bindings: Use Visitor to collect union types

Source/bindings/scripts/idl_types.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """IDL type handling.
 
 Classes:
 IdlTypeBase
  IdlType
  IdlUnionType
  IdlArrayOrSequenceType
@@ skipping 106 matching lines @@
     def __getattr__(self, name):
         # Default undefined attributes to None (analogous to Jinja variables).
         # This allows us to not define default properties in the base class, and
         # allows us to relay __getattr__ in IdlNullableType to the inner type.
         return None
 
     def resolve_typedefs(self, typedefs):
         raise NotImplementedError(
             'resolve_typedefs should be defined in subclasses')
 
+    def idl_types(self):
+        """A generator which yields IdlTypes which are referenced from |self|,
+        including itself."""
+        yield self
+
 
 ################################################################################
 # IdlType
 ################################################################################
 
 class IdlType(IdlTypeBase):
     # FIXME: incorporate Nullable, etc.
     # to support types like short?[] vs. short[]?, instead of treating these
     # as orthogonal properties (via flags).
     callback_functions = set(STANDARD_CALLBACK_FUNCTIONS)
@@ skipping 177 matching lines @@
         http://heycam.github.io/webidl/#dfn-type-name
         """
         return 'Or'.join(member_type.name for member_type in self.member_types)
 
     def resolve_typedefs(self, typedefs):
         self.member_types = [
             typedefs.get(member_type, member_type)
             for member_type in self.member_types]
         return self
 
+    def idl_types(self):
+        yield self
+        for member_type in self.member_types:
+            for idl_type in member_type.idl_types():
+                yield idl_type
+
 
 ################################################################################
 # IdlArrayOrSequenceType, IdlArrayType, IdlSequenceType
 ################################################################################
 
 class IdlArrayOrSequenceType(IdlTypeBase):
     """Base class for IdlArrayType and IdlSequenceType."""
 
     def __init__(self, element_type):
         super(IdlArrayOrSequenceType, self).__init__()
@@ skipping 16 matching lines @@
         return True
 
     @property
     def enum_values(self):
         return self.element_type.enum_values
 
     @property
     def enum_type(self):
         return self.element_type.enum_type
 
+    def idl_types(self):
+        yield self
+        for idl_type in self.element_type.idl_types():
+            yield idl_type
+
 
 class IdlArrayType(IdlArrayOrSequenceType):
     def __init__(self, element_type):
         super(IdlArrayType, self).__init__(element_type)
 
     def __str__(self):
         return '%s[]' % self.element_type
 
     @property
     def name(self):
@@ skipping 44 matching lines @@
     def is_nullable(self):
         return True
 
     @property
     def name(self):
         return self.inner_type.name + 'OrNull'
 
     def resolve_typedefs(self, typedefs):
         self.inner_type = self.inner_type.resolve_typedefs(typedefs)
         return self
+
+    def idl_types(self):
+        yield self
+        for idl_type in self.inner_type.idl_types():
+            yield idl_type