DevTools: Protocol handler generator for content

content/browser/devtools/protocol/devtools_protocol_handler_generator.py

+#!/usr/bin/env python
+# 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.
+
+import sys
+import string
+import json
+
+input_json_path = sys.argv[1]
+output_cc_path = sys.argv[2]
+output_h_path = sys.argv[3]
+
+header = """\
+// 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.
+
+// THIS FILE IS AUTOGENERATED. DO NOT EDIT.
+// Generated by
+//  content/public/browser/devtools_protocol_handler_generator.py from
+//  third_party/WebKit/Source/devtools/protocol.json
+"""
+
+template_h = string.Template(header + """\
+
+#ifndef CONTENT_BROWSER_DEVTOOLS_PROTOCOL_DEVTOOLS_PROTOCOL_HANDLER_IMPL_H_
+#define CONTENT_BROWSER_DEVTOOLS_PROTOCOL_DEVTOOLS_PROTOCOL_HANDLER_IMPL_H_
+
+#include "content/browser/devtools/devtools_protocol.h"
+#include "content/browser/devtools/protocol/devtools_protocol_frontend.h"
+
+namespace content {
+
+class RenderViewHostImpl;
+class DevToolsProtocolHandlerImpl;
+
+namespace devtools {
+
+${types}\
+
+}  // namespace devtools
+
+class DevToolsProtocolHandlerImpl : public DevToolsProtocol::Handler {
+ public:
+  typedef DevToolsProtocolFrontend::Response Response;
+  typedef DevToolsProtocolFrontend::ResponseStatus ResponseStatus;
+
+  DevToolsProtocolHandlerImpl();
+  virtual ~DevToolsProtocolHandlerImpl();
+  void OnClientDetached();
+  void SetRenderViewHost(RenderViewHostImpl* host);
+
+${getters}\
+
+ private:
+${friends}\
+
+${methods}\
+
+${fields}\
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_DEVTOOLS_PROTOCOL_DEVTOOLS_PROTOCOL_HANDLER_IMPL_H_
+""")
+
+tmpl_typedef = string.Template("""\
+namespace ${domain} {
+typedef ${param_type} ${declared_name};
+}  // namespace ${domain}
+""")
+
+tmpl_struct = string.Template("""\
+namespace ${domain} {
+struct ${declared_name} {
+ public:
+  ${declared_name}();
+
+${methods}\
+
+ private:
+  friend class ::content::DevToolsProtocolHandlerImpl;
+
+${fields}\
+};
+}  // namespace ${domain}
+""")
+
+tmpl_struct_setter = string.Template("""\
+  void set_${param}(${pass_type} ${param});
+""")
+
+tmpl_struct_field = string.Template("""\
+  ${param_type} ${param}_;
+  bool has_${param}_;
+""")
+
+tmpl_enum = string.Template("""\
+namespace ${domain} {
+namespace ${command_underscored} {
+${values}\
+}  // namespace ${command_underscored}
+}  // namespace ${domain}
+""")
+
+tmpl_enum_value = string.Template("""\
+extern const char k${Param}${Value}[];
+""")
+
+tmpl_enum_value_def = string.Template("""\
+const char k${Param}${Value}[] = "${value}";
+""")
+
+tmpl_handler = string.Template("""\
+namespace ${domain} {
+class ${Domain}Handler;
+}  // namespace domain
+""")
+
+tmpl_frontend = string.Template("""\
+namespace ${domain} {
+class Frontend : public DevToolsProtocolFrontend {
+ public:
+  Frontend(const EventCallback& event_callback,
+           const ResponseCallback& response_callback);
+  virtual ~Frontend();
+
+  void SendInvalidParamsResponse(
+      scoped_refptr<DevToolsProtocol::Command> command,
+      const std::string& message);
+  void SendInternalErrorResponse(
+      scoped_refptr<DevToolsProtocol::Command> command,
+      const std::string& message);
+  void SendServerErrorResponse(
+      scoped_refptr<DevToolsProtocol::Command> command,
+      const std::string& message);
+${methods}\
+};
+}  // namespace ${domain}
+""")
+
+tmpl_event = string.Template("""\
+  void ${Command}(
+      const ${Command}Params& params);
+""")
+
+tmpl_response = string.Template("""\
