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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 keyMirror
* @typechecks static-only
*/
'use strict';
var invariant = require('invariant');
/**
* Constructs an enumeration with keys equal to their value.
*
* For example:
*
* var COLORS = keyMirror({blue: null, red: null});
* var myColor = COLORS.blue;
* var isColorValid = !!COLORS[myColor];
*
* The last line could not be performed if the values of the generated enum were
* not equal to their keys.
*
* Input: {key1: val1, key2: val2}
* Output: {key1: key1, key2: key2}
*
* @param {object} obj
* @return {object}
*/
var keyMirror = function(obj) {
var ret = {};
var key;
invariant(
obj instanceof Object && !Array.isArray(obj),
'keyMirror(...): Argument must be an object.'
);
for (key in obj) {
if (!obj.hasOwnProperty(key)) {
continue;
}
ret[key] = key;
}
return ret;
};
module.exports = keyMirror;
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