mirror of
https://github.com/whoisclebs/lodash.git
synced 2026-02-01 07:47:49 +00:00
96 lines
3.4 KiB
JavaScript
96 lines
3.4 KiB
JavaScript
/**
|
|
* lodash 3.1.2 (Custom Build) <https://lodash.com/>
|
|
* Build: `lodash modern modularize exports="npm" -o ./`
|
|
* Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
|
|
* Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
|
|
* Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
|
|
* Available under MIT license <https://lodash.com/license>
|
|
*/
|
|
var baseCallback = require('lodash._basecallback'),
|
|
baseEach = require('lodash._baseeach'),
|
|
baseReduce = require('lodash._basereduce'),
|
|
isArray = require('lodash.isarray');
|
|
|
|
/**
|
|
* A specialized version of `_.reduce` for arrays without support for callback
|
|
* shorthands and `this` binding.
|
|
*
|
|
* @private
|
|
* @param {Array} array The array to iterate over.
|
|
* @param {Function} iteratee The function invoked per iteration.
|
|
* @param {*} [accumulator] The initial value.
|
|
* @param {boolean} [initFromArray] Specify using the first element of `array`
|
|
* as the initial value.
|
|
* @returns {*} Returns the accumulated value.
|
|
*/
|
|
function arrayReduce(array, iteratee, accumulator, initFromArray) {
|
|
var index = -1,
|
|
length = array.length;
|
|
|
|
if (initFromArray && length) {
|
|
accumulator = array[++index];
|
|
}
|
|
while (++index < length) {
|
|
accumulator = iteratee(accumulator, array[index], index, array);
|
|
}
|
|
return accumulator;
|
|
}
|
|
|
|
/**
|
|
* Creates a function for `_.reduce` or `_.reduceRight`.
|
|
*
|
|
* @private
|
|
* @param {Function} arrayFunc The function to iterate over an array.
|
|
* @param {Function} eachFunc The function to iterate over a collection.
|
|
* @returns {Function} Returns the new each function.
|
|
*/
|
|
function createReduce(arrayFunc, eachFunc) {
|
|
return function(collection, iteratee, accumulator, thisArg) {
|
|
var initFromArray = arguments.length < 3;
|
|
return (typeof iteratee == 'function' && thisArg === undefined && isArray(collection))
|
|
? arrayFunc(collection, iteratee, accumulator, initFromArray)
|
|
: baseReduce(collection, baseCallback(iteratee, thisArg, 4), accumulator, initFromArray, eachFunc);
|
|
};
|
|
}
|
|
|
|
/**
|
|
* 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 provided the first element of `collection` is used as the initial
|
|
* value. The `iteratee` is bound to `thisArg` and 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`, `sortByAll`,
|
|
* and `sortByOrder`
|
|
*
|
|
* @static
|
|
* @memberOf _
|
|
* @alias foldl, inject
|
|
* @category Collection
|
|
* @param {Array|Object|string} collection The collection to iterate over.
|
|
* @param {Function} [iteratee=_.identity] The function invoked per iteration.
|
|
* @param {*} [accumulator] The initial value.
|
|
* @param {*} [thisArg] The `this` binding of `iteratee`.
|
|
* @returns {*} Returns the accumulated value.
|
|
* @example
|
|
*
|
|
* _.reduce([1, 2], function(total, n) {
|
|
* return total + n;
|
|
* });
|
|
* // => 3
|
|
*
|
|
* _.reduce({ 'a': 1, 'b': 2 }, function(result, n, key) {
|
|
* result[key] = n * 3;
|
|
* return result;
|
|
* }, {});
|
|
* // => { 'a': 3, 'b': 6 } (iteration order is not guaranteed)
|
|
*/
|
|
var reduce = createReduce(arrayReduce, baseEach);
|
|
|
|
module.exports = reduce;
|