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