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 import java.util.*; 29 import sun.jvmstat.monitor.*; 30 31 /** 32 * A class implementing the ExpressionEvaluator to evaluate an expression 33 * in the context of the available monitoring data. 34 * 35 * @author Brian Doherty 36 * @since 1.5 37 */ 38 public class ExpressionExecuter implements ExpressionEvaluator { 39 private static final boolean debug = 40 Boolean.getBoolean("ExpressionEvaluator.debug"); 41 private MonitoredVm vm; 42 private HashMap<String, Object> map = new HashMap<String, Object>(); 43 44 ExpressionExecuter(MonitoredVm vm) { 45 this.vm = vm; 46 } 47 48 /* 49 * evaluate the given expression. 50 */ 51 public Object evaluate(Expression e) { 52 if (e == null) { 53 return null; 54 } 55 56 if (debug) { 57 System.out.println("Evaluating expression: " + e); 58 } 59 60 if (e instanceof Literal) { 61 return ((Literal)e).getValue(); 62 } 63 64 if (e instanceof Identifier) { 65 Identifier id = (Identifier)e; 66 if (map.containsKey(id.getName())) { 67 return map.get(id.getName()); 68 } else { 69 // cache the data values for coherency of the values over 70 // the life of this expression executer. 71 Monitor m = (Monitor)id.getValue(); 72 Object v = m.getValue(); 73 map.put(id.getName(), v); 74 return v; 75 } 76 } 77 78 Expression l = e.getLeft(); 79 Expression r = e.getRight(); 80 81 Operator op = e.getOperator(); 82 83 if (op == null) { 84 return evaluate(l); 85 } else { 86 double lval = ((Number)evaluate(l)).doubleValue(); 87 double rval = ((Number)evaluate(r)).doubleValue(); 88 double result = op.eval(lval, rval); 89 if (debug) { 90 System.out.println("Performed Operation: " + lval + op + rval 91 + " = " + result); 92 } 93 return Double.valueOf(result); 94 } 95 } 96 }