Source/bindings/scripts/unstable/v8_interface.py

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

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_attributes
from v8_globals import includes
import v8_methods
import v8_types
import v8_utilities
from v8_utilities import conditional_string, cpp_name, has_extended_attribute, has_extended_attribute_value, runtime_enabled_function_name


INTERFACE_H_INCLUDES = set([
    'bindings/v8/V8Binding.h',
    'bindings/v8/V8DOMWrapper.h',
    'bindings/v8/WrapperTypeInfo.h',
])
INTERFACE_CPP_INCLUDES = set([
    'RuntimeEnabledFeatures.h',
    'bindings/v8/ExceptionMessages.h',
    'bindings/v8/V8DOMConfiguration.h',
    'core/dom/ContextFeatures.h',
    'core/dom/Document.h',
    'platform/TraceEvent.h',
])


def generate_interface(interface):
    includes.clear()
    includes.update(INTERFACE_CPP_INCLUDES)
    header_includes = INTERFACE_H_INCLUDES

    parent_interface = interface.parent
    if parent_interface:
        header_includes.update(v8_types.includes_for_type(parent_interface))
    extended_attributes = interface.extended_attributes

    # [CheckSecurity]
    is_check_security = 'CheckSecurity' in extended_attributes
    if is_check_security:
        includes.update(['bindings/v8/BindingSecurity.h',
                         'bindings/v8/ExceptionState.h'])

    # [GenerateVisitDOMWrapper]
    generate_visit_dom_wrapper_function = extended_attributes.get('GenerateVisitDOMWrapper')
    if generate_visit_dom_wrapper_function:
        includes.update(['bindings/v8/V8GCController.h',
                         'core/dom/Element.h'])

    # [MeasureAs]
    is_measure_as = 'MeasureAs' in extended_attributes
    if is_measure_as:
        includes.add('core/frame/UseCounter.h')

    # [RaisesException=Constructor]
    is_constructor_raises_exception = extended_attributes.get('RaisesException') == 'Constructor'
    if is_constructor_raises_exception:
        includes.add('bindings/v8/ExceptionState.h')

    # [SpecialWrapFor]
    if 'SpecialWrapFor' in extended_attributes:
        special_wrap_for = extended_attributes['SpecialWrapFor'].split('|')
    else:
        special_wrap_for = []
    for special_wrap_interface in special_wrap_for:
        v8_types.add_includes_for_type(special_wrap_interface)

    # Constructors
    # [Constructor]
    has_constructor = 'Constructor' in extended_attributes
    if has_constructor:
        includes.add('bindings/v8/V8ObjectConstructor.h')

    # [EventConstructor]
    has_event_constructor = 'EventConstructor' in extended_attributes
    has_any_type_attributes = any(attribute
                                  for attribute in interface.attributes
                                  if attribute.idl_type == 'any')
    if has_event_constructor:
        includes.update(['bindings/v8/Dictionary.h',
                         'bindings/v8/V8ObjectConstructor.h'])
        if has_any_type_attributes:
            includes.add('bindings/v8/SerializedScriptValue.h')

