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'use strict'; |
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|
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Object.defineProperty(exports, "__esModule", { |
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value: true |
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}); |
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exports.default = transform; |
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|
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var _isArray = require('lodash/isArray'); |
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|
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var _isArray2 = _interopRequireDefault(_isArray); |
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|
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var _noop = require('lodash/noop'); |
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|
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var _noop2 = _interopRequireDefault(_noop); |
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|
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var _eachOf = require('./eachOf'); |
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|
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var _eachOf2 = _interopRequireDefault(_eachOf); |
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|
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var _once = require('./internal/once'); |
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|
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var _once2 = _interopRequireDefault(_once); |
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|
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var _wrapAsync = require('./internal/wrapAsync'); |
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|
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var _wrapAsync2 = _interopRequireDefault(_wrapAsync); |
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|
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; } |
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|
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/** |
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* A relative of `reduce`. Takes an Object or Array, and iterates over each |
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* element in series, each step potentially mutating an `accumulator` value. |
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* The type of the accumulator defaults to the type of collection passed in. |
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* |
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* @name transform |
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* @static |
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* @memberOf module:Collections |
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* @method |
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* @category Collection |
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* @param {Array|Iterable|Object} coll - A collection to iterate over. |
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* @param {*} [accumulator] - The initial state of the transform. If omitted, |
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* it will default to an empty Object or Array, depending on the type of `coll` |
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* @param {AsyncFunction} iteratee - A function applied to each item in the |
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* collection that potentially modifies the accumulator. |
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* Invoked with (accumulator, item, key, callback). |
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* @param {Function} [callback] - A callback which is called after all the |
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* `iteratee` functions have finished. Result is the transformed accumulator. |
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* Invoked with (err, result). |
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* @example |
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* |
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* async.transform([1,2,3], function(acc, item, index, callback) { |
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* // pointless async: |
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* process.nextTick(function() { |
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* acc.push(item * 2) |
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* callback(null) |
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* }); |
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* }, function(err, result) { |
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* // result is now equal to [2, 4, 6] |
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* }); |
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* |
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* @example |
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* |
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* async.transform({a: 1, b: 2, c: 3}, function (obj, val, key, callback) { |
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* setImmediate(function () { |
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* obj[key] = val * 2; |
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* callback(); |
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* }) |
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* }, function (err, result) { |
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* // result is equal to {a: 2, b: 4, c: 6} |
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* }) |
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*/ |
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function transform(coll, accumulator, iteratee, callback) { |
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if (arguments.length <= 3) { |
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callback = iteratee; |
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iteratee = accumulator; |
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accumulator = (0, _isArray2.default)(coll) ? [] : {}; |
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} |
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callback = (0, _once2.default)(callback || _noop2.default); |
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var _iteratee = (0, _wrapAsync2.default)(iteratee); |
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|
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(0, _eachOf2.default)(coll, function (v, k, cb) { |
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_iteratee(accumulator, v, k, cb); |
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}, function (err) { |
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callback(err, accumulator); |
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}); |
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} |
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module.exports = exports['default']; |
