/*

  * 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.

  */

 package org.apache.myfaces.el.unified;

 import java.util.Comparator;

 import java.util.List;

 import javax.el.ELResolver;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import org.apache.myfaces.config.RuntimeConfig;

 /**

  * Comparator for ELResolvers that shifts the Resolvers from

  * the faces-config to the front.

  * 

  * @author Jakob Korherr (latest modification by $Author$)

  * @version $Revision$ $Date$

  *

  * @since 1.2.10, 2.0.2

  */

 public class CustomFirstELResolverComparator implements Comparator<ELResolver>

 {

     private List<ELResolver> _facesConfigResolvers;

     public int compare(ELResolver r1, ELResolver r2)

     {

         List<ELResolver> facesConfigResolvers = _getFacesConfigElResolvers();

         if (facesConfigResolvers == null)

         {

             // no el-resolvers in faces-config

             return 0; // keep order

         }

         boolean r1FromFacesConfig = facesConfigResolvers.contains(r1);

         boolean r2FromFacesConfig = facesConfigResolvers.contains(r2);

         if (r1FromFacesConfig)

         {

             if (r2FromFacesConfig)

             {

                 // both are from faces-config

                 return 0; // keep order

             }

             else

             {

                 // only r1 is from faces-config

                 return -1;

             }

         }

         else

         {

             if (r2FromFacesConfig)

             {

                 // only r2 is from faces-config

                 return 1;

             }

             else

             {

                 // neither r1 nor r2 are from faces-config

                 return 0; // keep order

             }

         }

     }

     /**

      * Returns a List of all ELResolvers from the faces-config.

      * @return

      */

     private List<ELResolver> _getFacesConfigElResolvers()

     {

         if (_facesConfigResolvers == null)

         {

             ExternalContext externalContext

                     = FacesContext.getCurrentInstance().getExternalContext();

             RuntimeConfig runtimeConfig

                     = RuntimeConfig.getCurrentInstance(externalContext);

             _facesConfigResolvers 

                     = runtimeConfig.getFacesConfigElResolvers();

         }

         return _facesConfigResolvers;

     }

 }