msgs/channels/dispatchers/pollable.js

Message oriented programming for JavaScript

/*
 * Copyright 2012 the original author or authors
 * @license MIT, see LICENSE.txt for details
 *
 * @author Scott Andrews
 */

(function (define) {
	'use strict';

	/**
	 * Pollable dispatcher
	 */
	define(function (/* require */) {

		/**
		 * Store messages to be consumed later
		 *
		 * @param {Queue} queue the queuing strategy for this dispatcher. The
		 *   queue must support 'push' and 'shift' for adding and removing
		 *   message from the queue respectively. Queues may or may not be
		 *   durable. The default queue is an Array.
		 */
		function pollableDispatcher(queue) {
			var dispatcher = {};

			queue = queue || [];

			/**
			 * @returns {Message} the next message, may return undefined if no
			 * messages are available
			 */
			function receive() {
				return queue.shift();
			}

			/**
			 * Enqueue a message to be consumed later
			 *
			 * @param {Message} message the message to queue
			 * @param {Function} handlerResolver handler resolver
			 * @returns {boolean} true if enqueueing is successful
			 */
			dispatcher.dispatch = function dispatch(message /*, handlerResolver */) {
				try {
					return !!queue.push(message);
				}
				catch (e) {
					return false;
				}
			};

			dispatcher.channelMixins = {
				receive: receive
			};

			return dispatcher;
		}

		return pollableDispatcher;

	});

}(
	typeof define === 'function' && define.amd ? define : function (factory) { module.exports = factory(require); }
	// Boilerplate for AMD and Node
));