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 cc.squirreljme.emulator.terminal;

import cc.squirreljme.emulator.MLECallWouldFail;
import java.io.IOException;
import net.multiphasicapps.io.ByteDeque;

/**
 * This is a terminal pipe which manages its own buffer for output, it is
 * used for the output of sub-tasks to be allowed to be read by another task.
 *
 * @since 2020/07/06
 */
public final class BufferTerminalPipe
    implements TerminalPipe
{
    /** The backing double-ended byte queue for buffer data. */
    protected final ByteDeque deque =
        new ByteDeque();
    
    /** Has this been closed? */
    private boolean _closed;
    
    /**
     * {@inheritDoc}
     * @since 2020/07/06
     */
    @Override
    public final void close()
    {
        synchronized (this)
        {
            // Mark as closed
            this._closed = true;
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2020/07/06
     */
    @Override
    public final void flush()
        throws IOException
    {
        synchronized (this)
        {
            if (this._closed)
                throw new IOException("Cannot flush closed buffer pipe.");
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2020/07/06
     */
    @Override
    public final int read(byte[] __b, int __o, int __l)
        throws MLECallWouldFail
    {
        if (__b == null || __o < 0 || __l < 0 || (__o + __l) > __b.length)
            throw new MLECallWouldFail("Null or out of bounds argument.");
        
        synchronized (this)
        {
            int rv = this.deque.removeFirst(__b, __o, __l);
            
            // Check if a full end of file has been reached
            if (rv == 0 && this._closed && this.deque.isEmpty())
                return -1;
            return rv;
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2020/07/06
     */
    @Override
    public final void write(int __b)
        throws IOException
    {
        synchronized (this)
        {
            if (this._closed)
                throw new IOException("Cannot write to closed buffer pipe.");
            
            this.deque.addLast((byte)__b);
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2020/07/06
     */
    @Override
    public final void write(byte[] __b, int __o, int __l)
        throws IOException, MLECallWouldFail
    {
        if (__b == null || __o < 0 || __l < 0 || (__o + __l) > __b.length)
            throw new MLECallWouldFail("Null or out of bounds argument.");
        
        synchronized (this)
        {
            if (this._closed)
                throw new IOException("Cannot write to closed buffer pipe.");
                
            this.deque.addLast(__b, __o, __l);
        }
    }
}