Extract common logic from Backend.BaseClassName().

lib/html/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 294 matching lines @@
      self._members_emitter,
      self._top_level_emitter) = interface_emitter.Emit(
          interface_template + '$!TOP_LEVEL',
          ID=interface_name,
          EXTENDS=implements_str)
 
     self._type_comment_emitter.Emit("/// @domName $DOMNAME",
         DOMNAME=self._interface.doc_js_name)
 
     implementation_emitter = self._ImplementationEmitter()
-    base_class = self._backend.BaseClassName()
-    interface_type_info = self._type_registry.TypeInfo(self._interface.id)
-    implemented_interfaces = [interface_type_info.interface_name()] +\
+
+    base_class = self._backend.RootClassName()
+    if self._interface.parents:
+      supertype = self._interface.parents[0].type.id
+      if not IsDartCollectionType(supertype) and not IsPureInterface(supertype):
+        type_info = self._type_registry.TypeInfo(supertype)
+        if type_info.merged_into() and self._backend.ImplementsMergedMembers():
+          type_info = self._type_registry.TypeInfo(type_info.merged_into())
+        base_class = type_info.implementation_name()
+
+    implemented_interfaces = [interface_name] +\
                              self._backend.AdditionalImplementedInterfaces()
     self._implementation_members_emitter = implementation_emitter.Emit(
         self._backend.ImplementationTemplate(),
         CLASSNAME=self._interface_type_info.implementation_name(),
         EXTENDS=' extends %s' % base_class if base_class else '',
         IMPLEMENTS=' implements ' + ', '.join(implemented_interfaces),
         NATIVESPEC=self._backend.NativeSpec())
     self._backend.StartInterface(self._implementation_members_emitter)
 
     for constructor_info in constructors:
@@ skipping 256 matching lines @@
     self._type_registry = options.type_registry
     self._interface_type_info = self._type_registry.TypeInfo(self._interface.id)
     self._current_secondary_parent = None
 
   def ImplementsMergedMembers(self):
     return True
 
   def GenerateCallback(self, info):
     pass
 
-  def BaseClassName(self):
-    if not self._interface.parents:
-      return None
-    supertype = self._interface.parents[0].type.id
-    if IsDartCollectionType(supertype):
-      # List methods are injected in AddIndexer.
-      return None
-    if IsPureInterface(supertype):
-      return None
-    type_info = self._type_registry.TypeInfo(supertype)
-    if type_info.merged_into():
-      type_info = self._type_registry.TypeInfo(type_info.merged_into())
-    return type_info.implementation_name()
+  def RootClassName(self):
+    return None
 
   def AdditionalImplementedInterfaces(self):
     # TODO: Include all implemented interfaces, including other Lists.
     implements = []
     element_type = MaybeTypedArrayElementType(self._interface)
     if element_type:
       implements.append('List<%s>' % self._DartType(element_type))
     if self._HasJavaScriptIndexingBehaviour():
       implements.append('JavaScriptIndexingBehavior')
     return implements
@@ skipping 483 matching lines @@
 
     library_emitter = self._multiemitter.FileEmitter(library_file_path)
     library_file_dir = os.path.dirname(library_file_path)
     auxiliary_dir = os.path.relpath(auxiliary_dir, library_file_dir)
     imports_emitter = library_emitter.Emit(
         self._template, AUXILIARY_DIR=massage_path(auxiliary_dir))
     for path in sorted(self._path_to_emitter.keys()):
       relpath = os.path.relpath(path, library_file_dir)
       imports_emitter.Emit(
           "#source('$PATH');\n", PATH=massage_path(relpath))