/**
 * Singleton generator.
 *
 * @author Jeongho Nam - https://github.com/samchon
 */
export class Singleton<T, Args extends any[] = []> {
    private readonly closure_: (...args: Args) => T;
    private value_: T | object;

    public constructor(closure: (...args: Args) => T) {
        this.closure_ = closure;
        this.value_ = NOT_MOUNTED_YET;
    }

    public get(...args: Args): T {
        if (this.value_ === NOT_MOUNTED_YET)
            this.value_ = this.closure_(...args);
        return this.value_ as T;
    }
}

const NOT_MOUNTED_YET = {};