Andreas Hocevar
137 lines
4.1 KiB
JavaScript
137 lines
4.1 KiB
JavaScript
// Copyright 2013 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* @fileoverview Codec functions of the v8 wire protocol. Eventually we'd want
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* to support pluggable wire-format to improve wire efficiency and to enable
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* binary encoding. Such support will require an interface class, which
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* will be added later.
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*
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* @visibility {:internal}
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*/
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goog.provide('goog.labs.net.webChannel.WireV8');
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goog.require('goog.asserts');
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goog.require('goog.json');
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goog.require('goog.json.NativeJsonProcessor');
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goog.require('goog.structs');
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/**
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* The v8 codec class.
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*
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* @constructor
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* @struct
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*/
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goog.labs.net.webChannel.WireV8 = function() {
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/**
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* Parser for a response payload. The parser should return an array.
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* @private {!goog.string.Parser}
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*/
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this.parser_ = new goog.json.NativeJsonProcessor();
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};
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goog.scope(function() {
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var WireV8 = goog.labs.net.webChannel.WireV8;
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var Wire = goog.labs.net.webChannel.Wire;
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/**
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* Encodes a standalone message into the wire format.
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*
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* May throw exception if the message object contains any invalid elements.
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*
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* @param {!Object|!goog.structs.Map} message The message data.
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* V8 only support JS objects (or Map).
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* @param {!Array<string>} buffer The text buffer to write the message to.
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* @param {string=} opt_prefix The prefix for each field of the object.
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*/
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WireV8.prototype.encodeMessage = function(message, buffer, opt_prefix) {
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var prefix = opt_prefix || '';
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try {
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goog.structs.forEach(message, function(value, key) {
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var encodedValue = value;
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if (goog.isObject(value)) {
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encodedValue = goog.json.serialize(value);
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} // keep the fast-path for primitive types
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buffer.push(prefix + key + '=' + encodeURIComponent(encodedValue));
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});
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} catch (ex) {
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// We send a map here because lots of the retry logic relies on map IDs,
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// so we have to send something (possibly redundant).
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buffer.push(prefix + 'type' + '=' + encodeURIComponent('_badmap'));
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throw ex;
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}
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};
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/**
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* Encodes all the buffered messages of the forward channel.
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*
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* @param {!Array<Wire.QueuedMap>} messageQueue The message data.
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* V8 only support JS objects.
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* @param {number} count The number of messages to be encoded.
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* @param {?function(!Object)} badMapHandler Callback for bad messages.
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*/
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WireV8.prototype.encodeMessageQueue = function(messageQueue, count,
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badMapHandler) {
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var sb = ['count=' + count];
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var offset;
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if (count > 0) {
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// To save a bit of bandwidth, specify the base mapId and the rest as
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// offsets from it.
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offset = messageQueue[0].mapId;
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sb.push('ofs=' + offset);
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} else {
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offset = 0;
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}
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for (var i = 0; i < count; i++) {
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var mapId = messageQueue[i].mapId;
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var map = messageQueue[i].map;
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mapId -= offset;
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try {
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this.encodeMessage(map, sb, 'req' + mapId + '_');
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} catch (ex) {
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if (badMapHandler) {
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badMapHandler(map);
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}
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}
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}
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return sb.join('&');
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};
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/**
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* Decodes a standalone message received from the wire. May throw exception
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* if text is ill-formatted.
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*
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* Must be valid JSON as it is insecure to use eval() to decode JS literals;
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* and eval() is disallowed in Chrome apps too.
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*
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* Invalid JS literals include null array elements, quotas etc.
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*
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* @param {string} messageText The string content as received from the wire.
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* @return {*} The decoded message object.
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*/
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WireV8.prototype.decodeMessage = function(messageText) {
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var response = this.parser_.parse(messageText);
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goog.asserts.assert(goog.isArray(response)); // throw exception
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return response;
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};
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}); // goog.scope
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