Start unification of overload dispatcher generation.

tools/dom/scripts/systemhtml.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 system to generate
 Dart:html APIs from the IDL database."""
 
 import emitter
 import os
@@ skipping 838 matching lines @@
       self._members_emitter.Emit(
           '  $RENAME$ANNOTATIONS$MODIFIERS$TYPE$TARGET($PARAMS) native;\n',
           RENAME=self._RenamingAnnotation(info.declared_name, target),
           ANNOTATIONS=self._Annotations(info.type_name, info.declared_name),
           MODIFIERS='static ' if info.IsStatic() else '',
           TYPE=TypeOrNothing(native_return_type),
           TARGET=target,
           PARAMS=', '.join(target_parameters))
 
     def GenerateChecksAndCall(operation, argument_count):
-      checks = []
-      for i in range(0, argument_count):
-        argument = operation.arguments[i]
-        parameter_name = parameter_names[i]
-        test_type = self._DartType(argument.type.id)
-        if test_type in ['dynamic', 'Object']:
-          checks.append('?%s' % parameter_name)
-        elif test_type != parameter_types[i]:
-          checks.append('(?%s && (%s is %s || %s == null))' % (
-              parameter_name, parameter_name, test_type, parameter_name))
-
-      checks.extend(['!?%s' % name for name in parameter_names[argument_count:]])
-      # There can be multiple presence checks.  We need them all since a later
-      # optional argument could have been passed by name, leaving 'holes'.
-      GenerateCall(operation, argument_count, checks)
+      GenerateCall(operation, argument_count,
+          self._OverloadChecks(
+            operation,
+            parameter_names,
+            argument_count,
+            can_omit_type_check=lambda type, pos: type == parameter_types[pos]))
 
     # 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._IsOptional(operation, argument):
             GenerateChecksAndCall(operation, position)
         GenerateChecksAndCall(operation, len(operation.arguments))
       body.Emit(
           '    throw new ArgumentError("Incorrect number or type of arguments");'
@@ skipping 166 matching lines @@
     for library_name in libraries:
       self._libraries[library_name] = DartLibrary(
           library_name, template_loader, library_type, output_dir)
 
   def AddFile(self, basename, library_name, path):
     self._libraries[library_name].AddFile(path)
 
   def Emit(self, emitter, auxiliary_dir):
     for lib in self._libraries.values():
       lib.Emit(emitter, auxiliary_dir)