66 lines
2.3 KiB
JavaScript
66 lines
2.3 KiB
JavaScript
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/** @license MIT License (c) copyright 2010-2014 original author or authors */
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/** @author Brian Cavalier */
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/** @author John Hann */
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(function(define) { 'use strict';
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define(function() {
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return function generate(Promise) {
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var resolve = Promise.resolve;
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Promise.iterate = iterate;
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Promise.unfold = unfold;
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return Promise;
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/**
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* @deprecated Use github.com/cujojs/most streams and most.iterate
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* Generate a (potentially infinite) stream of promised values:
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* x, f(x), f(f(x)), etc. until condition(x) returns true
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* @param {function} f function to generate a new x from the previous x
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* @param {function} condition function that, given the current x, returns
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* truthy when the iterate should stop
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* @param {function} handler function to handle the value produced by f
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* @param {*|Promise} x starting value, may be a promise
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* @return {Promise} the result of the last call to f before
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* condition returns true
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*/
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function iterate(f, condition, handler, x) {
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return unfold(function(x) {
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return [x, f(x)];
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}, condition, handler, x);
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}
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/**
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* @deprecated Use github.com/cujojs/most streams and most.unfold
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* Generate a (potentially infinite) stream of promised values
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* by applying handler(generator(seed)) iteratively until
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* condition(seed) returns true.
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* @param {function} unspool function that generates a [value, newSeed]
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* given a seed.
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* @param {function} condition function that, given the current seed, returns
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* truthy when the unfold should stop
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* @param {function} handler function to handle the value produced by unspool
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* @param x {*|Promise} starting value, may be a promise
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* @return {Promise} the result of the last value produced by unspool before
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* condition returns true
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*/
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function unfold(unspool, condition, handler, x) {
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return resolve(x).then(function(seed) {
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return resolve(condition(seed)).then(function(done) {
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return done ? seed : resolve(unspool(seed)).spread(next);
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});
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});
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function next(item, newSeed) {
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return resolve(handler(item)).then(function() {
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return unfold(unspool, condition, handler, newSeed);
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});
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}
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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(); }));
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