001 // Copyright 2004, 2005 The Apache Software Foundation 002 // 003 // Licensed under the Apache License, Version 2.0 (the "License"); 004 // you may not use this file except in compliance with the License. 005 // You may obtain a copy of the License at 006 // 007 // http://www.apache.org/licenses/LICENSE-2.0 008 // 009 // Unless required by applicable law or agreed to in writing, software 010 // distributed under the License is distributed on an "AS IS" BASIS, 011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012 // See the License for the specific language governing permissions and 013 // limitations under the License. 014 015 package org.apache.tapestry.services.impl; 016 017 import java.util.HashMap; 018 import java.util.Map; 019 020 import ognl.Ognl; 021 022 import org.apache.hivemind.ApplicationRuntimeException; 023 import org.apache.tapestry.event.ResetEventListener; 024 import org.apache.tapestry.services.ExpressionCache; 025 026 /** 027 * @author Howard M. Lewis Ship 028 * @since 4.0 029 */ 030 public class ExpressionCacheImpl implements ExpressionCache, ResetEventListener 031 { 032 public synchronized void resetEventDidOccur() 033 { 034 _cache.clear(); 035 } 036 037 private Map _cache = new HashMap(); 038 039 public synchronized Object getCompiledExpression(String expression) 040 { 041 Object result = _cache.get(expression); 042 043 if (result == null) 044 { 045 result = parse(expression); 046 _cache.put(expression, result); 047 } 048 049 return result; 050 } 051 052 private Object parse(String expression) 053 { 054 try 055 { 056 return Ognl.parseExpression(expression); 057 } 058 catch (Exception ex) 059 { 060 throw new ApplicationRuntimeException(ImplMessages.unableToParseExpression( 061 expression, 062 ex), ex); 063 } 064 } 065 066 }