+  void Send${Command}Response(
+      scoped_refptr<DevToolsProtocol::Command> command,
+      const ${Command}Response& params);
+""")
+
+tmpl_getter = string.Template("""\
+  devtools::${domain}::${Domain}Handler* ${domain}();
+""")
+
+tmpl_friend = string.Template("""\
+  friend class devtools::${domain}::Frontend;
+""")
+
+tmpl_callback = string.Template("""\
+  scoped_refptr<DevToolsProtocol::Response>
+  On${Domain}${Command}(
+      scoped_refptr<DevToolsProtocol::Command> command);
+""")
+
+tmpl_to_value = string.Template("""\
+  static base::DictionaryValue* ToValue(
+      const devtools::${domain}::${declared_name}& src);
+""")
+
+tmpl_field = string.Template("""\
+  scoped_ptr<devtools::${domain}::${Domain}Handler> ${domain}_handler_;
+""")
+
+template_cc = string.Template(header + """\
+
+#include "content/browser/devtools/protocol/devtools_protocol_handler_impl.h"
+
+#include "base/bind.h"
+${includes}\
+
+namespace content {
+
+DevToolsProtocolHandlerImpl::DevToolsProtocolHandlerImpl() {
+${initializations}\
+}
+
+DevToolsProtocolHandlerImpl::~DevToolsProtocolHandlerImpl() {
+}
+
+void DevToolsProtocolHandlerImpl::OnClientDetached() {
+${client_detached}\
+}
+
+void DevToolsProtocolHandlerImpl::SetRenderViewHost(RenderViewHostImpl* host) {
+${set_rvh}\
+}
+
+namespace {
+
+typedef DevToolsProtocolFrontend::ResponseStatus ResponseStatus;
+
+bool CreateCommonResponse(
+    scoped_refptr<DevToolsProtocol::Command> command,
+    const DevToolsProtocolFrontend::Response& response,
+    scoped_refptr<DevToolsProtocol::Response>* protocol_response) {
+  switch (response.status()) {
+    case ResponseStatus::RESPONSE_STATUS_FALLTHROUGH:
+      *protocol_response = NULL;
+      break;
+    case ResponseStatus::RESPONSE_STATUS_OK:
+      return false;
+    case ResponseStatus::RESPONSE_STATUS_INVALID_PARAMS:
+      *protocol_response = command->InvalidParamResponse(response.message());
+      break;
+    case ResponseStatus::RESPONSE_STATUS_INTERNAL_ERROR:
+      *protocol_response = command->InternalErrorResponse(response.message());
+      break;
+    case ResponseStatus::RESPONSE_STATUS_SERVER_ERROR:
+      *protocol_response = command->ServerErrorResponse(response.message());
+      break;
+  }
+  return true;
+}
+
+}  // namespace
+
+${methods}\
+
+namespace devtools {
+
+${types}\
+
+}  // namespace devtools
+
+}  // namespace content
+""")
+
+tmpl_include = string.Template("""\
+#include "content/browser/devtools/protocol/${domain}_handler.h"
+""")
+
+tmpl_register = string.Template("""\
+  RegisterCommandHandler(
+      "${Domain}.${command}",
+      base::Bind(
+          &DevToolsProtocolHandlerImpl::On${Domain}${Command},
+          base::Unretained(this)));
+""")
+
+tmpl_init_handler = string.Template("""\
+  ${domain}_handler_.reset(new devtools::${domain}::${Domain}Handler());
+""")
+
+tmpl_init_frontend = string.Template("""\
+  ${domain}_handler_->SetFrontend(make_scoped_ptr(
+      new devtools::${domain}::Frontend(
+          base::Bind(&DevToolsProtocolHandlerImpl::SendNotification,
+                     base::Unretained(this)),
+          base::Bind(&DevToolsProtocolHandlerImpl::SendAsyncResponse,
+                     base::Unretained(this)))));
+""")
+
+tmpl_client_detached = string.Template("""\
+  ${domain}_handler_->OnClientDetached();
+""")
+
+tmpl_set_rvh = string.Template("""\
+  ${domain}_handler_->SetRenderViewHost(host);
+""")
+
+tmpl_getter_impl = string.Template("""\
+devtools::${domain}::${Domain}Handler*
+DevToolsProtocolHandlerImpl::${domain}() {
+  return ${domain}_handler_.get();
