Allow Dart code to register service protocol handlers

runtime/vm/service.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/service.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/globals.h"
 
@@ skipping 567 matching lines @@
     if (handler == NULL) {
       handler = FindRootEmbedderHandler(c_method_name);
     }
 
     if (handler != NULL) {
       EmbedderHandleMessage(handler, &js);
       js.PostReply();
       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;
   }
 }
 
 
 void Service::HandleRootMessage(const Array& msg_instance) {
   Isolate* isolate = Isolate::Current();
   InvokeMethod(isolate, msg_instance);
@@ skipping 264 matching lines @@
   while (current != NULL) {
     if (strcmp(name, current->name()) == 0) {
       return current;
     }
     current = current->next();
   }
   return NULL;
 }
 
 
+#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,
 };
 
 
 static bool GetIsolate(Isolate* isolate, JSONStream* js) {
   isolate->PrintJSON(js, false);
   return true;
 }
@@ skipping 2197 matching lines @@
     ServiceMethodDescriptor& method = service_methods_[i];
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 
 }  // namespace dart