65 lines
2.2 KiB
JavaScript
65 lines
2.2 KiB
JavaScript
var arrayEach = require('./_arrayEach'),
|
|
baseCreate = require('./_baseCreate'),
|
|
baseForOwn = require('./_baseForOwn'),
|
|
baseIteratee = require('./_baseIteratee'),
|
|
getPrototype = require('./_getPrototype'),
|
|
isArray = require('./isArray'),
|
|
isBuffer = require('./isBuffer'),
|
|
isFunction = require('./isFunction'),
|
|
isObject = require('./isObject'),
|
|
isTypedArray = require('./isTypedArray');
|
|
|
|
/**
|
|
* An alternative to `_.reduce`; this method transforms `object` to a new
|
|
* `accumulator` object which is the result of running each of its own
|
|
* enumerable string keyed properties thru `iteratee`, with each invocation
|
|
* potentially mutating the `accumulator` object. If `accumulator` is not
|
|
* provided, a new object with the same `[[Prototype]]` will be used. The
|
|
* iteratee is invoked with four arguments: (accumulator, value, key, object).
|
|
* Iteratee functions may exit iteration early by explicitly returning `false`.
|
|
*
|
|
* @static
|
|
* @memberOf _
|
|
* @since 1.3.0
|
|
* @category Object
|
|
* @param {Object} object The object to iterate over.
|
|
* @param {Function} [iteratee=_.identity] The function invoked per iteration.
|
|
* @param {*} [accumulator] The custom accumulator value.
|
|
* @returns {*} Returns the accumulated value.
|
|
* @example
|
|
*
|
|
* _.transform([2, 3, 4], function(result, n) {
|
|
* result.push(n *= n);
|
|
* return n % 2 == 0;
|
|
* }, []);
|
|
* // => [4, 9]
|
|
*
|
|
* _.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
|
|
* (result[value] || (result[value] = [])).push(key);
|
|
* }, {});
|
|
* // => { '1': ['a', 'c'], '2': ['b'] }
|
|
*/
|
|
function transform(object, iteratee, accumulator) {
|
|
var isArr = isArray(object),
|
|
isArrLike = isArr || isBuffer(object) || isTypedArray(object);
|
|
|
|
iteratee = baseIteratee(iteratee, 4);
|
|
if (accumulator == null) {
|
|
var Ctor = object && object.constructor;
|
|
if (isArrLike) {
|
|
accumulator = isArr ? new Ctor : [];
|
|
}
|
|
else if (isObject(object)) {
|
|
accumulator = isFunction(Ctor) ? baseCreate(getPrototype(object)) : {};
|
|
}
|
|
else {
|
|
accumulator = {};
|
|
}
|
|
}
|
|
(isArrLike ? arrayEach : baseForOwn)(object, function(value, index, object) {
|
|
return iteratee(accumulator, value, index, object);
|
|
});
|
|
return accumulator;
|
|
}
|
|
|
|
module.exports = transform;
|