element in value:
+          write(tag_bytes)
+          try:
+            write(local_struct_pack(format, element))
+          except SystemError:
+            EncodeNonFiniteOrRaise(write, element)
+      return EncodeRepeatedField
+    else:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeField(write, value):
+        write(tag_bytes)
+        try:
+          write(local_struct_pack(format, value))
+        except SystemError:
+          EncodeNonFiniteOrRaise(write, value)
+      return EncodeField
+
+  return SpecificEncoder
+
+
+# ====================================================================
+# Here we declare an encoder constructor for each field type.  These work
+# very similarly to sizer constructors, described earlier.
+
+
+Int32Encoder = Int64Encoder = EnumEncoder = _SimpleEncoder(
+    wire_format.WIRETYPE_VARINT, _EncodeSignedVarint, _SignedVarintSize)
+
+UInt32Encoder = UInt64Encoder = _SimpleEncoder(
+    wire_format.WIRETYPE_VARINT, _EncodeVarint, _VarintSize)
+
+SInt32Encoder = SInt64Encoder = _ModifiedEncoder(
+    wire_format.WIRETYPE_VARINT, _EncodeVarint, _VarintSize,
+    wire_format.ZigZagEncode)
+
+# Note that Python conveniently guarantees that when using the '<' prefix on
+# formats, they will also have the same size across all platforms (as opposed
+# to without the prefix, where their sizes depend on the C compiler's basic
+# type sizes).
+Fixed32Encoder  = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<I')
+Fixed64Encoder  = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<Q')
+SFixed32Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<i')
+SFixed64Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<q')
+FloatEncoder    = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED32, '<f')
+DoubleEncoder   = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED64, '<d')
+
+
+def BoolEncoder(field_number, is_repeated, is_packed):
+  """Returns an encoder for a boolean field."""
+
+  false_byte = chr(0)
+  true_byte = chr(1)
+  if is_packed:
+    tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+    local_EncodeVarint = _EncodeVarint
+    def EncodePackedField(write, value):
+      write(tag_bytes)
+      local_EncodeVarint(write, len(value))
+      for element in value:
+        if element:
+          write(true_byte)
+        else:
+          write(false_byte)
+    return EncodePackedField
+  elif is_repeated:
+    tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_VARINT)
+    def EncodeRepeatedField(write, value):
+      for element in value:
+        write(tag_bytes)
+        if element:
+          write(true_byte)
+        else:
+          write(false_byte)
+    return EncodeRepeatedField
+  else:
+    tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_VARINT)
+    def EncodeField(write, value):
+      write(tag_bytes)
+      if value:
+        return write(true_byte)
+      return write(false_byte)
+    return EncodeField
+
+
+def StringEncoder(field_number, is_repeated, is_packed):
+  """Returns an encoder for a string field."""
+
+  tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+  local_EncodeVarint = _EncodeVarint
+  local_len = len
+  assert not is_packed
+  if is_repeated:
+    def EncodeRepeatedField(write, value):
+      for element in value:
+        encoded = element.encode('utf-8')
+        write(tag)
+        local_EncodeVarint(write, local_len(encoded))
+        write(encoded)
+    return EncodeRepeatedField
+  else:
+    def EncodeField(write, value):
+      encoded = value.encode('utf-8')
+      write(tag)
+      local_EncodeVarint(write, local_len(encoded))
+      return write(encoded)
+    return EncodeField
+
+
+def BytesEncoder(field_number, is_repeated, is_packed):
+  """Returns an encoder for a bytes field."""
+
+  tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+  local_EncodeVarint = _EncodeVarint
+  local_len = len
+  assert not is_packed
+  if is_repeated:
+    def EncodeRepeatedField(write, value):
+      for element in value:
+        write(tag)
+        local_EncodeVarint(write, local_len(element))
+        write(element)
+    return EncodeRepeatedField
+  else:
+    def EncodeField(write, value):
+      write(tag)
+      local_EncodeVarint(write, local_len(value))
+      return write(value)
+    return EncodeField
+
+
+def GroupEncoder(field_number, is_repeated, is_packed):
+  """Returns an encoder for a group field."""
+
+  start_tag = TagBytes(field_number, wire_format.WIRETYPE_START_GROUP)
+  end_tag = TagBytes(field_number, wire_format.WIRETYPE_END_GROUP)
+  assert not is_packed
+  if is_repeated:
+    def EncodeRepeatedField(write, value):
+      for element in value:
+        write(start_tag)
+        element._InternalSerialize(write)
+        write(end_tag)
+    return EncodeRepeatedField
+  else:
+    def EncodeField(write, value):
+      write(start_tag)
+      value._InternalSerialize(write)
+      return write(end_tag)
+    return EncodeField
+
+
+def MessageEncoder(field_number, is_repeated, is_packed):
+  """Returns an encoder for a message field."""
+
+  tag = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+  local_EncodeVarint = _EncodeVarint
+  assert not is_packed
+  if is_repeated:
+    def EncodeRepeatedField(write, value):
+      for element in value:
+        write(tag)
+        local_EncodeVarint(write, element.ByteSize())
+        element._InternalSerialize(write)
+    return EncodeRepeatedField
+  else:
+    def EncodeField(write, value):
+      write(tag)
+      local_EncodeVarint(write, value.ByteSize())
+      return value._InternalSerialize(write)
+    return EncodeField
+
+
+# --------------------------------------------------------------------
+# As before, MessageSet is special.
+
+
+def MessageSetItemEncoder(field_number):
+  """Encoder for extensions of MessageSet.
+
+  The message set message looks like this:
+    message MessageSet {
+      repeated group Item = 1 {
+        required int32 type_id = 2;
+        required string message = 3;
+      }
+    }
+  """
+  start_bytes = "".join([
+      TagBytes(1, wire_format.WIRETYPE_START_GROUP),
+      TagBytes(2, wire_format.WIRETYPE_VARINT),
+      _VarintBytes(field_number),
+      TagBytes(3, wire_format.WIRETYPE_LENGTH_DELIMITED)])
+  end_bytes = TagBytes(1, wire_format.WIRETYPE_END_GROUP)
+  local_EncodeVarint = _EncodeVarint
+
+  def EncodeField(write, value):
+    write(start_bytes)
+    local_EncodeVarint(write, value.ByteSize())
+    value._InternalSerialize(write)
+    return write(end_bytes)
+
+  return EncodeField
diff --git a/generator/google/protobuf/internal/enum_type_wrapper.py b/generator/google/protobuf/internal/enum_type_wrapper.py
new file mode 100644
index 0000000..7b28645
--- /dev/null
+++ b/generator/google/protobuf/internal/enum_type_wrapper.py
@@ -0,0 +1,89 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A simple wrapper around enum types to expose utility functions.
+
+Instances are created as properties with the same name as the enum they wrap
+on proto classes.  For usage, see:
+  reflection_test.py
+"""
+
+__author__ = 'rabsatt@google.com (Kevin Rabsatt)'
+
+
+class EnumTypeWrapper(object):
+  """A utility for finding the names of enum values."""
+
+  DESCRIPTOR = None
+
+  def __init__(self, enum_type):
+    """Inits EnumTypeWrapper with an EnumDescriptor."""
+    self._enum_type = enum_type
+    self.DESCRIPTOR = enum_type;
+
+  def Name(self, number):
+    """Returns a string containing the name of an enum value."""
+    if number in self._enum_type.values_by_number:
+      return self._enum_type.values_by_number[number].name
+    raise ValueError('Enum %s has no name defined for value %d' % (
+        self._enum_type.name, number))
+
+  def Value(self, name):
+    """Returns the value coresponding to the given enum name."""
+    if name in self._enum_type.values_by_name:
+      return self._enum_type.values_by_name[name].number
+    raise ValueError('Enum %s has no value defined for name %s' % (
+        self._enum_type.name, name))
+
+  def keys(self):
+    """Return a list of the string names in the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+
+    return [value_descriptor.name
+            for value_descriptor in self._enum_type.values]
+
+  def values(self):
+    """Return a list of the integer values in the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+
+    return [value_descriptor.number
+            for value_descriptor in self._enum_type.values]
+
+  def items(self):
+    """Return a list of the (name, value) pairs of the enum.
+
+    These are returned in the order they were defined in the .proto file.
+    """
+    return [(value_descriptor.name, value_descriptor.number)
+            for value_descriptor in self._enum_type.values]
diff --git a/generator/google/protobuf/internal/message_listener.py b/generator/google/protobuf/internal/message_listener.py
new file mode 100644
index 0000000..1080234
--- /dev/null
+++ b/generator/google/protobuf/internal/message_listener.py
@@ -0,0 +1,78 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Defines a listener interface for observing certain
+state transitions on Message objects.
+
+Also defines a null implementation of this interface.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+
+class MessageListener(object):
+
+  """Listens for modifications made to a message.  Meant to be registered via
+  Message._SetListener().
+
+  Attributes:
+    dirty:  If True, then calling Modified() would be a no-op.  This can be
+            used to avoid these calls entirely in the common case.
+  """
+
+  def Modified(self):
+    """Called every time the message is modified in such a way that the parent
+    message may need to be updated.  This currently means either:
+    (a) The message was modified for the first time, so the parent message
+        should henceforth mark the message as present.
+    (b) The message's cached byte size became dirty -- i.e. the message was
+        modified for the first time after a previous call to ByteSize().
+        Therefore the parent should also mark its byte size as dirty.
+    Note that (a) implies (b), since new objects start out with a client cached
+    size (zero).  However, we document (a) explicitly because it is important.
+
+    Modified() will *only* be called in response to one of these two events --
+    not every time the sub-message is modified.
+
+    Note that if the listener's |dirty| attribute is true, then calling
+    Modified at the moment would be a no-op, so it can be skipped.  Performance-
+    sensitive callers should check this attribute directly before calling since
+    it will be true most of the time.
+    """
+
+    raise NotImplementedError
+
+
+class NullMessageListener(object):
+
+  """No-op MessageListener implementation."""
+
+  def Modified(self):
+    pass
diff --git a/generator/google/protobuf/internal/python_message.py b/generator/google/protobuf/internal/python_message.py
new file mode 100644
index 0000000..4bea57a
--- /dev/null
+++ b/generator/google/protobuf/internal/python_message.py
@@ -0,0 +1,1150 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# This code is meant to work on Python 2.4 and above only.
+#
+# TODO(robinson): Helpers for verbose, common checks like seeing if a
+# descriptor's cpp_type is CPPTYPE_MESSAGE.
+
+"""Contains a metaclass and helper functions used to create
+protocol message classes from Descriptor objects at runtime.
+
+Recall that a metaclass is the "type" of a class.
+(A class is to a metaclass what an instance is to a class.)
+
+In this case, we use the GeneratedProtocolMessageType metaclass
+to inject all the useful functionality into the classes
+output by the protocol compiler at compile-time.
+
+The upshot of all this is that the real implementation
+details for ALL pure-Python protocol buffers are *here in
+this file*.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+try:
+  from cStringIO import StringIO
+except ImportError:
+  from StringIO import StringIO
+import copy_reg
+import struct
+import weakref
+
+# We use "as" to avoid name collisions with variables.
+from google.protobuf.internal import containers
+from google.protobuf.internal import decoder
+from google.protobuf.internal import encoder
+from google.protobuf.internal import enum_type_wrapper
+from google.protobuf.internal import message_listener as message_listener_mod
+from google.protobuf.internal import type_checkers
+from google.protobuf.internal import wire_format
+from google.protobuf import descriptor as descriptor_mod
+from google.protobuf import message as message_mod
+from google.protobuf import text_format
+
+_FieldDescriptor = descriptor_mod.FieldDescriptor
+
+
+def NewMessage(bases, descriptor, dictionary):
+  _AddClassAttributesForNestedExtensions(descriptor, dictionary)
+  _AddSlots(descriptor, dictionary)
+  return bases
+
+
+def InitMessage(descriptor, cls):
+  cls._decoders_by_tag = {}
+  cls._extensions_by_name = {}
+  cls._extensions_by_number = {}
+  if (descriptor.has_options and
+      descriptor.GetOptions().message_set_wire_format):
+    cls._decoders_by_tag[decoder.MESSAGE_SET_ITEM_TAG] = (
+        decoder.MessageSetItemDecoder(cls._extensions_by_number))
+
+  # Attach stuff to each FieldDescriptor for quick lookup later on.
+  for field in descriptor.fields:
+    _AttachFieldHelpers(cls, field)
+
+  _AddEnumValues(descriptor, cls)
+  _AddInitMethod(descriptor, cls)
+  _AddPropertiesForFields(descriptor, cls)
+  _AddPropertiesForExtensions(descriptor, cls)
+  _AddStaticMethods(cls)
+  _AddMessageMethods(descriptor, cls)
+  _AddPrivateHelperMethods(cls)
+  copy_reg.pickle(cls, lambda obj: (cls, (), obj.__getstate__()))
+
+
+# Stateless helpers for GeneratedProtocolMessageType below.
+# Outside clients should not access these directly.
+#
+# I opted not to make any of these methods on the metaclass, to make it more
+# clear that I'm not really using any state there and to keep clients from
+# thinking that they have direct access to these construction helpers.
+
+
+def _PropertyName(proto_field_name):
+  """Returns the name of the public property attribute which
+  clients can use to get and (in some cases) set the value
+  of a protocol message field.
+
+  Args:
+    proto_field_name: The protocol message field name, exactly
+      as it appears (or would appear) in a .proto file.
+  """
+  # TODO(robinson): Escape Python keywords (e.g., yield), and test this support.
+  # nnorwitz makes my day by writing:
+  # """
+  # FYI.  See the keyword module in the stdlib. This could be as simple as:
+  #
+  # if keyword.iskeyword(proto_field_name):
+  #   return proto_field_name + "_"
+  # return proto_field_name
+  # """
+  # Kenton says:  The above is a BAD IDEA.  People rely on being able to use
+  #   getattr() and setattr() to reflectively manipulate field values.  If we
+  #   rename the properties, then every such user has to also make sure to apply
+  #   the same transformation.  Note that currently if you name a field "yield",
+  #   you can still access it just fine using getattr/setattr -- it's not even
+  #   that cumbersome to do so.
+  # TODO(kenton):  Remove this method entirely if/when everyone agrees with my
+  #   position.
+  return proto_field_name
+
+
+def _VerifyExtensionHandle(message, extension_handle):
+  """Verify that the given extension handle is valid."""
+
+  if not isinstance(extension_handle, _FieldDescriptor):
+    raise KeyError('HasExtension() expects an extension handle, got: %s' %
+                   extension_handle)
+
+  if not extension_handle.is_extension:
+    raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
+
+  if not extension_handle.containing_type:
+    raise KeyError('"%s" is missing a containing_type.'
+                   % extension_handle.full_name)
+
+  if extension_handle.containing_type is not message.DESCRIPTOR:
+    raise KeyError('Extension "%s" extends message type "%s", but this '
+                   'message is of type "%s".' %
+                   (extension_handle.full_name,
+                    extension_handle.containing_type.full_name,
+                    message.DESCRIPTOR.full_name))
+
+
+def _AddSlots(message_descriptor, dictionary):
+  """Adds a __slots__ entry to dictionary, containing the names of all valid
+  attributes for this message type.
