51 lines
1.5 KiB
JavaScript
51 lines
1.5 KiB
JavaScript
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/** @license MIT License (c) copyright 2011-2013 original author or authors */
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/**
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* pipeline.js
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*
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* Run a set of task functions in sequence, passing the result
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* of the previous as an argument to the next. Like a shell
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* pipeline, e.g. `cat file.txt | grep 'foo' | sed -e 's/foo/bar/g'
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*
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* @author Brian Cavalier
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* @author John Hann
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*/
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(function(define) {
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define(function(require) {
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var when = require('./when');
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var all = when.Promise.all;
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var slice = Array.prototype.slice;
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/**
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* Run array of tasks in a pipeline where the next
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* tasks receives the result of the previous. The first task
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* will receive the initialArgs as its argument list.
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* @param tasks {Array|Promise} array or promise for array of task functions
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* @param [initialArgs...] {*} arguments to be passed to the first task
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* @return {Promise} promise for return value of the final task
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*/
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return function pipeline(tasks /* initialArgs... */) {
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// Self-optimizing function to run first task with multiple
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// args using apply, but subsequence tasks via direct invocation
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var runTask = function(args, task) {
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runTask = function(arg, task) {
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return task(arg);
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};
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return task.apply(null, args);
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};
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return all(slice.call(arguments, 1)).then(function(args) {
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return when.reduce(tasks, function(arg, task) {
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return runTask(arg, task);
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}, args);
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});
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};
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});
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})(typeof define === 'function' && define.amd ? define : function (factory) { module.exports = factory(require); });
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