tiny-lru.cjs.js

'use strict';

class LRU {
    constructor(max = 0, ttl = 0) {
        this.first = null;
        this.items = {};
        this.last = null;
        this.max = max;
        this.size = 0;
        this.ttl = ttl;
    }
    has(key) {
        return key in this.items;
    }
    clear() {
        this.first = null;
        this.items = {};
        this.last = null;
        this.size = 0;
        return this;
    }
    delete(key) {
        if (this.has(key)) {
            const item = this.items[key];
            delete this.items[key];
            this.size--;
            if (item.prev !== null) {
                item.prev.next = item.next;
            }
            if (item.next !== null) {
                item.next.prev = item.prev;
            }
            if (this.first === item) {
                this.first = item.next;
            }
            if (this.last === item) {
                this.last = item.prev;
            }
        }
        return this;
    }
    evict() {
        const item = this.first;
        delete this.items[item.key];
        this.first = item.next;
        this.first.prev = null;
        this.size--;
        return this;
    }
    get(key) {
        let result;
        if (this.has(key)) {
            const item = this.items[key];
            if (this.ttl > 0 && item.expiry <= new Date().getTime()) {
                this.delete(key);
            }
            else {
                result = item.value;
                this.set(key, result, true);
            }
        }
        return result;
    }
    keys() {
        return Object.keys(this.items);
    }
    set(key, value, bypass = false) {
        let item;
        if (bypass || this.has(key)) {
            item = this.items[key];
            item.value = value;
            if (this.last !== item) {
                const last = this.last, next = item.next, prev = item.prev;
                if (this.first === item) {
                    this.first = item.next;
                }
                item.next = null;
                item.prev = this.last;
                last.next = item;
                if (prev !== null) {
                    prev.next = next;
                }
                if (next !== null) {
                    next.prev = prev;
                }
            }
        }
        else {
            if (this.max > 0 && this.size === this.max) {
                this.evict();
            }
            item = this.items[key] = {
                expiry: this.ttl > 0 ? new Date().getTime() + this.ttl : this.ttl,
                key: key,
                prev: this.last,
                next: null,
                value
            };
            if (++this.size === 1) {
                this.first = item;
            }
            else {
                this.last.next = item;
            }
        }
        this.last = item;
        return this;
    }
}
function factory(max = 1000, ttl = 0) {
    if (isNaN(max) || max < 0) {
        throw new TypeError("Invalid max value");
    }
    if (isNaN(ttl) || ttl < 0) {
        throw new TypeError("Invalid ttl value");
    }
    return new LRU(max, ttl);
}

module.exports = factory;