com.jfreeman.lazy.QuadThunk Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of lazy Show documentation

A library for type-safe, tractable lazy evaluation and late binding in Java.

There is a newer version: 0.6.0

package com.jfreeman.lazy;

import com.google.common.collect.ImmutableList;

import com.jfreeman.function.QuadFunction;

/**
 * A lazy value with four dependencies.
 *
 * @param  the type of the value
 * @param  the type of the first dependency
 * @param  the type of the second dependency
 * @param  the type of the third dependency
 * @param  the type of the fourth dependency
 * @author jfreeman
 */
public final class QuadThunk
    extends AbstractThunk
{
    private Lazy _depA;
    private Lazy _depB;
    private Lazy _depC;
    private Lazy _depD;
    private QuadFunction _func;

    private QuadThunk(
        Lazy a, Lazy b, Lazy c, Lazy d,
        QuadFunction func)
    {
        _depA = a;
        _depB = b;
        _depC = c;
        _depD = d;
        _func = func;
    }

    public static  QuadThunk of(
        Lazy a, Lazy b, Lazy c, Lazy d,
        QuadFunction func)
    {
        return new QuadThunk<>(a, b, c, d, func);
    }

    @Override
    public boolean isForced() {
        return _func == null;
    }

    @Override
    public Iterable> getDependencies()
        throws IllegalStateException
    {
        if (isForced()) {
            throw new IllegalStateException("already forced");
        }
        return ImmutableList.of(_depA, _depB, _depC, _depD);
    }

    @Override
    public T force()
        throws IllegalStateException
    {
        if (isForced()) {
            throw new IllegalStateException("already forced");
        }
        final A a = _depA.getValue();
        final B b = _depB.getValue();
        final C c = _depC.getValue();
        final D d = _depD.getValue();
        _value = _func.apply(a, b, c, d);
        _func = null;
        _depA = null;
        _depB = null;
        _depC = null;
        _depD = null;
        return _value;
    }
}