index.js
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/**
* lodash 4.2.0 (Custom Build) <https://lodash.com/>
* Build: `lodash modularize exports="npm" -o ./`
* Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
* Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
* Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
* Available under MIT license <https://lodash.com/license>
*/
var baseEach = require('lodash._baseeach'),
baseIteratee = require('lodash._baseiteratee'),
baseReduce = require('lodash._basereduce');
/**
* A specialized version of `_.reduce` for arrays without support for
* iteratee shorthands.
*
* @private
* @param {Array} array The array to iterate over.
* @param {Function} iteratee The function invoked per iteration.
* @param {*} [accumulator] The initial value.
* @param {boolean} [initAccum] Specify using the first element of `array` as the initial value.
* @returns {*} Returns the accumulated value.
*/
function arrayReduce(array, iteratee, accumulator, initAccum) {
var index = -1,
length = array.length;
if (initAccum && length) {
accumulator = array[++index];
}
while (++index < length) {
accumulator = iteratee(accumulator, array[index], index, array);
}
return accumulator;
}
/**
* Reduces `collection` to a value which is the accumulated result of running
* each element in `collection` through `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 _
* @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.
* @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);
}
/**
* Checks if `value` is classified as an `Array` object.
*
* @static
* @memberOf _
* @type {Function}
* @category Lang
* @param {*} value The value to check.
* @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
* @example
*
* _.isArray([1, 2, 3]);
* // => true
*
* _.isArray(document.body.children);
* // => false
*
* _.isArray('abc');
* // => false
*
* _.isArray(_.noop);
* // => false
*/
var isArray = Array.isArray;
module.exports = reduce;