+}
+""")
+
+tmpl_callback_impl = string.Template("""\
+scoped_refptr<DevToolsProtocol::Response>
+DevToolsProtocolHandlerImpl::On${Domain}${Command}(
+    scoped_refptr<DevToolsProtocol::Command> command) {
+${prep}\
+  Response response = ${domain}_handler_->${Command}(${args});
+  scoped_refptr<DevToolsProtocol::Response> protocol_response;
+  if (CreateCommonResponse(command, response, &protocol_response))
+    return protocol_response;
+  base::DictionaryValue* dict = new base::DictionaryValue();
+${wrap}\
+  return command->SuccessResponse(dict);
+}
+""")
+
+tmpl_callback_async_impl = string.Template("""\
+scoped_refptr<DevToolsProtocol::Response>
+DevToolsProtocolHandlerImpl::On${Domain}${Command}(
+    scoped_refptr<DevToolsProtocol::Command> command) {
+${prep}\
+  return ${domain}_handler_->${Command}(${args});
+}
+""")
+
+params_prep = """\
+  base::DictionaryValue* params = command->params();
+  if (!params)
+    return command->NoSuchMethodErrorResponse();
+"""
+
+tmpl_prep_req = string.Template("""\
+  ${param_type} in_${param}${init};
+  if (!params->Get${Type}("${proto_param}", &in_${param}))
+    return command->InvalidParamResponse("${proto_param}");
+""")
+
+tmpl_prep_req_list = string.Template("""\
+  base::ListValue* list_${param} = NULL;
+  if (!params->GetList("${proto_param}", &list_${param}))
+    return command->InvalidParamResponse("${proto_param}");
+  ${param_type} in_${param};
+  for (base::ListValue::const_iterator it =
+      list_${param}->begin(); it != list_${param}->end(); ++it) {
+    ${item_type} item${item_init};
+    if (!(*it)->GetAs${ItemType}(&item))
+      return command->InvalidParamResponse("${proto_param}");
+    in_${param}.push_back(item);
+  }
+""")
+
+tmpl_prep_opt = string.Template("""\
+  ${param_type} in_${param}${init};
+  bool ${param}_found = params->Get${Type}(
+      "${proto_param}",
+      &in_${param});
+""")
+
+tmpl_prep_output = string.Template("""\
+  ${param_type} out_${param}${init};
+""")
+
+tmpl_arg_req = string.Template("in_${param}")
+
+tmpl_arg_opt = string.Template(
+    "${param}_found ?\n          &in_${param} : NULL")
+
+tmpl_arg_output = string.Template("&out_${param}")
+
+tmpl_to_value_impl = string.Template("""\
+// static
+base::DictionaryValue* DevToolsProtocolHandlerImpl::ToValue(
+    const devtools::${domain}::${declared_name}& src) {
+  base::DictionaryValue* dict = new base::DictionaryValue();
+${dchecks}\
+${wrap}\
+  return dict;
+}
+""")
+
+tmpl_dcheck = string.Template("""\
+  DCHECK(${cond_name});
+""")
+
+tmpl_struct_impl = string.Template("""\
+namespace ${domain} {
+
+${declared_name}::${declared_name}()${fields} {
+}
+
+${methods}\
+
+}  // namespace ${domain}
+""")
+
+tmpl_struct_field_init = string.Template("has_${param}_(false)")
+
+tmpl_struct_setter_impl = string.Template("""\
+void ${declared_name}::set_${param}(
+    ${pass_type} ${param}) {
+  ${param}_ = ${param};
+  has_${param}_ = true;
+}
+""")
+
+tmpl_frontend_impl = string.Template("""\
+namespace ${domain} {
+
+Frontend::Frontend(const EventCallback& event_callback,
+                   const ResponseCallback& response_callback)
+    : DevToolsProtocolFrontend(event_callback, response_callback) {
+}
+
+Frontend::~Frontend() {
+}
+
+void Frontend::SendInvalidParamsResponse(
+    scoped_refptr<DevToolsProtocol::Command> command,
+    const std::string& message) {
+  SendAsyncResponse(command->InvalidParamResponse(message));
+}
+
+void Frontend::SendInternalErrorResponse(
+    scoped_refptr<DevToolsProtocol::Command> command,
