source: trip-planner-front/node_modules/webpack/lib/util/StackedMap.js@ 1ad8e64

Last change on this file since 1ad8e64 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

initial commit

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1/*
2 MIT License http://www.opensource.org/licenses/mit-license.php
3 Author Tobias Koppers @sokra
4*/
5
6"use strict";
7
8const TOMBSTONE = Symbol("tombstone");
9const UNDEFINED_MARKER = Symbol("undefined");
10
11/**
12 * @template T
13 * @typedef {T | undefined} Cell<T>
14 */
15
16/**
17 * @template T
18 * @typedef {T | typeof TOMBSTONE | typeof UNDEFINED_MARKER} InternalCell<T>
19 */
20
21/**
22 * @template K
23 * @template V
24 * @param {[K, InternalCell<V>]} pair the internal cell
25 * @returns {[K, Cell<V>]} its “safe” representation
26 */
27const extractPair = pair => {
28 const key = pair[0];
29 const val = pair[1];
30 if (val === UNDEFINED_MARKER || val === TOMBSTONE) {
31 return [key, undefined];
32 } else {
33 return /** @type {[K, Cell<V>]} */ (pair);
34 }
35};
36
37/**
38 * @template K
39 * @template V
40 */
41class StackedMap {
42 /**
43 * @param {Map<K, InternalCell<V>>[]=} parentStack an optional parent
44 */
45 constructor(parentStack) {
46 /** @type {Map<K, InternalCell<V>>} */
47 this.map = new Map();
48 /** @type {Map<K, InternalCell<V>>[]} */
49 this.stack = parentStack === undefined ? [] : parentStack.slice();
50 this.stack.push(this.map);
51 }
52
53 /**
54 * @param {K} item the key of the element to add
55 * @param {V} value the value of the element to add
56 * @returns {void}
57 */
58 set(item, value) {
59 this.map.set(item, value === undefined ? UNDEFINED_MARKER : value);
60 }
61
62 /**
63 * @param {K} item the item to delete
64 * @returns {void}
65 */
66 delete(item) {
67 if (this.stack.length > 1) {
68 this.map.set(item, TOMBSTONE);
69 } else {
70 this.map.delete(item);
71 }
72 }
73
74 /**
75 * @param {K} item the item to test
76 * @returns {boolean} true if the item exists in this set
77 */
78 has(item) {
79 const topValue = this.map.get(item);
80 if (topValue !== undefined) {
81 return topValue !== TOMBSTONE;
82 }
83 if (this.stack.length > 1) {
84 for (let i = this.stack.length - 2; i >= 0; i--) {
85 const value = this.stack[i].get(item);
86 if (value !== undefined) {
87 this.map.set(item, value);
88 return value !== TOMBSTONE;
89 }
90 }
91 this.map.set(item, TOMBSTONE);
92 }
93 return false;
94 }
95
96 /**
97 * @param {K} item the key of the element to return
98 * @returns {Cell<V>} the value of the element
99 */
100 get(item) {
101 const topValue = this.map.get(item);
102 if (topValue !== undefined) {
103 return topValue === TOMBSTONE || topValue === UNDEFINED_MARKER
104 ? undefined
105 : topValue;
106 }
107 if (this.stack.length > 1) {
108 for (let i = this.stack.length - 2; i >= 0; i--) {
109 const value = this.stack[i].get(item);
110 if (value !== undefined) {
111 this.map.set(item, value);
112 return value === TOMBSTONE || value === UNDEFINED_MARKER
113 ? undefined
114 : value;
115 }
116 }
117 this.map.set(item, TOMBSTONE);
118 }
119 return undefined;
120 }
121
122 _compress() {
123 if (this.stack.length === 1) return;
124 this.map = new Map();
125 for (const data of this.stack) {
126 for (const pair of data) {
127 if (pair[1] === TOMBSTONE) {
128 this.map.delete(pair[0]);
129 } else {
130 this.map.set(pair[0], pair[1]);
131 }
132 }
133 }
134 this.stack = [this.map];
135 }
136
137 asArray() {
138 this._compress();
139 return Array.from(this.map.keys());
140 }
141
142 asSet() {
143 this._compress();
144 return new Set(this.map.keys());
145 }
146
147 asPairArray() {
148 this._compress();
149 return Array.from(this.map.entries(), extractPair);
150 }
151
152 asMap() {
153 return new Map(this.asPairArray());
154 }
155
156 get size() {
157 this._compress();
158 return this.map.size;
159 }
160
161 createChild() {
162 return new StackedMap(this.stack);
163 }
164}
165
166module.exports = StackedMap;
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