/*

  * $Id: ELContextImpl.java 836180 2009-11-14 14:00:02Z apetrelli $

  *

  * 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.tiles.el;

 import java.lang.reflect.Method;

 import java.util.HashMap;

 import java.util.Map;

 import javax.el.ELContext;

 import javax.el.ELResolver;

 import javax.el.FunctionMapper;

 import javax.el.ValueExpression;

 import javax.el.VariableMapper;

 /**

  * Implementation of ELContext.<br>

  * Copied from Apache Tomcat 6.0.16 source code.

  *

  * @since 2.2.1

  */

 public class ELContextImpl extends ELContext {

     /**

      * A null function mapper.

      */

     private static final FunctionMapper NULL_FUNCTION_MAPPER = new FunctionMapper() {

         @Override

         public Method resolveFunction(String prefix, String localName) {

             return null;

         }

     };

     /**

      * Default implementation for the variable mapper.

      */

     private static final class VariableMapperImpl extends VariableMapper {

         /**

          * The mapped variables.

          */

         private Map<String, ValueExpression> vars;

         /** {@inheritDoc} */

         @Override

         public ValueExpression resolveVariable(String variable) {

             if (vars == null) {

                 return null;

             }

             return vars.get(variable);

         }

         /** {@inheritDoc} */

         @Override

         public ValueExpression setVariable(String variable,

                 ValueExpression expression) {

             if (vars == null) {

                 vars = new HashMap<String, ValueExpression>();

             }

             return vars.put(variable, expression);

         }

     }

     /**

      * The EL resolver to use.

      */

     private final ELResolver resolver;

     /**

      * The function mapper to use.

      */

     private FunctionMapper functionMapper = NULL_FUNCTION_MAPPER;

     /**

      * The variable mapper to use.

      */

     private VariableMapper variableMapper;

     /**

      * Constructor.

      *

      * @param resolver The resolver to use.

      */

     public ELContextImpl(ELResolver resolver) {

         this.resolver = resolver;

     }

     /** {@inheritDoc} */

     @Override

     public ELResolver getELResolver() {

         return this.resolver;

     }

     /** {@inheritDoc} */

     @Override

     public FunctionMapper getFunctionMapper() {

         return this.functionMapper;

     }

     /** {@inheritDoc} */

     @Override

     public VariableMapper getVariableMapper() {

         if (this.variableMapper == null) {

             this.variableMapper = new VariableMapperImpl();

         }

         return this.variableMapper;

     }

     /**

      * Sets the function mapper to use.

      *

      * @param functionMapper The function mapper.

      * @since 2.2.1

      */

     public void setFunctionMapper(FunctionMapper functionMapper) {

         this.functionMapper = functionMapper;

     }

     /**

      * Sets the variable mapper to use.

      *

      * @param variableMapper The variable mapper.

      * @since 2.2.1

      */

     public void setVariableMapper(VariableMapper variableMapper) {

         this.variableMapper = variableMapper;

     }

 }