SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package net.multiphasicapps.squirrelquarrel.units;

import cc.squirreljme.runtime.cldc.debug.Debugging;

/**
 * This is a reference which points to a unit, it is used to allow units to
 * refer to other units and having it where they can be referenced without
 * needing to handle unit removal themselves. Since units would be garbage
 * collected, it would be unspecified using references when units actually
 * go away.
 *
 * @since 2018/03/19
 */
public final class UnitReference
{
    /** The unit ID. */
    protected final int id;
    
    /** The referring unit. */
    private volatile Unit _unit;
    
    /**
     * Initializes the reference to the given unit.
     *
     * @param __u The unit to link to.
     * @throws NullPointerException On null arguments.
     * @since 2018/03/19
     */
    public UnitReference(Unit __u)
        throws NullPointerException
    {
        if (__u == null)
            throw new NullPointerException("NARG");
        
        this.id = __u.id();
        this._unit = __u;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/03/19
     */
    @Override
    public final boolean equals(Object __o)
    {
        if (this == __o)
            return true;
        
        if (!(__o instanceof UnitReference))
            return false;
        
        return this.id == ((UnitReference)__o).id;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/03/19
     */
    @Override
    public final int hashCode()
    {
        return this.id;
    }
    
    /**
     * Returns the unit this is a reference to or {@code null} if it has been
     * deleted/killed.
     *
     * @return The unit this points to or {@code null} if it has been
     * deleted/killed.
     * @since 2018/03/19
     */
    public final Unit get()
    {
        throw Debugging.todo();
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/03/19
     */
    @Override
    public final String toString()
    {
        throw Debugging.todo();
    }
}