Refactor the event-generation code to locate it in systemhtml.py.

client/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."""
 
 from systemfrog import *
 from systeminterface import *
@@ skipping 365 matching lines @@
   'waiting': 'waiting',
   'webkitAnimationEnd': 'animationEnd',
   'webkitAnimationIteration': 'animationIteration',
   'webkitAnimationStart': 'animationStart',
   'webkitfullscreenchange': 'fullscreenChange',
   'webkitfullscreenerror': 'fullscreenError',
   'webkitSpeechChange': 'speechChange',
   'webkitTransitionEnd': 'transitionEnd'
 }
 
+# These classes require an explicit declaration for the "on" method even though
+# they don't declare any unique events, because the concrete class hierarchy
+# doesn't match the interface hierarchy.
+_html_explicit_event_classes = set(['DocumentFragment'])
+
 def _OnAttributeToEventName(on_method):
   event_name = on_method.id[2:]
   if event_name in _on_attribute_to_event_name_mapping:
     return _on_attribute_to_event_name_mapping[event_name]
   else:
     return event_name
 
 def _DomToHtmlEvents(interface_id, events):
   event_names = set(map(_OnAttributeToEventName, events)) 
   if interface_id in _html_manual_events:
@@ skipping 93 matching lines @@
       return ['Events']
     else:
       names = []
       for interface in interfaces_with_events:
         names.append(interface.id + 'Events')
       return names
 
   def _ImplClassName(self, type_name):
     return '_' + type_name + 'Impl'
 
+  def GetEventAttributes(self, interface):
+    events =  set([attr for attr in interface.attributes
+                   if self._generator._IsEventAttribute(interface, attr)])
+
+    if events or interface.id in _html_explicit_event_classes:
+      return events
+
 class HtmlSystem(System):
 
   def __init__(self, templates, database, emitters, output_dir, generator):
     super(HtmlSystem, self).__init__(
         templates, database, emitters, output_dir)
     self._shared = HtmlSystemShared(database, generator)
 
 class HtmlInterfacesSystem(HtmlSystem):
 
   def __init__(self, templates, database, emitters, output_dir, generator):
@@ skipping 112 matching lines @@
       self._members_emitter.Emit(
           '\n'
           '  $CTOR(int length);\n'
           '\n'
           '  $CTOR.fromList(List<$TYPE> list);\n'
           '\n'
           '  $CTOR.fromBuffer(ArrayBuffer buffer);\n',
         CTOR=self._interface.id,
         TYPE=DartType(element_type))
 
+    events = self._shared.GetEventAttributes(self._interface)
+    if events == set():

[Jacob, 2012/03/08 18:38:09]

writing 
if events == set(): 
looks really odd
can you write
if len(events) > 0: 
  self.AddEventAttributes(events)
else:
  self.AddParentEvent()

instead?

[nweiz, 2012/03/08 20:47:16]

len(None) doesn't work, and I don't want to make the if statement have an extra
branch unnecessarily by checking for None early. "== set()" best expresses the
semantics here.

+      self.AddParentEvent()
+    elif events:
+      self.AddEventAttributes(events)
+
   def AddAttribute(self, getter, setter):
     html_getter_name = self._shared.RenameInHtmlLibrary(
       self._interface, getter.id, 'get:')
     html_setter_name = self._shared.RenameInHtmlLibrary(
       self._interface, getter.id, 'set:')
 
     if not html_getter_name:
       getter = None
     if not html_setter_name:
       setter = None
@@ skipping 30 matching lines @@
                                  TYPE=info.type_name,         
                                  NAME=html_name,
                                  PARAMS=info.ParametersInterfaceDeclaration())
 
   def FinishInterface(self):
     pass
 
   def AddConstant(self, constant):
     self._EmitConstant(self._members_emitter, constant)
 
+  def AddParentEvent(self):
+    parent_event_classes = self._shared.GetParentsEventsClasses(
+        self._interface)
+    if len(parent_event_classes) != 1:
+      raise Exception('Only one parent event class allowed '
+          + self._interface.id)
+
+    self._members_emitter.Emit('\n  $TYPE get on();\n',
+                               TYPE=parent_event_classes[0])
+
   def AddEventAttributes(self, event_attrs):
     event_attrs = _DomToHtmlEvents(self._interface.id, event_attrs)
     self._shared._event_classes.add(self._interface.id)
     events_interface = self._interface.id + 'Events'
     self._members_emitter.Emit('\n  $TYPE get on();\n',
                                TYPE=events_interface)
+
     events_members = self._emitter.Emit(
         '\ninterface $INTERFACE extends $PARENTS {\n$!MEMBERS}\n',
         INTERFACE=events_interface,
         PARENTS=', '.join(
             self._shared.GetParentsEventsClasses(self._interface)))
 
     for event_name in event_attrs:
       if event_name in _html_event_names:
         events_members.Emit('\n  EventListenerList get $NAME();\n',
           NAME=_html_event_names[event_name])
@@ skipping 54 matching lines @@
         NATIVESPEC=' native "' + native_spec + '"')
 
     if element_type:
       self.AddTypedArrayConstructors(element_type)
 
     # Emit a factory provider class for the constructor.
     constructor_info = AnalyzeConstructor(interface)
     if constructor_info:
       self._EmitFactoryProvider(interface_name, constructor_info)
 
