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.engine;
016    
017    import java.util.HashMap;
018    import java.util.Map;
019    
020    import org.apache.hivemind.ApplicationRuntimeException;
021    import org.apache.hivemind.ClassResolver;
022    import org.apache.hivemind.Resource;
023    import org.apache.tapestry.IScript;
024    import org.apache.tapestry.Tapestry;
025    import org.apache.tapestry.coerce.ValueConverter;
026    import org.apache.tapestry.event.ResetEventListener;
027    import org.apache.tapestry.script.ScriptParser;
028    import org.apache.tapestry.services.ExpressionEvaluator;
029    import org.apache.tapestry.util.xml.DocumentParseException;
030    
031    /**
032     * Provides basic access to scripts available on the classpath. Scripts are cached in memory once
033     * parsed.
034     * 
035     * @author Howard Lewis Ship
036     * @since 1.0.2
037     */
038    
039    public class DefaultScriptSource implements IScriptSource, ResetEventListener
040    {
041        private ClassResolver _classResolver;
042    
043        /** @since 4.0 */
044        private ExpressionEvaluator _expressionEvaluator;
045    
046        /** @since 4.0 */
047        private ValueConverter _valueConverter;
048    
049        private Map _cache = new HashMap();
050    
051        public synchronized void resetEventDidOccur()
052        {
053            _cache.clear();
054        }
055    
056        public synchronized IScript getScript(Resource resource)
057        {
058            IScript result = (IScript) _cache.get(resource);
059    
060            if (result != null)
061                return result;
062    
063            result = parse(resource);
064    
065            _cache.put(resource, result);
066    
067            return result;
068        }
069    
070        private IScript parse(Resource resource)
071        {
072            ScriptParser parser = new ScriptParser(_classResolver, _expressionEvaluator,
073                    _valueConverter);
074    
075            try
076            {
077                return parser.parse(resource);
078            }
079            catch (DocumentParseException ex)
080            {
081                throw new ApplicationRuntimeException(Tapestry.format(
082                        "DefaultScriptSource.unable-to-parse-script",
083                        resource), ex);
084            }
085        }
086    
087        public void setClassResolver(ClassResolver classResolver)
088        {
089            _classResolver = classResolver;
090        }
091    
092        /** @since 4.0 */
093        public void setExpressionEvaluator(ExpressionEvaluator expressionEvaluator)
094        {
095            _expressionEvaluator = expressionEvaluator;
096        }
097    
098        /** @since 4.0 */
099        public void setValueConverter(ValueConverter valueConverter)
100        {
101            _valueConverter = valueConverter;
102        }
103    }