001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.el;
018    
019    import javax.servlet.jsp.el.ELException;
020    
021    /**
022     *
023     * <p>The implementation of the not operator
024     * 
025     * @author Nathan Abramson - Art Technology Group
026     * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: bayard $
027     **/
028    
029    public class NotOperator
030      extends UnaryOperator
031    {
032      //-------------------------------------
033      // Singleton
034      //-------------------------------------
035    
036      public static final NotOperator SINGLETON =
037        new NotOperator ();
038    
039      //-------------------------------------
040      /**
041       *
042       * Constructor
043       **/
044      public NotOperator ()
045      {
046      }
047    
048      //-------------------------------------
049      // Expression methods
050      //-------------------------------------
051      /**
052       *
053       * Returns the symbol representing the operator
054       **/
055      public String getOperatorSymbol ()
056      {
057        return "not";
058      }
059    
060      //-------------------------------------
061      /**
062       *
063       * Applies the operator to the given value
064       **/
065      public Object apply (Object pValue)
066        throws ELException
067      {
068        // Coerce the value to a boolean
069        boolean val = Coercions.coerceToBoolean (pValue).booleanValue ();
070    
071        return PrimitiveObjects.getBoolean (!val);
072      }
073    
074      //-------------------------------------
075    }