+    events = self._shared.GetEventAttributes(self._interface)
+    if events == set():
+      self.AddParentEvent()
+    elif events:
+      self.AddEventAttributes(events)
+
   def _EmitFactoryProvider(self, interface_name, constructor_info):
     template_file = 'factoryprovider_%s.darttemplate' % interface_name
     template = self._system._templates.TryLoad(template_file)
     if not template:
       template = self._system._templates.Load('factoryprovider.darttemplate')
 
     factory_provider = '_' + interface_name + 'FactoryProvider'
     emitter = self._system._ImplFileEmitter(factory_provider)
     emitter.Emit(
         template,
@@ skipping 204 matching lines @@
             ' native "$(RETURN)$(THIS).$NAME($PARAMNAMES);";\n')
     else:
       self._members_emitter.Emit(
           '\n'
           '  $TYPE $NAME($PARAMS) native;\n',
           TYPE=self._NarrowOutputType(info.type_name),
           NAME=info.name,
           PARAMS=info.ParametersImplementationDeclaration(
               lambda type_name: self._NarrowInputType(type_name)))
 
+  def AddParentEvent(self):

[Jacob, 2012/03/08 18:38:09]

seems like there is duplicated code in AddParentEvent and AddEventAttributes.
Can you unify?

[nweiz, 2012/03/08 20:47:16]

Done.

+    parent_event_classes = self._shared.GetParentsEventsClasses(
+        self._interface)
+    if len(parent_event_classes) != 1:
+      raise Exception('Only one parent event class allowed '
+          + self._interface.id)
+
+    self._members_emitter.Emit(
+        '\n  $TYPE get on() =>\n    new $TYPE($EVENTTARGET);\n',
+        TYPE=parent_event_classes[0],
+        EVENTTARGET='_jsDocument' if self._interface.id == 'Document'
+            else 'this')
+
   def AddEventAttributes(self, event_attrs):
     event_attrs = _DomToHtmlEvents(self._interface.id, event_attrs)
     events_class = '_' + self._interface.id + 'EventsImpl'
     events_interface = self._interface.id + 'Events'
     self._members_emitter.Emit(
         '\n  $TYPE get on() =>\n    new $TYPE($EVENTTARGET);\n',
         TYPE=events_class,
         EVENTTARGET='_jsDocument' if self._interface.id == 'Document'
             else 'this')
 
@@ skipping 235 matching lines @@
     if dom_name != 'Document':
       self._members_emitter.Emit(
           '  $(CLASSNAME)._wrap(ptr) : super._wrap(ptr);\n',
           CLASSNAME=self._class_name)
 
     # Emit a factory provider class for the constructor.
     constructor_info = AnalyzeConstructor(interface)
     if constructor_info:
       self._EmitFactoryProvider(interface_name, constructor_info)
 
+    events = self._shared.GetEventAttributes(self._interface)
+    if events == set():
+      self.AddParentEvent()
+    elif events:
+      self.AddEventAttributes(events)
+
   def _EmitFactoryProvider(self, interface_name, constructor_info):
     template_file = 'factoryprovider_%s.darttemplate' % interface_name
     template = self._system._templates.TryLoad(template_file)
     if not template:
       template = self._system._templates.Load('factoryprovider.darttemplate')
 
     factory_provider = '_' + interface_name + 'FactoryProvider'
     emitter = self._system._ImplFileEmitter(factory_provider)
     emitter.Emit(
         template,
@@ skipping 92 matching lines @@
         THIS=self.DomObjectName())
 
   def AddSecondaryAttribute(self, interface, getter, setter):
     self._SecondaryContext(interface)
     self.AddAttribute(getter, setter)
 
   def AddSecondaryOperation(self, interface, info):
     self._SecondaryContext(interface)
     self.AddOperation(info)
 
+  def AddParentEvent(self):
+    parent_event_classes = self._shared.GetParentsEventsClasses(
+        self._interface)
+    if len(parent_event_classes) != 1:
+      raise Exception('Only one parent event class allowed '
+          + self._interface.id)
+
+    self._members_emitter.Emit(
+        '\n'
+        '  $TYPE get on() {\n'
+        '    if (_on == null) _on = new $TYPE($EVENTTARGET);\n'
+        '    return _on;\n'
+        '  }\n',
+        TYPE=parent_event_classes[0],
+        EVENTTARGET='_wrappedDocumentPtr' if self._interface.id == 'Document'
+            else 'this')
+
   def AddEventAttributes(self, event_attrs):
     event_attrs = _DomToHtmlEvents(self._interface.id, event_attrs)
     events_class = '_' + self._interface.id + 'EventsImpl'
     events_interface = self._interface.id + 'Events'
     self._members_emitter.Emit(
         '\n'
         '  $TYPE get on() {\n'
         '    if (_on == null) _on = new $TYPE($EVENTTARGET);\n'
         '    return _on;\n'
         '  }\n',
@@ skipping 353 matching lines @@
     # dispatch has removed f(X), leaving only f(Y), but there is no guarantee
     # that Y = Z-X, so we need to check for Y.
     true_code = emitter.Emit(
         '$(INDENT)if ($COND) {\n'
         '$!TRUE'
         '$(INDENT)}\n',
         COND=test, INDENT=indent)
     self.GenerateDispatch(
         true_code, info, indent + '  ', position + 1, positive)
     return True