'use strict';
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var name = require('fn.name');
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/**
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* Wrap callbacks to prevent double execution.
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*
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* @param {Function} fn Function that should only be called once.
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* @returns {Function} A async wrapped callback which prevents multiple executions.
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* @public
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*/
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module.exports = function one(fn) {
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var called = 0
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, value;
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/**
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* The function that prevents double execution.
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*
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* @async
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* @public
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*/
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async function onetime() {
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if (called) return value;
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called = 1;
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value = await fn.apply(this, arguments);
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fn = null;
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return value;
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}
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//
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// To make debugging more easy we want to use the name of the supplied
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// function. So when you look at the functions that are assigned to event
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// listeners you don't see a load of `onetime` functions but actually the
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// names of the functions that this module will call.
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//
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// NOTE: We cannot override the `name` property, as that is `readOnly`
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// property, so displayName will have to do.
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//
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onetime.displayName = name(fn);
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return onetime;
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};
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