IDL: Union type support for attributes

Source/bindings/scripts/v8_attributes.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # 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
@@ skipping 107 matching lines @@
         'is_explicit_nullable': idl_type.is_explicit_nullable,
         'is_partial_interface_member':
             'PartialInterfaceImplementedAs' in extended_attributes,
         'is_per_world_bindings': 'PerWorldBindings' in extended_attributes,
         'is_read_only': attribute.is_read_only,
         'is_reflect': is_reflect,
         'is_replaceable': 'Replaceable' in attribute.extended_attributes,
         'is_static': attribute.is_static,
         'is_url': 'URL' in extended_attributes,
         'is_unforgeable': 'Unforgeable' in extended_attributes,
+        'is_union_type': idl_type.is_union_type,
         'measure_as': v8_utilities.measure_as(attribute),  # [MeasureAs]
         'name': attribute.name,
         'only_exposed_to_private_script': is_only_exposed_to_private_script,
         'per_context_enabled_function': v8_utilities.per_context_enabled_function_name(attribute),  # [PerContextEnabled]
         'private_script_v8_value_to_local_cpp_value': idl_type.v8_value_to_local_cpp_value(
             extended_attributes, 'v8Value', 'cppValue', isolate='scriptState->isolate()', used_in_private_script=True),
         'property_attributes': property_attributes(attribute),
         'put_forwards': 'PutForwards' in extended_attributes,
         'reflect_empty': extended_attributes.get('ReflectEmpty'),
         'reflect_invalid': extended_attributes.get('ReflectInvalid', ''),
@@ skipping 89 matching lines @@
     # static member functions, which for instance members (non-static members)
     # take *impl as their first argument
     if ('PartialInterfaceImplementedAs' in attribute.extended_attributes and
         not 'ImplementedInPrivateScript' in attribute.extended_attributes and
         not attribute.is_static):
         arguments.append('*impl')
     if attribute.idl_type.is_explicit_nullable:
         arguments.append('isNull')
     if context['is_getter_raises_exception']:
         arguments.append('exceptionState')
+    # Union type attribute getters take impl class object as the last argument
+    # and set value to it, not returning the value.
+    if attribute.idl_type.is_union_type:
+        arguments.append('result')
     return '%s(%s)' % (getter_name, ', '.join(arguments))
 
 
 CONTENT_ATTRIBUTE_GETTER_NAMES = {
     'boolean': 'fastHasAttribute',
     'long': 'getIntegralAttribute',
     'unsigned long': 'getUnsignedIntegralAttribute',
 }
 
 
@@ skipping 254 matching lines @@
     lambda self: strip_suffix(self.base_type, 'Constructor'))
 
 
 def is_constructor_attribute(attribute):
     # FIXME: replace this with [ConstructorAttribute] extended attribute
     return attribute.idl_type.name.endswith('Constructor')
 
 
 def constructor_getter_context(interface, attribute, context):
     context['needs_constructor_getter_callback'] = context['measure_as'] or context['deprecate_as']