    template_contents = {
        'conditional_string': conditional_string(interface),  # [Conditional]
        'constructor_arguments': constructor_arguments(interface),
        'cpp_class': cpp_name(interface),
        'generate_visit_dom_wrapper_function': generate_visit_dom_wrapper_function,
        'has_constructor': has_constructor,
        'has_custom_legacy_call_as_function': has_extended_attribute_value(interface, 'Custom', 'LegacyCallAsFunction'),  # [Custom=LegacyCallAsFunction]
        'has_custom_to_v8': has_extended_attribute_value(interface, 'Custom', 'ToV8'),  # [Custom=ToV8]
        'has_custom_wrap': has_extended_attribute_value(interface, 'Custom', 'Wrap'),  # [Custom=Wrap]
        'has_event_constructor': has_event_constructor,
        'has_any_type_attributes': has_any_type_attributes,
        'has_visit_dom_wrapper': (
            # [Custom=Wrap], [GenerateVisitDOMWrapper]
            has_extended_attribute_value(interface, 'Custom', 'VisitDOMWrapper') or
            'GenerateVisitDOMWrapper' in extended_attributes),
        'header_includes': header_includes,
        'interface_name': interface.name,
        'is_active_dom_object': 'ActiveDOMObject' in extended_attributes,  # [ActiveDOMObject]
        'is_check_security': is_check_security,
        'is_constructor_call_with_document': has_extended_attribute_value(
            interface, 'ConstructorCallWith', 'Document'),  # [ConstructorCallWith=Document]
        'is_constructor_call_with_execution_context': has_extended_attribute_value(
            interface, 'ConstructorCallWith', 'ExecutionContext'),  # [ConstructorCallWith=ExeuctionContext]
        'is_constructor_raises_exception': is_constructor_raises_exception,
        'is_dependent_lifetime': 'DependentLifetime' in extended_attributes,  # [DependentLifetime]
        'length': 1 if has_event_constructor else 0,  # FIXME: more complex in general, see discussion of length in http://heycam.github.io/webidl/#es-interface-call
        'measure_as': v8_utilities.measure_as(interface),  # [MeasureAs]
        'parent_interface': parent_interface,
        'runtime_enabled_function': runtime_enabled_function_name(interface),  # [RuntimeEnabled]
        'special_wrap_for': special_wrap_for,
        'v8_class': v8_utilities.v8_class_name(interface),
    }

    template_contents.update({
        'constants': [generate_constant(constant) for constant in interface.constants],
        'do_not_check_constants': 'DoNotCheckConstants' in extended_attributes,
    })

    attributes = [v8_attributes.generate_attribute(interface, attribute)
                  for attribute in interface.attributes]
    template_contents.update({
        'attributes': attributes,
        'has_accessors': any(attribute['is_expose_js_accessors'] for attribute in attributes),
        'has_constructor_attributes': any(attribute['constructor_type'] for attribute in attributes),
        'has_per_context_enabled_attributes': any(attribute['per_context_enabled_function'] for attribute in attributes),
        'has_replaceable_attributes': any(attribute['is_replaceable'] for attribute in attributes),
    })

    methods = [v8_methods.generate_method(interface, method)
               for method in interface.operations]
    generate_overloads(methods)
    for method in methods:
        method['do_generate_method_configuration'] = (
            method['do_not_check_signature'] and
            not method['per_context_enabled_function'] and
            # For overloaded methods, only generate one accessor
            ('overload_index' not in method or method['overload_index'] == 1))

    template_contents.update({
        'has_origin_safe_method_setter': any(
            method['is_check_security_for_frame'] and not method['is_read_only']
            for method in methods),
        'has_method_configuration': any(method['do_generate_method_configuration'] for method in methods),
        'has_per_context_enabled_methods': any(method['per_context_enabled_function'] for method in methods),
        'methods': methods,
    })

    return template_contents


# [DeprecateAs], [Reflect], [RuntimeEnabled]
def generate_constant(constant):
    # (Blink-only) string literals are unquoted in tokenizer, must be re-quoted
    # in C++.
    if constant.idl_type == 'DOMString':
        value = '"%s"' % constant.value
    else:
        value = constant.value

    constant_parameter = {
        'name': constant.name,
        # FIXME: use 'reflected_name' as correct 'name'
        'reflected_name': constant.extended_attributes.get('Reflect', constant.name),
        'runtime_enabled_function': runtime_enabled_function_name(constant),
        'value': value,
    }
    return constant_parameter


def generate_overloads(methods):
    generate_overloads_by_type(methods, is_static=False)  # Regular methods
    generate_overloads_by_type(methods, is_static=True)


def generate_overloads_by_type(methods, is_static):
    # Generates |overloads| template values and modifies |methods| in place;
    # |is_static| flag used (instead of partitioning list in 2) because need to
    # iterate over original list of methods to modify in place
    method_counts = {}
    for method in methods:
        if method['is_static'] != is_static:
            continue
        name = method['name']
        method_counts.setdefault(name, 0)
        method_counts[name] += 1

    # Filter to only methods that are actually overloaded
    overloaded_method_counts = dict((name, count)
                                    for name, count in method_counts.iteritems()
                                    if count > 1)

