1 | ;
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2 |
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3 | Object.defineProperty(exports, "__esModule", {
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4 | value: true
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5 | });
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6 | exports.default = transform;
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7 |
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8 | var _eachOf = require('./eachOf');
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9 |
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10 | var _eachOf2 = _interopRequireDefault(_eachOf);
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11 |
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12 | var _once = require('./internal/once');
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13 |
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14 | var _once2 = _interopRequireDefault(_once);
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15 |
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16 | var _wrapAsync = require('./internal/wrapAsync');
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17 |
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18 | var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
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19 |
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20 | var _promiseCallback = require('./internal/promiseCallback');
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21 |
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22 | function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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23 |
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24 | /**
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25 | * A relative of `reduce`. Takes an Object or Array, and iterates over each
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26 | * element in parallel, each step potentially mutating an `accumulator` value.
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27 | * The type of the accumulator defaults to the type of collection passed in.
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28 | *
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29 | * @name transform
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30 | * @static
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31 | * @memberOf module:Collections
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32 | * @method
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33 | * @category Collection
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34 | * @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
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35 | * @param {*} [accumulator] - The initial state of the transform. If omitted,
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36 | * it will default to an empty Object or Array, depending on the type of `coll`
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37 | * @param {AsyncFunction} iteratee - A function applied to each item in the
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38 | * collection that potentially modifies the accumulator.
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39 | * Invoked with (accumulator, item, key, callback).
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40 | * @param {Function} [callback] - A callback which is called after all the
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41 | * `iteratee` functions have finished. Result is the transformed accumulator.
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42 | * Invoked with (err, result).
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43 | * @returns {Promise} a promise, if no callback provided
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44 | * @example
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45 | *
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46 | * async.transform([1,2,3], function(acc, item, index, callback) {
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47 | * // pointless async:
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48 | * process.nextTick(function() {
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49 | * acc[index] = item * 2
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50 | * callback(null)
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51 | * });
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52 | * }, function(err, result) {
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53 | * // result is now equal to [2, 4, 6]
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54 | * });
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55 | *
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56 | * @example
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57 | *
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58 | * async.transform({a: 1, b: 2, c: 3}, function (obj, val, key, callback) {
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59 | * setImmediate(function () {
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60 | * obj[key] = val * 2;
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61 | * callback();
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62 | * })
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63 | * }, function (err, result) {
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64 | * // result is equal to {a: 2, b: 4, c: 6}
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65 | * })
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66 | */
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67 | function transform(coll, accumulator, iteratee, callback) {
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68 | if (arguments.length <= 3 && typeof accumulator === 'function') {
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69 | callback = iteratee;
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70 | iteratee = accumulator;
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71 | accumulator = Array.isArray(coll) ? [] : {};
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72 | }
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73 | callback = (0, _once2.default)(callback || (0, _promiseCallback.promiseCallback)());
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74 | var _iteratee = (0, _wrapAsync2.default)(iteratee);
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75 |
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76 | (0, _eachOf2.default)(coll, (v, k, cb) => {
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77 | _iteratee(accumulator, v, k, cb);
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78 | }, err => callback(err, accumulator));
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79 | return callback[_promiseCallback.PROMISE_SYMBOL];
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80 | }
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81 | module.exports = exports['default']; |
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