+    const std::string& message) {
+  SendAsyncResponse(command->InternalErrorResponse(message));
+}
+
+void Frontend::SendServerErrorResponse(
+    scoped_refptr<DevToolsProtocol::Command> command,
+    const std::string& message) {
+  SendAsyncResponse(command->ServerErrorResponse(message));
+}
+
+${methods}\
+
+}  // namespace ${domain}
+""")
+
+tmpl_event_impl = string.Template("""\
+void Frontend::${Command}(
+    const ${Command}Params& params) {
+  SendNotification("${Domain}.${command}",
+      DevToolsProtocolHandlerImpl::ToValue(params));
+}
+""")
+
+tmpl_response_impl = string.Template("""\
+void Frontend::Send${Command}Response(
+    scoped_refptr<DevToolsProtocol::Command> command,
+    const ${Command}Response& params) {
+  SendAsyncResponse(
+      command->SuccessResponse(DevToolsProtocolHandlerImpl::ToValue(params)));
+}
+""")
+
+tmpl_wrap = string.Template("""\
+  dict->Set${Type}("${proto_param}", ${var_name});
+""")
+
+tmpl_wrap_dict = string.Template("""\
+  dict->Set("${proto_param}",
+      DevToolsProtocolHandlerImpl::ToValue(${var_name}));
+""")
+
+tmpl_wrap_obj = string.Template("""\
+  dict->Set("${proto_param}", ${var_name});
+""")
+
+tmpl_wrap_list = string.Template("""\
+  base::ListValue* list_${param} = new base::ListValue();
+  for (${param_type}::const_iterator it =
+      ${var_name}.begin(); it != ${var_name}.end(); ++it) {
+${append}\
+  }
+  dict->Set("${proto_param}", list_${param});
+""")
+
+tmpl_append = string.Template("""\
+    list_${param}->Append${Type}(*it);
+""")
+
+tmpl_append_dict = string.Template("""\
+    list_${param}->Append(DevToolsProtocolHandlerImpl::ToValue(*it));
+""")
+
+tmpl_append_obj = string.Template("""\
+    list_${param}->Append(*it);
+""")
+
+tmpl_wrap_opt = string.Template("""\
+  if (${cond_name})
+    dict->Set${Type}("${proto_param}", ${var_name});
+""")
+
+tmpl_typename = string.Template("devtools::${domain}::${declared_name}")
+
+def Capitalize(s):
+  return s[:1].upper() + s[1:]
+
+def Decapitalize(s):
+  return s.lower()
+
+def Uncamelcase(s):
+  result = ""
+  for i, c in enumerate(s):
+    if c.isupper():
+      if (i > 0) and ((i < len(s)-1) and s[i+1].islower() or s[i-1].islower()):
+        result += "_"
+      result += c.lower()
+    else:
+      result += c
+  return result
+
+types = {}
+json_api = json.loads(open(input_json_path, "r").read())
+type_decls = []
+type_impls = []
+handler_methods = []
+handler_method_impls = []
+
+for json_domain in json_api["domains"]:
+  if "types" in json_domain:
+    for json_type in json_domain["types"]:
+      types["%s.%s" % (json_domain["domain"], json_type["id"])] = json_type
+
+def DeclareStruct(json_properties, mapping):
+  methods = []
+  fields = []
+  fields_init = []
+  method_impls = []
+  dchecks = []
+  wrap = []
+  for json_prop in json_properties:
+    prop_map = mapping.copy()
+    prop_map["proto_param"] = json_prop["name"]
+    prop_map["param"] = Uncamelcase(json_prop["name"])
+    prop_map["var_name"] = "src.%s_" % prop_map["param"]
+    prop_map["cond_name"] = "src.has_%s_" % prop_map["param"]
+    ResolveType(json_prop, prop_map)
+    prop_map["declared_name"] = mapping["declared_name"]
+    methods.append(tmpl_struct_setter.substitute(prop_map))
+    fields.append(tmpl_struct_field.substitute(prop_map))
+    fields_init.append(tmpl_struct_field_init.substitute(prop_map))
+    method_impls.append(tmpl_struct_setter_impl.substitute(prop_map))
+    if json_prop.get("optional"):
+      if param_map["Type"] in ["List", "Dictionary"]:
+        # TODO(vkuzkokov) Implement.
