org.armedbear.lisp.SpecialBinding Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of abcl Show documentation
Common Lisp implementation running on the JVM
There is a newer version: 1.9.2
/*
 * SpecialBinding.java
 *
 * Copyright (C) 2002-2008 Peter Graves
 * $Id$
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */

package org.armedbear.lisp;

final public class SpecialBinding
{
    /** The index in the specials array of the symbol
     *  to which this value belongs.
     */
    final int idx;

    /** The value bound */
    public LispObject value;

    SpecialBinding(int idx, LispObject value)
    {
        this.idx = idx;
        this.value = value;
    }

    /** Return the value of the binding,
     * checking a valid binding.
     *
     * If the binding is invalid, an unbound variable error
     * is raised.
     */
    final public LispObject getValue()
    {
        if (value == null)
            // return or not: error doesn't return anyway
            Lisp.error(new UnboundVariable(LispThread.specialNames.get(new Integer(idx)).get()));

        return value;
    }

    /** Sets the value of the binding.
     *
     * Note: this method can only be called when the
     *    binding is the one which is currently visible.
     */
    final public void setValue(LispObject value)
    {
        this.value = value;
    }
}