Medplum

// SPDX-FileCopyrightText: Copyright Orangebot, Inc. and Medplum contributors // SPDX-License-Identifier: Apache-2.0 /** * LRU cache (least recently used) * Source: https://stackoverflow.com/a/46432113 */ export class LRUCache<T> { private readonly max: number; private readonly cache: Map<string, T>; constructor(max = 10) { this.max = max; this.cache = new Map(); } /** * Deletes all values from the cache. */ clear(): void { this.cache.clear(); } /** * Returns the value for the given key. * @param key - The key to retrieve. * @returns The value if found; undefined otherwise. */ get(key: string): T | undefined { const item = this.cache.get(key); if (item) { this.cache.delete(key); this.cache.set(key, item); } return item; } /** * Sets the value for the given key. * @param key - The key to set. * @param val - The value to set. */ set(key: string, val: T): void { if (this.cache.has(key)) { this.cache.delete(key); } else if (this.cache.size >= this.max) { this.cache.delete(this.first()); } this.cache.set(key, val); } /** * Deletes the value for the given key. * @param key - The key to delete. */ delete(key: string): void { this.cache.delete(key); } /** * Returns the list of all keys in the cache. * @returns The array of keys in the cache. */ keys(): IterableIterator<string> { return this.cache.keys(); } private first(): string { // This works because the Map class maintains ordered keys. return this.cache.keys().next().value as string; } }