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>This is the superclass for all binary operators
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 abstract class BinaryOperator
030    {
031      //-------------------------------------
032      /**
033       *
034       * Constructor
035       **/
036      public BinaryOperator ()
037      {
038      }
039    
040      //-------------------------------------
041      // Expression methods
042      //-------------------------------------
043      /**
044       *
045       * Returns the symbol representing the operator
046       **/
047      public abstract String getOperatorSymbol ();
048    
049      //-------------------------------------
050      /**
051       *
052       * Applies the operator to the given pair of values
053       **/
054      public abstract Object apply (Object pLeft,
055                                    Object pRight)
056        throws ELException;
057    
058      //-------------------------------------
059      /**
060       *
061       * Returns true if evaluation is necessary given the specified Left
062       * value.  The And/OrOperators make use of this
063       **/
064      public boolean shouldEvaluate (Object pLeft)
065      {
066        return true;
067      }
068    
069      //-------------------------------------
070      /**
071       *
072       * Returns true if the operator expects its arguments to be coerced
073       * to Booleans.  The And/Or operators set this to true.
074       **/
075      public boolean shouldCoerceToBoolean ()
076      {
077        return false;
078      }
079    
080      //-------------------------------------
081    }