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node_modules/when/lib/decorators/iterate.js
Maintainability
85.86
Lines of code
59
Difficulty
17.16
Estimated Errors
0.23
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/** @license MIT License (c) copyright 2010-2014 original author or authors */ /** @author Brian Cavalier */ /** @author John Hann */ (function(define) { 'use strict'; define(function() { return function generate(Promise) { var resolve = Promise.resolve; Promise.iterate = iterate; Promise.unfold = unfold; return Promise; /** * Generate a (potentially infinite) stream of promised values: * x, f(x), f(f(x)), etc. until condition(x) returns true * @param {function} f function to generate a new x from the previous x * @param {function} condition function that, given the current x, returns * truthy when the iterate should stop * @param {function} handler function to handle the value produced by f * @param {*|Promise} x starting value, may be a promise * @return {Promise} the result of the last call to f before * condition returns true */ function iterate(f, condition, handler, x) { return unfold(function(x) { return [x, f(x)]; }, condition, handler, x); } /** * Generate a (potentially infinite) stream of promised values * by applying handler(generator(seed)) iteratively until * condition(seed) returns true. * @param {function} unspool function that generates a [value, newSeed] * given a seed. * @param {function} condition function that, given the current seed, returns * truthy when the unfold should stop * @param {function} handler function to handle the value produced by unspool * @param x {*|Promise} starting value, may be a promise * @return {Promise} the result of the last value produced by unspool before * condition returns true */ function unfold(unspool, condition, handler, x) { return resolve(x).then(function(seed) { return resolve(condition(seed)).then(function(done) { return done ? seed : resolve(unspool(seed)).spread(next); }); }); function next(item, newSeed) { return resolve(handler(item)).then(function() { return unfold(unspool, condition, handler, newSeed); }); } } }; }); }(typeof define === 'function' && define.amd ? define : function(factory) { module.exports = factory(); }));