+        raise Exception(
+          "Optional array and object properties are not implemented")
+      wrap.append(tmpl_wrap_opt.substitute(prop_map))
+    else:
+      dchecks.append(tmpl_dcheck.substitute(prop_map));
+      if not "wrap" in prop_map:
+        raise Exception("Arrays of arrays are not implemented")
+      wrap.append(prop_map["wrap"])
+
+  type_decls.append(tmpl_struct.substitute(mapping,
+      methods = "".join(methods),
+      fields = "".join(fields)))
+  fields_init_str = ""
+  if len(fields_init) > 0:
+    fields_init_str = "\n    : " + (",\n      ".join(fields_init))
+  type_impls.append(tmpl_struct_impl.substitute(mapping,
+      fields = fields_init_str,
+      methods = "\n".join(method_impls)))
+  handler_methods.append(tmpl_to_value.substitute(mapping))
+  handler_method_impls.append(tmpl_to_value_impl.substitute(mapping,
+      dchecks = "".join(dchecks),
+      wrap = "".join(wrap)))
+
+def ResolveRef(json, mapping):
+  dot_pos = json["$ref"].find(".")
+  if dot_pos == -1:
+    domain_name = mapping["Domain"]
+    type_name = json["$ref"]
+  else:
+    domain_name = json["$ref"][:dot_pos]
+    type_name = json["$ref"][dot_pos + 1:]
+  json_type = types["%s.%s" % (domain_name, type_name)]
+  mapping["declared_name"] = Capitalize(type_name)
+  mapping["Domain"] = domain_name
+  mapping["domain"] = Decapitalize(domain_name)
+  mapping["param_type"] = tmpl_typename.substitute(mapping)
+  if json_type.get("enum"):
+    # TODO(vkuzkokov) Implement. Approximate template:
+    # namespace ${domain} { const char k${declared_name}${Value}; }
+    raise Exception("Named enumerations are not implemented")
+  ResolveType(json_type, mapping)
+  if not "___struct_declared" in json_type:
+    json_type["___struct_declared"] = True;
+    if (json_type.get("type") == "object") and ("properties" in json_type):
+      DeclareStruct(json_type["properties"], mapping)
+    else:
+      type_decls.append(tmpl_typedef.substitute(mapping))
+  mapping["param_type"] = tmpl_typename.substitute(mapping)
+
+def ResolveArray(json, mapping):
+  items_map = mapping.copy()
+  ResolveType(json["items"], items_map)
+  mapping["param_type"] = "std::vector<%s>" % items_map["param_type"]
+  mapping["Type"] = "List"
+  if "append" in items_map:
+    mapping["wrap"] = tmpl_wrap_list.substitute(mapping,
+        append = items_map["append"])
+  mapping["pass_type"] = "const %s&" % mapping["param_type"]
+  mapping["prep_req"] = tmpl_prep_req_list.substitute(mapping,
+      item_type = items_map["param_type"],
+      item_init = items_map["init"],
+      ItemType = items_map["Type"])
+  # TODO(vkuzkokov) mapping["append"]: template for array of arrays.
