/*

 * Copyright 2004 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.tools.jstat;

/**

 * A class that represents a mathematical expression as a tree structure

 * containing operators as interior nodes and operands as leaves. The

 * operands can be literals or lazily bound variables.

 *

 * @author Brian Doherty

 * @since 1.5

 */

public class Expression {

    private static int nextOrdinal;

    private boolean debug = Boolean.getBoolean("Expression.debug");

    private Expression left;

    private Expression right;

    private Operator operator;

    private int ordinal = nextOrdinal++;

    Expression() {

        if (debug) {

            System.out.println("Expression " + ordinal + " created");

        }

    }

    void setLeft(Expression left) {

        if (debug) {

            System.out.println("Setting left on " + ordinal + " to " + left);

        }

        this.left = left;

    }

    Expression getLeft() {

        return left;

    }

    void setRight(Expression right) {

        if (debug) {

            System.out.println("Setting right on " + ordinal + " to " + right);

        }

        this.right = right;

    }

    Expression getRight() {

        return right;

    }

    void setOperator(Operator o) {

        if (debug) {

            System.out.println("Setting operator on " + ordinal + " to " + o);

        }

        this.operator = o;

    }

    Operator getOperator() {

        return operator;

    }

    public String toString() {

        StringBuilder b = new StringBuilder();

        b.append('(');

        if (left != null) {

            b.append(left.toString());

        }

        if (operator != null) {

            b.append(operator.toString());

            if (right != null) {

                b.append(right.toString());

            }

        }

        b.append(')');

        return b.toString();

    }

}