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 net.multiphasicapps.io;

import cc.squirreljme.runtime.cldc.debug.Debugging;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;

/**
 * Represents a future section.
 *
 * @since 2020/12/04
 */
public class ChunkFutureSection
    implements ChunkFuture
{
    /** The kind of section this is. */
    protected final ChunkFutureSectionKind kind;
    
    /** The section this refers to. */
    protected final Reference<ChunkSection> section;
    
    /** The offset for the section. */
    protected final int offset;
    
    /**
     * Initializes a future section reference.
     * 
     * @param __kind The kind of value to use.
     * @param __section The section to reference.
     * @param __off The offset to use.
     * @throws NullPointerException On null arguments.
     * @since 2020/12/04
     */
    public ChunkFutureSection(ChunkFutureSectionKind __kind,
        ChunkSection __section, int __off)
        throws NullPointerException
    {
        if (__kind == null || __section == null)
            throw new NullPointerException("NARG");
        
        this.kind = __kind;
        this.section = new WeakReference<>(__section);
        this.offset = __off;
    }
    
    /**
     * {@inheritDoc}
     * @since 2020/12/04
     */
    @Override
    public int get()
    {
        /* {@squirreljme.error BD07 Section was garbage collected.} */
        ChunkSection section = this.section.get();
        if (section == null)
            throw new IllegalStateException("BD07");
        
        switch (this.kind)
        {
            case ADDRESS:
                return section._writeAddr + this.offset;
            
            case SIZE:
                return section._writeSize + this.offset;
            
            default:
                throw Debugging.oops();
        }
    }
}