IDL: Put generated union type containers in separate files

Source/bindings/scripts/code_generator_v8.py

Index: Source/bindings/scripts/code_generator_v8.py
diff --git a/Source/bindings/scripts/code_generator_v8.py b/Source/bindings/scripts/code_generator_v8.py
index 42fb98cfffb7dc58d5df3f95c3ba9be00664eb7a..dfb8bf0606ffa0bf521e4de82b6cab92a8f1f74e 100644
--- a/Source/bindings/scripts/code_generator_v8.py
+++ b/Source/bindings/scripts/code_generator_v8.py
@@ -323,40 +323,103 @@ class CodeGeneratorUnionType(object):
         self.target_component = target_component
         set_global_type_info(info_provider)
 
-    def generate_code(self):
-        union_types = self.info_provider.union_types
-        if not union_types:
-            return ()
-        header_template = self.jinja_env.get_template('union.h')
-        cpp_template = self.jinja_env.get_template('union.cpp')
-        template_context = v8_union.union_context(
-            union_types, self.info_provider.interfaces_info)
+    def _collect_unique_unions(self, union_types):
+        """This method iterates over |union_types| to remove duplicated entries
+        in |union_types| and to collect additional information (e.g. whether we
+        need to generate *OrNull class). Returns a dict which contains the
+        information.
+        """
+        unique_unions = {}
+        for union_type in union_types:
+            cpp_type = union_type.cpp_type
+            if cpp_type not in unique_unions.keys():
+                unique_unions[cpp_type] = {
+                    'union_type': union_type,
+                }
+            if union_type.includes_nullable_type:
+                unique_unions[cpp_type]['needs_ornull_converter'] = True
+        return unique_unions
+
+    def _generate_container_code(self, name, union_type_dict):
+        """Generates a union type container into separate .h/.cpp files.
+        Returns the path and its contents as a tuple.
+        """
+        header_template = self.jinja_env.get_template('union_container.h')
+        cpp_template = self.jinja_env.get_template('union_container.cpp')
+        template_context = v8_union.container_context(
+            union_type_dict['union_type'], self.info_provider.interfaces_info)
         template_context['code_generator'] = module_pyname
-        capitalized_component = self.target_component.capitalize()
-        template_context['header_filename'] = 'bindings/%s/v8/UnionTypes%s.h' % (
-            self.target_component, capitalized_component)
-        template_context['macro_guard'] = 'UnionType%s_h' % capitalized_component
+        template_context['needs_ornull_converter'] = (
+            union_type_dict.get('needs_ornull_converter'))
+
+        header_text = header_template.render(template_context)
+        cpp_text = cpp_template.render(template_context)
+        header_path = posixpath.join(self.output_dir, '%s.h' % name)
+        cpp_path = posixpath.join(self.output_dir, '%s.cpp' % name)
+        return (
+            (header_path, header_text),
+            (cpp_path, cpp_text),
+        )
 
+    def _generate_aggregate_header(self, names):
+        """Generates a header file which contains all union type container
+        headers.
+        FIXME: We might want to remove the aggregated header once we directly
+        include necessary header files in Blink side.
+        """
+        capitalized_component = self.target_component.capitalize()
+        context = {
+            'code_generator': module_pyname,
+            'header_includes': sorted([
+                'bindings/%s/v8/%s.h' % (self.target_component, name)
+                for name in names]),
+            'macro_guard': 'UnionType%s_h' % capitalized_component,
+        }
         # Add UnionTypesCore.h as a dependency when we generate modules union types
         # because we only generate union type containers which are used by both
         # core and modules in UnionTypesCore.h.
         # FIXME: This is an ad hoc workaround and we need a general way to
         # handle core <-> modules dependency.
         if self.target_component == 'modules':
-            template_context['header_includes'] = sorted(
-                template_context['header_includes'] +
+            context['header_includes'] = sorted(
+                context['header_includes'] +
                 ['bindings/core/v8/UnionTypesCore.h'])
-
-        header_text = header_template.render(template_context)
-        cpp_text = cpp_template.render(template_context)
+        template = self.jinja_env.get_template('union.h')
+        header_text = template.render(context)
         header_path = posixpath.join(self.output_dir,
                                      'UnionTypes%s.h' % capitalized_component)
+        return (header_path, header_text)
+
+    def _generate_aggregate_cpp(self, names):
+        """Generates a cpp file which contains all union type container
+        implementations. We need this aggregated cpp file as the output of
+        a GYP/GN rule.
+        """
+        capitalized_component = self.target_component.capitalize()
+        context = {
+            'code_generator': module_pyname,
+            'cpp_files': sorted([
+                'bindings/%s/v8/%s.cpp' % (self.target_component, name)
+                for name in names]),
+        }
+        template = self.jinja_env.get_template('union.cpp')
+        cpp_text = template.render(context)
         cpp_path = posixpath.join(self.output_dir,
                                   'UnionTypes%s.cpp' % capitalized_component)
-        return (
-            (header_path, header_text),
-            (cpp_path, cpp_text),
-        )
+        return (cpp_path, cpp_text)
+
+    def generate_code(self):
+        unique_unions = self._collect_unique_unions(
+            self.info_provider.union_types)
+        if not unique_unions:
+            return ()
+        outputs = set()
+        for name, union_type_dict in unique_unions.iteritems():
+            outputs.update(self._generate_container_code(name, union_type_dict))
+
+        outputs.add(self._generate_aggregate_header(unique_unions.keys()))
+        outputs.add(self._generate_aggregate_cpp(unique_unions.keys()))
+        return outputs
 
 
 def initialize_jinja_env(cache_dir):