Proper support for ForceOptional.

tools/dom/scripts/systemnative.py

 #!/usr/bin/python
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 """This module provides shared functionality for the systems to generate
 native binding from the IDL database."""
 
 import emitter
 import os
@@ skipping 243 matching lines @@
         INTERFACE=self._interface.id,
         INCLUDES=self._GenerateCPPIncludes(self._cpp_impl_includes),
         CALLBACKS=self._cpp_definitions_emitter.Fragments(),
         RESOLVER=self._cpp_resolver_emitter.Fragments(),
         DART_IMPLEMENTATION_CLASS=self._interface_type_info.implementation_name(),
         DART_IMPLEMENTATION_LIBRARY='dart:%s' % self._renamer.GetLibraryName(self._interface))
 
   def _GenerateCPPHeader(self):
     to_native_emitter = emitter.Emitter()
     if self._interface_type_info.custom_to_native():
-      to_native_emitter.Emit(
-          '    static PassRefPtr<NativeType> toNative(Dart_Handle handle, Dart_Handle& exception);\n')
+      return_type = 'PassRefPtr<NativeType>'
+      to_native_body = ';'
     else:
-      to_native_emitter.Emit(
-          '    static NativeType* toNative(Dart_Handle handle, Dart_Handle& exception)\n'
+      return_type = 'NativeType*'
+      to_native_body = emitter.Format(
+          '\n'
           '    {\n'
           '        return DartDOMWrapper::unwrapDartWrapper<Dart$INTERFACE>(handle, exception);\n'
-          '    }\n',
+          '    }',
           INTERFACE=self._interface.id)
 
+    to_native_emitter.Emit(
+        '    static $RETURN_TYPE toNative(Dart_Handle handle, Dart_Handle& exception)$TO_NATIVE_BODY\n'
+        '\n'
+        '    static $RETURN_TYPE toNativeWithNullCheck(Dart_Handle handle, Dart_Handle& exception)\n'
+        '    {\n'
+        '        return Dart_IsNull(handle) ? 0 : toNative(handle, exception);\n'
+        '    }\n',
+        RETURN_TYPE=return_type,
+        TO_NATIVE_BODY=to_native_body,
+        INTERFACE=self._interface.id)
+
     to_dart_emitter = emitter.Emitter()
 
     ext_attrs = self._interface.ext_attrs
 
     if ('CustomToJS' in ext_attrs or
         ('CustomToJSObject' in ext_attrs and 'TypedArray' not in ext_attrs) or
         'PureInterface' in ext_attrs or
         'CPPPureInterface' in ext_attrs or
         self._interface_type_info.custom_to_dart()):
       to_dart_emitter.Emit(
@@ skipping 560 matching lines @@
       return '%s::%s' % (self._interface_type_info.idl_type(), function_name)
     return '%s%s' % (self._interface_type_info.receiver(), function_name)
 
   def _IsArgumentOptionalInWebCore(self, operation, argument):
     if not IsOptional(argument):
       return False
     if 'Callback' in argument.ext_attrs:
       return False
     if operation.id in ['addEventListener', 'removeEventListener'] and argument.id == 'useCapture':
       return False
-    # Another option would be to adjust in IDLs, but let's keep it here for now
-    # as it's a single instance.
-    if self._interface.id == 'CSSStyleDeclaration' and operation.id == 'setProperty' and argument.id == 'priority':
+    if 'ForceOptional' in argument.ext_attrs:
       return False
     if argument.type.id == 'Dictionary':
       return False
     return True
 
   def _GenerateCPPIncludes(self, includes):
     return ''.join(['#include %s\n' % include for include in sorted(includes)])
 
   def _ToWebKitName(self, name):
     name = name[0].lower() + name[1:]
@@ skipping 53 matching lines @@
             '    if (Dart_NativeFunction func = $CLASS_NAME::resolver(name, argumentCount))\n'
             '        return func;\n',
             CLASS_NAME=os.path.splitext(os.path.basename(path))[0])
 
 def _IsOptionalStringArgumentInInitEventMethod(interface, operation, argument):
   return (
       interface.id.endswith('Event') and
       operation.id.startswith('init') and
       argument.ext_attrs.get('Default') == 'Undefined' and
       argument.type.id == 'DOMString')