+
+  Args:
+    message_descriptor: A Descriptor instance describing this message type.
+    dictionary: Class dictionary to which we'll add a '__slots__' entry.
+  """
+  dictionary['__slots__'] = ['_cached_byte_size',
+                             '_cached_byte_size_dirty',
+                             '_fields',
+                             '_unknown_fields',
+                             '_is_present_in_parent',
+                             '_listener',
+                             '_listener_for_children',
+                             '__weakref__']
+
+
+def _IsMessageSetExtension(field):
+  return (field.is_extension and
+          field.containing_type.has_options and
+          field.containing_type.GetOptions().message_set_wire_format and
+          field.type == _FieldDescriptor.TYPE_MESSAGE and
+          field.message_type == field.extension_scope and
+          field.label == _FieldDescriptor.LABEL_OPTIONAL)
+
+
+def _AttachFieldHelpers(cls, field_descriptor):
+  is_repeated = (field_descriptor.label == _FieldDescriptor.LABEL_REPEATED)
+  is_packed = (field_descriptor.has_options and
+               field_descriptor.GetOptions().packed)
+
+  if _IsMessageSetExtension(field_descriptor):
+    field_encoder = encoder.MessageSetItemEncoder(field_descriptor.number)
+    sizer = encoder.MessageSetItemSizer(field_descriptor.number)
+  else:
+    field_encoder = type_checkers.TYPE_TO_ENCODER[field_descriptor.type](
+        field_descriptor.number, is_repeated, is_packed)
+    sizer = type_checkers.TYPE_TO_SIZER[field_descriptor.type](
+        field_descriptor.number, is_repeated, is_packed)
+
+  field_descriptor._encoder = field_encoder
+  field_descriptor._sizer = sizer
+  field_descriptor._default_constructor = _DefaultValueConstructorForField(
+      field_descriptor)
+
+  def AddDecoder(wiretype, is_packed):
+    tag_bytes = encoder.TagBytes(field_descriptor.number, wiretype)
+    cls._decoders_by_tag[tag_bytes] = (
+        type_checkers.TYPE_TO_DECODER[field_descriptor.type](
+            field_descriptor.number, is_repeated, is_packed,
+            field_descriptor, field_descriptor._default_constructor))
+
+  AddDecoder(type_checkers.FIELD_TYPE_TO_WIRE_TYPE[field_descriptor.type],
+             False)
+
+  if is_repeated and wire_format.IsTypePackable(field_descriptor.type):
+    # To support wire compatibility of adding packed = true, add a decoder for
+    # packed values regardless of the field's options.
+    AddDecoder(wire_format.WIRETYPE_LENGTH_DELIMITED, True)
+
+
+def _AddClassAttributesForNestedExtensions(descriptor, dictionary):
+  extension_dict = descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    assert extension_name not in dictionary
+    dictionary[extension_name] = extension_field
+
+
+def _AddEnumValues(descriptor, cls):
+  """Sets class-level attributes for all enum fields defined in this message.
+
+  Also exporting a class-level object that can name enum values.
+
+  Args:
+    descriptor: Descriptor object for this message type.
+    cls: Class we're constructing for this message type.
+  """
+  for enum_type in descriptor.enum_types:
+    setattr(cls, enum_type.name, enum_type_wrapper.EnumTypeWrapper(enum_type))
+    for enum_value in enum_type.values:
+      setattr(cls, enum_value.name, enum_value.number)
+
+
+def _DefaultValueConstructorForField(field):
+  """Returns a function which returns a default value for a field.
+
+  Args:
+    field: FieldDescriptor object for this field.
+
+  The returned function has one argument:
+    message: Message instance containing this field, or a weakref proxy
+      of same.
+
+  That function in turn returns a default value for this field.  The default
+    value may refer back to |message| via a weak reference.
+  """
+
+  if field.label == _FieldDescriptor.LABEL_REPEATED:
+    if field.has_default_value and field.default_value != []:
+      raise ValueError('Repeated field default value not empty list: %s' % (
+          field.default_value))
+    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      # We can't look at _concrete_class yet since it might not have
+      # been set.  (Depends on order in which we initialize the classes).
+      message_type = field.message_type
+      def MakeRepeatedMessageDefault(message):
+        return containers.RepeatedCompositeFieldContainer(
+            message._listener_for_children, field.message_type)
+      return MakeRepeatedMessageDefault
+    else:
+      type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
+      def MakeRepeatedScalarDefault(message):
+        return containers.RepeatedScalarFieldContainer(
+            message._listener_for_children, type_checker)
+      return MakeRepeatedScalarDefault
+
+  if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    # _concrete_class may not yet be initialized.
+    message_type = field.message_type
+    def MakeSubMessageDefault(message):
+      result = message_type._concrete_class()
+      result._SetListener(message._listener_for_children)
+      return result
+    return MakeSubMessageDefault
+
+  def MakeScalarDefault(message):
+    # TODO(protobuf-team): This may be broken since there may not be
+    # default_value.  Combine with has_default_value somehow.
+    return field.default_value
+  return MakeScalarDefault
+
+
+def _AddInitMethod(message_descriptor, cls):
+  """Adds an __init__ method to cls."""
+  fields = message_descriptor.fields
+  def init(self, **kwargs):
+    self._cached_byte_size = 0
+    self._cached_byte_size_dirty = len(kwargs) > 0
+    self._fields = {}
+    # _unknown_fields is () when empty for efficiency, and will be turned into
+    # a list if fields are added.
+    self._unknown_fields = ()
+    self._is_present_in_parent = False
+    self._listener = message_listener_mod.NullMessageListener()
+    self._listener_for_children = _Listener(self)
+    for field_name, field_value in kwargs.iteritems():
+      field = _GetFieldByName(message_descriptor, field_name)
+      if field is None:
+        raise TypeError("%s() got an unexpected keyword argument '%s'" %
+                        (message_descriptor.name, field_name))
+      if field.label == _FieldDescriptor.LABEL_REPEATED:
+        copy = field._default_constructor(self)
+        if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:  # Composite
+          for val in field_value:
+            copy.add().MergeFrom(val)
+        else:  # Scalar
+          copy.extend(field_value)
+        self._fields[field] = copy
+      elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        copy = field._default_constructor(self)
+        copy.MergeFrom(field_value)
+        self._fields[field] = copy
+      else:
+        setattr(self, field_name, field_value)
+
+  init.__module__ = None
+  init.__doc__ = None
+  cls.__init__ = init
+
+
+def _GetFieldByName(message_descriptor, field_name):
+  """Returns a field descriptor by field name.
+
+  Args:
+    message_descriptor: A Descriptor describing all fields in message.
+    field_name: The name of the field to retrieve.
+  Returns:
+    The field descriptor associated with the field name.
+  """
+  try:
+    return message_descriptor.fields_by_name[field_name]
+  except KeyError:
+    raise ValueError('Protocol message has no "%s" field.' % field_name)
+
+
+def _AddPropertiesForFields(descriptor, cls):
+  """Adds properties for all fields in this protocol message type."""
+  for field in descriptor.fields:
+    _AddPropertiesForField(field, cls)
+
+  if descriptor.is_extendable:
+    # _ExtensionDict is just an adaptor with no state so we allocate a new one
+    # every time it is accessed.
+    cls.Extensions = property(lambda self: _ExtensionDict(self))
+
+
+def _AddPropertiesForField(field, cls):
+  """Adds a public property for a protocol message field.
+  Clients can use this property to get and (in the case
+  of non-repeated scalar fields) directly set the value
+  of a protocol message field.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  # Catch it if we add other types that we should
+  # handle specially here.
+  assert _FieldDescriptor.MAX_CPPTYPE == 10
+
+  constant_name = field.name.upper() + "_FIELD_NUMBER"
+  setattr(cls, constant_name, field.number)
+
+  if field.label == _FieldDescriptor.LABEL_REPEATED:
+    _AddPropertiesForRepeatedField(field, cls)
+  elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    _AddPropertiesForNonRepeatedCompositeField(field, cls)
+  else:
+    _AddPropertiesForNonRepeatedScalarField(field, cls)
+
+
+def _AddPropertiesForRepeatedField(field, cls):
+  """Adds a public property for a "repeated" protocol message field.  Clients
+  can use this property to get the value of the field, which will be either a
+  _RepeatedScalarFieldContainer or _RepeatedCompositeFieldContainer (see
+  below).
+
+  Note that when clients add values to these containers, we perform
+  type-checking in the case of repeated scalar fields, and we also set any
+  necessary "has" bits as a side-effect.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+
+  def getter(self):
+    field_value = self._fields.get(field)
+    if field_value is None:
+      # Construct a new object to represent this field.
+      field_value = field._default_constructor(self)
+
+      # Atomically check if another thread has preempted us and, if not, swap
+      # in the new object we just created.  If someone has preempted us, we
+      # take that object and discard ours.
+      # WARNING:  We are relying on setdefault() being atomic.  This is true
+      #   in CPython but we haven't investigated others.  This warning appears
+      #   in several other locations in this file.
+      field_value = self._fields.setdefault(field, field_value)
+    return field_value
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+
+  # We define a setter just so we can throw an exception with a more
+  # helpful error message.
+  def setter(self, new_value):
+    raise AttributeError('Assignment not allowed to repeated field '
+                         '"%s" in protocol message object.' % proto_field_name)
+
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForNonRepeatedScalarField(field, cls):
+  """Adds a public property for a nonrepeated, scalar protocol message field.
+  Clients can use this property to get and directly set the value of the field.
+  Note that when the client sets the value of a field by using this property,
+  all necessary "has" bits are set as a side-effect, and we also perform
+  type-checking.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+  type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
+  default_value = field.default_value
+  valid_values = set()
+
+  def getter(self):
+    # TODO(protobuf-team): This may be broken since there may not be
+    # default_value.  Combine with has_default_value somehow.
+    return self._fields.get(field, default_value)
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+  def setter(self, new_value):
+    type_checker.CheckValue(new_value)
+    self._fields[field] = new_value
+    # Check _cached_byte_size_dirty inline to improve performance, since scalar
+    # setters are called frequently.
+    if not self._cached_byte_size_dirty:
+      self._Modified()
+
+  setter.__module__ = None
+  setter.__doc__ = 'Setter for %s.' % proto_field_name
+
+  # Add a property to encapsulate the getter/setter.
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForNonRepeatedCompositeField(field, cls):
+  """Adds a public property for a nonrepeated, composite protocol message field.
+  A composite field is a "group" or "message" field.
+
+  Clients can use this property to get the value of the field, but cannot
+  assign to the property directly.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  # TODO(robinson): Remove duplication with similar method
+  # for non-repeated scalars.
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+
+  # TODO(komarek): Can anyone explain to me why we cache the message_type this
+  # way, instead of referring to field.message_type inside of getter(self)?
+  # What if someone sets message_type later on (which makes for simpler
+  # dyanmic proto descriptor and class creation code).
+  message_type = field.message_type
+
+  def getter(self):
+    field_value = self._fields.get(field)
+    if field_value is None:
+      # Construct a new object to represent this field.
+      field_value = message_type._concrete_class()  # use field.message_type?
+      field_value._SetListener(self._listener_for_children)
+
+      # Atomically check if another thread has preempted us and, if not, swap
+      # in the new object we just created.  If someone has preempted us, we
+      # take that object and discard ours.
+      # WARNING:  We are relying on setdefault() being atomic.  This is true
+      #   in CPython but we haven't investigated others.  This warning appears
+      #   in several other locations in this file.
+      field_value = self._fields.setdefault(field, field_value)
+    return field_value
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+
+  # We define a setter just so we can throw an exception with a more
+  # helpful error message.
+  def setter(self, new_value):
+    raise AttributeError('Assignment not allowed to composite field '
+                         '"%s" in protocol message object.' % proto_field_name)
+
+  # Add a property to encapsulate the getter.
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForExtensions(descriptor, cls):
+  """Adds properties for all fields in this protocol message type."""
+  extension_dict = descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    constant_name = extension_name.upper() + "_FIELD_NUMBER"
+    setattr(cls, constant_name, extension_field.number)
+
+
+def _AddStaticMethods(cls):
+  # TODO(robinson): This probably needs to be thread-safe(?)
+  def RegisterExtension(extension_handle):
+    extension_handle.containing_type = cls.DESCRIPTOR
+    _AttachFieldHelpers(cls, extension_handle)
+
+    # Try to insert our extension, failing if an extension with the same number
+    # already exists.
+    actual_handle = cls._extensions_by_number.setdefault(
+        extension_handle.number, extension_handle)
+    if actual_handle is not extension_handle:
+      raise AssertionError(
+          'Extensions "%s" and "%s" both try to extend message type "%s" with '
+          'field number %d.' %
+          (extension_handle.full_name, actual_handle.full_name,
+           cls.DESCRIPTOR.full_name, extension_handle.number))
+
+    cls._extensions_by_name[extension_handle.full_name] = extension_handle
+
+    handle = extension_handle  # avoid line wrapping
+    if _IsMessageSetExtension(handle):
+      # MessageSet extension.  Also register under type name.
+      cls._extensions_by_name[
+          extension_handle.message_type.full_name] = extension_handle
+
+  cls.RegisterExtension = staticmethod(RegisterExtension)
+
+  def FromString(s):
+    message = cls()
+    message.MergeFromString(s)
+    return message
+  cls.FromString = staticmethod(FromString)
+
+
+def _IsPresent(item):
+  """Given a (FieldDescriptor, value) tuple from _fields, return true if the
+  value should be included in the list returned by ListFields()."""
+
+  if item[0].label == _FieldDescriptor.LABEL_REPEATED:
+    return bool(item[1])
+  elif item[0].cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    return item[1]._is_present_in_parent
+  else:
+    return True
+
+
+def _AddListFieldsMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def ListFields(self):
+    all_fields = [item for item in self._fields.iteritems() if _IsPresent(item)]
+    all_fields.sort(key = lambda item: item[0].number)
+    return all_fields
+
+  cls.ListFields = ListFields
+
+
+def _AddHasFieldMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  singular_fields = {}
+  for field in message_descriptor.fields:
+    if field.label != _FieldDescriptor.LABEL_REPEATED:
+      singular_fields[field.name] = field
+
+  def HasField(self, field_name):
+    try:
+      field = singular_fields[field_name]
+    except KeyError:
+      raise ValueError(
+          'Protocol message has no singular "%s" field.' % field_name)
+
+    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      value = self._fields.get(field)
+      return value is not None and value._is_present_in_parent
+    else:
+      return field in self._fields
+  cls.HasField = HasField
+
+
+def _AddClearFieldMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def ClearField(self, field_name):
+    try:
+      field = message_descriptor.fields_by_name[field_name]
+    except KeyError:
+      raise ValueError('Protocol message has no "%s" field.' % field_name)
+
+    if field in self._fields:
+      # Note:  If the field is a sub-message, its listener will still point
+      #   at us.  That's fine, because the worst than can happen is that it
+      #   will call _Modified() and invalidate our byte size.  Big deal.
+      del self._fields[field]
+
+    # Always call _Modified() -- even if nothing was changed, this is
+    # a mutating method, and thus calling it should cause the field to become
+    # present in the parent message.
