SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// Multi-Phasic Applications: 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 cc.squirreljme.runtime.cldc.util;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.util.ListIterator;

/**
 * Wraps a {@link ListIterator} of references, will throw
 * {@link IllegalStateException} if any elements were garbage collected.
 *
 * @param <T> The type to use.
 * @since 2022/08/27
 */
public final class ReferenceListIterator<T>
    implements ListIterator<T>
{
    /** The iterator used. */
    protected final ListIterator<Reference<T>> iterator;
    
    /**
     * Initializes the iterator wrapper.
     * 
     * @param __iterator The iterator.
     * @throws NullPointerException On null arguments.
     * @since 2022/08/27
     */
    public ReferenceListIterator(ListIterator<Reference<T>> __iterator)
        throws NullPointerException
    {
        if (__iterator == null)
            throw new NullPointerException("NARG");
        
        this.iterator = __iterator;
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @SuppressWarnings("unchecked")
    @Override
    public void add(T __v)
    {
        ListIterator<Reference<T>> iterator = this.iterator;
        
        if (__v == null)
            iterator.add(null);
        else if (__v instanceof Reference)
            iterator.add((Reference<T>)__v);
        else
            iterator.add(new WeakReference<T>(__v));
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public boolean hasNext()
    {
        return this.iterator.hasNext();
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public boolean hasPrevious()
    {
        return this.iterator.hasPrevious();
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public T next()
    {
        Reference<T> ref = this.iterator.next();
        
        if (ref == null)
            return null;
        
        T rv = ref.get();
        if (rv == null)
            throw new IllegalStateException("GCGC");
        
        return rv;
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public int nextIndex()
    {
        return this.iterator.nextIndex();
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public T previous()
    {
        Reference<T> ref = this.iterator.previous();
        
        if (ref == null)
            return null;
        
        T rv = ref.get();
        if (rv == null)
            throw new IllegalStateException("GCGC");
        
        return rv;
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public int previousIndex()
    {
        return this.iterator.previousIndex();
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @Override
    public void remove()
    {
        this.iterator.remove();
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/08/27
     */
    @SuppressWarnings("unchecked")
    @Override
    public void set(T __v)
    {
        ListIterator<Reference<T>> iterator = this.iterator;
        
        if (__v == null)
            iterator.set(null);
        else if (__v instanceof Reference)
            iterator.set((Reference<T>)__v);
        else
            iterator.set(new WeakReference<T>(__v));
    }
}