You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

124 lines
2.0 KiB

2 years ago
'use strict';
class QuickLRU {
constructor(options = {}) {
if (!(options.maxSize && options.maxSize > 0)) {
throw new TypeError('`maxSize` must be a number greater than 0');
}
this.maxSize = options.maxSize;
this.onEviction = options.onEviction;
this.cache = new Map();
this.oldCache = new Map();
this._size = 0;
}
_set(key, value) {
this.cache.set(key, value);
this._size++;
if (this._size >= this.maxSize) {
this._size = 0;
if (typeof this.onEviction === 'function') {
for (const [key, value] of this.oldCache.entries()) {
this.onEviction(key, value);
}
}
this.oldCache = this.cache;
this.cache = new Map();
}
}
get(key) {
if (this.cache.has(key)) {
return this.cache.get(key);
}
if (this.oldCache.has(key)) {
const value = this.oldCache.get(key);
this.oldCache.delete(key);
this._set(key, value);
return value;
}
}
set(key, value) {
if (this.cache.has(key)) {
this.cache.set(key, value);
} else {
this._set(key, value);
}
return this;
}
has(key) {
return this.cache.has(key) || this.oldCache.has(key);
}
peek(key) {
if (this.cache.has(key)) {
return this.cache.get(key);
}
if (this.oldCache.has(key)) {
return this.oldCache.get(key);
}
}
delete(key) {
const deleted = this.cache.delete(key);
if (deleted) {
this._size--;
}
return this.oldCache.delete(key) || deleted;
}
clear() {
this.cache.clear();
this.oldCache.clear();
this._size = 0;
}
* keys() {
for (const [key] of this) {
yield key;
}
}
* values() {
for (const [, value] of this) {
yield value;
}
}
* [Symbol.iterator]() {
for (const item of this.cache) {
yield item;
}
for (const item of this.oldCache) {
const [key] = item;
if (!this.cache.has(key)) {
yield item;
}
}
}
get size() {
let oldCacheSize = 0;
for (const key of this.oldCache.keys()) {
if (!this.cache.has(key)) {
oldCacheSize++;
}
}
return Math.min(this._size + oldCacheSize, this.maxSize);
}
}
module.exports = QuickLRU;