80 lines
2.1 KiB
JavaScript
80 lines
2.1 KiB
JavaScript
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'use strict';
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.unfold = unfold;
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var _Stream = require('../Stream');
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var _Stream2 = _interopRequireDefault(_Stream);
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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/**
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* Compute a stream by unfolding tuples of future values from a seed value
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* Event times may be controlled by returning a Promise from f
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* @param {function(seed:*):{value:*, seed:*, done:boolean}|Promise<{value:*, seed:*, done:boolean}>} f unfolding function accepts
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* a seed and returns a new tuple with a value, new seed, and boolean done flag.
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* If tuple.done is true, the stream will end.
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* @param {*} seed seed value
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* @returns {Stream} stream containing all value of all tuples produced by the
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* unfolding function.
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*/
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function unfold(f, seed) {
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return new _Stream2.default(new UnfoldSource(f, seed));
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} /** @license MIT License (c) copyright 2010-2016 original author or authors */
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/** @author Brian Cavalier */
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/** @author John Hann */
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function UnfoldSource(f, seed) {
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this.f = f;
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this.value = seed;
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}
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UnfoldSource.prototype.run = function (sink, scheduler) {
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return new Unfold(this.f, this.value, sink, scheduler);
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};
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function Unfold(f, x, sink, scheduler) {
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this.f = f;
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this.sink = sink;
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this.scheduler = scheduler;
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this.active = true;
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var self = this;
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function err(e) {
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self.sink.error(self.scheduler.now(), e);
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}
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function start(unfold) {
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return stepUnfold(unfold, x);
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}
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Promise.resolve(this).then(start).catch(err);
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}
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Unfold.prototype.dispose = function () {
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this.active = false;
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};
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function stepUnfold(unfold, x) {
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var f = unfold.f;
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return Promise.resolve(f(x)).then(function (tuple) {
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return continueUnfold(unfold, tuple);
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});
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}
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function continueUnfold(unfold, tuple) {
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if (tuple.done) {
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unfold.sink.end(unfold.scheduler.now(), tuple.value);
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return tuple.value;
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}
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unfold.sink.event(unfold.scheduler.now(), tuple.value);
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if (!unfold.active) {
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return tuple.value;
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}
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return stepUnfold(unfold, tuple.seed);
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}
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