@croct/cache/lruCache.js

An abstraction layer for caching.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.LruCache = void 0;
/**
 * In-memory Least Recently Used (LRU) cache.
 */
class LruCache {
    constructor(capacity) {
        this.cache = new Map();
        this.capacity = capacity;
    }
    /**
     * Initializes a new instance with the given capacity.
     *
     * @param {number} capacity The maximum number of entries in the cache. Must be a
     *      positive safe integer.
     */
    static ofCapacity(capacity) {
        if (!Number.isSafeInteger(capacity) || capacity < 1) {
            throw new Error('LRU capacity must be a positive safe integer.');
        }
        return new this(capacity);
    }
    get(key, loader) {
        if (!this.cache.has(key)) {
            return loader(key);
        }
        const value = this.cache.get(key);
        // Reposition the key as the most recently used value
        this.cache.delete(key);
        this.cache.set(key, value);
        return Promise.resolve(value);
    }
    set(key, value) {
        this.cache.set(key, value);
        this.prune();
        return Promise.resolve();
    }
    delete(key) {
        this.cache.delete(key);
        return Promise.resolve();
    }
    prune() {
        while (this.cache.size > this.capacity) {
            const leastRecentlyUsedKey = this.cache
                .keys()
                .next();
            this.cache.delete(leastRecentlyUsedKey.value);
        }
    }
}
exports.LruCache = LruCache;