| 1 | /**
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| 2 | * Lo-Dash 2.4.0 (Custom Build) <http://lodash.com/>
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| 3 | * Build: `lodash modularize modern exports="npm" -o ./npm/`
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| 4 | * Copyright 2012-2013 The Dojo Foundation <http://dojofoundation.org/>
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| 5 | * Based on Underscore.js 1.5.2 <http://underscorejs.org/LICENSE>
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| 6 | * Copyright 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
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| 7 | * Available under MIT license <http://lodash.com/license>
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| 8 | */
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| 9 | var createAggregator = require('lodash._createaggregator');
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| 10 |
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| 11 | /**
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| 12 | * Creates an object composed of keys generated from the results of running
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| 13 | * each element of the collection through the given callback. The corresponding
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| 14 | * value of each key is the last element responsible for generating the key.
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| 15 | * The callback is bound to `thisArg` and invoked with three arguments;
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| 16 | * (value, index|key, collection).
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| 17 | *
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| 18 | * If a property name is provided for `callback` the created "_.pluck" style
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| 19 | * callback will return the property value of the given element.
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| 20 | *
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| 21 | * If an object is provided for `callback` the created "_.where" style callback
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| 22 | * will return `true` for elements that have the properties of the given object,
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| 23 | * else `false`.
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| 24 | *
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| 25 | * @static
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| 26 | * @memberOf _
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| 27 | * @category Collections
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| 28 | * @param {Array|Object|string} collection The collection to iterate over.
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| 29 | * @param {Function|Object|string} [callback=identity] The function called
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| 30 | * per iteration. If a property name or object is provided it will be used
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| 31 | * to create a "_.pluck" or "_.where" style callback, respectively.
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| 32 | * @param {*} [thisArg] The `this` binding of `callback`.
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| 33 | * @returns {Object} Returns the composed aggregate object.
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| 34 | * @example
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| 35 | *
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| 36 | * var keys = [
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| 37 | * { 'dir': 'left', 'code': 97 },
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| 38 | * { 'dir': 'right', 'code': 100 }
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| 39 | * ];
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| 40 | *
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| 41 | * _.indexBy(keys, 'dir');
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| 42 | * // => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
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| 43 | *
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| 44 | * _.indexBy(keys, function(key) { return String.fromCharCode(key.code); });
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| 45 | * // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
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| 46 | *
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| 47 | * _.indexBy(characters, function(key) { this.fromCharCode(key.code); }, String);
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| 48 | * // => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
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| 49 | */
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| 50 | var indexBy = createAggregator(function(result, value, key) {
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| 51 | result[key] = value;
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| 52 | });
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| 53 |
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| 54 | module.exports = indexBy;
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