IDL: Support nullable union types

Source/bindings/scripts/v8_types.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 175 matching lines @@
     if idl_type.is_interface_type:
         implemented_as_class = idl_type.implemented_as
         if raw_type:
             return implemented_as_class + '*'
         new_type = 'Member' if used_in_cpp_sequence else 'RawPtr'
         ptr_type = cpp_ptr_type(('PassRefPtr' if used_as_rvalue_type else 'RefPtr'), new_type, idl_type.gc_type)
         return cpp_template_type(ptr_type, implemented_as_class)
     if idl_type.is_dictionary:
         return base_idl_type
     if idl_type.is_union_type:
-        return idl_type.name
+        return idl_type.as_union_type.name
 
     # Default, assume native type is a pointer with same type name as idl type
     return base_idl_type + '*'
 
 
 def cpp_type_initializer(idl_type):
     """Returns a string containing a C++ initialization statement for the
     corresponding type.
 
     |idl_type| argument is of type IdlType.
@@ skipping 303 matching lines @@
         return ''
 
     # Array or sequence types
     native_array_element_type = idl_type.native_array_element_type
     if native_array_element_type:
         return v8_value_to_cpp_value_array_or_sequence(native_array_element_type, v8_value, index)
 
     # Simple types
     idl_type = idl_type.preprocessed_type
     add_includes_for_type(idl_type)
-    base_idl_type = idl_type.name if idl_type.is_union_type else idl_type.base_type
+    base_idl_type = idl_type.as_union_type.name if idl_type.is_union_type else idl_type.base_type
 
     if 'EnforceRange' in extended_attributes:
         arguments = ', '.join([v8_value, 'EnforceRange', 'exceptionState'])
     elif 'Clamp' in extended_attributes:
         arguments = ', '.join([v8_value, 'Clamp', 'exceptionState'])
     elif idl_type.v8_conversion_needs_exception_state:
         arguments = ', '.join([v8_value, 'exceptionState'])
     else:
         arguments = v8_value
 
@@ skipping 324 matching lines @@
 
 
 def cpp_type_has_null_value(idl_type):
     # - String types (String/AtomicString) represent null as a null string,
     #   i.e. one for which String::isNull() returns true.
     # - Enum types, as they are implemented as Strings.
     # - Wrapper types (raw pointer or RefPtr/PassRefPtr) represent null as
     #   a null pointer.
     # - 'Object' type. We use ScriptValue for object type.
     return (idl_type.is_string_type or idl_type.is_wrapper_type or
-            idl_type.is_enum or idl_type.base_type == 'object')
+            idl_type.is_enum or idl_type.is_union_type or
+            idl_type.base_type == 'object')
 
 IdlTypeBase.cpp_type_has_null_value = property(cpp_type_has_null_value)
 
 
 def is_implicit_nullable(idl_type):
     # Nullable type where the corresponding C++ type supports a null value.
     return idl_type.is_nullable and idl_type.cpp_type_has_null_value
 
 
 def is_explicit_nullable(idl_type):
     # Nullable type that isn't implicit nullable (see above.) For such types,
     # we use Nullable<T> or similar explicit ways to represent a null value.
     return idl_type.is_nullable and not idl_type.is_implicit_nullable
 
 IdlTypeBase.is_implicit_nullable = property(is_implicit_nullable)
 IdlUnionType.is_implicit_nullable = False
 IdlTypeBase.is_explicit_nullable = property(is_explicit_nullable)