package org.apache.maven.plugin.assembly.utils;

 /*

  * 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 org.codehaus.plexus.logging.Logger;

 import org.codehaus.plexus.util.interpolation.ValueSource;

 import org.codehaus.plexus.util.introspection.ReflectionValueExtractor;

 /**

  * @version $Id: PrefixedObjectBasedValueSource.java 610981 2008-01-10 23:10:00Z vsiveton $

  */

 public class PrefixedObjectBasedValueSource

     implements ValueSource

 {

     private String prefix;

     private final Object root;

     private final Logger logger;

     public PrefixedObjectBasedValueSource( String prefix, Object root )

     {

         this.prefix = prefix;

         this.root = root;

         logger = null;

     }

     public PrefixedObjectBasedValueSource( String prefix, Object root, Logger logger )

     {

         this.prefix = prefix;

         this.root = root;

         this.logger = logger;

     }

     public Object getValue( String expression )

     {

         if ( ( expression == null ) || !expression.startsWith( prefix ) )

         {

             return null;

         }

         String realExpr = expression.substring( prefix.length() );

         if ( realExpr.startsWith( "." ) )

         {

             realExpr = realExpr.substring( 1 );

         }

         Object value = null;

         try

         {

             value = ReflectionValueExtractor.evaluate( realExpr, root, false );

         }

         catch ( Exception e )

         {

             if ( ( logger != null ) && logger.isDebugEnabled() )

             {

                 logger.debug( "Failed to extract \'" + realExpr + "\' from: " + root + " (full expression was: \'" + expression + "\').", e );

             }

         }

         return value;

     }

 }