    # Add overload information only to overloaded methods, so template code can
    # easily verify if a function is overloaded
    method_overloads = {}
    for method in methods:
        name = method['name']
        if (method['is_static'] != is_static or
            name not in overloaded_method_counts):
            continue
        # Overload index includes self, so first append, then compute index
        method_overloads.setdefault(name, []).append(method)
        method.update({
            'overload_index': len(method_overloads[name]),
            'overload_resolution_expression': overload_resolution_expression(method),
        })

    # Resolution function is generated after last overloaded function;
    # package necessary information into |method.overloads| for that method.
    for method in methods:
        if (method['is_static'] != is_static or
            'overload_index' not in method):
            continue
        name = method['name']
        if method['overload_index'] != overloaded_method_counts[name]:
            continue
        overloads = method_overloads[name]
        method['overloads'] = {
            'name': name,
            'methods': overloads,
            'minimum_number_of_required_arguments': min(
                overload['number_of_required_arguments']
                for overload in overloads),
        }


def overload_resolution_expression(method):
    # Expression is an OR of ANDs: each term in the OR corresponds to a
    # possible argument count for a given method, with type checks.
    # FIXME: Blink's overload resolution algorithm is incorrect, per:
    # https://code.google.com/p/chromium/issues/detail?id=293561
    # Properly:
    # 1. Compute effective overload set.
    # 2. First check type list length.
    # 3. If multiple entries for given length, compute distinguishing argument
    #    index and have check for that type.
    arguments = method['arguments']
    overload_checks = [overload_check_expression(method, index)
                       # check *omitting* optional arguments at |index| and up:
                       # index 0 => argument_count 0 (no arguments)
                       # index 1 => argument_count 1 (index 0 argument only)
                       for index, argument in enumerate(arguments)
                       if argument['is_optional']]
    # FIXME: this is wrong if a method has optional arguments and a variadic
    # one, though there are not yet any examples of this
    if not method['is_variadic']:
        # Includes all optional arguments (len = last index + 1)
        overload_checks.append(overload_check_expression(method, len(arguments)))
    return ' || '.join('(%s)' % check for check in overload_checks)


def overload_check_expression(method, argument_count):
    overload_checks = ['info.Length() == %s' % argument_count]
    arguments = method['arguments'][:argument_count]
    overload_checks.extend(overload_check_argument(index, argument)
                           for index, argument in
                           enumerate(arguments))
    return ' && '.join('(%s)' % check for check in overload_checks if check)


def overload_check_argument(index, argument):
    cpp_value = 'info[%s]' % index
    idl_type = argument['idl_type']
    # FIXME: proper type checking, sharing code with attributes and methods
    if idl_type == 'DOMString' and argument['is_strict_type_checking']:
        return ' || '.join(['%s->IsNull()' % cpp_value,
                            '%s->IsUndefined()' % cpp_value,
                            '%s->IsString()' % cpp_value,
                            '%s->IsObject()' % cpp_value])
    if v8_types.array_or_sequence_type(idl_type):
        return '%s->IsArray()' % cpp_value
    if v8_types.is_wrapper_type(idl_type):
        type_check = 'V8{idl_type}::hasInstance({cpp_value}, info.GetIsolate(), worldType(info.GetIsolate()))'.format(idl_type=idl_type, cpp_value=cpp_value)
        if argument['is_nullable']:
            type_check = ' || '.join(['%s->IsNull()' % cpp_value, type_check])
        return type_check
    return None


def constructor_arguments(interface):
    arguments = []
    # [ConstructorCallWith=ExecutionContext]
    if has_extended_attribute_value(interface, 'ConstructorCallWith', 'ExecutionContext'):
        arguments.append('context')
    # [ConstructorCallWith=Document]
    if has_extended_attribute_value(interface, 'ConstructorCallWith', 'Document'):
        arguments.append('document')
    # FIXME: actual arguments!
    # [RaisesException=Constructor]
    if interface.extended_attributes.get('RaisesException') == 'Constructor':
        arguments.append('exceptionState')
    return arguments