booklet

const cache = new Map()
let last_key = 1

export function make(default_value) {
    const key = last_key++;
    if (key >= Number.MAX_SAFE_INTEGER) {
        throw new globalThis.Error("booklet: system limit reached.")
    }

    cache.set(key, default_value)
    return key
}

export function get(key) {
    return cache.get(key)
}

export function update(key, updater) {
    const new_value = updater(cache.get(key));
    cache.set(key, new_value);
    return new_value;
}