package org.codehaus.plexus.util.introspection;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 import java.lang.reflect.Method;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.StringTokenizer;

 import org.codehaus.plexus.util.StringUtils;

 /**

  * Using simple dotted expressions extract the values from a MavenProject

  * instance, For example we might want to extract a value like:

  * project.build.sourceDirectory

  *

  * @author <a href="mailto:jason@maven.org">Jason van Zyl </a>

  * @version $Id: ReflectionValueExtractor.java 591654 2007-11-03 17:14:56Z dennisl $

  */

 public class ReflectionValueExtractor

 {

     private static Class[] args = new Class[ 0 ];

     private static Object[] params = new Object[ 0 ];

     private static ClassMap classMap;

     private static Map classMaps = new HashMap();

     private ReflectionValueExtractor()

     {

     }

     public static Object evaluate( String expression, Object root )

         throws Exception

     {

         return evaluate( expression, root, true );

     }

     // TODO: don't throw Exception

     public static Object evaluate( String expression, Object root, boolean trimRootToken )

         throws Exception

     {

         // if the root token refers to the supplied root object parameter, remove it.

         if ( trimRootToken )

         {

             expression = expression.substring( expression.indexOf( '.' ) + 1 );

         }

         Object value = root;

         // ----------------------------------------------------------------------

         // Walk the dots and retrieve the ultimate value desired from the

         // MavenProject instance.

         // ----------------------------------------------------------------------

         StringTokenizer parser = new StringTokenizer( expression, "." );

         while ( parser.hasMoreTokens() )

         {

             String token = parser.nextToken();

             if ( value == null )

             {

                 return null;

             }

             classMap = getClassMap( value.getClass() );

             String methodBase = StringUtils.capitalizeFirstLetter( token );

             String methodName = "get" + methodBase;

             Method method = classMap.findMethod( methodName, args );

             if ( method == null )

             {

                 // perhaps this is a boolean property??

                 methodName = "is" + methodBase;

                 method = classMap.findMethod( methodName, args );

             }

             if ( method == null )

             {

                 return null;

             }

             value = method.invoke( value, params );

         }

         return value;

     }

     private static ClassMap getClassMap( Class clazz )

     {

         classMap = (ClassMap) classMaps.get( clazz );

         if ( classMap == null )

         {

             classMap = new ClassMap( clazz );

             classMaps.put( clazz, classMap );

         }

         return classMap;

     }

 }