Rework overloads/optionals dispatch to use new ?a syntax.

lib/html/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 564 matching lines @@
     operation = info.operations[0]
 
     if 'CheckSecurityForNode' in operation.ext_attrs:
       # FIXME: exclude from interface as well.
       return
 
     is_custom = 'Custom' in operation.ext_attrs
     has_optional_arguments = any(self._IsArgumentOptionalInWebCore(operation, argument) for argument in operation.arguments)
     needs_dispatcher = not is_custom and (len(info.operations) > 1 or has_optional_arguments)
 
-    if not needs_dispatcher:
-      type_renamer = self._DartType
-      default_value = 'null'
-    else:
-      type_renamer = lambda x: 'Dynamic'
-      default_value = '_null'
-
     dart_declaration = '%s%s %s(%s)' % (
         'static ' if info.IsStatic() else '',
         self._DartType(info.type_name),
         html_name,
-        info.ParametersImplementationDeclaration(type_renamer, default_value))
+        info.ParametersImplementationDeclaration(
+            (lambda x: 'Dynamic') if needs_dispatcher else self._DartType))
 
     if not needs_dispatcher:
       # Bind directly to native implementation
       argument_count = (0 if info.IsStatic() else 1) + len(info.param_infos)
       cpp_callback_name = self._GenerateNativeBinding(
           info.name, argument_count, dart_declaration, 'Callback', is_custom)
       if not is_custom:
         self._GenerateOperationNativeCallback(operation, operation.arguments, cpp_callback_name)
     else:
       self._GenerateDispatcher(info.operations, dart_declaration, [info.name for info in info.param_infos])
@@ skipping 28 matching lines @@
 
       dart_declaration = '%s%s _%s(%s)' % (
           'static ' if operation.is_static else '',
           self._DartType(operation.type.id), overload_name, argument_list)
       cpp_callback_name = self._GenerateNativeBinding(
           overload_name, (0 if operation.is_static else 1) + argument_count,
           dart_declaration, 'Callback', False)
       self._GenerateOperationNativeCallback(operation, operation.arguments[:argument_count], cpp_callback_name)
 
     def GenerateChecksAndCall(operation, argument_count):
-      checks = ['%s === _null' % name for name in argument_names]
+      checks = ['!?%s' % name for name in argument_names]
       for i in range(0, argument_count):
         argument = operation.arguments[i]
         argument_name = argument_names[i]
         checks[i] = '(%s is %s || %s === null)' % (
             argument_name, self._DartType(argument.type.id), argument_name)
       GenerateCall(operation, argument_count, checks)
 
     # TODO: Optimize the dispatch to avoid repeated checks.
     if len(operations) > 1:
       for operation in operations:
         for position, argument in enumerate(operation.arguments):
           if self._IsArgumentOptionalInWebCore(operation, argument):
             GenerateChecksAndCall(operation, position)
         GenerateChecksAndCall(operation, len(operation.arguments))
       body.Emit('    throw "Incorrect number or type of arguments";\n');
     else:
       operation = operations[0]
       argument_count = len(operation.arguments)
       for position, argument in list(enumerate(operation.arguments))[::-1]:
         if self._IsArgumentOptionalInWebCore(operation, argument):
-          check = '%s !== _null' % argument_names[position]
+          check = '?%s' % argument_names[position]
           # argument_count instead of position + 1 is used here to cover one
           # complicated case with the effectively optional argument in the middle.
           # Consider foo(x, [Optional] y, [Optional=DefaultIsNullString] z)
           # (as of now it's modelled after HTMLMediaElement.webkitAddKey).
           # y is optional in WebCore, while z is not.
-          # In this case, if y !== _null, we'd like to emit foo(x, y, z) invocation, not
-          # foo(x, y).
+          # In this case, if y was actually passed, we'd like to emit foo(x, y, z) invocation,
+          # not foo(x, y).
           GenerateCall(operation, argument_count, [check])
           argument_count = position
       GenerateCall(operation, argument_count, [])
 
   def SecondaryContext(self, interface):
     pass
 
   def _GenerateOperationNativeCallback(self, operation, arguments, cpp_callback_name):
     webcore_function_name = operation.ext_attrs.get('ImplementedAs', operation.id)
     function_expression = self._GenerateWebCoreFunctionExpression(webcore_function_name, operation)
@@ skipping 276 matching lines @@
     parent_interface = _FindInHierarchy(database, parent_interface, test)
     if parent_interface:
       return parent_interface
 
 def _ToWebKitName(name):
   name = name[0].lower() + name[1:]
   name = re.sub(r'^(hTML|uRL|jS|xML|xSLT)', lambda s: s.group(1).lower(),
                 name)
   return re.sub(r'^(create|exclusive)', lambda s: 'is' + s.group(1).capitalize(),
                 name)