turing.promise.js

/*!
 * Turing Promise
 * Copyright (C) 2010-2011 Alex R. Young
 * MIT Licensed
 */

/**
 * The Turing Promise module.
 */
define('turing.promise', ['turing.core'], function(turing) {
  function PromiseModule(global) {
    /**
     * The Promise class.
     */
    function Promise() {
      var self = this;
      this.pending = [];

      /**
       * Resolves a promise.
       *
       * @param {Object} A value
       */
      this.resolve = function(result) {
        self.complete('resolve', result);
      },

      /**
       * Rejects a promise.
       *
       * @param {Object} A value
       */
      this.reject = function(result) {
        self.complete('reject', result);
      }
    }

    Promise.prototype = {
      /**
       * Adds a success and failure handler for completion of this Promise object.
       *
       * @param {Function} success The success handler 
       * @param {Function} success The failure handler
       * @returns {Promise} `this`
       */
      then: function(success, failure) {
        this.pending.push({ resolve: success, reject: failure });
        return this;
      },

      /**
       * Runs through each pending 'thenable' based on type (resolve, reject).
       *
       * @param {String} type The thenable type
       * @param {Object} result A value
       */
      complete: function(type, result) {
        while (this.pending[0]) {
          this.pending.shift()[type](result);
        }
      }
    };

    /**
      * Chained Promises:
      *
      *     global().delay(1000).then(function() {
      *       assert.ok((new Date()).valueOf() - start >= 1000);  
      *     });
      *
      */
    var chain = {};

    turing.init(function() {
      if (arguments.length === 0)
        return chain;
    });

    chain.delay = function(ms) {
      var p = new turing.Promise();
      setTimeout(p.resolve, ms);
      return p;
    };

    global.Promise = Promise;
  }

  if (typeof module !== 'undefined') {
    module.exports = function(t) {
      return PromiseModule(t);
    }
  } else {
    PromiseModule(turing);
  }

  return turing.Promise;
});