1 files changed, 141 insertions, 0 deletions
diff --git a/src/js/fiveui/js/messenger.js b/src/js/fiveui/js/messenger.js
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+++ b/src/js/fiveui/js/messenger.js
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+/*
+ * Module     : messenger.js
+ * Copyright  : (c) 2011-2012, Galois, Inc.
+ *
+ * Maintainer :
+ * Stability  : Provisional
+ * Portability: Portable
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+var fiveui = fiveui || {};
+
+(function() {
+
+/**
+ * @constructor
+ * @param {{on: function(!string, function(*)), emit: function(!string, *)}}
+ *    channel The object containing on and emit.
+ */
+fiveui.Messenger = function(channel) {
+  this.callbacks = {};
+  this.handlers = {};
+
+  this.channel = channel;
+  this.channel.on(fiveui.Messenger.type, _.bind(this._handler, this));
+};
+
+fiveui.Messenger.type = "fiveui_messaging_type";
+
+_.extend(fiveui.Messenger.prototype, {
+
+  /**
+   * @param {!string} type The message type to send.
+   * @param {?Object} data The payload (which can be null).
+   * @param {?function(?Object)} callback An optional callback to be
+   * invoked in response.
+   */
+  send: function(type, data, callback){
+    var id = null;
+    if (callback) {
+      id = this._newId();
+      this.callbacks[id] = callback;
+    }
+
+    var payload = new fiveui.Messenger.Payload(false, type, data, id);
+    this.channel.emit(fiveui.Messenger.type, payload);
+  },
+
+  /**
+   * Register a handler for the specified message type.
+   *
+   * @param {!string} type The message type.
+   * @param {!function(*)} callback The function to call when a message
+   * of the specified type is received.
+   */
+  register: function(type, callback) {
+    if(null == this.handlers[type]) {
+      this.handlers[type] = [];
+    }
+    this.handlers[type].push(callback);
+  },
+
+  _handler: function(payload) {
+    if (payload.isCallback && payload.id != null) {
+      // this is a callback invocation, lookup the callback and invoke it:
+      this.callbacks[payload.id](payload.data);
+
+      // remove the callback:
+      this._remove(payload.id);
+    } else {
+      // look up a handler and invoke it, passing in the response fn:
+      var hs = this.handlers[payload.type];
+      if (hs && hs.length > 0) {
+
+        // this is a new incomming message.
+        // create a response function:
+        var respond = function(respData) {
+          this.channel.emit(fiveui.Messenger.type,
+                 new fiveui.Messenger.Payload(true, payload.type, respData, payload.id));
+        };
+
+        // iterate over the handlers, invoking them with the response callback.
+        _.each(hs, function(h) {
+          h(payload.data, _.bind(respond, this));
+        }, this);
+      }
+    }
+  },
+
+  /**
+   * Remove a callback from the map of callbacks.
+   *
+   * @param {!number} callbackId The id of the callback to remove.
+   */
+  _remove: function(callbackId) {
+    delete this.callbacks[callbackId];
+  },
+
+  /**
+   * @return {!number} The next unique id for a callback.
+   */
+  _newId: function() {
+    var list = Object.keys(this.callbacks);
+    return fiveui.utils.getNewId(list);
+  }
+
+});
+
+/**
+ * @constructor
+ * @param {!boolean} isCallback True if this is in response to a
+ * message, false if this is requesting a callback.
+ * @param {!string} type
+ * @param {?Object} data
+ * @param {!number} id Callback id to invoke, or in which this is a response.
+ */
+fiveui.Messenger.Payload = function(isCallback, type, data, id) {
+  this.isCallback = isCallback;
+  this.type = type;
+  this.id = id;
+  this.__defineGetter__('data', function() {
+                          return JSON.parse(this.rawData);
+                        });
+  this.__defineSetter__('data', function(obj){
+                          this.rawData = JSON.stringify(obj);
+                        });
+  this.data = data;
+};
+
+})();