+    self._Modified()
+
+  cls.ClearField = ClearField
+
+
+def _AddClearExtensionMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def ClearExtension(self, extension_handle):
+    _VerifyExtensionHandle(self, extension_handle)
+
+    # Similar to ClearField(), above.
+    if extension_handle in self._fields:
+      del self._fields[extension_handle]
+    self._Modified()
+  cls.ClearExtension = ClearExtension
+
+
+def _AddClearMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def Clear(self):
+    # Clear fields.
+    self._fields = {}
+    self._unknown_fields = ()
+    self._Modified()
+  cls.Clear = Clear
+
+
+def _AddHasExtensionMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def HasExtension(self, extension_handle):
+    _VerifyExtensionHandle(self, extension_handle)
+    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
+      raise KeyError('"%s" is repeated.' % extension_handle.full_name)
+
+    if extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      value = self._fields.get(extension_handle)
+      return value is not None and value._is_present_in_parent
+    else:
+      return extension_handle in self._fields
+  cls.HasExtension = HasExtension
+
+
+def _AddEqualsMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def __eq__(self, other):
+    if (not isinstance(other, message_mod.Message) or
+        other.DESCRIPTOR != self.DESCRIPTOR):
+      return False
+
+    if self is other:
+      return True
+
+    if not self.ListFields() == other.ListFields():
+      return False
+
+    # Sort unknown fields because their order shouldn't affect equality test.
+    unknown_fields = list(self._unknown_fields)
+    unknown_fields.sort()
+    other_unknown_fields = list(other._unknown_fields)
+    other_unknown_fields.sort()
+
+    return unknown_fields == other_unknown_fields
+
+  cls.__eq__ = __eq__
+
+
+def _AddStrMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def __str__(self):
+    return text_format.MessageToString(self)
+  cls.__str__ = __str__
+
+
+def _AddUnicodeMethod(unused_message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def __unicode__(self):
+    return text_format.MessageToString(self, as_utf8=True).decode('utf-8')
+  cls.__unicode__ = __unicode__
+
+
+def _AddSetListenerMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def SetListener(self, listener):
+    if listener is None:
+      self._listener = message_listener_mod.NullMessageListener()
+    else:
+      self._listener = listener
+  cls._SetListener = SetListener
+
+
+def _BytesForNonRepeatedElement(value, field_number, field_type):
+  """Returns the number of bytes needed to serialize a non-repeated element.
+  The returned byte count includes space for tag information and any
+  other additional space associated with serializing value.
+
+  Args:
+    value: Value we're serializing.
+    field_number: Field number of this value.  (Since the field number
+      is stored as part of a varint-encoded tag, this has an impact
+      on the total bytes required to serialize the value).
+    field_type: The type of the field.  One of the TYPE_* constants
+      within FieldDescriptor.
+  """
+  try:
+    fn = type_checkers.TYPE_TO_BYTE_SIZE_FN[field_type]
+    return fn(field_number, value)
+  except KeyError:
+    raise message_mod.EncodeError('Unrecognized field type: %d' % field_type)
+
+
+def _AddByteSizeMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def ByteSize(self):
+    if not self._cached_byte_size_dirty:
+      return self._cached_byte_size
+
+    size = 0
+    for field_descriptor, field_value in self.ListFields():
+      size += field_descriptor._sizer(field_value)
+
+    for tag_bytes, value_bytes in self._unknown_fields:
+      size += len(tag_bytes) + len(value_bytes)
+
+    self._cached_byte_size = size
+    self._cached_byte_size_dirty = False
+    self._listener_for_children.dirty = False
+    return size
+
+  cls.ByteSize = ByteSize
+
+
+def _AddSerializeToStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def SerializeToString(self):
+    # Check if the message has all of its required fields set.
+    errors = []
+    if not self.IsInitialized():
+      raise message_mod.EncodeError(
+          'Message %s is missing required fields: %s' % (
+          self.DESCRIPTOR.full_name, ','.join(self.FindInitializationErrors())))
+    return self.SerializePartialToString()
+  cls.SerializeToString = SerializeToString
+
+
+def _AddSerializePartialToStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def SerializePartialToString(self):
+    out = StringIO()
+    self._InternalSerialize(out.write)
+    return out.getvalue()
+  cls.SerializePartialToString = SerializePartialToString
+
+  def InternalSerialize(self, write_bytes):
+    for field_descriptor, field_value in self.ListFields():
+      field_descriptor._encoder(write_bytes, field_value)
+    for tag_bytes, value_bytes in self._unknown_fields:
+      write_bytes(tag_bytes)
+      write_bytes(value_bytes)
+  cls._InternalSerialize = InternalSerialize
+
+
+def _AddMergeFromStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def MergeFromString(self, serialized):
+    length = len(serialized)
+    try:
+      if self._InternalParse(serialized, 0, length) != length:
+        # The only reason _InternalParse would return early is if it
+        # encountered an end-group tag.
+        raise message_mod.DecodeError('Unexpected end-group tag.')
+    except IndexError:
+      raise message_mod.DecodeError('Truncated message.')
+    except struct.error, e:
+      raise message_mod.DecodeError(e)
+    return length   # Return this for legacy reasons.
+  cls.MergeFromString = MergeFromString
+
+  local_ReadTag = decoder.ReadTag
+  local_SkipField = decoder.SkipField
+  decoders_by_tag = cls._decoders_by_tag
+
+  def InternalParse(self, buffer, pos, end):
+    self._Modified()
+    field_dict = self._fields
+    unknown_field_list = self._unknown_fields
+    while pos != end:
+      (tag_bytes, new_pos) = local_ReadTag(buffer, pos)
+      field_decoder = decoders_by_tag.get(tag_bytes)
+      if field_decoder is None:
+        value_start_pos = new_pos
+        new_pos = local_SkipField(buffer, new_pos, end, tag_bytes)
+        if new_pos == -1:
+          return pos
+        if not unknown_field_list:
+          unknown_field_list = self._unknown_fields = []
+        unknown_field_list.append((tag_bytes, buffer[value_start_pos:new_pos]))
+        pos = new_pos
+      else:
+        pos = field_decoder(buffer, new_pos, end, self, field_dict)
+    return pos
+  cls._InternalParse = InternalParse
+
+
+def _AddIsInitializedMethod(message_descriptor, cls):
+  """Adds the IsInitialized and FindInitializationError methods to the
+  protocol message class."""
+
+  required_fields = [field for field in message_descriptor.fields
+                           if field.label == _FieldDescriptor.LABEL_REQUIRED]
+
+  def IsInitialized(self, errors=None):
+    """Checks if all required fields of a message are set.
+
+    Args:
+      errors:  A list which, if provided, will be populated with the field
+               paths of all missing required fields.
+
+    Returns:
+      True iff the specified message has all required fields set.
+    """
+
+    # Performance is critical so we avoid HasField() and ListFields().
+
+    for field in required_fields:
+      if (field not in self._fields or
+          (field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE and
+           not self._fields[field]._is_present_in_parent)):
+        if errors is not None:
+          errors.extend(self.FindInitializationErrors())
+        return False
+
+    for field, value in self._fields.iteritems():
+      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        if field.label == _FieldDescriptor.LABEL_REPEATED:
+          for element in value:
+            if not element.IsInitialized():
+              if errors is not None:
+                errors.extend(self.FindInitializationErrors())
+              return False
+        elif value._is_present_in_parent and not value.IsInitialized():
+          if errors is not None:
+            errors.extend(self.FindInitializationErrors())
+          return False
+
+    return True
+
+  cls.IsInitialized = IsInitialized
+
+  def FindInitializationErrors(self):
+    """Finds required fields which are not initialized.
+
+    Returns:
+      A list of strings.  Each string is a path to an uninitialized field from
+      the top-level message, e.g. "foo.bar[5].baz".
+    """
+
+    errors = []  # simplify things
+
+    for field in required_fields:
+      if not self.HasField(field.name):
+        errors.append(field.name)
+
+    for field, value in self.ListFields():
+      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        if field.is_extension:
+          name = "(%s)" % field.full_name
+        else:
+          name = field.name
+
+        if field.label == _FieldDescriptor.LABEL_REPEATED:
+          for i in xrange(len(value)):
+            element = value[i]
+            prefix = "%s[%d]." % (name, i)
+            sub_errors = element.FindInitializationErrors()
+            errors += [ prefix + error for error in sub_errors ]
+        else:
+          prefix = name + "."
+          sub_errors = value.FindInitializationErrors()
+          errors += [ prefix + error for error in sub_errors ]
+
+    return errors
+
+  cls.FindInitializationErrors = FindInitializationErrors
+
+
+def _AddMergeFromMethod(cls):
+  LABEL_REPEATED = _FieldDescriptor.LABEL_REPEATED
+  CPPTYPE_MESSAGE = _FieldDescriptor.CPPTYPE_MESSAGE
+
+  def MergeFrom(self, msg):
+    if not isinstance(msg, cls):
+      raise TypeError(
+          "Parameter to MergeFrom() must be instance of same class: "
+          "expected %s got %s." % (cls.__name__, type(msg).__name__))
+
+    assert msg is not self
+    self._Modified()
+
+    fields = self._fields
+
+    for field, value in msg._fields.iteritems():
+      if field.label == LABEL_REPEATED:
+        field_value = fields.get(field)
+        if field_value is None:
+          # Construct a new object to represent this field.
+          field_value = field._default_constructor(self)
+          fields[field] = field_value
+        field_value.MergeFrom(value)
+      elif field.cpp_type == CPPTYPE_MESSAGE:
+        if value._is_present_in_parent:
+          field_value = fields.get(field)
+          if field_value is None:
+            # Construct a new object to represent this field.
+            field_value = field._default_constructor(self)
+            fields[field] = field_value
+          field_value.MergeFrom(value)
+      else:
+        self._fields[field] = value
+
+    if msg._unknown_fields:
+      if not self._unknown_fields:
+        self._unknown_fields = []
+      self._unknown_fields.extend(msg._unknown_fields)
+
+  cls.MergeFrom = MergeFrom
+
+
+def _AddMessageMethods(message_descriptor, cls):
+  """Adds implementations of all Message methods to cls."""
+  _AddListFieldsMethod(message_descriptor, cls)
+  _AddHasFieldMethod(message_descriptor, cls)
+  _AddClearFieldMethod(message_descriptor, cls)
+  if message_descriptor.is_extendable:
+    _AddClearExtensionMethod(cls)
+    _AddHasExtensionMethod(cls)
+  _AddClearMethod(message_descriptor, cls)
+  _AddEqualsMethod(message_descriptor, cls)
+  _AddStrMethod(message_descriptor, cls)
+  _AddUnicodeMethod(message_descriptor, cls)
+  _AddSetListenerMethod(cls)
+  _AddByteSizeMethod(message_descriptor, cls)
+  _AddSerializeToStringMethod(message_descriptor, cls)
+  _AddSerializePartialToStringMethod(message_descriptor, cls)
+  _AddMergeFromStringMethod(message_descriptor, cls)
+  _AddIsInitializedMethod(message_descriptor, cls)
+  _AddMergeFromMethod(cls)
+
+
+def _AddPrivateHelperMethods(cls):
+  """Adds implementation of private helper methods to cls."""
+
+  def Modified(self):
+    """Sets the _cached_byte_size_dirty bit to true,
+    and propagates this to our listener iff this was a state change.
+    """
+
+    # Note:  Some callers check _cached_byte_size_dirty before calling
+    #   _Modified() as an extra optimization.  So, if this method is ever
+    #   changed such that it does stuff even when _cached_byte_size_dirty is
+    #   already true, the callers need to be updated.
+    if not self._cached_byte_size_dirty:
+      self._cached_byte_size_dirty = True
+      self._listener_for_children.dirty = True
+      self._is_present_in_parent = True
+      self._listener.Modified()
+
+  cls._Modified = Modified
+  cls.SetInParent = Modified
+
+
+class _Listener(object):
+
+  """MessageListener implementation that a parent message registers with its
+  child message.
+
+  In order to support semantics like:
+
+    foo.bar.baz.qux = 23
+    assert foo.HasField('bar')
+
+  ...child objects must have back references to their parents.
+  This helper class is at the heart of this support.
+  """
+
+  def __init__(self, parent_message):
+    """Args:
+      parent_message: The message whose _Modified() method we should call when
+        we receive Modified() messages.
+    """
+    # This listener establishes a back reference from a child (contained) object
+    # to its parent (containing) object.  We make this a weak reference to avoid
+    # creating cyclic garbage when the client finishes with the 'parent' object
+    # in the tree.
+    if isinstance(parent_message, weakref.ProxyType):
+      self._parent_message_weakref = parent_message
+    else:
+      self._parent_message_weakref = weakref.proxy(parent_message)
+
+    # As an optimization, we also indicate directly on the listener whether
+    # or not the parent message is dirty.  This way we can avoid traversing
+    # up the tree in the common case.
+    self.dirty = False
+
+  def Modified(self):
+    if self.dirty:
+      return
+    try:
+      # Propagate the signal to our parents iff this is the first field set.
+      self._parent_message_weakref._Modified()
+    except ReferenceError:
+      # We can get here if a client has kept a reference to a child object,
+      # and is now setting a field on it, but the child's parent has been
+      # garbage-collected.  This is not an error.
+      pass
+
+
+# TODO(robinson): Move elsewhere?  This file is getting pretty ridiculous...
+# TODO(robinson): Unify error handling of "unknown extension" crap.
+# TODO(robinson): Support iteritems()-style iteration over all
+# extensions with the "has" bits turned on?
+class _ExtensionDict(object):
+
+  """Dict-like container for supporting an indexable "Extensions"
+  field on proto instances.
+
+  Note that in all cases we expect extension handles to be
+  FieldDescriptors.
+  """
+
+  def __init__(self, extended_message):
+    """extended_message: Message instance for which we are the Extensions dict.
+    """
+
+    self._extended_message = extended_message
+
+  def __getitem__(self, extension_handle):
+    """Returns the current value of the given extension handle."""
+
+    _VerifyExtensionHandle(self._extended_message, extension_handle)
+
+    result = self._extended_message._fields.get(extension_handle)
+    if result is not None:
+      return result
+
+    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
+      result = extension_handle._default_constructor(self._extended_message)
+    elif extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      result = extension_handle.message_type._concrete_class()
+      try:
+        result._SetListener(self._extended_message._listener_for_children)
+      except ReferenceError:
+        pass
+    else:
+      # Singular scalar -- just return the default without inserting into the
+      # dict.
+      return extension_handle.default_value
+
+    # Atomically check if another thread has preempted us and, if not, swap
+    # in the new object we just created.  If someone has preempted us, we
+    # take that object and discard ours.
+    # WARNING:  We are relying on setdefault() being atomic.  This is true
+    #   in CPython but we haven't investigated others.  This warning appears
+    #   in several other locations in this file.
+    result = self._extended_message._fields.setdefault(
+        extension_handle, result)
+
+    return result
+
+  def __eq__(self, other):
+    if not isinstance(other, self.__class__):
+      return False
+
+    my_fields = self._extended_message.ListFields()
+    other_fields = other._extended_message.ListFields()
+
+    # Get rid of non-extension fields.
