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 and 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 AndOperator
030      extends BinaryOperator
031    {
032      //-------------------------------------
033      // Singleton
034      //-------------------------------------
035    
036      public static final AndOperator SINGLETON =
037        new AndOperator ();
038    
039      //-------------------------------------
040      /**
041       *
042       * Constructor
043       **/
044      public AndOperator ()
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 "and";
058      }
059    
060      //-------------------------------------
061      /**
062       *
063       * Applies the operator to the given value
064       **/
065      public Object apply (Object pLeft,
066                           Object pRight)
067        throws ELException
068      {
069        // Coerce the values to booleans
070        boolean left = 
071          Coercions.coerceToBoolean (pLeft).booleanValue ();
072        boolean right = 
073          Coercions.coerceToBoolean (pRight).booleanValue ();
074    
075        return PrimitiveObjects.getBoolean (left && right);
076      }
077    
078      //-------------------------------------
079      /**
080       *
081       * Returns true if evaluation is necessary given the specified Left
082       * value.  The And/OrOperators make use of this
083       **/
084      public boolean shouldEvaluate (Object pLeft)
085      {
086        return
087          (pLeft instanceof Boolean) &&
088          ((Boolean) pLeft).booleanValue () == true;
089      }
090    
091      //-------------------------------------
092      /**
093       *
094       * Returns true if the operator expects its arguments to be coerced
095       * to Booleans.  The And/Or operators set this to true.
096       **/
097      public boolean shouldCoerceToBoolean ()
098      {
099        return true;
100      }
101    
102      //-------------------------------------
103    }