/*
 * This file is part of the Javassist toolkit.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License.  You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Javassist.
 *
 * The Initial Developer of the Original Code is Shigeru Chiba.  Portions
 * created by Shigeru Chiba are Copyright (C) 1999-2003 Shigeru Chiba.
 * All Rights Reserved.
 *
 * Contributor(s):
 *
 * The development of this software is supported in part by the PRESTO
 * program (Sakigake Kenkyu 21) of Japan Science and Technology Corporation.
 */

package javassist.compiler.ast;

import java.io.Serializable;
import javassist.compiler.CompileError;

/**
 * Abstract Syntax Tree.  An ASTree object represents a node of
 * a binary tree.  If the node is a leaf node, both <code>getLeft()</code>
 * and <code>getRight()</code> returns null.
 */
public abstract class ASTree implements Serializable {
    public ASTree getLeft() { return null; }

    public ASTree getRight() { return null; }

    public void setLeft(ASTree _left) {}

    public void setRight(ASTree _right) {}

    /**
     * Is a method for the visitor pattern.  It calls
     * <code>atXXX()</code> on the given visitor, where
     * <code>XXX</code> is the class name of the node object.
     */
    public abstract void accept(Visitor v) throws CompileError;

    public String toString() {
	StringBuffer sbuf = new StringBuffer();
	sbuf.append('<');
	sbuf.append(getTag());
	sbuf.append('>');
	return sbuf.toString();
    }

    /**
     * Returns the type of this node.  This method is used by
     * <code>toString()</code>.
     */
    protected String getTag() {
	String name = getClass().getName();
	return name.substring(name.lastIndexOf('.') + 1);
    }
}