+    my_fields    = [ field for field in my_fields    if field.is_extension ]
+    other_fields = [ field for field in other_fields if field.is_extension ]
+
+    return my_fields == other_fields
+
+  def __ne__(self, other):
+    return not self == other
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  # Note that this is only meaningful for non-repeated, scalar extension
+  # fields.  Note also that we may have to call _Modified() when we do
+  # successfully set a field this way, to set any necssary "has" bits in the
+  # ancestors of the extended message.
+  def __setitem__(self, extension_handle, value):
+    """If extension_handle specifies a non-repeated, scalar extension
+    field, sets the value of that field.
+    """
+
+    _VerifyExtensionHandle(self._extended_message, extension_handle)
+
+    if (extension_handle.label == _FieldDescriptor.LABEL_REPEATED or
+        extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE):
+      raise TypeError(
+          'Cannot assign to extension "%s" because it is a repeated or '
+          'composite type.' % extension_handle.full_name)
+
+    # It's slightly wasteful to lookup the type checker each time,
+    # but we expect this to be a vanishingly uncommon case anyway.
+    type_checker = type_checkers.GetTypeChecker(
+        extension_handle.cpp_type, extension_handle.type)
+    type_checker.CheckValue(value)
+    self._extended_message._fields[extension_handle] = value
+    self._extended_message._Modified()
+
+  def _FindExtensionByName(self, name):
+    """Tries to find a known extension with the specified name.
+
+    Args:
+      name: Extension full name.
+
+    Returns:
+      Extension field descriptor.
+    """
+    return self._extended_message._extensions_by_name.get(name, None)
diff --git a/generator/google/protobuf/internal/type_checkers.py b/generator/google/protobuf/internal/type_checkers.py
new file mode 100644
index 0000000..2b3cd4d
--- /dev/null
+++ b/generator/google/protobuf/internal/type_checkers.py
@@ -0,0 +1,286 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides type checking routines.
+
+This module defines type checking utilities in the forms of dictionaries:
+
+VALUE_CHECKERS: A dictionary of field types and a value validation object.
+TYPE_TO_BYTE_SIZE_FN: A dictionary with field types and a size computing
+  function.
+TYPE_TO_SERIALIZE_METHOD: A dictionary with field types and serialization
+  function.
+FIELD_TYPE_TO_WIRE_TYPE: A dictionary with field typed and their
+  coresponding wire types.
+TYPE_TO_DESERIALIZE_METHOD: A dictionary with field types and deserialization
+  function.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+from google.protobuf.internal import decoder
+from google.protobuf.internal import encoder
+from google.protobuf.internal import wire_format
+from google.protobuf import descriptor
+
+_FieldDescriptor = descriptor.FieldDescriptor
+
+
+def GetTypeChecker(cpp_type, field_type):
+  """Returns a type checker for a message field of the specified types.
+
+  Args:
+    cpp_type: C++ type of the field (see descriptor.py).
+    field_type: Protocol message field type (see descriptor.py).
+
+  Returns:
+    An instance of TypeChecker which can be used to verify the types
+    of values assigned to a field of the specified type.
+  """
+  if (cpp_type == _FieldDescriptor.CPPTYPE_STRING and
+      field_type == _FieldDescriptor.TYPE_STRING):
+    return UnicodeValueChecker()
+  return _VALUE_CHECKERS[cpp_type]
+
+
+# None of the typecheckers below make any attempt to guard against people
+# subclassing builtin types and doing weird things.  We're not trying to
+# protect against malicious clients here, just people accidentally shooting
+# themselves in the foot in obvious ways.
+
+class TypeChecker(object):
+
+  """Type checker used to catch type errors as early as possible
+  when the client is setting scalar fields in protocol messages.
+  """
+
+  def __init__(self, *acceptable_types):
+    self._acceptable_types = acceptable_types
+
+  def CheckValue(self, proposed_value):
+    if not isinstance(proposed_value, self._acceptable_types):
+      message = ('%.1024r has type %s, but expected one of: %s' %
+                 (proposed_value, type(proposed_value), self._acceptable_types))
+      raise TypeError(message)
+
+
+# IntValueChecker and its subclasses perform integer type-checks
+# and bounds-checks.
+class IntValueChecker(object):
+
+  """Checker used for integer fields.  Performs type-check and range check."""
+
+  def CheckValue(self, proposed_value):
+    if not isinstance(proposed_value, (int, long)):
+      message = ('%.1024r has type %s, but expected one of: %s' %
+                 (proposed_value, type(proposed_value), (int, long)))
+      raise TypeError(message)
+    if not self._MIN <= proposed_value <= self._MAX:
+      raise ValueError('Value out of range: %d' % proposed_value)
+
+
+class UnicodeValueChecker(object):
+
+  """Checker used for string fields."""
+
+  def CheckValue(self, proposed_value):
+    if not isinstance(proposed_value, (str, unicode)):
+      message = ('%.1024r has type %s, but expected one of: %s' %
+                 (proposed_value, type(proposed_value), (str, unicode)))
+      raise TypeError(message)
+
+    # If the value is of type 'str' make sure that it is in 7-bit ASCII
+    # encoding.
+    if isinstance(proposed_value, str):
+      try:
+        unicode(proposed_value, 'ascii')
+      except UnicodeDecodeError:
+        raise ValueError('%.1024r has type str, but isn\'t in 7-bit ASCII '
+                         'encoding. Non-ASCII strings must be converted to '
+                         'unicode objects before being added.' %
+                         (proposed_value))
+
+
+class Int32ValueChecker(IntValueChecker):
+  # We're sure to use ints instead of longs here since comparison may be more
+  # efficient.
+  _MIN = -2147483648
+  _MAX = 2147483647
+
+
+class Uint32ValueChecker(IntValueChecker):
+  _MIN = 0
+  _MAX = (1 << 32) - 1
+
+
+class Int64ValueChecker(IntValueChecker):
+  _MIN = -(1 << 63)
+  _MAX = (1 << 63) - 1
+
+
+class Uint64ValueChecker(IntValueChecker):
+  _MIN = 0
+  _MAX = (1 << 64) - 1
+
+
+# Type-checkers for all scalar CPPTYPEs.
+_VALUE_CHECKERS = {
+    _FieldDescriptor.CPPTYPE_INT32: Int32ValueChecker(),
+    _FieldDescriptor.CPPTYPE_INT64: Int64ValueChecker(),
+    _FieldDescriptor.CPPTYPE_UINT32: Uint32ValueChecker(),
+    _FieldDescriptor.CPPTYPE_UINT64: Uint64ValueChecker(),
+    _FieldDescriptor.CPPTYPE_DOUBLE: TypeChecker(
+        float, int, long),
+    _FieldDescriptor.CPPTYPE_FLOAT: TypeChecker(
+        float, int, long),
+    _FieldDescriptor.CPPTYPE_BOOL: TypeChecker(bool, int),
+    _FieldDescriptor.CPPTYPE_ENUM: Int32ValueChecker(),
+    _FieldDescriptor.CPPTYPE_STRING: TypeChecker(str),
+    }
+
+
+# Map from field type to a function F, such that F(field_num, value)
+# gives the total byte size for a value of the given type.  This
+# byte size includes tag information and any other additional space
+# associated with serializing "value".
+TYPE_TO_BYTE_SIZE_FN = {
+    _FieldDescriptor.TYPE_DOUBLE: wire_format.DoubleByteSize,
+    _FieldDescriptor.TYPE_FLOAT: wire_format.FloatByteSize,
+    _FieldDescriptor.TYPE_INT64: wire_format.Int64ByteSize,
+    _FieldDescriptor.TYPE_UINT64: wire_format.UInt64ByteSize,
+    _FieldDescriptor.TYPE_INT32: wire_format.Int32ByteSize,
+    _FieldDescriptor.TYPE_FIXED64: wire_format.Fixed64ByteSize,
+    _FieldDescriptor.TYPE_FIXED32: wire_format.Fixed32ByteSize,
+    _FieldDescriptor.TYPE_BOOL: wire_format.BoolByteSize,
+    _FieldDescriptor.TYPE_STRING: wire_format.StringByteSize,
+    _FieldDescriptor.TYPE_GROUP: wire_format.GroupByteSize,
+    _FieldDescriptor.TYPE_MESSAGE: wire_format.MessageByteSize,
+    _FieldDescriptor.TYPE_BYTES: wire_format.BytesByteSize,
+    _FieldDescriptor.TYPE_UINT32: wire_format.UInt32ByteSize,
+    _FieldDescriptor.TYPE_ENUM: wire_format.EnumByteSize,
+    _FieldDescriptor.TYPE_SFIXED32: wire_format.SFixed32ByteSize,
+    _FieldDescriptor.TYPE_SFIXED64: wire_format.SFixed64ByteSize,
+    _FieldDescriptor.TYPE_SINT32: wire_format.SInt32ByteSize,
+    _FieldDescriptor.TYPE_SINT64: wire_format.SInt64ByteSize
+    }
+
+
+# Maps from field types to encoder constructors.
+TYPE_TO_ENCODER = {
+    _FieldDescriptor.TYPE_DOUBLE: encoder.DoubleEncoder,
+    _FieldDescriptor.TYPE_FLOAT: encoder.FloatEncoder,
+    _FieldDescriptor.TYPE_INT64: encoder.Int64Encoder,
+    _FieldDescriptor.TYPE_UINT64: encoder.UInt64Encoder,
+    _FieldDescriptor.TYPE_INT32: encoder.Int32Encoder,
+    _FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Encoder,
+    _FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Encoder,
+    _FieldDescriptor.TYPE_BOOL: encoder.BoolEncoder,
+    _FieldDescriptor.TYPE_STRING: encoder.StringEncoder,
+    _FieldDescriptor.TYPE_GROUP: encoder.GroupEncoder,
+    _FieldDescriptor.TYPE_MESSAGE: encoder.MessageEncoder,
+    _FieldDescriptor.TYPE_BYTES: encoder.BytesEncoder,
+    _FieldDescriptor.TYPE_UINT32: encoder.UInt32Encoder,
+    _FieldDescriptor.TYPE_ENUM: encoder.EnumEncoder,
+    _FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Encoder,
+    _FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Encoder,
+    _FieldDescriptor.TYPE_SINT32: encoder.SInt32Encoder,
+    _FieldDescriptor.TYPE_SINT64: encoder.SInt64Encoder,
+    }
+
+
+# Maps from field types to sizer constructors.
+TYPE_TO_SIZER = {
+    _FieldDescriptor.TYPE_DOUBLE: encoder.DoubleSizer,
+    _FieldDescriptor.TYPE_FLOAT: encoder.FloatSizer,
+    _FieldDescriptor.TYPE_INT64: encoder.Int64Sizer,
+    _FieldDescriptor.TYPE_UINT64: encoder.UInt64Sizer,
+    _FieldDescriptor.TYPE_INT32: encoder.Int32Sizer,
+    _FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Sizer,
+    _FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Sizer,
+    _FieldDescriptor.TYPE_BOOL: encoder.BoolSizer,
+    _FieldDescriptor.TYPE_STRING: encoder.StringSizer,
+    _FieldDescriptor.TYPE_GROUP: encoder.GroupSizer,
+    _FieldDescriptor.TYPE_MESSAGE: encoder.MessageSizer,
+    _FieldDescriptor.TYPE_BYTES: encoder.BytesSizer,
+    _FieldDescriptor.TYPE_UINT32: encoder.UInt32Sizer,
+    _FieldDescriptor.TYPE_ENUM: encoder.EnumSizer,
+    _FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Sizer,
+    _FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Sizer,
+    _FieldDescriptor.TYPE_SINT32: encoder.SInt32Sizer,
+    _FieldDescriptor.TYPE_SINT64: encoder.SInt64Sizer,
+    }
+
+
+# Maps from field type to a decoder constructor.
+TYPE_TO_DECODER = {
+    _FieldDescriptor.TYPE_DOUBLE: decoder.DoubleDecoder,
+    _FieldDescriptor.TYPE_FLOAT: decoder.FloatDecoder,
+    _FieldDescriptor.TYPE_INT64: decoder.Int64Decoder,
+    _FieldDescriptor.TYPE_UINT64: decoder.UInt64Decoder,
+    _FieldDescriptor.TYPE_INT32: decoder.Int32Decoder,
+    _FieldDescriptor.TYPE_FIXED64: decoder.Fixed64Decoder,
+    _FieldDescriptor.TYPE_FIXED32: decoder.Fixed32Decoder,
+    _FieldDescriptor.TYPE_BOOL: decoder.BoolDecoder,
+    _FieldDescriptor.TYPE_STRING: decoder.StringDecoder,
+    _FieldDescriptor.TYPE_GROUP: decoder.GroupDecoder,
+    _FieldDescriptor.TYPE_MESSAGE: decoder.MessageDecoder,
+    _FieldDescriptor.TYPE_BYTES: decoder.BytesDecoder,
+    _FieldDescriptor.TYPE_UINT32: decoder.UInt32Decoder,
+    _FieldDescriptor.TYPE_ENUM: decoder.EnumDecoder,
+    _FieldDescriptor.TYPE_SFIXED32: decoder.SFixed32Decoder,
+    _FieldDescriptor.TYPE_SFIXED64: decoder.SFixed64Decoder,
+    _FieldDescriptor.TYPE_SINT32: decoder.SInt32Decoder,
+    _FieldDescriptor.TYPE_SINT64: decoder.SInt64Decoder,
+    }
+
+# Maps from field type to expected wiretype.
+FIELD_TYPE_TO_WIRE_TYPE = {
+    _FieldDescriptor.TYPE_DOUBLE: wire_format.WIRETYPE_FIXED64,
+    _FieldDescriptor.TYPE_FLOAT: wire_format.WIRETYPE_FIXED32,
+    _FieldDescriptor.TYPE_INT64: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_UINT64: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_INT32: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_FIXED64: wire_format.WIRETYPE_FIXED64,
+    _FieldDescriptor.TYPE_FIXED32: wire_format.WIRETYPE_FIXED32,
+    _FieldDescriptor.TYPE_BOOL: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_STRING:
+      wire_format.WIRETYPE_LENGTH_DELIMITED,
+    _FieldDescriptor.TYPE_GROUP: wire_format.WIRETYPE_START_GROUP,
+    _FieldDescriptor.TYPE_MESSAGE:
+      wire_format.WIRETYPE_LENGTH_DELIMITED,
+    _FieldDescriptor.TYPE_BYTES:
+      wire_format.WIRETYPE_LENGTH_DELIMITED,
+    _FieldDescriptor.TYPE_UINT32: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_ENUM: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_SFIXED32: wire_format.WIRETYPE_FIXED32,
+    _FieldDescriptor.TYPE_SFIXED64: wire_format.WIRETYPE_FIXED64,
+    _FieldDescriptor.TYPE_SINT32: wire_format.WIRETYPE_VARINT,
+    _FieldDescriptor.TYPE_SINT64: wire_format.WIRETYPE_VARINT,
+    }
diff --git a/generator/google/protobuf/internal/wire_format.py b/generator/google/protobuf/internal/wire_format.py
new file mode 100644
index 0000000..c941fe1
--- /dev/null
+++ b/generator/google/protobuf/internal/wire_format.py
@@ -0,0 +1,268 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Constants and static functions to support protocol buffer wire format."""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+import struct
+from google.protobuf import descriptor
+from google.protobuf import message
+
+
+TAG_TYPE_BITS = 3  # Number of bits used to hold type info in a proto tag.
+TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1  # 0x7
+
+# These numbers identify the wire type of a protocol buffer value.
+# We use the least-significant TAG_TYPE_BITS bits of the varint-encoded
+# tag-and-type to store one of these WIRETYPE_* constants.
+# These values must match WireType enum in google/protobuf/wire_format.h.
+WIRETYPE_VARINT = 0
+WIRETYPE_FIXED64 = 1
+WIRETYPE_LENGTH_DELIMITED = 2
+WIRETYPE_START_GROUP = 3
+WIRETYPE_END_GROUP = 4
+WIRETYPE_FIXED32 = 5
+_WIRETYPE_MAX = 5
+
+
+# Bounds for various integer types.
+INT32_MAX = int((1 << 31) - 1)
+INT32_MIN = int(-(1 << 31))
+UINT32_MAX = (1 << 32) - 1
+
+INT64_MAX = (1 << 63) - 1
+INT64_MIN = -(1 << 63)
+UINT64_MAX = (1 << 64) - 1
+
+# "struct" format strings that will encode/decode the specified formats.
+FORMAT_UINT32_LITTLE_ENDIAN = '<I'
+FORMAT_UINT64_LITTLE_ENDIAN = '<Q'
+FORMAT_FLOAT_LITTLE_ENDIAN = '<f'
+FORMAT_DOUBLE_LITTLE_ENDIAN = '<d'
+
+
+# We'll have to provide alternate implementations of AppendLittleEndian*() on
+# any architectures where these checks fail.
+if struct.calcsize(FORMAT_UINT32_LITTLE_ENDIAN) != 4:
+  raise AssertionError('Format "I" is not a 32-bit number.')
+if struct.calcsize(FORMAT_UINT64_LITTLE_ENDIAN) != 8:
+  raise AssertionError('Format "Q" is not a 64-bit number.')
+
+
+def PackTag(field_number, wire_type):
+  """Returns an unsigned 32-bit integer that encodes the field number and
+  wire type information in standard protocol message wire format.
+
+  Args:
+    field_number: Expected to be an integer in the range [1, 1 << 29)
+    wire_type: One of the WIRETYPE_* constants.
+  """
+  if not 0 <= wire_type <= _WIRETYPE_MAX:
+    raise message.EncodeError('Unknown wire type: %d' % wire_type)
+  return (field_number << TAG_TYPE_BITS) | wire_type
+
+
+def UnpackTag(tag):
+  """The inverse of PackTag().  Given an unsigned 32-bit number,
+  returns a (field_number, wire_type) tuple.
+  """
+  return (tag >> TAG_TYPE_BITS), (tag & TAG_TYPE_MASK)
+
+
+def ZigZagEncode(value):
+  """ZigZag Transform:  Encodes signed integers so that they can be
+  effectively used with varint encoding.  See wire_format.h for
+  more details.
+  """
+  if value >= 0:
+    return value << 1
+  return (value << 1) ^ (~0)
+
+
+def ZigZagDecode(value):
+  """Inverse of ZigZagEncode()."""
+  if not value & 0x1:
+    return value >> 1
+  return (value >> 1) ^ (~0)
+
+
+
+# The *ByteSize() functions below return the number of bytes required to
+# serialize "field number + type" information and then serialize the value.
+
+
+def Int32ByteSize(field_number, int32):
+  return Int64ByteSize(field_number, int32)
+
+
+def Int32ByteSizeNoTag(int32):
+  return _VarUInt64ByteSizeNoTag(0xffffffffffffffff & int32)
+
+
+def Int64ByteSize(field_number, int64):
+  # Have to convert to uint before calling UInt64ByteSize().
+  return UInt64ByteSize(field_number, 0xffffffffffffffff & int64)
+
+
+def UInt32ByteSize(field_number, uint32):
+  return UInt64ByteSize(field_number, uint32)
+
+
+def UInt64ByteSize(field_number, uint64):
+  return TagByteSize(field_number) + _VarUInt64ByteSizeNoTag(uint64)
+
+
+def SInt32ByteSize(field_number, int32):
+  return UInt32ByteSize(field_number, ZigZagEncode(int32))
+
+
+def SInt64ByteSize(field_number, int64):
+  return UInt64ByteSize(field_number, ZigZagEncode(int64))
+
+
+def Fixed32ByteSize(field_number, fixed32):
+  return TagByteSize(field_number) + 4
+
+
+def Fixed64ByteSize(field_number, fixed64):
+  return TagByteSize(field_number) + 8
+
+
+def SFixed32ByteSize(field_number, sfixed32):
+  return TagByteSize(field_number) + 4
+
+
+def SFixed64ByteSize(field_number, sfixed64):
+  return TagByteSize(field_number) + 8
+
+
+def FloatByteSize(field_number, flt):
+  return TagByteSize(field_number) + 4
+
+
+def DoubleByteSize(field_number, double):
+  return TagByteSize(field_number) + 8
+
+
+def BoolByteSize(field_number, b):
+  return TagByteSize(field_number) + 1
+
+
+def EnumByteSize(field_number, enum):
+  return UInt32ByteSize(field_number, enum)
+
+
+def StringByteSize(field_number, string):
+  return BytesByteSize(field_number, string.encode('utf-8'))
+
+
+def BytesByteSize(field_number, b):
+  return (TagByteSize(field_number)
+          + _VarUInt64ByteSizeNoTag(len(b))
+          + len(b))
+
+
+def GroupByteSize(field_number, message):
+  return (2 * TagByteSize(field_number)  # START and END group.
+          + message.ByteSize())
+
+
+def MessageByteSize(field_number, message):
+  return (TagByteSize(field_number)
+          + _VarUInt64ByteSizeNoTag(message.ByteSize())
+          + message.ByteSize())
+
+
+def MessageSetItemByteSize(field_number, msg):
+  # First compute the sizes of the tags.
+  # There are 2 tags for the beginning and ending of the repeated group, that
+  # is field number 1, one with field number 2 (type_id) and one with field
+  # number 3 (message).
+  total_size = (2 * TagByteSize(1) + TagByteSize(2) + TagByteSize(3))
+
+  # Add the number of bytes for type_id.
+  total_size += _VarUInt64ByteSizeNoTag(field_number)
+
+  message_size = msg.ByteSize()
+
+  # The number of bytes for encoding the length of the message.
+  total_size += _VarUInt64ByteSizeNoTag(message_size)
+
+  # The size of the message.
+  total_size += message_size
+  return total_size
+
+
+def TagByteSize(field_number):
+  """Returns the bytes required to serialize a tag with this field number."""
+  # Just pass in type 0, since the type won't affect the tag+type size.
+  return _VarUInt64ByteSizeNoTag(PackTag(field_number, 0))
+
+
+# Private helper function for the *ByteSize() functions above.
+
+def _VarUInt64ByteSizeNoTag(uint64):
+  """Returns the number of bytes required to serialize a single varint
+  using boundary value comparisons. (unrolled loop optimization -WPierce)
+  uint64 must be unsigned.
+  """
+  if uint64 <= 0x7f: return 1
+  if uint64 <= 0x3fff: return 2
+  if uint64 <= 0x1fffff: return 3
+  if uint64 <= 0xfffffff: return 4
+  if uint64 <= 0x7ffffffff: return 5
+  if uint64 <= 0x3ffffffffff: return 6
+  if uint64 <= 0x1ffffffffffff: return 7
+  if uint64 <= 0xffffffffffffff: return 8
+  if uint64 <= 0x7fffffffffffffff: return 9
+  if uint64 > UINT64_MAX:
+    raise message.EncodeError('Value out of range: %d' % uint64)
+  return 10
+
+
+NON_PACKABLE_TYPES = (
+  descriptor.FieldDescriptor.TYPE_STRING,
+  descriptor.FieldDescriptor.TYPE_GROUP,
+  descriptor.FieldDescriptor.TYPE_MESSAGE,
+  descriptor.FieldDescriptor.TYPE_BYTES
+)
+
+
+def IsTypePackable(field_type):
+  """Return true iff packable = true is valid for fields of this type.
+
+  Args:
+    field_type: a FieldDescriptor::Type value.
+
+  Returns:
+    True iff fields of this type are packable.
+  """
+  return field_type not in NON_PACKABLE_TYPES
diff --git a/generator/google/protobuf/message.py b/generator/google/protobuf/message.py
new file mode 100644
index 0000000..6ec2f8b
--- /dev/null
+++ b/generator/google/protobuf/message.py
@@ -0,0 +1,280 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# TODO(robinson): We should just make these methods all "pure-virtual" and move
+# all implementation out, into reflection.py for now.
+
+
+"""Contains an abstract base class for protocol messages."""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+
+class Error(Exception): pass
+class DecodeError(Error): pass
+class EncodeError(Error): pass
+
+
+class Message(object):
+
+  """Abstract base class for protocol messages.
+
+  Protocol message classes are almost always generated by the protocol
+  compiler.  These generated types subclass Message and implement the methods
+  shown below.
+
+  TODO(robinson): Link to an HTML document here.
+
+  TODO(robinson): Document that instances of this class will also
+  have an Extensions attribute with __getitem__ and __setitem__.
+  Again, not sure how to best convey this.
+
+  TODO(robinson): Document that the class must also have a static
+    RegisterExtension(extension_field) method.
+    Not sure how to best express at this point.
+  """
+
+  # TODO(robinson): Document these fields and methods.
+
+  __slots__ = []
+
+  DESCRIPTOR = None
+
+  def __deepcopy__(self, memo=None):
+    clone = type(self)()
+    clone.MergeFrom(self)
+    return clone
+
+  def __eq__(self, other_msg):
+    """Recursively compares two messages by value and structure."""
+    raise NotImplementedError
+
+  def __ne__(self, other_msg):
+    # Can't just say self != other_msg, since that would infinitely recurse. :)
+    return not self == other_msg
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  def __str__(self):
+    """Outputs a human-readable representation of the message."""
+    raise NotImplementedError
+
+  def __unicode__(self):
+    """Outputs a human-readable representation of the message."""
+    raise NotImplementedError
+
+  def MergeFrom(self, other_msg):
+    """Merges the contents of the specified message into current message.
+
+    This method merges the contents of the specified message into the current
+    message. Singular fields that are set in the specified message overwrite
+    the corresponding fields in the current message. Repeated fields are
+    appended. Singular sub-messages and groups are recursively merged.
+
+    Args:
+      other_msg: Message to merge into the current message.
+    """
+    raise NotImplementedError
+
+  def CopyFrom(self, other_msg):
+    """Copies the content of the specified message into the current message.
+
+    The method clears the current message and then merges the specified
+    message using MergeFrom.
+
+    Args:
+      other_msg: Message to copy into the current one.
+    """
+    if self is other_msg:
+      return
+    self.Clear()
+    self.MergeFrom(other_msg)
+
+  def Clear(self):
+    """Clears all data that was set in the message."""
+    raise NotImplementedError
+
+  def SetInParent(self):
+    """Mark this as present in the parent.
+
+    This normally happens automatically when you assign a field of a
+    sub-message, but sometimes you want to make the sub-message
+    present while keeping it empty.  If you find yourself using this,
+    you may want to reconsider your design."""
+    raise NotImplementedError
+
+  def IsInitialized(self):
+    """Checks if the message is initialized.
+
+    Returns:
+      The method returns True if the message is initialized (i.e. all of its
+      required fields are set).
+    """
+    raise NotImplementedError
+
+  # TODO(robinson): MergeFromString() should probably return None and be
+  # implemented in terms of a helper that returns the # of bytes read.  Our
+  # deserialization routines would use the helper when recursively
+  # deserializing, but the end user would almost always just want the no-return
+  # MergeFromString().
+
+  def MergeFromString(self, serialized):
+    """Merges serialized protocol buffer data into this message.
+
+    When we find a field in |serialized| that is already present
+    in this message:
+      - If it's a "repeated" field, we append to the end of our list.
+      - Else, if it's a scalar, we overwrite our field.
+      - Else, (it's a nonrepeated composite), we recursively merge
+        into the existing composite.
+
+    TODO(robinson): Document handling of unknown fields.
+
+    Args:
+      serialized: Any object that allows us to call buffer(serialized)
+        to access a string of bytes using the buffer interface.
+
+    TODO(robinson): When we switch to a helper, this will return None.
+
+    Returns:
+      The number of bytes read from |serialized|.
+      For non-group messages, this will always be len(serialized),
+      but for messages which are actually groups, this will
+      generally be less than len(serialized), since we must
+      stop when we reach an END_GROUP tag.  Note that if
+      we *do* stop because of an END_GROUP tag, the number
+      of bytes returned does not include the bytes
+      for the END_GROUP tag information.
+    """
+    raise NotImplementedError
+
+  def ParseFromString(self, serialized):
+    """Like MergeFromString(), except we clear the object first."""
+    self.Clear()
+    self.MergeFromString(serialized)
+
+  def SerializeToString(self):
+    """Serializes the protocol message to a binary string.
+
+    Returns:
+      A binary string representation of the message if all of the required
+      fields in the message are set (i.e. the message is initialized).
+
+    Raises:
+      message.EncodeError if the message isn't initialized.
+    """
+    raise NotImplementedError
+
+  def SerializePartialToString(self):
+    """Serializes the protocol message to a binary string.
+
+    This method is similar to SerializeToString but doesn't check if the
+    message is initialized.
+
+    Returns:
+      A string representation of the partial message.
+    """
+    raise NotImplementedError
+
+  # TODO(robinson): Decide whether we like these better
+  # than auto-generated has_foo() and clear_foo() methods
+  # on the instances themselves.  This way is less consistent
+  # with C++, but it makes reflection-type access easier and
+  # reduces the number of magically autogenerated things.
+  #
+  # TODO(robinson): Be sure to document (and test) exactly
+  # which field names are accepted here.  Are we case-sensitive?
+  # What do we do with fields that share names with Python keywords
+  # like 'lambda' and 'yield'?
+  #
+  # nnorwitz says:
+  # """
+  # Typically (in python), an underscore is appended to names that are
+  # keywords. So they would become lambda_ or yield_.
+  # """
+  def ListFields(self):
+    """Returns a list of (FieldDescriptor, value) tuples for all
+    fields in the message which are not empty.  A singular field is non-empty
+    if HasField() would return true, and a repeated field is non-empty if
+    it contains at least one element.  The fields are ordered by field
+    number"""
+    raise NotImplementedError
+
+  def HasField(self, field_name):
+    """Checks if a certain field is set for the message. Note if the
+    field_name is not defined in the message descriptor, ValueError will be
+    raised."""
+    raise NotImplementedError
+
+  def ClearField(self, field_name):
+    raise NotImplementedError
+
+  def HasExtension(self, extension_handle):
+    raise NotImplementedError
+
+  def ClearExtension(self, extension_handle):
+    raise NotImplementedError
+
+  def ByteSize(self):
+    """Returns the serialized size of this message.
+    Recursively calls ByteSize() on all contained messages.
+    """
+    raise NotImplementedError
+
+  def _SetListener(self, message_listener):
+    """Internal method used by the protocol message implementation.
+    Clients should not call this directly.
