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| 1 | +/* | |
| 2 | + * Copyright (c) 2004, 2010, 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 sun.jvmstat.monitor.*; | |
| 29 | + | |
| 30 | +/** | |
| 31 | + * A class implementing the ExpressionEvaluator to resolve unresolved | |
| 32 | + * symbols in an Expression in the context of the available monitoring data. | |
| 33 | + * This class also performs some minimal optimizations of the expressions, | |
| 34 | + * such as simplification of constant subexpressions. | |
| 35 | + * | |
| 36 | + * @author Brian Doherty | |
| 37 | + * @since 1.5 | |
| 38 | + */ | |
| 39 | +public class ExpressionResolver implements ExpressionEvaluator { | |
| 40 | + private static boolean debug = Boolean.getBoolean("ExpressionResolver.debug"); | |
| 41 | + private MonitoredVm vm; | |
| 42 | + | |
| 43 | + ExpressionResolver(MonitoredVm vm) { | |
| 44 | + this.vm = vm; | |
| 45 | + } | |
| 46 | + | |
| 47 | + /* | |
| 48 | + * evaluate the given expression. evaluation in this case means | |
| 49 | + * to resolve the counter names in the expression | |
| 50 | + */ | |
| 51 | + public Object evaluate(Expression e) throws MonitorException { | |
| 52 | + | |
| 53 | + if (e == null) { | |
| 54 | + return null; | |
| 55 | + } | |
| 56 | + | |
| 57 | + if (debug) { | |
| 58 | + System.out.println("Resolving Expression:" + e); | |
| 59 | + } | |
| 60 | + | |
| 61 | + if (e instanceof Identifier) { | |
| 62 | + Identifier id = (Identifier)e; | |
| 63 | + | |
| 64 | + // check if it's already resolved | |
| 65 | + if (id.isResolved()) { | |
| 66 | + return id; | |
| 67 | + } | |
| 68 | + | |
| 69 | + // look it up | |
| 70 | + Monitor m = vm.findByName(id.getName()); | |
| 71 | + if (m == null) { | |
| 72 | + System.err.println("Warning: Unresolved Symbol: " | |
| 73 | + + id.getName() + " substituted NaN"); | |
| 74 | + return new Literal(new Double(Double.NaN)); | |
| 75 | + } | |
| 76 | + if (m.getVariability() == Variability.CONSTANT) { | |
| 77 | + if (debug) { | |
| 78 | + System.out.println("Converting constant " + id.getName() | |
| 79 | + + " to literal with value " | |
| 80 | + + m.getValue()); | |
| 81 | + } | |
| 82 | + return new Literal(m.getValue()); | |
| 83 | + } | |
| 84 | + id.setValue(m); | |
| 85 | + return id; | |
| 86 | + } | |
| 87 | + | |
| 88 | + if (e instanceof Literal) { | |
| 89 | + return e; | |
| 90 | + } | |
| 91 | + | |
| 92 | + Expression l = null; | |
| 93 | + Expression r = null; | |
| 94 | + | |
| 95 | + if (e.getLeft() != null) { | |
| 96 | + l = (Expression)evaluate(e.getLeft()); | |
| 97 | + } | |
| 98 | + if (e.getRight() != null) { | |
| 99 | + r = (Expression)evaluate(e.getRight()); | |
| 100 | + } | |
| 101 | + | |
| 102 | + if (l != null && r != null) { | |
| 103 | + if ((l instanceof Literal) && (r instanceof Literal)) { | |
| 104 | + Literal ll = (Literal)l; | |
| 105 | + Literal rl = (Literal)r; | |
| 106 | + boolean warn = false; | |
| 107 | + | |
| 108 | + Double nan = new Double(Double.NaN); | |
| 109 | + if (ll.getValue() instanceof String) { | |
| 110 | + warn = true; ll.setValue(nan); | |
| 111 | + } | |
| 112 | + if (rl.getValue() instanceof String) { | |
| 113 | + warn = true; rl.setValue(nan); | |
| 114 | + } | |
| 115 | + if (debug && warn) { | |
| 116 | + System.out.println("Warning: String literal in " | |
| 117 | + + "numerical expression: " | |
| 118 | + + "substitutied NaN"); | |
| 119 | + } | |
| 120 | + | |
| 121 | + // perform the operation | |
| 122 | + Number ln = (Number)ll.getValue(); | |
| 123 | + Number rn = (Number)rl.getValue(); | |
| 124 | + double result = e.getOperator().eval(ln.doubleValue(), | |
| 125 | + rn.doubleValue()); | |
| 126 | + if (debug) { | |
| 127 | + System.out.println("Converting expression " + e | |
| 128 | + + " (left = " + ln.doubleValue() + ")" | |
| 129 | + + " (right = " + rn.doubleValue() + ")" | |
| 130 | + + " to literal value " + result); | |
| 131 | + } | |
| 132 | + return new Literal(new Double(result)); | |
| 133 | + } | |
| 134 | + } | |
| 135 | + | |
| 136 | + if (l != null && r == null) { | |
| 137 | + return l; | |
| 138 | + } | |
| 139 | + | |
| 140 | + e.setLeft(l); | |
| 141 | + e.setRight(r); | |
| 142 | + | |
| 143 | + return e; | |
| 144 | + } | |
| 145 | +} | |