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