1 | 'use strict';
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2 |
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3 | const Assert = require('@hapi/hoek/lib/assert');
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4 | const Clone = require('@hapi/hoek/lib/clone');
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5 |
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6 | const Common = require('./common');
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7 |
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8 |
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9 | const internals = {
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10 | max: 1000,
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11 | supported: new Set(['undefined', 'boolean', 'number', 'string'])
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12 | };
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13 |
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14 |
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15 | exports.provider = {
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16 |
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17 | provision(options) {
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18 |
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19 | return new internals.Cache(options);
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20 | }
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21 | };
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22 |
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23 |
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24 |
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25 |
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26 | internals.Cache = class {
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27 |
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28 | constructor(options = {}) {
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29 |
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30 | Common.assertOptions(options, ['max']);
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31 | Assert(options.max === undefined || options.max && options.max > 0 && isFinite(options.max), 'Invalid max cache size');
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32 |
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33 | this._max = options.max || internals.max;
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34 |
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35 | this._map = new Map();
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36 | this._list = new internals.List();
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37 | }
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38 |
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39 | get length() {
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40 |
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41 | return this._map.size;
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42 | }
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43 |
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44 | set(key, value) {
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45 |
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46 | if (key !== null &&
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47 | !internals.supported.has(typeof key)) {
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48 |
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49 | return;
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50 | }
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51 |
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52 | let node = this._map.get(key);
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53 | if (node) {
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54 | node.value = value;
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55 | this._list.first(node);
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56 | return;
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57 | }
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58 |
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59 | node = this._list.unshift({ key, value });
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60 | this._map.set(key, node);
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61 | this._compact();
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62 | }
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63 |
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64 | get(key) {
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65 |
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66 | const node = this._map.get(key);
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67 | if (node) {
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68 | this._list.first(node);
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69 | return Clone(node.value);
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70 | }
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71 | }
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72 |
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73 | _compact() {
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74 |
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75 | if (this._map.size > this._max) {
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76 | const node = this._list.pop();
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77 | this._map.delete(node.key);
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78 | }
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79 | }
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80 | };
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81 |
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82 |
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83 | internals.List = class {
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84 |
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85 | constructor() {
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86 |
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87 | this.tail = null;
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88 | this.head = null;
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89 | }
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90 |
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91 | unshift(node) {
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92 |
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93 | node.next = null;
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94 | node.prev = this.head;
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95 |
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96 | if (this.head) {
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97 | this.head.next = node;
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98 | }
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99 |
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100 | this.head = node;
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101 |
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102 | if (!this.tail) {
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103 | this.tail = node;
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104 | }
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105 |
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106 | return node;
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107 | }
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108 |
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109 | first(node) {
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110 |
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111 | if (node === this.head) {
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112 | return;
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113 | }
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114 |
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115 | this._remove(node);
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116 | this.unshift(node);
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117 | }
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118 |
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119 | pop() {
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120 |
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121 | return this._remove(this.tail);
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122 | }
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123 |
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124 | _remove(node) {
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125 |
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126 | const { next, prev } = node;
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127 |
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128 | next.prev = prev;
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129 |
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130 | if (prev) {
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131 | prev.next = next;
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132 | }
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133 |
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134 | if (node === this.tail) {
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135 | this.tail = next;
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136 | }
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137 |
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138 | node.prev = null;
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139 | node.next = null;
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140 |
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141 | return node;
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142 | }
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143 | };
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