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119 lines
2.8 KiB
JavaScript

'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]);
}
};
module.exports.default = module.exports;
/* 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;
};