+
+    Sets a listener that this message will call on certain state transitions.
+
+    The purpose of this method is to register back-edges from children to
+    parents at runtime, for the purpose of setting "has" bits and
+    byte-size-dirty bits in the parent and ancestor objects whenever a child or
+    descendant object is modified.
+
+    If the client wants to disconnect this Message from the object tree, she
+    explicitly sets callback to None.
+
+    If message_listener is None, unregisters any existing listener.  Otherwise,
+    message_listener must implement the MessageListener interface in
+    internal/message_listener.py, and we discard any listener registered
+    via a previous _SetListener() call.
+    """
+    raise NotImplementedError
+
+  def __getstate__(self):
+    """Support the pickle protocol."""
+    return dict(serialized=self.SerializePartialToString())
+
+  def __setstate__(self, state):
+    """Support the pickle protocol."""
+    self.__init__()
+    self.ParseFromString(state['serialized'])
diff --git a/generator/google/protobuf/message_factory.py b/generator/google/protobuf/message_factory.py
new file mode 100644
index 0000000..36e2fef
--- /dev/null
+++ b/generator/google/protobuf/message_factory.py
@@ -0,0 +1,113 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Provides a factory class for generating dynamic messages."""
+
+__author__ = 'matthewtoia@google.com (Matt Toia)'
+
+from google.protobuf import descriptor_database
+from google.protobuf import descriptor_pool
+from google.protobuf import message
+from google.protobuf import reflection
+
+
+class MessageFactory(object):
+  """Factory for creating Proto2 messages from descriptors in a pool."""
+
+  def __init__(self):
+    """Initializes a new factory."""
+    self._classes = {}
+
+  def GetPrototype(self, descriptor):
+    """Builds a proto2 message class based on the passed in descriptor.
+
+    Passing a descriptor with a fully qualified name matching a previous
+    invocation will cause the same class to be returned.
+
+    Args:
+      descriptor: The descriptor to build from.
+
+    Returns:
+      A class describing the passed in descriptor.
+    """
+
+    if descriptor.full_name not in self._classes:
+      result_class = reflection.GeneratedProtocolMessageType(
+          descriptor.name.encode('ascii', 'ignore'),
+          (message.Message,),
+          {'DESCRIPTOR': descriptor})
+      self._classes[descriptor.full_name] = result_class
+      for field in descriptor.fields:
+        if field.message_type:
+          self.GetPrototype(field.message_type)
+    return self._classes[descriptor.full_name]
+
+
+_DB = descriptor_database.DescriptorDatabase()
+_POOL = descriptor_pool.DescriptorPool(_DB)
+_FACTORY = MessageFactory()
+
+
+def GetMessages(file_protos):
+  """Builds a dictionary of all the messages available in a set of files.
+
+  Args:
+    file_protos: A sequence of file protos to build messages out of.
+
+  Returns:
+    A dictionary containing all the message types in the files mapping the
+    fully qualified name to a Message subclass for the descriptor.
+  """
+
+  result = {}
+  for file_proto in file_protos:
+    _DB.Add(file_proto)
+  for file_proto in file_protos:
+    for desc in _GetAllDescriptors(file_proto.message_type, file_proto.package):
+      result[desc.full_name] = _FACTORY.GetPrototype(desc)
+  return result
+
+
+def _GetAllDescriptors(desc_protos, package):
+  """Gets all levels of nested message types as a flattened list of descriptors.
+
+  Args:
+    desc_protos: The descriptor protos to process.
+    package: The package where the protos are defined.
+
+  Yields:
+    Each message descriptor for each nested type.
+  """
+
+  for desc_proto in desc_protos:
+    name = '.'.join((package, desc_proto.name))
+    yield _POOL.FindMessageTypeByName(name)
+    for nested_desc in _GetAllDescriptors(desc_proto.nested_type, name):
+      yield nested_desc
diff --git a/generator/google/protobuf/reflection.py b/generator/google/protobuf/reflection.py
new file mode 100644
index 0000000..9570fd5
--- /dev/null
+++ b/generator/google/protobuf/reflection.py
@@ -0,0 +1,169 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# This code is meant to work on Python 2.4 and above only.
+
+"""Contains a metaclass and helper functions used to create
+protocol message classes from Descriptor objects at runtime.
+
+Recall that a metaclass is the "type" of a class.
+(A class is to a metaclass what an instance is to a class.)
+
+In this case, we use the GeneratedProtocolMessageType metaclass
+to inject all the useful functionality into the classes
+output by the protocol compiler at compile-time.
+
+The upshot of all this is that the real implementation
+details for ALL pure-Python protocol buffers are *here in
+this file*.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+
+from google.protobuf.internal import api_implementation
+from google.protobuf import descriptor as descriptor_mod
+from google.protobuf import message
+
+_FieldDescriptor = descriptor_mod.FieldDescriptor
+
+
+if api_implementation.Type() == 'cpp':
+  if api_implementation.Version() == 2:
+    from google.protobuf.internal.cpp import cpp_message
+    _NewMessage = cpp_message.NewMessage
+    _InitMessage = cpp_message.InitMessage
+  else:
+    from google.protobuf.internal import cpp_message
+    _NewMessage = cpp_message.NewMessage
+    _InitMessage = cpp_message.InitMessage
+else:
+  from google.protobuf.internal import python_message
+  _NewMessage = python_message.NewMessage
+  _InitMessage = python_message.InitMessage
+
+
+class GeneratedProtocolMessageType(type):
+
+  """Metaclass for protocol message classes created at runtime from Descriptors.
+
+  We add implementations for all methods described in the Message class.  We
+  also create properties to allow getting/setting all fields in the protocol
+  message.  Finally, we create slots to prevent users from accidentally
+  "setting" nonexistent fields in the protocol message, which then wouldn't get
+  serialized / deserialized properly.
+
+  The protocol compiler currently uses this metaclass to create protocol
+  message classes at runtime.  Clients can also manually create their own
+  classes at runtime, as in this example:
+
+  mydescriptor = Descriptor(.....)
+  class MyProtoClass(Message):
+    __metaclass__ = GeneratedProtocolMessageType
+    DESCRIPTOR = mydescriptor
+  myproto_instance = MyProtoClass()
+  myproto.foo_field = 23
+  ...
+  """
+
+  # Must be consistent with the protocol-compiler code in
+  # proto2/compiler/internal/generator.*.
+  _DESCRIPTOR_KEY = 'DESCRIPTOR'
+
+  def __new__(cls, name, bases, dictionary):
+    """Custom allocation for runtime-generated class types.
+
+    We override __new__ because this is apparently the only place
+    where we can meaningfully set __slots__ on the class we're creating(?).
+    (The interplay between metaclasses and slots is not very well-documented).
+
+    Args:
+      name: Name of the class (ignored, but required by the
+        metaclass protocol).
+      bases: Base classes of the class we're constructing.
+        (Should be message.Message).  We ignore this field, but
+        it's required by the metaclass protocol
+      dictionary: The class dictionary of the class we're
+        constructing.  dictionary[_DESCRIPTOR_KEY] must contain
+        a Descriptor object describing this protocol message
+        type.
+
+    Returns:
+      Newly-allocated class.
+    """
+    descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
+    bases = _NewMessage(bases, descriptor, dictionary)
+    superclass = super(GeneratedProtocolMessageType, cls)
+
+    new_class = superclass.__new__(cls, name, bases, dictionary)
+    setattr(descriptor, '_concrete_class', new_class)
+    return new_class
+
+  def __init__(cls, name, bases, dictionary):
+    """Here we perform the majority of our work on the class.
+    We add enum getters, an __init__ method, implementations
+    of all Message methods, and properties for all fields
+    in the protocol type.
+
+    Args:
+      name: Name of the class (ignored, but required by the
+        metaclass protocol).
+      bases: Base classes of the class we're constructing.
+        (Should be message.Message).  We ignore this field, but
+        it's required by the metaclass protocol
+      dictionary: The class dictionary of the class we're
+        constructing.  dictionary[_DESCRIPTOR_KEY] must contain
+        a Descriptor object describing this protocol message
+        type.
+    """
+    descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
+    _InitMessage(descriptor, cls)
+    superclass = super(GeneratedProtocolMessageType, cls)
+    superclass.__init__(name, bases, dictionary)
+
+
+def ParseMessage(descriptor, byte_str):
+  """Generate a new Message instance from this Descriptor and a byte string.
+
+  Args:
+    descriptor: Protobuf Descriptor object
+    byte_str: Serialized protocol buffer byte string
+
+  Returns:
+    Newly created protobuf Message object.
+  """
+
+  class _ResultClass(message.Message):
+    __metaclass__ = GeneratedProtocolMessageType
+    DESCRIPTOR = descriptor
+
+  new_msg = _ResultClass()
+  new_msg.ParseFromString(byte_str)
+  return new_msg
diff --git a/generator/google/protobuf/service.py b/generator/google/protobuf/service.py
new file mode 100644
index 0000000..180b70e
--- /dev/null
+++ b/generator/google/protobuf/service.py
@@ -0,0 +1,226 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""DEPRECATED:  Declares the RPC service interfaces.
+
+This module declares the abstract interfaces underlying proto2 RPC
+services.  These are intended to be independent of any particular RPC
+implementation, so that proto2 services can be used on top of a variety
+of implementations.  Starting with version 2.3.0, RPC implementations should
+not try to build on these, but should instead provide code generator plugins
+which generate code specific to the particular RPC implementation.  This way
+the generated code can be more appropriate for the implementation in use
+and can avoid unnecessary layers of indirection.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+
+class RpcException(Exception):
+  """Exception raised on failed blocking RPC method call."""
+  pass
+
+
+class Service(object):
+
+  """Abstract base interface for protocol-buffer-based RPC services.
+
+  Services themselves are abstract classes (implemented either by servers or as
+  stubs), but they subclass this base interface. The methods of this
+  interface can be used to call the methods of the service without knowing
+  its exact type at compile time (analogous to the Message interface).
+  """
+
+  def GetDescriptor():
+    """Retrieves this service's descriptor."""
+    raise NotImplementedError
+
+  def CallMethod(self, method_descriptor, rpc_controller,
+                 request, done):
+    """Calls a method of the service specified by method_descriptor.
+
+    If "done" is None then the call is blocking and the response
+    message will be returned directly.  Otherwise the call is asynchronous
+    and "done" will later be called with the response value.
+
+    In the blocking case, RpcException will be raised on error.
+
+    Preconditions:
+    * method_descriptor.service == GetDescriptor
+    * request is of the exact same classes as returned by
+      GetRequestClass(method).
+    * After the call has started, the request must not be modified.
+    * "rpc_controller" is of the correct type for the RPC implementation being
+      used by this Service.  For stubs, the "correct type" depends on the
+      RpcChannel which the stub is using.
+
+    Postconditions:
+    * "done" will be called when the method is complete.  This may be
+      before CallMethod() returns or it may be at some point in the future.
+    * If the RPC failed, the response value passed to "done" will be None.
+      Further details about the failure can be found by querying the
+      RpcController.
+    """
+    raise NotImplementedError
+
+  def GetRequestClass(self, method_descriptor):
+    """Returns the class of the request message for the specified method.
+
+    CallMethod() requires that the request is of a particular subclass of
+    Message. GetRequestClass() gets the default instance of this required
+    type.
+
+    Example:
+      method = service.GetDescriptor().FindMethodByName("Foo")
+      request = stub.GetRequestClass(method)()
+      request.ParseFromString(input)
+      service.CallMethod(method, request, callback)
+    """
+    raise NotImplementedError
+
+  def GetResponseClass(self, method_descriptor):
+    """Returns the class of the response message for the specified method.
+
+    This method isn't really needed, as the RpcChannel's CallMethod constructs
+    the response protocol message. It's provided anyway in case it is useful
+    for the caller to know the response type in advance.
+    """
+    raise NotImplementedError
+
+
+class RpcController(object):
+
+  """An RpcController mediates a single method call.
+
+  The primary purpose of the controller is to provide a way to manipulate
+  settings specific to the RPC implementation and to find out about RPC-level
+  errors. The methods provided by the RpcController interface are intended
+  to be a "least common denominator" set of features which we expect all
+  implementations to support.  Specific implementations may provide more
+  advanced features (e.g. deadline propagation).
+  """
+
+  # Client-side methods below
+
+  def Reset(self):
+    """Resets the RpcController to its initial state.
+
+    After the RpcController has been reset, it may be reused in
+    a new call. Must not be called while an RPC is in progress.
+    """
+    raise NotImplementedError
+
+  def Failed(self):
+    """Returns true if the call failed.
+
+    After a call has finished, returns true if the call failed.  The possible
+    reasons for failure depend on the RPC implementation.  Failed() must not
+    be called before a call has finished.  If Failed() returns true, the
+    contents of the response message are undefined.
+    """
+    raise NotImplementedError
+
+  def ErrorText(self):
+    """If Failed is true, returns a human-readable description of the error."""
+    raise NotImplementedError
+
+  def StartCancel(self):
+    """Initiate cancellation.
+
+    Advises the RPC system that the caller desires that the RPC call be
+    canceled.  The RPC system may cancel it immediately, may wait awhile and
+    then cancel it, or may not even cancel the call at all.  If the call is
+    canceled, the "done" callback will still be called and the RpcController
+    will indicate that the call failed at that time.
+    """
+    raise NotImplementedError
+
+  # Server-side methods below
+
+  def SetFailed(self, reason):
+    """Sets a failure reason.
+
+    Causes Failed() to return true on the client side.  "reason" will be
+    incorporated into the message returned by ErrorText().  If you find
+    you need to return machine-readable information about failures, you
+    should incorporate it into your response protocol buffer and should
+    NOT call SetFailed().
+    """
+    raise NotImplementedError
+
+  def IsCanceled(self):
+    """Checks if the client cancelled the RPC.
+
+    If true, indicates that the client canceled the RPC, so the server may
+    as well give up on replying to it.  The server should still call the
+    final "done" callback.
+    """
+    raise NotImplementedError
+
+  def NotifyOnCancel(self, callback):
+    """Sets a callback to invoke on cancel.
+
+    Asks that the given callback be called when the RPC is canceled.  The
+    callback will always be called exactly once.  If the RPC completes without
+    being canceled, the callback will be called after completion.  If the RPC
+    has already been canceled when NotifyOnCancel() is called, the callback
+    will be called immediately.
+
+    NotifyOnCancel() must be called no more than once per request.
+    """
+    raise NotImplementedError
+
+
+class RpcChannel(object):
+
+  """Abstract interface for an RPC channel.
+
+  An RpcChannel represents a communication line to a service which can be used
+  to call that service's methods.  The service may be running on another
+  machine. Normally, you should not use an RpcChannel directly, but instead
+  construct a stub {@link Service} wrapping it.  Example:
+
+  Example:
+    RpcChannel channel = rpcImpl.Channel("remotehost.example.com:1234")
+    RpcController controller = rpcImpl.Controller()
+    MyService service = MyService_Stub(channel)
+    service.MyMethod(controller, request, callback)
+  """
+
+  def CallMethod(self, method_descriptor, rpc_controller,
+                 request, response_class, done):
+    """Calls the method identified by the descriptor.
