Support optional callbacks.

client/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 514 matching lines @@
       dispatch_emitter: an dispatch_emitter for the body of a block of code.
       info: the compound information about the operation and its overloads.
       indent: an indentation string for generated code.
       operation: the IDLOperation to call.
     """
 
     # FIXME: support ImplementedBy callbacks.
     if 'ImplementedBy' in operation.ext_attrs:
       return
 
-    for op in self._interface.operations:
-      if op.id != operation.id or len(op.arguments) <= len(operation.arguments):
-        continue
-      next_argument = op.arguments[len(operation.arguments)]
-      if next_argument.is_optional and 'Callback' in next_argument.ext_attrs:
-        # FIXME: '[Optional, Callback]' arguments could be non-optional in
-        # webcore. We need to fix overloads handling to generate native
-        # callbacks properly.
-        return
-
     self._native_version += 1
     native_name = info.name
     if self._native_version > 1:
       native_name = '%s_%s' % (native_name, self._native_version)
     argument_list = ', '.join([info.arg_infos[i][0]
                                for (i, arg) in enumerate(operation.arguments)])
 
     # Generate dispatcher.
     if info.type_name != 'void':
       dispatch_emitter.Emit('$(INDENT)return _$NATIVENAME($ARGS);\n',
@@ skipping 174 matching lines @@
       callback = emitter.Format(template, **template_parameters)
 
     self._cpp_definitions_emitter.Emit(callback)
 
   def _GenerateParameterAdapter(self, emitter, idl_argument, index):
     type_info = GetIDLTypeInfo(idl_argument.type)
     (adapter_type, include_name) = type_info.parameter_adapter_info()
     if include_name:
       self._cpp_impl_includes[include_name] = 1
     flags = ''
-    if idl_argument.ext_attrs.get('Optionial') == 'DefaultIsNullString':
-      flags = ', DartUtilities::ConvertNullToEmptyString'
+    if (idl_argument.ext_attrs.get('Optionial') == 'DefaultIsNullString' or
+        ('Optional' in idl_argument.ext_attrs and 'Callback' in idl_argument.ext_attrs)):
+      flags = ', DartUtilities::ConvertNullToDefaultValue'
     emitter.Emit(
         '\n'
         '        const $ADAPTER_TYPE $NAME(Dart_GetNativeArgument(args, $INDEX)$FLAGS);\n'
         '        if (!$NAME.conversionSuccessful()) {\n'
         '            exception = $NAME.exception();\n'
         '            goto fail;\n'
         '        }\n',
         ADAPTER_TYPE=adapter_type,
         NAME=idl_argument.id,
         INDEX=index + 1,
@@ skipping 28 matching lines @@
     namespace = 'HTMLNames'
     svg_exceptions = ['class', 'id', 'onabort', 'onclick', 'onerror', 'onload',
                       'onmousedown', 'onmousemove', 'onmouseout', 'onmouseover',
                       'onmouseup', 'onresize', 'onscroll', 'onunload']
     if self._interface.id.startswith('SVG') and not attr.id in svg_exceptions:
       namespace = 'SVGNames'
     self._cpp_impl_includes[namespace] = 1
 
     attribute_name = attr.ext_attrs['Reflect'] or attr.id.lower()
     return 'WebCore::%s::%sAttr' % (namespace, attribute_name)