// MIT license (by Elan Shanker).
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(function(globals) {
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'use strict';
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var executeSync = function(){
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var args = Array.prototype.slice.call(arguments);
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if (typeof args[0] === 'function'){
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args[0].apply(null, args.splice(1));
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}
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};
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var executeAsync = function(fn){
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if (typeof setImmediate === 'function') {
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setImmediate(fn);
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} else if (typeof process !== 'undefined' && process.nextTick) {
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process.nextTick(fn);
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} else {
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setTimeout(fn, 0);
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}
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};
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var makeIterator = function (tasks) {
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var makeCallback = function (index) {
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var fn = function () {
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if (tasks.length) {
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tasks[index].apply(null, arguments);
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}
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return fn.next();
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};
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fn.next = function () {
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return (index < tasks.length - 1) ? makeCallback(index + 1): null;
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};
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return fn;
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};
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return makeCallback(0);
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};
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var _isArray = Array.isArray || function(maybeArray){
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return Object.prototype.toString.call(maybeArray) === '[object Array]';
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};
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var waterfall = function (tasks, callback, forceAsync) {
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var nextTick = forceAsync ? executeAsync : executeSync;
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callback = callback || function () {};
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if (!_isArray(tasks)) {
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var err = new Error('First argument to waterfall must be an array of functions');
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return callback(err);
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}
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if (!tasks.length) {
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return callback();
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}
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var wrapIterator = function (iterator) {
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return function (err) {
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if (err) {
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callback.apply(null, arguments);
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callback = function () {};
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} else {
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var args = Array.prototype.slice.call(arguments, 1);
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var next = iterator.next();
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if (next) {
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args.push(wrapIterator(next));
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} else {
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args.push(callback);
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}
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nextTick(function () {
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iterator.apply(null, args);
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});
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}
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};
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};
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wrapIterator(makeIterator(tasks))();
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};
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if (typeof define !== 'undefined' && define.amd) {
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define([], function () {
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return waterfall;
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}); // RequireJS
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} else if (typeof module !== 'undefined' && module.exports) {
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module.exports = waterfall; // CommonJS
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} else {
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globals.waterfall = waterfall; // <script>
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}
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})(this);
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