+
+def ResolveObject(json, mapping):
+  mapping["Type"] = "Dictionary"
+  if "properties" in json:
+    if not "declared_name" in mapping:
+      mapping["declared_name"] = ("%s%s" %
+          (mapping["Command"], Capitalize(mapping["proto_param"])))
+      mapping["param_type"] = tmpl_typename.substitute(mapping)
+      DeclareStruct(json["properties"], mapping)
+    mapping["append"] = tmpl_append_dict.substitute(mapping)
+    mapping["wrap"] = tmpl_wrap_dict.substitute(mapping)
+    mapping["pass_type"] = "const %s&" % mapping["param_type"]
+  else:
+    mapping["param_type"] = "base::DictionaryValue*"
+    mapping["append"] = tmpl_append_obj.substitute(mapping)
+    mapping["wrap"] = tmpl_wrap_obj.substitute(mapping)
+    mapping["pass_type"] = mapping["param_type"]
+
+def ResolvePrimitive(json, mapping):
+  jsonrpc_type = json["type"]
+  if jsonrpc_type == "boolean":
+    mapping["param_type"] = "bool"
+    mapping["Type"] = "Boolean"
+    mapping["init"] = " = false"
+  elif jsonrpc_type == "integer":
+    mapping["param_type"] = "int"
+    mapping["Type"] = "Integer"
+    mapping["init"] = " = 0"
+  elif jsonrpc_type == "number":
+    mapping["param_type"] = "double"
+    mapping["Type"] = "Double"
+    mapping["init"] = " = 0.0"
+  elif jsonrpc_type == "string":
+    mapping["param_type"] = "std::string"
+    mapping["pass_type"] = "const std::string&"
+    mapping["Type"] = "String"
+    if "enum" in json:
+      values = []
+      value_defs = []
+      mapping["command_underscored"] = Uncamelcase(mapping["command"])
+      mapping["Param"] = Capitalize(mapping["proto_param"])
+      for enum_value in json["enum"]:
+        values.append(tmpl_enum_value.substitute(mapping,
+            Value = Capitalize(enum_value)))
+        value_defs.append(tmpl_enum_value_def.substitute(mapping,
+            value = enum_value,
+            Value = Capitalize(enum_value)))
+      type_decls.append(tmpl_enum.substitute(mapping,
+          values = "".join(values)))
+      type_impls.append(tmpl_enum.substitute(mapping,
+          values = "".join(value_defs)))
+  else:
+    raise Exception("Unknown type: %s" % json_type)
+  mapping["wrap"] = tmpl_wrap.substitute(mapping)
+  mapping["append"] = tmpl_append.substitute(mapping)
+  mapping["prep_req"] = tmpl_prep_req.substitute(mapping)
+  if jsonrpc_type != "string":
+    mapping["pass_type"] = mapping["param_type"]
+
+def ResolveType(json, mapping):
+  mapping["init"] = ""
+  if "$ref" in json:
+    ResolveRef(json, mapping)
+  elif "type" in json:
+    jsonrpc_type = json["type"]
+    if jsonrpc_type == "array":
+      ResolveArray(json, mapping)
+    elif jsonrpc_type == "object":
+      ResolveObject(json, mapping)
+    else:
+      ResolvePrimitive(json, mapping)
+  else:
+    raise Exception("Unknown type at %s.%s %s" %
+        (mapping["Domain"], mapping["command"], mapping["proto_param"]))
+
+getters = []
+friends = []
+fields = []
+
+includes = []
+initializations = []
+client_detached = []
+set_rvh = []
+
+for json_domain in json_api["domains"]:
+  domain_map = {}
+  domain_map["Domain"] = json_domain["domain"]
+  domain_map["domain"] = Decapitalize(json_domain["domain"])
+
+  frontend_methods = []
+  frontend_method_impls = []
+  domain_empty = True
+  domain_needs_frontend = False
+
+  if "commands" in json_domain:
+    for json_command in json_domain["commands"]:
+      if (not ("handlers" in json_command) or
+          not ("browser" in json_command["handlers"])):
+        continue
+      domain_empty = False
+
+      command_map = domain_map.copy()
+      command_map["command"] = json_command["name"]
+      command_map["Command"] = Capitalize(json_command["name"])
+
+      prep = []
+      args = []
+
+      if "parameters" in json_command:
+        for json_param in json_command["parameters"]:
+          param_map = command_map.copy()
+          param_map["proto_param"] = json_param["name"]
+          param_map["param"] = Uncamelcase(json_param["name"])
+          param_map["var_name"] = "in_%s" % param_map["param"]
+
+          ResolveType(json_param, param_map)
+          if len(prep) == 0:
+            prep.append(params_prep)
+          if json_param.get("optional"):
+            if param_map["Type"] in ["List", "Dictionary"]:
+              # TODO(vkuzkokov) Implement transformation of base::ListValue
+              # to std::vector and base::DictonaryValue to struct.
+              raise Exception(
+                  "Optional array and object parameters are not implemented")
+            prep.append(tmpl_prep_opt.substitute(param_map))
+            args.append(tmpl_arg_opt.substitute(param_map))
+          else:
+            prep.append(param_map["prep_req"])
+            args.append(tmpl_arg_req.substitute(param_map))
+
+      if json_command.get("async"):
+        domain_needs_frontend = True
+        json_returns = []
+        if "returns" in json_command:
+          json_returns = json_command["returns"]
+        command_map["declared_name"] = "%sResponse" % command_map["Command"]
+        DeclareStruct(json_returns, command_map)
+        # TODO(vkuzkokov) Pass async callback instance similar to how
+        # InspectorBackendDispatcher does it. This, however, can work
+        # only if Blink and Chrome are in the same repo.
