var baseAssignValue = require('./_baseAssignValue'),

createAggregator = require('./_createAggregator');

/**

* Creates an object composed of keys generated from the results of running
* each element of `collection` thru `iteratee`. The corresponding value of
* each key is the last element responsible for generating the key. The
* iteratee is invoked with one argument: (value).
*
* @static
* @memberOf _
* @since 4.0.0
* @category Collection
* @param {Array|Object} collection The collection to iterate over.
* @param {Function} [iteratee=_.identity] The iteratee to transform keys.
* @returns {Object} Returns the composed aggregate object.
* @example
*
* var array = [
*   { 'dir': 'left', 'code': 97 },
*   { 'dir': 'right', 'code': 100 }
* ];
*
* _.keyBy(array, function(o) {
*   return String.fromCharCode(o.code);
* });
* // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
*
* _.keyBy(array, 'dir');
* // => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
*/

var keyBy = createAggregator(function(result, value, key) {

baseAssignValue(result, key, value);

});

module.exports = keyBy;