package edu.rice.comp322;

import java.util.function.Supplier;

public class Lazy<T> {

    private T contents;
    private Supplier<T> supplier;

    private Lazy(Supplier<T> supplier) {
        contents = null;
        this.supplier = supplier;
    }

    public static <T> Lazy<T> of(Supplier<T> supplier) {
        return new Lazy(supplier);
    }

    /**
     * Get the value out of the memo. If it's already computed, then just return it.
     * If it's not, then compute it, then return it.
     */
    public T get() {
        if (contents != null) {
            return contents;
        }
        if (supplier != null) {
            contents = supplier.get();
            supplier = null;
        }
        return contents;
    }
}