| OLD | NEW |
|---|
| (Empty) |
| 1 <!DOCTYPE html> | |
| 2 <!-- | |
| 3 Copyright (c) 2014 The Chromium Authors. All rights reserved. | |
| 4 Use of this source code is governed by a BSD-style license that can be | |
| 5 found in the LICENSE file. | |
| 6 --> | |
| 7 | |
| 8 <link rel="import" href="/tracing/base/base.html"> | |
| 9 | |
| 10 <script> | |
| 11 'use strict'; | |
| 12 | |
| 13 tr.exportTo('tr.b', function() { | |
| 14 /** | |
| 15 * Returns the only element in the iterable. If the iterable is empty or has | |
| 16 * more than one element, an error is thrown. | |
| 17 */ | |
| 18 function getOnlyElement(iterable) { | |
| 19 const iterator = iterable[Symbol.iterator](); | |
| 20 | |
| 21 const firstIteration = iterator.next(); | |
| 22 if (firstIteration.done) { | |
| 23 throw new Error('getOnlyElement was passed an empty iterable.'); | |
| 24 } | |
| 25 | |
| 26 const secondIteration = iterator.next(); | |
| 27 if (!secondIteration.done) { | |
| 28 throw new Error( | |
| 29 'getOnlyElement was passed an iterable with multiple elements.'); | |
| 30 } | |
| 31 | |
| 32 return firstIteration.value; | |
| 33 } | |
| 34 | |
| 35 /** | |
| 36 * Returns the first element in the iterable. If the iterable is empty, an | |
| 37 * error is thrown. | |
| 38 */ | |
| 39 function getFirstElement(iterable) { | |
| 40 const iterator = iterable[Symbol.iterator](); | |
| 41 const result = iterator.next(); | |
| 42 if (result.done) { | |
| 43 throw new Error('getFirstElement was passed an empty iterable.'); | |
| 44 } | |
| 45 | |
| 46 return result.value; | |
| 47 } | |
| 48 | |
| 49 function compareArrays(x, y, elementCmp) { | |
| 50 const minLength = Math.min(x.length, y.length); | |
| 51 let i; | |
| 52 for (i = 0; i < minLength; i++) { | |
| 53 const tmp = elementCmp(x[i], y[i]); | |
| 54 if (tmp) return tmp; | |
| 55 } | |
| 56 if (x.length === y.length) return 0; | |
| 57 | |
| 58 if (x[i] === undefined) return -1; | |
| 59 | |
| 60 return 1; | |
| 61 } | |
| 62 | |
| 63 /** | |
| 64 * Returns a new Map with items grouped by the return value of the | |
| 65 * specified function being called on each item. | |
| 66 * @param {!Array.<!*>} ary The array being iterated through | |
| 67 * @param {!function(!*):!*} callback The mapping function between the array | |
| 68 * value and the map key. | |
| 69 * @param {*=} opt_this | |
| 70 */ | |
| 71 function groupIntoMap(ary, callback, opt_this, opt_arrayConstructor) { | |
| 72 const arrayConstructor = opt_arrayConstructor || Array; | |
| 73 const results = new Map(); | |
| 74 for (const element of ary) { | |
| 75 const key = callback.call(opt_this, element); | |
| 76 let items = results.get(key); | |
| 77 if (items === undefined) { | |
| 78 items = new arrayConstructor(); | |
| 79 results.set(key, items); | |
| 80 } | |
| 81 items.push(element); | |
| 82 } | |
| 83 return results; | |
| 84 } | |
| 85 | |
| 86 function inPlaceFilter(array, predicate, opt_this) { | |
| 87 opt_this = opt_this || this; | |
| 88 let nextPosition = 0; | |
| 89 for (let i = 0; i < array.length; i++) { | |
| 90 if (!predicate.call(opt_this, array[i], i)) continue; | |
| 91 if (nextPosition < i) { | |
| 92 array[nextPosition] = array[i]; // Move elements only if necessary. | |
| 93 } | |
| 94 nextPosition++; | |
| 95 } | |
| 96 | |
| 97 if (nextPosition < array.length) { | |
| 98 array.length = nextPosition; // Truncate the array only if necessary. | |
| 99 } | |
| 100 } | |
| 101 | |
| 102 /** | |
| 103 * Convert an array of dictionaries to a dictionary of arrays. | |
| 104 * | |
| 105 * The keys of the resulting dictionary are a union of the keys of all | |
| 106 * dictionaries in the provided array. Each array in the resulting dictionary | |
| 107 * has the same length as the provided array and contains the values of its | |
| 108 * key in the dictionaries in the provided array. Example: | |
| 109 * | |
| 110 * INPUT: | |
| 111 * | |
| 112 * [ | |
| 113 * {a: 6, b: 5 }, | |
| 114 * undefined, | |
| 115 * {a: 4, b: 3, c: 2}, | |
| 116 * { b: 1, c: 0} | |
| 117 * ] | |
| 118 * | |
| 119 * OUTPUT: | |
| 120 * | |
| 121 * { | |
| 122 * a: [6, undefined, 4, undefined], | |
| 123 * b: [5, undefined, 3, 1 ], | |
| 124 * c: [undefined, undefined, 2, 0 ] | |
| 125 * } | |
| 126 * | |
| 127 * @param {!Array} array Array of items to be inverted. If opt_dictGetter | |
| 128 * is not provided, all elements of the array must be either undefined, | |
| 129 * or dictionaries. | |
| 130 * @param {?(function(*): (!Object|undefined))=} opt_dictGetter Optional | |
| 131 * function mapping defined elements of array to dictionaries. | |
| 132 * @param {*=} opt_this Optional 'this' context for opt_dictGetter. | |
| 133 */ | |
| 134 function invertArrayOfDicts(array, opt_dictGetter, opt_this) { | |
| 135 opt_this = opt_this || this; | |
| 136 const result = {}; | |
| 137 for (let i = 0; i < array.length; i++) { | |
| 138 const item = array[i]; | |
| 139 if (item === undefined) continue; | |
| 140 const dict = opt_dictGetter ? opt_dictGetter.call(opt_this, item) : item; | |
| 141 if (dict === undefined) continue; | |
| 142 for (const key in dict) { | |
| 143 let valueList = result[key]; | |
| 144 if (valueList === undefined) { | |
| 145 result[key] = valueList = new Array(array.length); | |
| 146 } | |
| 147 valueList[i] = dict[key]; | |
| 148 } | |
| 149 } | |
| 150 return result; | |
| 151 } | |
| 152 | |
| 153 function setsEqual(a, b) { | |
| 154 if (!(a instanceof Set) || !(b instanceof Set)) return false; | |
| 155 if (a.size !== b.size) return false; | |
| 156 // Avoid Array.from() here -- it creates garbage. | |
| 157 for (const x of a) { | |
| 158 if (!b.has(x)) return false; | |
| 159 } | |
| 160 return true; | |
| 161 } | |
| 162 | |
| 163 return { | |
| 164 compareArrays, | |
| 165 getOnlyElement, | |
| 166 getFirstElement, | |
| 167 groupIntoMap, | |
| 168 inPlaceFilter, | |
| 169 invertArrayOfDicts, | |
| 170 setsEqual, | |
| 171 }; | |
| 172 }); | |
| 173 </script> | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2995843002:
Merge iteration_helpers into utils.html. (Closed)
