var baseFlatten = require('./_baseFlatten'),
baseRest = require('./_baseRest'),
baseUniq = require('./_baseUniq'),
isArrayLikeObject = require('./isArrayLikeObject'),
last = require('./last');
/**
* This method is like `_.union` except that it accepts `comparator` which
* is invoked to compare elements of `arrays`. Result values are chosen from
* the first array in which the value occurs. The comparator is invoked
* with two arguments: (arrVal, othVal).
*
* @static
* @memberOf _
* @since 4.0.0
* @category Array
* @param {...Array} [arrays] The arrays to inspect.
* @param {Function} [comparator] The comparator invoked per element.
* @returns {Array} Returns the new array of combined values.
* @example
*
* var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
* var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
*
* _.unionWith(objects, others, _.isEqual);
* // => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
*/
var unionWith = baseRest(function(arrays) {
var comparator = last(arrays);
comparator = typeof comparator == 'function' ? comparator : undefined;
return baseUniq(baseFlatten(arrays, 1, isArrayLikeObject, true), undefined, comparator);
});
module.exports = unionWith;