| /* |
| * Copyright (c) 2004, 2010, 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; |
| |
| import sun.jvmstat.monitor.*; |
| |
| /** |
| * A class implementing the ExpressionEvaluator to resolve unresolved |
| * symbols in an Expression in the context of the available monitoring data. |
| * This class also performs some minimal optimizations of the expressions, |
| * such as simplification of constant subexpressions. |
| * |
| * @author Brian Doherty |
| * @since 1.5 |
| */ |
| public class ExpressionResolver implements ExpressionEvaluator { |
| private static boolean debug = Boolean.getBoolean("ExpressionResolver.debug"); |
| private MonitoredVm vm; |
| |
| ExpressionResolver(MonitoredVm vm) { |
| this.vm = vm; |
| } |
| |
| /* |
| * evaluate the given expression. evaluation in this case means |
| * to resolve the counter names in the expression |
| */ |
| public Object evaluate(Expression e) throws MonitorException { |
| |
| if (e == null) { |
| return null; |
| } |
| |
| if (debug) { |
| System.out.println("Resolving Expression:" + e); |
| } |
| |
| if (e instanceof Identifier) { |
| Identifier id = (Identifier)e; |
| |
| // check if it's already resolved |
| if (id.isResolved()) { |
| return id; |
| } |
| |
| // look it up |
| Monitor m = vm.findByName(id.getName()); |
| if (m == null) { |
| System.err.println("Warning: Unresolved Symbol: " |
| + id.getName() + " substituted NaN"); |
| return new Literal(Double.valueOf(Double.NaN)); |
| } |
| if (m.getVariability() == Variability.CONSTANT) { |
| if (debug) { |
| System.out.println("Converting constant " + id.getName() |
| + " to literal with value " |
| + m.getValue()); |
| } |
| return new Literal(m.getValue()); |
| } |
| id.setValue(m); |
| return id; |
| } |
| |
| if (e instanceof Literal) { |
| return e; |
| } |
| |
| Expression l = null; |
| Expression r = null; |
| |
| if (e.getLeft() != null) { |
| l = (Expression)evaluate(e.getLeft()); |
| } |
| if (e.getRight() != null) { |
| r = (Expression)evaluate(e.getRight()); |
| } |
| |
| if (l != null && r != null) { |
| if ((l instanceof Literal) && (r instanceof Literal)) { |
| Literal ll = (Literal)l; |
| Literal rl = (Literal)r; |
| boolean warn = false; |
| |
| Double nan = Double.valueOf(Double.NaN); |
| if (ll.getValue() instanceof String) { |
| warn = true; ll.setValue(nan); |
| } |
| if (rl.getValue() instanceof String) { |
| warn = true; rl.setValue(nan); |
| } |
| if (debug && warn) { |
| System.out.println("Warning: String literal in " |
| + "numerical expression: " |
| + "substitutied NaN"); |
| } |
| |
| // perform the operation |
| Number ln = (Number)ll.getValue(); |
| Number rn = (Number)rl.getValue(); |
| double result = e.getOperator().eval(ln.doubleValue(), |
| rn.doubleValue()); |
| if (debug) { |
| System.out.println("Converting expression " + e |
| + " (left = " + ln.doubleValue() + ")" |
| + " (right = " + rn.doubleValue() + ")" |
| + " to literal value " + result); |
| } |
| return new Literal(Double.valueOf(result)); |
| } |
| } |
| |
| if (l != null && r == null) { |
| return l; |
| } |
| |
| e.setLeft(l); |
| e.setRight(r); |
| |
| return e; |
| } |
| } |