/* $Id$ */
   /*
    * 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.commons.el;
  import java.lang.reflect.Method;
  import java.util.HashMap;
  import java.util.Map;
  
  import javax.servlet.jsp.el.ELException;
  import javax.servlet.jsp.el.Expression;
  import javax.servlet.jsp.el.ExpressionEvaluator;
  import javax.servlet.jsp.el.FunctionMapper;
  import javax.servlet.jsp.el.VariableResolver;
  
  import org.apache.commons.el.ExpressionEvaluatorImpl;
  
  import junit.framework.TestCase;
  
  /**
   * @author Jamie Taylor
   *
   */
  public class FunctionBindingTest extends TestCase {
      public static String before() {return "before";}
      public static String after() {return "after";}
      public static String echo(final String s) {return s;}
      private static class UpdatableFunctionMapper implements FunctionMapper {
          private Map mappings = new HashMap();
          public void setMapping(
                  final String name,
                  final Method function) 
          {
              mappings.put(name,function);
          }
          public Method resolveFunction(
                  final String prefix, 
                  final String localName) 
          {
              return (Method)mappings.get(localName);
          }
      }
      
      public void testFunctionBinding() throws ELException, NoSuchMethodException{
          final String theExpression = "${theFunction()}";
          final String nestedExpression = "${echo(theFunction())}";
          final VariableResolver emptyVariableResolver = new VariableResolver() {
              public Object resolveVariable(String arg0) throws ELException {
                  return null;
              }
          };
          final UpdatableFunctionMapper fm = new UpdatableFunctionMapper();
          final Method before = FunctionBindingTest.class.getDeclaredMethod("before",new Class[0]);
          final Method after = FunctionBindingTest.class.getDeclaredMethod("after",new Class[0]);
          final Method echo = FunctionBindingTest.class.getDeclaredMethod("echo", new Class[]{String.class});
          final ExpressionEvaluator evaluator = new ExpressionEvaluatorImpl();
          fm.setMapping("theFunction",before);
          fm.setMapping("echo", echo);
          
          final Expression expr = evaluator.parseExpression(theExpression, String.class, fm);
          final Expression nestedExpr = evaluator.parseExpression(nestedExpression, String.class, fm);
          assertEquals(
             "before",
             expr.evaluate(emptyVariableResolver));
          assertEquals(
             "before",
             nestedExpr.evaluate(emptyVariableResolver));
          
          fm.setMapping("theFunction",after);
          assertEquals(
             "after",
             evaluator.evaluate(theExpression, String.class, emptyVariableResolver, fm));
          assertEquals(
             "before",
             expr.evaluate(emptyVariableResolver));
          assertEquals(
             "after",
             evaluator.evaluate(nestedExpression, String.class, emptyVariableResolver, fm));
          assertEquals(
             "before",
             nestedExpr.evaluate(emptyVariableResolver));
      }
  }