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