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Diffstat (limited to 'node_modules/fbjs/lib/emptyFunction.js.flow')
-rw-r--r-- | node_modules/fbjs/lib/emptyFunction.js.flow | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/node_modules/fbjs/lib/emptyFunction.js.flow b/node_modules/fbjs/lib/emptyFunction.js.flow new file mode 100644 index 000000000..26076b07c --- /dev/null +++ b/node_modules/fbjs/lib/emptyFunction.js.flow @@ -0,0 +1,37 @@ +/** + * 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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