+
+    Call the given method of the remote service.  The signature of this
+    procedure looks the same as Service.CallMethod(), but the requirements
+    are less strict in one important way:  the request object doesn't have to
+    be of any specific class as long as its descriptor is method.input_type.
+    """
+    raise NotImplementedError
diff --git a/generator/google/protobuf/service_reflection.py b/generator/google/protobuf/service_reflection.py
new file mode 100644
index 0000000..851e83e
--- /dev/null
+++ b/generator/google/protobuf/service_reflection.py
@@ -0,0 +1,284 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Contains metaclasses used to create protocol service and service stub
+classes from ServiceDescriptor objects at runtime.
+
+The GeneratedServiceType and GeneratedServiceStubType metaclasses are used to
+inject all useful functionality into the classes output by the protocol
+compiler at compile-time.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+
+class GeneratedServiceType(type):
+
+  """Metaclass for service classes created at runtime from ServiceDescriptors.
+
+  Implementations for all methods described in the Service class are added here
+  by this class. We also create properties to allow getting/setting all fields
+  in the protocol message.
+
+  The protocol compiler currently uses this metaclass to create protocol service
+  classes at runtime. Clients can also manually create their own classes at
+  runtime, as in this example:
+
+  mydescriptor = ServiceDescriptor(.....)
+  class MyProtoService(service.Service):
+    __metaclass__ = GeneratedServiceType
+    DESCRIPTOR = mydescriptor
+  myservice_instance = MyProtoService()
+  ...
+  """
+
+  _DESCRIPTOR_KEY = 'DESCRIPTOR'
+
+  def __init__(cls, name, bases, dictionary):
+    """Creates a message service class.
+
+    Args:
+      name: Name of the class (ignored, but required by the metaclass
+        protocol).
+      bases: Base classes of the class being constructed.
+      dictionary: The class dictionary of the class being constructed.
+        dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
+        describing this protocol service type.
+    """
+    # Don't do anything if this class doesn't have a descriptor. This happens
+    # when a service class is subclassed.
+    if GeneratedServiceType._DESCRIPTOR_KEY not in dictionary:
+      return
+    descriptor = dictionary[GeneratedServiceType._DESCRIPTOR_KEY]
+    service_builder = _ServiceBuilder(descriptor)
+    service_builder.BuildService(cls)
+
+
+class GeneratedServiceStubType(GeneratedServiceType):
+
+  """Metaclass for service stubs created at runtime from ServiceDescriptors.
+
+  This class has similar responsibilities as GeneratedServiceType, except that
+  it creates the service stub classes.
+  """
+
+  _DESCRIPTOR_KEY = 'DESCRIPTOR'
+
+  def __init__(cls, name, bases, dictionary):
+    """Creates a message service stub class.
+
+    Args:
+      name: Name of the class (ignored, here).
+      bases: Base classes of the class being constructed.
+      dictionary: The class dictionary of the class being constructed.
+        dictionary[_DESCRIPTOR_KEY] must contain a ServiceDescriptor object
+        describing this protocol service type.
+    """
+    super(GeneratedServiceStubType, cls).__init__(name, bases, dictionary)
+    # Don't do anything if this class doesn't have a descriptor. This happens
+    # when a service stub is subclassed.
+    if GeneratedServiceStubType._DESCRIPTOR_KEY not in dictionary:
+      return
+    descriptor = dictionary[GeneratedServiceStubType._DESCRIPTOR_KEY]
+    service_stub_builder = _ServiceStubBuilder(descriptor)
+    service_stub_builder.BuildServiceStub(cls)
+
+
+class _ServiceBuilder(object):
+
+  """This class constructs a protocol service class using a service descriptor.
+
+  Given a service descriptor, this class constructs a class that represents
+  the specified service descriptor. One service builder instance constructs
+  exactly one service class. That means all instances of that class share the
+  same builder.
+  """
+
+  def __init__(self, service_descriptor):
+    """Initializes an instance of the service class builder.
+
+    Args:
+      service_descriptor: ServiceDescriptor to use when constructing the
+        service class.
+    """
+    self.descriptor = service_descriptor
+
+  def BuildService(self, cls):
+    """Constructs the service class.
+
+    Args:
+      cls: The class that will be constructed.
+    """
+
+    # CallMethod needs to operate with an instance of the Service class. This
+    # internal wrapper function exists only to be able to pass the service
+    # instance to the method that does the real CallMethod work.
+    def _WrapCallMethod(srvc, method_descriptor,
+                        rpc_controller, request, callback):
+      return self._CallMethod(srvc, method_descriptor,
+                       rpc_controller, request, callback)
+    self.cls = cls
+    cls.CallMethod = _WrapCallMethod
+    cls.GetDescriptor = staticmethod(lambda: self.descriptor)
+    cls.GetDescriptor.__doc__ = "Returns the service descriptor."
+    cls.GetRequestClass = self._GetRequestClass
+    cls.GetResponseClass = self._GetResponseClass
+    for method in self.descriptor.methods:
+      setattr(cls, method.name, self._GenerateNonImplementedMethod(method))
+
+  def _CallMethod(self, srvc, method_descriptor,
+                  rpc_controller, request, callback):
+    """Calls the method described by a given method descriptor.
+
+    Args:
+      srvc: Instance of the service for which this method is called.
+      method_descriptor: Descriptor that represent the method to call.
+      rpc_controller: RPC controller to use for this method's execution.
+      request: Request protocol message.
+      callback: A callback to invoke after the method has completed.
+    """
+    if method_descriptor.containing_service != self.descriptor:
+      raise RuntimeError(
+          'CallMethod() given method descriptor for wrong service type.')
+    method = getattr(srvc, method_descriptor.name)
+    return method(rpc_controller, request, callback)
+
+  def _GetRequestClass(self, method_descriptor):
+    """Returns the class of the request protocol message.
+
+    Args:
+      method_descriptor: Descriptor of the method for which to return the
+        request protocol message class.
+
+    Returns:
+      A class that represents the input protocol message of the specified
+      method.
+    """
+    if method_descriptor.containing_service != self.descriptor:
+      raise RuntimeError(
+          'GetRequestClass() given method descriptor for wrong service type.')
+    return method_descriptor.input_type._concrete_class
+
+  def _GetResponseClass(self, method_descriptor):
+    """Returns the class of the response protocol message.
+
+    Args:
+      method_descriptor: Descriptor of the method for which to return the
+        response protocol message class.
+
+    Returns:
+      A class that represents the output protocol message of the specified
+      method.
+    """
+    if method_descriptor.containing_service != self.descriptor:
+      raise RuntimeError(
+          'GetResponseClass() given method descriptor for wrong service type.')
+    return method_descriptor.output_type._concrete_class
+
+  def _GenerateNonImplementedMethod(self, method):
+    """Generates and returns a method that can be set for a service methods.
+
+    Args:
+      method: Descriptor of the service method for which a method is to be
+        generated.
+
+    Returns:
+      A method that can be added to the service class.
+    """
+    return lambda inst, rpc_controller, request, callback: (
+        self._NonImplementedMethod(method.name, rpc_controller, callback))
+
+  def _NonImplementedMethod(self, method_name, rpc_controller, callback):
+    """The body of all methods in the generated service class.
+
+    Args:
+      method_name: Name of the method being executed.
+      rpc_controller: RPC controller used to execute this method.
+      callback: A callback which will be invoked when the method finishes.
+    """
+    rpc_controller.SetFailed('Method %s not implemented.' % method_name)
+    callback(None)
+
+
+class _ServiceStubBuilder(object):
+
+  """Constructs a protocol service stub class using a service descriptor.
+
+  Given a service descriptor, this class constructs a suitable stub class.
+  A stub is just a type-safe wrapper around an RpcChannel which emulates a
+  local implementation of the service.
+
+  One service stub builder instance constructs exactly one class. It means all
+  instances of that class share the same service stub builder.
+  """
+
+  def __init__(self, service_descriptor):
+    """Initializes an instance of the service stub class builder.
+
+    Args:
+      service_descriptor: ServiceDescriptor to use when constructing the
+        stub class.
+    """
+    self.descriptor = service_descriptor
+
+  def BuildServiceStub(self, cls):
+    """Constructs the stub class.
+
+    Args:
+      cls: The class that will be constructed.
+    """
+
+    def _ServiceStubInit(stub, rpc_channel):
+      stub.rpc_channel = rpc_channel
+    self.cls = cls
+    cls.__init__ = _ServiceStubInit
+    for method in self.descriptor.methods:
+      setattr(cls, method.name, self._GenerateStubMethod(method))
+
+  def _GenerateStubMethod(self, method):
+    return (lambda inst, rpc_controller, request, callback=None:
+        self._StubMethod(inst, method, rpc_controller, request, callback))
+
+  def _StubMethod(self, stub, method_descriptor,
+                  rpc_controller, request, callback):
+    """The body of all service methods in the generated stub class.
+
+    Args:
+      stub: Stub instance.
+      method_descriptor: Descriptor of the invoked method.
+      rpc_controller: Rpc controller to execute the method.
+      request: Request protocol message.
+      callback: A callback to execute when the method finishes.
+    Returns:
+      Response message (in case of blocking call).
+    """
+    return stub.rpc_channel.CallMethod(
+        method_descriptor, rpc_controller, request,
+        method_descriptor.output_type._concrete_class, callback)
diff --git a/generator/google/protobuf/text_format.py b/generator/google/protobuf/text_format.py
new file mode 100644
index 0000000..24dd07f
--- /dev/null
+++ b/generator/google/protobuf/text_format.py
@@ -0,0 +1,739 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Contains routines for printing protocol messages in text format."""
+
+__author__ = 'kenton@google.com (Kenton Varda)'
+
+import cStringIO
+import re
+
+from collections import deque
+from google.protobuf.internal import type_checkers
+from google.protobuf import descriptor
+
+__all__ = [ 'MessageToString', 'PrintMessage', 'PrintField',
+            'PrintFieldValue', 'Merge' ]
+
+
+_INTEGER_CHECKERS = (type_checkers.Uint32ValueChecker(),
+                     type_checkers.Int32ValueChecker(),
+                     type_checkers.Uint64ValueChecker(),
+                     type_checkers.Int64ValueChecker())
+_FLOAT_INFINITY = re.compile('-?inf(?:inity)?f?', re.IGNORECASE)
+_FLOAT_NAN = re.compile('nanf?', re.IGNORECASE)
+
+
+class ParseError(Exception):
+  """Thrown in case of ASCII parsing error."""
+
+
+def MessageToString(message, as_utf8=False, as_one_line=False):
+  out = cStringIO.StringIO()
+  PrintMessage(message, out, as_utf8=as_utf8, as_one_line=as_one_line)
+  result = out.getvalue()
+  out.close()
+  if as_one_line:
+    return result.rstrip()
+  return result
+
+
+def PrintMessage(message, out, indent=0, as_utf8=False, as_one_line=False):
+  for field, value in message.ListFields():
+    if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+      for element in value:
+        PrintField(field, element, out, indent, as_utf8, as_one_line)
+    else:
+      PrintField(field, value, out, indent, as_utf8, as_one_line)
+
+
+def PrintField(field, value, out, indent=0, as_utf8=False, as_one_line=False):
+  """Print a single field name/value pair.  For repeated fields, the value
+  should be a single element."""
+
+  out.write(' ' * indent);
+  if field.is_extension:
+    out.write('[')
+    if (field.containing_type.GetOptions().message_set_wire_format and
+        field.type == descriptor.FieldDescriptor.TYPE_MESSAGE and
+        field.message_type == field.extension_scope and
+        field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL):
+      out.write(field.message_type.full_name)
+    else:
+      out.write(field.full_name)
+    out.write(']')
+  elif field.type == descriptor.FieldDescriptor.TYPE_GROUP:
+    # For groups, use the capitalized name.
+    out.write(field.message_type.name)
+  else:
+    out.write(field.name)
+
+  if field.cpp_type != descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+    # The colon is optional in this case, but our cross-language golden files
+    # don't include it.
+    out.write(': ')
+
+  PrintFieldValue(field, value, out, indent, as_utf8, as_one_line)
+  if as_one_line:
+    out.write(' ')
+  else:
+    out.write('\n')
+
+
+def PrintFieldValue(field, value, out, indent=0,
+                    as_utf8=False, as_one_line=False):
+  """Print a single field value (not including name).  For repeated fields,
+  the value should be a single element."""
+
+  if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+    if as_one_line:
+      out.write(' { ')
+      PrintMessage(value, out, indent, as_utf8, as_one_line)
+      out.write('}')
+    else:
+      out.write(' {\n')
+      PrintMessage(value, out, indent + 2, as_utf8, as_one_line)
+      out.write(' ' * indent + '}')
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
+    enum_value = field.enum_type.values_by_number.get(value, None)
+    if enum_value is not None:
+      out.write(enum_value.name)
+    else:
+      out.write(str(value))
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
+    out.write('\"')
+    if type(value) is unicode:
+      out.write(_CEscape(value.encode('utf-8'), as_utf8))
+    else:
+      out.write(_CEscape(value, as_utf8))
+    out.write('\"')
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
+    if value:
+      out.write("true")
+    else:
+      out.write("false")
+  else:
+    out.write(str(value))
+
+
+def Merge(text, message):
+  """Merges an ASCII representation of a protocol message into a message.
+
+  Args:
+    text: Message ASCII representation.
+    message: A protocol buffer message to merge into.
+
+  Raises:
+    ParseError: On ASCII parsing problems.
+  """
+  tokenizer = _Tokenizer(text)
+  while not tokenizer.AtEnd():
+    _MergeField(tokenizer, message)
+
+
+def _MergeField(tokenizer, message):
+  """Merges a single protocol message field into a message.
+
+  Args:
+    tokenizer: A tokenizer to parse the field name and values.
+    message: A protocol message to record the data.
+
+  Raises:
+    ParseError: In case of ASCII parsing problems.
+  """
+  message_descriptor = message.DESCRIPTOR
+  if tokenizer.TryConsume('['):
+    name = [tokenizer.ConsumeIdentifier()]
+    while tokenizer.TryConsume('.'):
+      name.append(tokenizer.ConsumeIdentifier())
+    name = '.'.join(name)
+
+    if not message_descriptor.is_extendable:
+      raise tokenizer.ParseErrorPreviousToken(
+          'Message type "%s" does not have extensions.' %
+          message_descriptor.full_name)
+    field = message.Extensions._FindExtensionByName(name)
+    if not field:
+      raise tokenizer.ParseErrorPreviousToken(
+          'Extension "%s" not registered.' % name)
+    elif message_descriptor != field.containing_type:
+      raise tokenizer.ParseErrorPreviousToken(
+          'Extension "%s" does not extend message type "%s".' % (
+              name, message_descriptor.full_name))
+    tokenizer.Consume(']')
+  else:
+    name = tokenizer.ConsumeIdentifier()
+    field = message_descriptor.fields_by_name.get(name, None)
+
+    # Group names are expected to be capitalized as they appear in the
+    # .proto file, which actually matches their type names, not their field
+    # names.
