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/* * Copyright (c) 2004, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.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();    }}