117 lines
2.7 KiB
JavaScript
117 lines
2.7 KiB
JavaScript
'use strict';
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module.exports = function (PromiseArgument) {
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var Promise;
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function throat(size, fn) {
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var queue = new Queue();
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function run(fn, self, args) {
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if (size) {
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size--;
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var result = new Promise(function (resolve) {
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resolve(fn.apply(self, args));
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});
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result.then(release, release);
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return result;
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} else {
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return new Promise(function (resolve) {
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queue.push(new Delayed(resolve, fn, self, args));
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});
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}
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}
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function release() {
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size++;
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if (!queue.isEmpty()) {
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var next = queue.shift();
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next.resolve(run(next.fn, next.self, next.args));
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}
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}
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if (typeof size === 'function') {
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var temp = fn;
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fn = size;
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size = temp;
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}
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if (typeof size !== 'number') {
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throw new TypeError(
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'Expected throat size to be a number but got ' + typeof size
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);
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}
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if (fn !== undefined && typeof fn !== 'function') {
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throw new TypeError(
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'Expected throat fn to be a function but got ' + typeof fn
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);
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}
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if (typeof fn === 'function') {
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return function () {
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var args = [];
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for (var i = 0; i < arguments.length; i++) {
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args.push(arguments[i]);
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}
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return run(fn, this, args);
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};
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} else {
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return function (fn) {
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if (typeof fn !== 'function') {
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throw new TypeError(
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'Expected throat fn to be a function but got ' + typeof fn
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);
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}
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var args = [];
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for (var i = 1; i < arguments.length; i++) {
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args.push(arguments[i]);
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}
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return run(fn, this, args);
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};
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}
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}
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if (arguments.length === 1 && typeof PromiseArgument === 'function') {
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Promise = PromiseArgument;
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return throat;
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} else {
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Promise = module.exports.Promise;
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if (typeof Promise !== 'function') {
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throw new Error(
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'You must provide a Promise polyfill for this library to work in older environments'
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);
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}
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return throat(arguments[0], arguments[1]);
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}
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};
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/* istanbul ignore next */
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if (typeof Promise === 'function') {
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module.exports.Promise = Promise;
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}
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function Delayed(resolve, fn, self, args) {
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this.resolve = resolve;
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this.fn = fn;
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this.self = self || null;
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this.args = args;
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}
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function Queue() {
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this._s1 = [];
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this._s2 = [];
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}
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Queue.prototype.push = function (value) {
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this._s1.push(value);
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};
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Queue.prototype.shift = function () {
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var s2 = this._s2;
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if (s2.length === 0) {
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var s1 = this._s1;
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if (s1.length === 0) {
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return;
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}
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this._s1 = s2;
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s2 = this._s2 = s1.reverse();
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}
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return s2.pop();
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};
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Queue.prototype.isEmpty = function () {
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return !this._s1.length && !this._s2.length;
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};
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