Support generation of constructors in the most common case.

client/dom/scripts/dartgenerator.py

Index: client/dom/scripts/dartgenerator.py
diff --git a/client/dom/scripts/dartgenerator.py b/client/dom/scripts/dartgenerator.py
index e267c905996abb0c91c02932c43c029da3c663ef..06db322a2b8d726031e67661836fd6dc98d341a2 100755
--- a/client/dom/scripts/dartgenerator.py
+++ b/client/dom/scripts/dartgenerator.py
@@ -2705,21 +2705,67 @@ class NativeImplementationGenerator(WrappingInterfaceGenerator):
     self._cpp_resolver_emitter = emitter.Emitter()
 
     # Generate constructor.
-    # FIXME: add proper support for non-custom constructors.
-    if ('CustomConstructor' in self._interface.ext_attrs or
-        'V8CustomConstructor' in self._interface.ext_attrs or
-        self._interface.id in ['FileReader', 'WebKitCSSMatrix', 'XSLTProcessor']):
+    # WebKit IDLs may define constructors with arguments.  Currently this form is not supported
+    # (see b/1721).  There is custom implementation for some of them, the rest are just ignored
+    # for now.
+    SUPPORTED_CONSTRUCTORS_WITH_ARGS = [ 'WebKitCSSMatrix' ]
+    UNSUPPORTED_CONSTRUCTORS_WITH_ARGS = [
+        'EventSource',
+        'MediaStream',
+        'PeerConnection',
+        'ShadowRoot',
+        'SharedWorker',
+        'TextTrackCue',
+        'Worker' ]
+    if self._IsConstructable() and self._interface.id not in UNSUPPORTED_CONSTRUCTORS_WITH_ARGS:

[podivilov, 2012/02/17 17:47:20]

Please use early return.

       self._cpp_resolver_emitter.Emit(
           '    if (name == "$(INTERFACE_NAME)_constructor_Callback")\n'
           '        return Dart$(INTERFACE_NAME)Internal::constructorCallback;\n',
           INTERFACE_NAME=self._interface.id)
-      self._cpp_declarations_emitter.Emit(
-          '\n'
-          'void constructorCallback(Dart_NativeArguments);\n')
+
+      if self._interface.id not in SUPPORTED_CONSTRUCTORS_WITH_ARGS and 'Constructor' in self._interface.ext_attrs:

[podivilov, 2012/02/17 17:47:20]

Early return as well: if custom, just emit declaration and return.

+        raises_dom_exceptions = 'ConstructorRaisesException' in self._interface.ext_attrs
+        raises_dart_exceptions = raises_dom_exceptions
+        type_info = GetIDLTypeInfo(self._interface)
+        arguments = []
+        parameter_definitions = ''
+        if 'CallWith' in self._interface.ext_attrs:
+          call_with = self._interface.ext_attrs['CallWith']
+          if call_with == 'ScriptExecutionContext':
+            raises_dart_exceptions = True
+            parameter_definitions = (
+                '        ScriptExecutionContext* context = DartUtilities::scriptExecutionContext();\n'
+                '        if (!context) {\n'
+                '            exception = Dart_NewString("Failed to create an object");\n'
+                '            goto fail;\n'
+                '        }\n')
+            arguments = ['context']
+          else:
+            raise Exception('Unsupported CallWith=%s attribute' % call_with)
+
+        self._GenerateNativeCallbackBase(
+            callback_name='constructorCallback',
+            idl_node=self._interface,
+            parameter_definitions=parameter_definitions,
+            function_name='%s::create' % type_info.native_type(),
+            arguments=arguments,
+            idl_return_type=self._interface,
+            raises_dart_exceptions=raises_dart_exceptions,
+            raises_dom_exceptions=raises_dom_exceptions,
+            needs_receiver=False)
+      else:
+        self._cpp_declarations_emitter.Emit(
+            '\n'
+            'void constructorCallback(Dart_NativeArguments);\n')
+
 
   def _ImplClassName(self, interface_name):
     return interface_name + 'Implementation'
 
+  def _IsConstructable(self):
+    # FIXME: support ConstructorTemplate.
+    return set(['CustomConstructor', 'V8CustomConstructor', 'Constructor']) & set(self._interface.ext_attrs)
+
   def FinishInterface(self):
     base = self._BaseClassName(self._interface)
     self._dart_impl_emitter.Emit(
@@ -3035,10 +3081,23 @@ class NativeImplementationGenerator(WrappingInterfaceGenerator):
   def _GenerateNativeCallback(self, callback_name, idl_node,
       parameter_definitions, function_name, arguments, idl_return_type,
       raises_dart_exceptions, raises_dom_exceptions):
-    receiver = self._interface_type_info.receiver()
+    self._GenerateNativeCallbackBase(

[podivilov, 2012/02/17 17:47:20]

I think such trampolines make the code messy. Could you please avoid them?

+        callback_name=callback_name,
+        idl_node=idl_node,
+        parameter_definitions=parameter_definitions,
+        function_name=self._interface_type_info.receiver() + function_name,
+        arguments=arguments,
+        idl_return_type=idl_return_type,
+        raises_dart_exceptions=raises_dart_exceptions,
+        raises_dom_exceptions=raises_dom_exceptions,
+        needs_receiver=True)
+
+  def _GenerateNativeCallbackBase(self, callback_name, idl_node,
+      parameter_definitions, function_name, arguments, idl_return_type,
+      raises_dart_exceptions, raises_dom_exceptions, needs_receiver):
     if raises_dom_exceptions:
       arguments.append('ec')
-    callback = '%s%s(%s)' % (receiver, function_name, ', '.join(arguments))
+    callback = '%s(%s)' % (function_name, ', '.join(arguments))

[podivilov, 2012/02/17 17:47:20]

Could you please replace "function_name, arguments" with "invocation", and
include receiver declaration in parameter_definitions? It would require some
duplication, but will result in a clean and straightforward code.

 
     nested_templates = []
     if idl_return_type and idl_return_type.id != 'void':
@@ -3084,9 +3143,7 @@ class NativeImplementationGenerator(WrappingInterfaceGenerator):
 
     nested_templates.append(
         '    {\n'
-        '        $WEBCORE_CLASS_NAME* receiver = DartDOMWrapper::receiver< $WEBCORE_CLASS_NAME >(args);\n'
         '$PARAMETER_DEFINITIONS'
-        '\n'
         '$BODY'
         '        return;\n'
         '    }\n')
@@ -3113,11 +3170,15 @@ class NativeImplementationGenerator(WrappingInterfaceGenerator):
         'WEBCORE_CLASS_NAME': self._interface_type_info.native_type(),
         'PARAMETER_DEFINITIONS': parameter_definitions,
     }
+    if needs_receiver:
+      template_parameters['PARAMETER_DEFINITIONS'] = emitter.Format(
+          '        $WEBCORE_CLASS_NAME* receiver = DartDOMWrapper::receiver< $WEBCORE_CLASS_NAME >(args);\n'
+          '        $PARAMETER_DEFINITIONS\n',
+          **template_parameters)
+
     for template in nested_templates:
       template_parameters['BODY'] = callback
-      callback_emitter = emitter.Emitter()
-      callback_emitter.Emit(template, **template_parameters)
-      callback = ''.join(callback_emitter.Fragments())
+      callback = emitter.Format(template, **template_parameters)
 
     self._cpp_definitions_emitter.Emit(callback)