node_modules/when/lib/scheduler.js

/** @license MIT License (c) copyright 2010-2014 original author or authors */

/** @author Brian Cavalier */

/** @author John Hann */

(function(define) { 'use strict';

define(function(require) {

    var Queue = require('./Queue');

    // Credit to Twisol (https://github.com/Twisol) for suggesting

    // this type of extensible queue + trampoline approach for next-tick conflation.

    function Scheduler(enqueue) {

        this._enqueue = enqueue;

        this._handlerQueue = new Queue(15);

        this._afterQueue = new Queue(5);

        this._running = false;

        var self = this;

        this.drain = function() {

            self._drain();

        };

    }

    /**

     * Enqueue a task. If the queue is not currently scheduled to be

     * drained, schedule it.

     * @param {function} task

     */

    Scheduler.prototype.enqueue = function(task) {

        this._handlerQueue.push(task);

        if(!this._running) {

            this._running = true;

            this._enqueue(this.drain);

        }

    };

    Scheduler.prototype.afterQueue = function(f, x, y) {

        this._afterQueue.push(f);

        this._afterQueue.push(x);

        this._afterQueue.push(y);

        if(!this._running) {

            this._running = true;

            this._enqueue(this.drain);

        }

    };

    /**

     * Drain the handler queue entirely, being careful to allow the

     * queue to be extended while it is being processed, and to continue

     * processing until it is truly empty.

     */

    Scheduler.prototype._drain = function() {

        var q = this._handlerQueue;

        while(q.length > 0) {

            q.shift().run();

        }

        this._running = false;

        q = this._afterQueue;

        while(q.length > 0) {

            q.shift()(q.shift(), q.shift());

        }

    };

    return Scheduler;

});

}(typeof define === 'function' && define.amd ? define : function(factory) { module.exports = factory(require); }));