+        args.append("command")
+        handler_method_impls.append(
+            tmpl_callback_async_impl.substitute(command_map,
+                prep = "".join(prep),
+                args = "\n      " + ",\n      ".join(args)))
+        frontend_methods.append(tmpl_response.substitute(command_map))
+        frontend_method_impls.append(tmpl_response_impl.substitute(command_map))
+      else:
+        wrap = []
+        if "returns" in json_command:
+          for json_param in json_command["returns"]:
+            param_map = command_map.copy()
+            param_map["proto_param"] = json_param["name"]
+            param_map["param"] = Uncamelcase(json_param["name"])
+            param_map["var_name"] = "out_%s" % param_map["param"]
+
+            if json_param.get("optional"):
+              # TODO(vkuzkokov) Implement Optional<T> for value types.
+              raise Exception("Optional return values are not implemented")
+            ResolveType(json_param, param_map)
+            prep.append(tmpl_prep_output.substitute(param_map))
+            args.append(tmpl_arg_output.substitute(param_map))
+            if not "wrap" in param_map:
+              raise Exception("Arrays of arrays are not implemented")
+            wrap.append(param_map["wrap"])
+
+        args_str = ""
+        if len(args) > 0:
+          args_str = "\n      " + ",\n      ".join(args)
+        handler_method_impls.append(tmpl_callback_impl.substitute(command_map,
+            prep = "".join(prep),
+            args = args_str,
+            wrap = "".join(wrap)))
+
+      initializations.append(tmpl_register.substitute(command_map))
+      handler_methods.append(tmpl_callback.substitute(command_map))
+
+  if "events" in json_domain:
+    for json_event in json_domain["events"]:
+      if (not ("handlers" in json_event) or
+          not ("browser" in json_event["handlers"])):
+        continue
+      domain_empty = False
+      domain_needs_frontend = True
+
+      event_map = domain_map.copy()
+      event_map["command"] = json_event["name"]
+      event_map["Command"] = Capitalize(json_event["name"])
+
+      json_parameters = []
+      if "parameters" in json_event:
+        json_parameters = json_event["parameters"]
+      event_map["declared_name"] = "%sParams" % event_map["Command"]
+      DeclareStruct(json_parameters, event_map);
+
+      frontend_methods.append(tmpl_event.substitute(event_map))
+      frontend_method_impls.append(tmpl_event_impl.substitute(event_map))
+
+  if domain_empty:
+    continue
+  type_decls.append(tmpl_handler.substitute(domain_map))
+  getters.append(tmpl_getter.substitute(domain_map))
+  fields.append(tmpl_field.substitute(domain_map))
+  includes.append(tmpl_include.substitute(domain_map))
+  initializations.append(tmpl_init_handler.substitute(domain_map))
+  client_detached.append(tmpl_client_detached.substitute(domain_map))
+  set_rvh.append(tmpl_set_rvh.substitute(domain_map))
+  handler_method_impls.append(tmpl_getter_impl.substitute(domain_map))
+  if domain_needs_frontend:
+    type_decls.append(tmpl_frontend.substitute(domain_map,
+        methods = "".join(frontend_methods)))
+    friends.append(tmpl_friend.substitute(domain_map))
+    initializations.append(tmpl_init_frontend.substitute(domain_map))
+    type_impls.append(tmpl_frontend_impl.substitute(domain_map,
+        methods = "\n".join(frontend_method_impls)))
+
+
+output_h_file = open(output_h_path, "w")
+output_cc_file = open(output_cc_path, "w")
+
+output_h_file.write(template_h.substitute({},
+    types = "\n".join(type_decls),
+    getters = "".join(getters),
+    friends = "".join(friends),
+    methods = "".join(handler_methods),
+    fields = "".join(fields)))
+output_h_file.close()
+
+output_cc_file.write(template_cc.substitute({},
+    includes = "".join(includes),
+    initializations = "".join(initializations),
+    client_detached = "".join(client_detached),
+    set_rvh = "".join(set_rvh),
+    methods = "\n".join(handler_method_impls),
+    types = "\n".join(type_impls)))
+output_cc_file.close()