IDL: Use Nullable for union type return value

Source/bindings/scripts/v8_methods.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 286 matching lines @@
     # static member functions, which for instance members (non-static members)
     # take *impl as their first argument
     if ('PartialInterfaceImplementedAs' in method.extended_attributes and
         not 'ImplementedInPrivateScript' in method.extended_attributes and
         not method.is_static):
         cpp_arguments.append('*impl')
     cpp_arguments.extend(cpp_argument(argument) for argument in arguments)
 
     this_union_arguments = method.idl_type and method.idl_type.union_arguments
     if this_union_arguments:
-        cpp_arguments.extend(this_union_arguments)
+        cpp_arguments.extend([member_argument['cpp_value']
+                              for member_argument in this_union_arguments])
 
     if 'ImplementedInPrivateScript' in method.extended_attributes:
         if method.idl_type.name != 'void':
             cpp_arguments.append('&result')
     elif ('RaisesException' in method.extended_attributes or
         (method.is_constructor and
          has_extended_attribute_value(interface, 'RaisesException', 'Constructor'))):
         cpp_arguments.append('exceptionState')
 
     if method.name == 'Constructor':
@@ skipping 76 matching lines @@
     property_attributes_list = []
     if 'NotEnumerable' in extended_attributes:
         property_attributes_list.append('v8::DontEnum')
     if 'Unforgeable' in extended_attributes:
         property_attributes_list.append('v8::ReadOnly')
     if property_attributes_list:
         property_attributes_list.insert(0, 'v8::DontDelete')
     return property_attributes_list
 
 
+def union_member_argument_context(idl_type, index):
+    """Returns a context of union member for argument."""
+    this_cpp_value = 'result%d' % index
+    this_cpp_type = idl_type.cpp_type
+    cpp_return_value = this_cpp_value
+
+    if not idl_type.cpp_type_has_null_value:
+        this_cpp_type = v8_types.cpp_template_type('Nullable', this_cpp_type)
+        cpp_return_value = '%s.get()' % this_cpp_value
+
+    if idl_type.is_string_type:
+        null_check_value = '!%s.isNull()' % this_cpp_value
+    else:
+        null_check_value = this_cpp_value
+
+    return {
+        'cpp_type': this_cpp_type,
+        'cpp_value': this_cpp_value,
+        'null_check_value': null_check_value,
+        'v8_set_return_value': idl_type.v8_set_return_value(
+            cpp_value=cpp_return_value,
+            release=idl_type.release),
+    }
+
+
 def union_arguments(idl_type):
-    """Return list of ['result0Enabled', 'result0', 'result1Enabled', ...] for union types, for use in setting return value"""
-    return [arg
-            for i in range(len(idl_type.member_types))
-            for arg in ['result%sEnabled' % i, 'result%s' % i]]
+    return [union_member_argument_context(member_idl_type, index)
+            for index, member_idl_type
+            in enumerate(idl_type.member_types)]
 
 
 def argument_default_cpp_value(argument):
     if not argument.default_value:
         return None
     return argument.idl_type.literal_cpp_value(argument.default_value)
 
 IdlTypeBase.union_arguments = None
 IdlUnionType.union_arguments = property(union_arguments)
 IdlArgument.default_cpp_value = property(argument_default_cpp_value)