1 /* 2 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package sun.tools.jstat; 27 28 /** 29 * A class that represents a mathematical expression as a tree structure 30 * containing operators as interior nodes and operands as leaves. The 31 * operands can be literals or lazily bound variables. 32 * 33 * @author Brian Doherty 34 * @since 1.5 35 */ 36 public class Expression { 37 private static int nextOrdinal; 38 private boolean debug = Boolean.getBoolean("Expression.debug"); 39 private Expression left; 40 private Expression right; 41 private Operator operator; 42 private int ordinal = nextOrdinal++; 43 44 Expression() { 45 if (debug) { 46 System.out.println("Expression " + ordinal + " created"); 47 } 48 } 49 50 void setLeft(Expression left) { 51 if (debug) { 52 System.out.println("Setting left on " + ordinal + " to " + left); 53 } 54 this.left = left; 55 } 56 57 Expression getLeft() { 58 return left; 59 } 60 61 void setRight(Expression right) { 62 if (debug) { 63 System.out.println("Setting right on " + ordinal + " to " + right); 64 } 65 this.right = right; 66 } 67 68 Expression getRight() { 69 return right; 70 } 71 72 void setOperator(Operator o) { 73 if (debug) { 74 System.out.println("Setting operator on " + ordinal + " to " + o); 75 } 76 this.operator = o; 77 } 78 79 Operator getOperator() { 80 return operator; 81 } 82 83 public String toString() { 84 StringBuilder b = new StringBuilder(); 85 b.append('('); 86 if (left != null) { 87 b.append(left.toString()); 88 } 89 if (operator != null) { 90 b.append(operator.toString()); 91 if (right != null) { 92 b.append(right.toString()); 93 } 94 } 95 b.append(')'); 96 return b.toString(); 97 } 98 }