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