37 lines
1.1 KiB
Plaintext
37 lines
1.1 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule emptyFunction
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* @flow
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*/
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function makeEmptyFunction<T>(arg: T): (...args: Array<any>) => T {
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return function () {
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return arg;
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};
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}
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/**
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* This function accepts and discards inputs; it has no side effects. This is
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* primarily useful idiomatically for overridable function endpoints which
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* always need to be callable, since JS lacks a null-call idiom ala Cocoa.
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*/
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const emptyFunction: (...args: Array<any>) => void = function () {};
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emptyFunction.thatReturns = makeEmptyFunction;
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emptyFunction.thatReturnsFalse = makeEmptyFunction(false);
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emptyFunction.thatReturnsTrue = makeEmptyFunction(true);
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emptyFunction.thatReturnsNull = makeEmptyFunction(null);
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emptyFunction.thatReturnsThis = function () {
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return this;
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};
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emptyFunction.thatReturnsArgument = function (arg) {
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return arg;
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};
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module.exports = emptyFunction;
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