36 lines
847 B
JavaScript
36 lines
847 B
JavaScript
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"use strict";
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var isFunction = require("../function/is-function");
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module.exports = function (executor) {
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var Constructor;
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if (isFunction(this)) {
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Constructor = this;
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} else if (typeof Promise === "function") {
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Constructor = Promise;
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} else {
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throw new TypeError("Could not resolve Promise constuctor");
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}
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var lazyThen;
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var promise = new Constructor(function (resolve, reject) {
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lazyThen = function (onSuccess, onFailure) {
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if (!hasOwnProperty.call(this, "then")) {
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// Sanity check
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throw new Error("Unexpected (inherited) lazy then invocation");
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}
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try { executor(resolve, reject); }
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catch (reason) { reject(reason); }
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delete this.then;
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return this.then(onSuccess, onFailure);
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};
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});
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return Object.defineProperty(promise, "then", {
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configurable: true,
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writable: true,
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value: lazyThen
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});
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};
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