Mojo: add javascript bindings for request/response

mojo/public/bindings/js/codec.js

 // 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.
 
 define("mojo/public/bindings/js/codec", function() {
 
   // Memory -------------------------------------------------------------------
 
   function store8(memory, pointer, val) {
     memory[pointer] = val;
@@ skipping 66 matching lines @@
 
   Buffer.prototype.createViewOfAllocatedMemory = function() {
     return new Uint8Array(this.memory.buffer, 0, this.next);
   };
 
   // Constants ----------------------------------------------------------------
 
   var kArrayHeaderSize = 8;
   var kStructHeaderSize = 8;
   var kMessageHeaderSize = 16;
+  var kMessageWithRequestIDHeaderSize = 24;
 
   // Decoder ------------------------------------------------------------------
 
   function Decoder(memory, handles, base) {
     this.memory = memory;
     this.handles = handles;
     this.base = base;
     this.next = base;
     this.viewU32 = new Uint32Array(
         this.memory.buffer, 0,
@@ skipping 183 matching lines @@
 
   Encoder.prototype.encodeStringPointer = function(val) {
     // TODO(abarth): This won't be right once we support UTF-8.
     var encodedSize = kArrayHeaderSize + val.length;
     var encoder = this.createAndEncodeEncoder(encodedSize);
     encoder.encodeString(val);
   };
 
   // Message ------------------------------------------------------------------
 
+  var kMessageExpectsResponse = 1 << 0;
+  var kMessageIsResponse      = 1 << 1;
+
   function Message(memory, handles) {
     this.memory = memory;
     this.handles = handles;
   }
 
+  Message.prototype.setRequestID = function(requestID) {
+    // TODO(darin): Verify that space was reserved for this field!
+    store64(this.memory, 4 + 4 + 4 + 4, requestID);
+  };
+
+  Message.prototype.getFlags = function() {
+    // Skip over num_bytes, num_fields, and message_name.
+    return load32(this.memory, 4 + 4 + 4);
+  };
+
   // MessageBuilder -----------------------------------------------------------
 
   function MessageBuilder(messageName, payloadSize) {
     // Currently, we don't compute the payload size correctly ahead of time.
     // Instead, we resize the buffer at the end.
     var numberOfBytes = kMessageHeaderSize + payloadSize;
     this.buffer = new Buffer(numberOfBytes);
     this.handles = [];
     var encoder = this.createEncoder(kMessageHeaderSize);
     encoder.write32(kMessageHeaderSize);
     encoder.write32(2);  // num_fields.
     encoder.write32(messageName);
     encoder.write32(0);  // flags.
   }
 
   MessageBuilder.prototype.createEncoder = function(size) {
     var pointer = this.buffer.alloc(size);
     return new Encoder(this.buffer, this.handles, pointer);
-  }
+  };
 
   MessageBuilder.prototype.encodeStruct = function(cls, val) {
     cls.encode(this.createEncoder(cls.encodedSize), val);
   };
 
   MessageBuilder.prototype.finish = function() {
     // TODO(abarth): Rather than resizing the buffer at the end, we could
     // compute the size we need ahead of time, like we do in C++.
     var memory = this.buffer.createViewOfAllocatedMemory();
     var message = new Message(memory, this.handles);
     this.buffer = null;
     this.handles = null;
     this.encoder = null;
     return message;
   };
 
+  // MessageWithRequestIDBuilder -----------------------------------------------
+
+  function MessageWithRequestIDBuilder(messageName, payloadSize, flags,
+                                       requestID) {
+    // Currently, we don't compute the payload size correctly ahead of time.
+    // Instead, we resize the buffer at the end.
+    var numberOfBytes = kMessageWithRequestIDHeaderSize + payloadSize;
+    this.buffer = new Buffer(numberOfBytes);
+    this.handles = [];
+    var encoder = this.createEncoder(kMessageWithRequestIDHeaderSize);
+    encoder.write32(kMessageWithRequestIDHeaderSize);
+    encoder.write32(3);  // num_fields.

[abarth-chromium, 2014/03/26 18:26:32]

Should we make this a named constant?

+    encoder.write32(messageName);
+    encoder.write32(flags);
+    encoder.write64(requestID);
+  }
+
+  MessageWithRequestIDBuilder.prototype =
+      Object.create(MessageBuilder.prototype);
+  MessageWithRequestIDBuilder.prototype.constructor =
+      MessageWithRequestIDBuilder;
+
   // MessageReader ------------------------------------------------------------
 
   function MessageReader(message) {
     this.decoder = new Decoder(message.memory, message.handles, 0);
     var messageHeaderSize = this.decoder.read32();
     this.payloadSize = message.memory.length - messageHeaderSize;
-    var numberOfFields = this.decoder.read32();
-    // TODO: better handling of messages of different size.
+    var numFields = this.decoder.read32();
     this.messageName = this.decoder.read32();
-    var flags = this.decoder.read32();
+    this.flags = this.decoder.read32();
+    if (numFields >= 3)
+      this.requestID = this.decoder.read64();
+    this.decoder.skip(messageHeaderSize - this.decoder.next);
   }
 
   MessageReader.prototype.decodeStruct = function(cls) {
     return cls.decode(this.decoder);
   };
 
   // Built-in types -----------------------------------------------------------
 
   function Uint8() {
   }
@@ skipping 92 matching lines @@
   };
 
   Handle.encode = function(encoder, val) {
     encoder.encodeHandle(val);
   };
 
   var exports = {};
   exports.align = align;
   exports.Message = Message;
   exports.MessageBuilder = MessageBuilder;
+  exports.MessageWithRequestIDBuilder = MessageWithRequestIDBuilder;
   exports.MessageReader = MessageReader;
   exports.kArrayHeaderSize = kArrayHeaderSize;
   exports.kStructHeaderSize = kStructHeaderSize;
   exports.kMessageHeaderSize = kMessageHeaderSize;
+  exports.kMessageExpectsResponse = kMessageExpectsResponse;
+  exports.kMessageIsResponse = kMessageIsResponse;
   exports.Uint8 = Uint8;
   exports.Uint16 = Uint16;
   exports.Uint32 = Uint32;
   exports.Uint64 = Uint64;
   exports.PointerTo = PointerTo;
   exports.ArrayOf = ArrayOf;
   exports.Handle = Handle;
   return exports;
 });