+    if not field:
+      field = message_descriptor.fields_by_name.get(name.lower(), None)
+      if field and field.type != descriptor.FieldDescriptor.TYPE_GROUP:
+        field = None
+
+    if (field and field.type == descriptor.FieldDescriptor.TYPE_GROUP and
+        field.message_type.name != name):
+      field = None
+
+    if not field:
+      raise tokenizer.ParseErrorPreviousToken(
+          'Message type "%s" has no field named "%s".' % (
+              message_descriptor.full_name, name))
+
+  if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+    tokenizer.TryConsume(':')
+
+    if tokenizer.TryConsume('<'):
+      end_token = '>'
+    else:
+      tokenizer.Consume('{')
+      end_token = '}'
+
+    if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+      if field.is_extension:
+        sub_message = message.Extensions[field].add()
+      else:
+        sub_message = getattr(message, field.name).add()
+    else:
+      if field.is_extension:
+        sub_message = message.Extensions[field]
+      else:
+        sub_message = getattr(message, field.name)
+      sub_message.SetInParent()
+
+    while not tokenizer.TryConsume(end_token):
+      if tokenizer.AtEnd():
+        raise tokenizer.ParseErrorPreviousToken('Expected "%s".' % (end_token))
+      _MergeField(tokenizer, sub_message)
+  else:
+    _MergeScalarField(tokenizer, message, field)
+
+
+def _MergeScalarField(tokenizer, message, field):
+  """Merges a single protocol message scalar field into a message.
+
+  Args:
+    tokenizer: A tokenizer to parse the field value.
+    message: A protocol message to record the data.
+    field: The descriptor of the field to be merged.
+
+  Raises:
+    ParseError: In case of ASCII parsing problems.
+    RuntimeError: On runtime errors.
+  """
+  tokenizer.Consume(':')
+  value = None
+
+  if field.type in (descriptor.FieldDescriptor.TYPE_INT32,
+                    descriptor.FieldDescriptor.TYPE_SINT32,
+                    descriptor.FieldDescriptor.TYPE_SFIXED32):
+    value = tokenizer.ConsumeInt32()
+  elif field.type in (descriptor.FieldDescriptor.TYPE_INT64,
+                      descriptor.FieldDescriptor.TYPE_SINT64,
+                      descriptor.FieldDescriptor.TYPE_SFIXED64):
+    value = tokenizer.ConsumeInt64()
+  elif field.type in (descriptor.FieldDescriptor.TYPE_UINT32,
+                      descriptor.FieldDescriptor.TYPE_FIXED32):
+    value = tokenizer.ConsumeUint32()
+  elif field.type in (descriptor.FieldDescriptor.TYPE_UINT64,
+                      descriptor.FieldDescriptor.TYPE_FIXED64):
+    value = tokenizer.ConsumeUint64()
+  elif field.type in (descriptor.FieldDescriptor.TYPE_FLOAT,
+                      descriptor.FieldDescriptor.TYPE_DOUBLE):
+    value = tokenizer.ConsumeFloat()
+  elif field.type == descriptor.FieldDescriptor.TYPE_BOOL:
+    value = tokenizer.ConsumeBool()
+  elif field.type == descriptor.FieldDescriptor.TYPE_STRING:
+    value = tokenizer.ConsumeString()
+  elif field.type == descriptor.FieldDescriptor.TYPE_BYTES:
+    value = tokenizer.ConsumeByteString()
+  elif field.type == descriptor.FieldDescriptor.TYPE_ENUM:
+    value = tokenizer.ConsumeEnum(field)
+  else:
+    raise RuntimeError('Unknown field type %d' % field.type)
+
+  if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+    if field.is_extension:
+      message.Extensions[field].append(value)
+    else:
+      getattr(message, field.name).append(value)
+  else:
+    if field.is_extension:
+      message.Extensions[field] = value
+    else:
+      setattr(message, field.name, value)
+
+
+class _Tokenizer(object):
+  """Protocol buffer ASCII representation tokenizer.
+
+  This class handles the lower level string parsing by splitting it into
+  meaningful tokens.
+
+  It was directly ported from the Java protocol buffer API.
+  """
+
+  _WHITESPACE = re.compile('(\\s|(#.*$))+', re.MULTILINE)
+  _TOKEN = re.compile(
+      '[a-zA-Z_][0-9a-zA-Z_+-]*|'           # an identifier
+      '[0-9+-][0-9a-zA-Z_.+-]*|'            # a number
+      '\"([^\"\n\\\\]|\\\\.)*(\"|\\\\?$)|'  # a double-quoted string
+      '\'([^\'\n\\\\]|\\\\.)*(\'|\\\\?$)')  # a single-quoted string
+  _IDENTIFIER = re.compile('\w+')
+
+  def __init__(self, text_message):
+    self._text_message = text_message
+
+    self._position = 0
+    self._line = -1
+    self._column = 0
+    self._token_start = None
+    self.token = ''
+    self._lines = deque(text_message.split('\n'))
+    self._current_line = ''
+    self._previous_line = 0
+    self._previous_column = 0
+    self._SkipWhitespace()
+    self.NextToken()
+
+  def AtEnd(self):
+    """Checks the end of the text was reached.
+
+    Returns:
+      True iff the end was reached.
+    """
+    return self.token == ''
+
+  def _PopLine(self):
+    while len(self._current_line) <= self._column:
+      if not self._lines:
+        self._current_line = ''
+        return
+      self._line += 1
+      self._column = 0
+      self._current_line = self._lines.popleft()
+
+  def _SkipWhitespace(self):
+    while True:
+      self._PopLine()
+      match = self._WHITESPACE.match(self._current_line, self._column)
+      if not match:
+        break
+      length = len(match.group(0))
+      self._column += length
+
+  def TryConsume(self, token):
+    """Tries to consume a given piece of text.
+
+    Args:
+      token: Text to consume.
+
+    Returns:
+      True iff the text was consumed.
+    """
+    if self.token == token:
+      self.NextToken()
+      return True
+    return False
+
+  def Consume(self, token):
+    """Consumes a piece of text.
+
+    Args:
+      token: Text to consume.
+
+    Raises:
+      ParseError: If the text couldn't be consumed.
+    """
+    if not self.TryConsume(token):
+      raise self._ParseError('Expected "%s".' % token)
+
+  def ConsumeIdentifier(self):
+    """Consumes protocol message field identifier.
+
+    Returns:
+      Identifier string.
+
+    Raises:
+      ParseError: If an identifier couldn't be consumed.
+    """
+    result = self.token
+    if not self._IDENTIFIER.match(result):
+      raise self._ParseError('Expected identifier.')
+    self.NextToken()
+    return result
+
+  def ConsumeInt32(self):
+    """Consumes a signed 32bit integer number.
+
+    Returns:
+      The integer parsed.
+
+    Raises:
+      ParseError: If a signed 32bit integer couldn't be consumed.
+    """
+    try:
+      result = ParseInteger(self.token, is_signed=True, is_long=False)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeUint32(self):
+    """Consumes an unsigned 32bit integer number.
+
+    Returns:
+      The integer parsed.
+
+    Raises:
+      ParseError: If an unsigned 32bit integer couldn't be consumed.
+    """
+    try:
+      result = ParseInteger(self.token, is_signed=False, is_long=False)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeInt64(self):
+    """Consumes a signed 64bit integer number.
+
+    Returns:
+      The integer parsed.
+
+    Raises:
+      ParseError: If a signed 64bit integer couldn't be consumed.
+    """
+    try:
+      result = ParseInteger(self.token, is_signed=True, is_long=True)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeUint64(self):
+    """Consumes an unsigned 64bit integer number.
+
+    Returns:
+      The integer parsed.
+
+    Raises:
+      ParseError: If an unsigned 64bit integer couldn't be consumed.
+    """
+    try:
+      result = ParseInteger(self.token, is_signed=False, is_long=True)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeFloat(self):
+    """Consumes an floating point number.
+
+    Returns:
+      The number parsed.
+
+    Raises:
+      ParseError: If a floating point number couldn't be consumed.
+    """
+    try:
+      result = ParseFloat(self.token)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeBool(self):
+    """Consumes a boolean value.
+
+    Returns:
+      The bool parsed.
+
+    Raises:
+      ParseError: If a boolean value couldn't be consumed.
+    """
+    try:
+      result = ParseBool(self.token)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeString(self):
+    """Consumes a string value.
+
+    Returns:
+      The string parsed.
+
+    Raises:
+      ParseError: If a string value couldn't be consumed.
+    """
+    bytes = self.ConsumeByteString()
+    try:
+      return unicode(bytes, 'utf-8')
+    except UnicodeDecodeError, e:
+      raise self._StringParseError(e)
+
+  def ConsumeByteString(self):
+    """Consumes a byte array value.
+
+    Returns:
+      The array parsed (as a string).
+
+    Raises:
+      ParseError: If a byte array value couldn't be consumed.
+    """
+    list = [self._ConsumeSingleByteString()]
+    while len(self.token) > 0 and self.token[0] in ('\'', '"'):
+      list.append(self._ConsumeSingleByteString())
+    return "".join(list)
+
+  def _ConsumeSingleByteString(self):
+    """Consume one token of a string literal.
+
+    String literals (whether bytes or text) can come in multiple adjacent
+    tokens which are automatically concatenated, like in C or Python.  This
+    method only consumes one token.
+    """
+    text = self.token
+    if len(text) < 1 or text[0] not in ('\'', '"'):
+      raise self._ParseError('Expected string.')
+
+    if len(text) < 2 or text[-1] != text[0]:
+      raise self._ParseError('String missing ending quote.')
+
+    try:
+      result = _CUnescape(text[1:-1])
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ConsumeEnum(self, field):
+    try:
+      result = ParseEnum(field, self.token)
+    except ValueError, e:
+      raise self._ParseError(str(e))
+    self.NextToken()
+    return result
+
+  def ParseErrorPreviousToken(self, message):
+    """Creates and *returns* a ParseError for the previously read token.
+
+    Args:
+      message: A message to set for the exception.
+
+    Returns:
+      A ParseError instance.
+    """
+    return ParseError('%d:%d : %s' % (
+        self._previous_line + 1, self._previous_column + 1, message))
+
+  def _ParseError(self, message):
+    """Creates and *returns* a ParseError for the current token."""
+    return ParseError('%d:%d : %s' % (
+        self._line + 1, self._column + 1, message))
+
+  def _StringParseError(self, e):
+    return self._ParseError('Couldn\'t parse string: ' + str(e))
+
+  def NextToken(self):
+    """Reads the next meaningful token."""
+    self._previous_line = self._line
+    self._previous_column = self._column
+
+    self._column += len(self.token)
+    self._SkipWhitespace()
+
+    if not self._lines and len(self._current_line) <= self._column:
+      self.token = ''
+      return
+
+    match = self._TOKEN.match(self._current_line, self._column)
+    if match:
+      token = match.group(0)
+      self.token = token
+    else:
+      self.token = self._current_line[self._column]
+
+
+# text.encode('string_escape') does not seem to satisfy our needs as it
+# encodes unprintable characters using two-digit hex escapes whereas our
+# C++ unescaping function allows hex escapes to be any length.  So,
+# "\0011".encode('string_escape') ends up being "\\x011", which will be
+# decoded in C++ as a single-character string with char code 0x11.
+def _CEscape(text, as_utf8):
+  def escape(c):
+    o = ord(c)
+    if o == 10: return r"\n"   # optional escape
+    if o == 13: return r"\r"   # optional escape
+    if o ==  9: return r"\t"   # optional escape
+    if o == 39: return r"\'"   # optional escape
+
+    if o == 34: return r'\"'   # necessary escape
+    if o == 92: return r"\\"   # necessary escape
+
+    # necessary escapes
+    if not as_utf8 and (o >= 127 or o < 32): return "\\%03o" % o
+    return c
+  return "".join([escape(c) for c in text])
+
+
+_CUNESCAPE_HEX = re.compile(r'(\\+)x([0-9a-fA-F])(?![0-9a-fA-F])')
+
+
+def _CUnescape(text):
+  def ReplaceHex(m):
+    # Only replace the match if the number of leading back slashes is odd. i.e.
+    # the slash itself is not escaped.
+    if len(m.group(1)) & 1:
+      return m.group(1) + 'x0' + m.group(2)
+    return m.group(0)
+
+  # This is required because the 'string_escape' encoding doesn't
+  # allow single-digit hex escapes (like '\xf').
+  result = _CUNESCAPE_HEX.sub(ReplaceHex, text)
+  return result.decode('string_escape')
+
+
+def ParseInteger(text, is_signed=False, is_long=False):
+  """Parses an integer.
+
+  Args:
+    text: The text to parse.
+    is_signed: True if a signed integer must be parsed.
+    is_long: True if a long integer must be parsed.
+
+  Returns:
+    The integer value.
+
+  Raises:
+    ValueError: Thrown Iff the text is not a valid integer.
+  """
+  # Do the actual parsing. Exception handling is propagated to caller.
+  try:
+    result = int(text, 0)
+  except ValueError:
+    raise ValueError('Couldn\'t parse integer: %s' % text)
+
+  # Check if the integer is sane. Exceptions handled by callers.
+  checker = _INTEGER_CHECKERS[2 * int(is_long) + int(is_signed)]
+  checker.CheckValue(result)
+  return result
+
+
+def ParseFloat(text):
+  """Parse a floating point number.
+
+  Args:
+    text: Text to parse.
+
+  Returns:
+    The number parsed.
+
+  Raises:
+    ValueError: If a floating point number couldn't be parsed.
+  """
+  try:
+    # Assume Python compatible syntax.
+    return float(text)
+  except ValueError:
+    # Check alternative spellings.
+    if _FLOAT_INFINITY.match(text):
+      if text[0] == '-':
+        return float('-inf')
+      else:
+        return float('inf')
+    elif _FLOAT_NAN.match(text):
+      return float('nan')
+    else:
+      # assume '1.0f' format
+      try:
+        return float(text.rstrip('f'))
+      except ValueError:
+        raise ValueError('Couldn\'t parse float: %s' % text)
+
+
+def ParseBool(text):
+  """Parse a boolean value.
+
+  Args:
+    text: Text to parse.
+
+  Returns:
+    Boolean values parsed
+
+  Raises:
+    ValueError: If text is not a valid boolean.
+  """
+  if text in ('true', 't', '1'):
+    return True
+  elif text in ('false', 'f', '0'):
+    return False
+  else:
+    raise ValueError('Expected "true" or "false".')
+
+
+def ParseEnum(field, value):
+  """Parse an enum value.
+
+  The value can be specified by a number (the enum value), or by
+  a string literal (the enum name).
+
+  Args:
+    field: Enum field descriptor.
+    value: String value.
+
+  Returns:
+    Enum value number.
+
+  Raises:
+    ValueError: If the enum value could not be parsed.
+  """
+  enum_descriptor = field.enum_type
+  try:
+    number = int(value, 0)
+  except ValueError:
+    # Identifier.
+    enum_value = enum_descriptor.values_by_name.get(value, None)
+    if enum_value is None:
+      raise ValueError(
+          'Enum type "%s" has no value named %s.' % (
+              enum_descriptor.full_name, value))
+  else:
+    # Numeric value.
+    enum_value = enum_descriptor.values_by_number.get(number, None)
+    if enum_value is None:
+      raise ValueError(
+          'Enum type "%s" has no value with number %d.' % (
+              enum_descriptor.full_name, number))
+  return enum_value.number