53 lines
1.6 KiB
JavaScript
53 lines
1.6 KiB
JavaScript
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"use strict";
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module.exports = asPromise;
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/**
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* Callback as used by {@link util.asPromise}.
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* @typedef asPromiseCallback
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* @type {function}
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* @param {Error|null} error Error, if any
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* @param {...*} params Additional arguments
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* @returns {undefined}
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*/
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/**
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* Returns a promise from a node-style callback function.
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* @memberof util
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* @param {asPromiseCallback} fn Function to call
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* @param {*} ctx Function context
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* @param {...*} params Function arguments
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* @returns {Promise<*>} Promisified function
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*/
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function asPromise(fn, ctx/*, varargs */) {
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var params = new Array(arguments.length - 1),
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offset = 0,
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index = 2,
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pending = true;
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while (index < arguments.length)
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params[offset++] = arguments[index++];
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return new Promise(function executor(resolve, reject) {
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params[offset] = function callback(err/*, varargs */) {
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if (pending) {
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pending = false;
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if (err)
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reject(err);
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else {
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var params = new Array(arguments.length - 1),
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offset = 0;
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while (offset < params.length)
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params[offset++] = arguments[offset];
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resolve.apply(null, params);
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}
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}
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};
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try {
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fn.apply(ctx || null, params);
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} catch (err) {
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if (pending) {
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pending = false;
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reject(err);
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}
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}
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});
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}
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