Source/bindings/scripts/unstable/v8_attributes.py

# Copyright (C) 2013 Google Inc. All rights reserved.
#
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"""Generate template values for attributes.

FIXME: Not currently used in build.
This is a rewrite of the Perl IDL compiler in Python, but is not complete.
Once it is complete, we will switch all IDL files over to Python at once.
Until then, please work on the Perl IDL compiler.
For details, see bug http://crbug.com/239771
"""

import v8_types
import v8_utilities
from v8_utilities import cpp_name, has_extended_attribute, uncapitalize


def generate_attributes(interface):
    def generate_attribute(attribute):
        attribute_contents, attribute_includes = generate_attribute_and_includes(interface, attribute)
        includes.update(attribute_includes)
        return attribute_contents

    includes = set()
    contents = generate_attributes_common(interface)
    contents['attributes'] = [generate_attribute(attribute) for attribute in interface.attributes]
    contents['has_runtime_enabled_attributes'] = any(attribute['runtime_enabled_function_name'] for attribute in contents['attributes'])
    return contents, includes


def generate_attributes_common(interface):
    attributes = interface.attributes
    v8_class_name = v8_utilities.v8_class_name(interface)
    return {
        # Size 0 constant array is not allowed in VC++
        'number_of_attributes': 'WTF_ARRAY_LENGTH(%sAttributes)' % v8_class_name if attributes else '0',
        'attribute_templates': '%sAttributes' % v8_class_name if attributes else '0',
    }


def generate_attribute_and_includes(interface, attribute):
    idl_type = attribute.data_type
    extended_attributes = attribute.extended_attributes
    this_is_keep_alive_for_gc = is_keep_alive_for_gc(attribute)
    contents = {
        'access_control_list': access_control_list(attribute),
        'cached_attribute_validation_method': extended_attributes.get('CachedAttribute'),
        'conditional_string': v8_utilities.generate_conditional_string(attribute),
        'cpp_type': v8_types.cpp_type(idl_type),
        'runtime_enabled_function_name': v8_utilities.runtime_enabled_function_name(attribute),  # EnabledAtRuntime
        'idl_type': idl_type,
        'is_keep_alive_for_gc': this_is_keep_alive_for_gc,
        'is_nullable': attribute.is_nullable,
        'is_static': attribute.is_static,
        'name': attribute.name,
        'property_attributes': property_attributes(attribute),
        'v8_type': v8_types.v8_type(idl_type),
    }
    if has_extended_attribute(attribute, ('Custom', 'CustomGetter')):
        contents['is_custom_getter'] = True
        return contents, set()

    cpp_value = getter_expression(interface, attribute, contents)
    # [GetterRaisesException], [RaisesException]
    is_getter_raises_exception = has_extended_attribute(attribute, ('GetterRaisesException', 'RaisesException'))
    # Normally we can inline the function call into the return statement to
    # avoid the overhead of using a Ref<> temporary, but for some cases
    # (nullable types, EventHandler, [CachedAttribute], or if there are
    # exceptions), we need to use a local variable.
    # FIXME: check if compilers are smart enough to inline this, and if so,
    # always use a local variable (for readability and CG simplicity).
    if (attribute.is_nullable or
        idl_type == 'EventHandler' or
        'CachedAttribute' in extended_attributes or
        is_getter_raises_exception):
        contents['cpp_value_original'] = cpp_value
        cpp_value = 'value'
    contents['cpp_value'] = cpp_value

    if this_is_keep_alive_for_gc:
        return_v8_value_statement = 'v8SetReturnValue(info, wrapper);'
        includes = v8_types.includes_for_type(idl_type)
        includes.add('bindings/v8/V8HiddenPropertyName.h')
    else:
        return_v8_value_statement, includes = v8_types.v8_set_return_value(idl_type, cpp_value, callback_info='info', isolate='info.GetIsolate()', extended_attributes=extended_attributes, script_wrappable='imp')
    contents['return_v8_value_statement'] = return_v8_value_statement

    if (idl_type == 'EventHandler' and
        interface.name in ['Window', 'WorkerGlobalScope'] and
        attribute.name == 'onerror'):
            includes.add('bindings/v8/V8ErrorHandler.h')

    # [CheckSecurityForNode]
    is_check_security_for_node = 'CheckSecurityForNode' in extended_attributes
    if is_check_security_for_node:
        includes.add('bindings/v8/BindingSecurity.h')
    v8_utilities.generate_measure_as(attribute, contents, includes)  # [MeasureAs]

    # [DeprecateAs]
    v8_utilities.generate_deprecate_as(attribute, contents, includes)
    if is_check_security_for_node or is_getter_raises_exception:
        includes.update(set(['bindings/v8/ExceptionMessages.h',
                             'bindings/v8/ExceptionState.h']))

    contents.update({
        'is_activity_logging_getter': v8_utilities.has_activity_logging(attribute, includes, 'Getter'),  # [ActivityLogging=Access|Getter]
        'is_check_security_for_node': is_check_security_for_node,
        'is_getter_raises_exception': is_getter_raises_exception,
    })

    return contents, includes


def getter_expression(interface, attribute, contents):
    this_getter_name = getter_name(interface, attribute)
    arguments = v8_utilities.call_with_arguments(attribute, contents)
    if attribute.is_nullable:
        arguments.append('isNull')
    if has_extended_attribute(attribute, ('GetterRaisesException', 'RaisesException')):
        arguments.append('es')
    if attribute.data_type == 'EventHandler':
        arguments.append('isolatedWorldForIsolate(info.GetIsolate())')
    return '%s(%s)' % (this_getter_name, ', '.join(arguments))


def getter_name(interface, attribute):
    getter_method_name = uncapitalize(cpp_name(attribute))
    if attribute.is_static:
        return '%s::%s' % (interface.name, getter_method_name)
    return 'imp->%s' % getter_method_name


def is_keep_alive_for_gc(attribute):
    idl_type = attribute.data_type
    extended_attributes = attribute.extended_attributes
    return (
        'KeepAttributeAliveForGC' in extended_attributes or
        # For readonly attributes, for performance reasons we keep the attribute
        # wrapper alive while the owner wrapper is alive, because the attribute
        # never changes.
        (attribute.is_read_only and
         v8_types.wrapper_type(idl_type) and
         # There are some exceptions, however:
         not(
             # Node lifetime is managed by object grouping.
             v8_types.dom_node_type(idl_type) or
             # A self-reference is unnecessary.
             attribute.name == 'self' or
             # FIXME: Remove these hard-coded hacks.
             idl_type in ['EventHandler', 'Promise', 'Window'] or
             idl_type.startswith('HTML'))))


# [DoNotCheckSecurity], [DoNotCheckSecurityOnGetter], [DoNotCheckSecurityOnSetter]
def access_control_list(attribute):
    extended_attributes = attribute.extended_attributes
    if 'DoNotCheckSecurity' in extended_attributes:
        access_control = ['v8::ALL_CAN_READ']
        if not attribute.is_read_only:
            access_control.append('v8::ALL_CAN_WRITE')
        return access_control
    if 'DoNotCheckSecurityOnSetter' in extended_attributes:
        return ['v8::ALL_CAN_WRITE']
    if 'DoNotCheckSecurityOnGetter' in extended_attributes:
        return ['v8::ALL_CAN_READ']
    return ['v8::DEFAULT']


# [NotEnumerable]
def property_attributes(attribute):
    property_attributes_list = []
    if 'NotEnumerable' in attribute.extended_attributes:
        property_attributes_list.append('v8::DontEnum')
    return property_attributes_list or ['v8::None']