J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2004 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 = new Double(((Number)evaluate(l)).doubleValue()); |
| 87 | Double rval = new Double(((Number)evaluate(r)).doubleValue()); |
| 88 | double result = op.eval(lval.doubleValue(), rval.doubleValue()); |
| 89 | if (debug) { |
| 90 | System.out.println("Performed Operation: " + lval + op + rval |
| 91 | + " = " + result); |
| 92 | } |
| 93 | return new Double(result); |
| 94 | } |
| 95 | } |
| 96 | } |