Allow Dart code to register service protocol handlers

runtime/vm/service.cc

Index: runtime/vm/service.cc
diff --git a/runtime/vm/service.cc b/runtime/vm/service.cc
index 61d0e07f91a60d8908eb891bee0dc2ec01beabcd..ae4ce21dc172e3b407d1e1f5401df69192d950e1 100644
--- a/runtime/vm/service.cc
+++ b/runtime/vm/service.cc
@@ -585,6 +585,15 @@ void Service::InvokeMethod(Isolate* isolate, const Array& msg) {
       return;
     }
 
+    if (ExtensionHandlerExists(method_name)) {
+      const Array& response =
+          Array::Handle(Array::New(3));
+      InvokeExtensionHandler(method_name, param_keys, param_values, response);
+      PostExtensionResponse(response, &js);
+      js.PostReply();
+      return;
+    }
+
     PrintUnrecognizedMethodError(&js);
     js.PostReply();
     return;
@@ -869,6 +878,78 @@ EmbedderServiceHandler* Service::FindRootEmbedderHandler(
 }
 
 
+#define EXTENSION_HANDLER_RESPONSE_LENGTH 3
+
+bool Service::ExtensionHandlerExists(const String& method) {
+  ASSERT(!method.IsNull());
+  const Library& developer_lib = Library::Handle(Library::DeveloperLibrary());
+  ASSERT(!developer_lib.IsNull());
+  const Function& extension_exists = Function::Handle(
+      developer_lib.LookupLocalFunction(Symbols::_extensionExists()));
+  ASSERT(!extension_exists.IsNull());
+  const Array& arguments = Array::Handle(Array::New(1));
+  ASSERT(!arguments.IsNull());
+  arguments.SetAt(0, method);
+  return (DartEntry::InvokeFunction(extension_exists, arguments) ==
+          Object::bool_true().raw());
+}
+
+
+bool Service::InvokeExtensionHandler(const String& method_name,
+                                     const Array& parameter_keys,
+                                     const Array& parameter_values,
+                                     const Array& response) {
+  ASSERT(!method_name.IsNull());
+  ASSERT(!parameter_keys.IsNull());
+  ASSERT(!parameter_values.IsNull());
+  ASSERT(!response.IsNull());
+  ASSERT(response.Length() == EXTENSION_HANDLER_RESPONSE_LENGTH);
+  const Library& developer_lib = Library::Handle(Library::DeveloperLibrary());
+  ASSERT(!developer_lib.IsNull());
+  const Function& invoke_extension = Function::Handle(
+      developer_lib.LookupLocalFunction(Symbols::_invokeExtension()));
+  ASSERT(!invoke_extension.IsNull());
+  const Array& arguments = Array::Handle(Array::New(4));
+  arguments.SetAt(0, method_name);
+  arguments.SetAt(1, parameter_keys);
+  arguments.SetAt(2, parameter_values);
+  arguments.SetAt(3, response);
+  return (DartEntry::InvokeFunction(invoke_extension, arguments) ==
+          Object::bool_true().raw());
+}
+
+
+void Service::PostExtensionResponse(const Array& response, JSONStream* js) {
+  ASSERT(!response.IsNull());
+  ASSERT(response.Length() == EXTENSION_HANDLER_RESPONSE_LENGTH);
+  const Object& result = Object::Handle(response.At(0));
+  const Object& error_code = Object::Handle(response.At(1));
+  const Object& error_message = Object::Handle(response.At(2));
+  if (!result.IsNull()) {
+    if (!result.IsString()) {
+      js->PrintError(kInternalError,
+                     "Extension error: response[0] must be a String.");
+      return;
+    }
+    TextBuffer* buffer = js->buffer();
+    buffer->AddString(String::Cast(result).ToCString());
+  } else {
+    if (!error_code.IsInteger()) {
+      js->PrintError(kInternalError,
+                     "Extension error: response[1] must be an int.");
+      return;
+    }
+    if (!error_message.IsString()) {
+      js->PrintError(kInternalError,
+                     "Extension error: response[2] must be a String.");
+      return;
+    }
+    js->PrintError(Integer::Cast(error_code).AsInt64Value(),
+                   String::Cast(error_message).ToCString());
+  }
+}
+
+
 static const MethodParameter* get_isolate_params[] = {
   ISOLATE_PARAMETER,
   NULL,