var arrayReduce = require('./_arrayReduce'),
baseEach = require('./_baseEach'),
baseIteratee = require('./_baseIteratee'),
baseReduce = require('./_baseReduce'),
isArray = require('./isArray');
/**
* Reduces `collection` to a value which is the accumulated result of running
* each element in `collection` thru `iteratee`, where each successive
* invocation is supplied the return value of the previous. If `accumulator`
* is not given, the first element of `collection` is used as the initial
* value. The iteratee is invoked with four arguments:
* (accumulator, value, index|key, collection).
*
* Many lodash methods are guarded to work as iteratees for methods like
* `_.reduce`, `_.reduceRight`, and `_.transform`.
*
* The guarded methods are:
* `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`,
* and `sortBy`
*
* @static
* @memberOf _
* @since 0.1.0
* @category Collection
* @param {Array|Object} collection The collection to iterate over.
* @param {Function} [iteratee=_.identity] The function invoked per iteration.
* @param {*} [accumulator] The initial value.
* @returns {*} Returns the accumulated value.
* @see _.reduceRight
* @example
*
* _.reduce([1, 2], function(sum, n) {
* return sum + n;
* }, 0);
* // => 3
*
* _.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
* (result[value] || (result[value] = [])).push(key);
* return result;
* }, {});
* // => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
*/
function reduce(collection, iteratee, accumulator) {
var func = isArray(collection) ? arrayReduce : baseReduce,
initAccum = arguments.length < 3;
return func(collection, baseIteratee(iteratee, 4), accumulator, initAccum, baseEach);
}
module.exports = reduce;