/*

  * 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.util.List;

 import java.util.Iterator;

 import java.util.ArrayList;

 import javax.servlet.jsp.el.ELException;

 import javax.servlet.jsp.el.FunctionMapper;

 import javax.servlet.jsp.el.VariableResolver;

 /**

  *

  * <p>An expression representing a binary operator on a value

  * 

  * @author Nathan Abramson - Art Technology Group

  * @author Shawn Bayern

  * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: bayard $

  **/

 public class BinaryOperatorExpression

   extends Expression

 {

   //-------------------------------------

   // Properties

   //-------------------------------------

   // property expression

   Expression mExpression;

   public Expression getExpression ()

   { return mExpression; }

   public void setExpression (Expression pExpression)

   { mExpression = pExpression; }

   //-------------------------------------

   // property operators

   List mOperators;

   public List getOperators ()

   { return mOperators; }

   public void setOperators (List pOperators)

   { mOperators = pOperators; }

   //-------------------------------------

   // property expressions

   List mExpressions;

   public List getExpressions ()

   { return mExpressions; }

   public void setExpressions (List pExpressions)

   { mExpressions = pExpressions; }

   //-------------------------------------

   /**

    *

    * Constructor

    **/

   public BinaryOperatorExpression (Expression pExpression,

                                    List pOperators,

                                    List pExpressions)

   {

     mExpression = pExpression;

     mOperators = pOperators;

     mExpressions = pExpressions;

   }

   //-------------------------------------

   // Expression methods

   //-------------------------------------

   /**

    *

    * Returns the expression in the expression language syntax

    **/

   public String getExpressionString ()

   {

     StringBuffer buf = new StringBuffer ();

     buf.append ("(");

     buf.append (mExpression.getExpressionString ());

     for (int i = 0, size = mOperators.size(); i < size; i++) {

       BinaryOperator operator = (BinaryOperator) mOperators.get (i);

       Expression expression = (Expression) mExpressions.get (i);

       buf.append (" ");

       buf.append (operator.getOperatorSymbol ());

       buf.append (" ");

       buf.append (expression.getExpressionString ());

     }

     buf.append (")");

     return buf.toString ();

   }

   //-------------------------------------

   /**

    *

    * Evaluates to the literal value

    **/

   public Object evaluate (VariableResolver pResolver,

                           FunctionMapper functions)

     throws ELException

   {

     Object value = mExpression.evaluate (pResolver, functions);

     for (int i = 0, size = mOperators.size(); i < size; i++) {

       BinaryOperator operator = (BinaryOperator) mOperators.get (i);

       // For the And/Or operators, we need to coerce to a boolean

       // before testing if we shouldEvaluate

       if (operator.shouldCoerceToBoolean ()) {

         value = Coercions.coerceToBoolean (value);

       }

       if (operator.shouldEvaluate (value)) {

         Expression expression = (Expression) mExpressions.get (i);

         Object nextValue = expression.evaluate (pResolver,

                                                 functions);

         value = operator.apply (value, nextValue);

       }

     }

     return value;

   }

     public Expression bindFunctions(final FunctionMapper functions) throws ELException {

         final List args = new ArrayList(mExpressions.size());

         for (Iterator argIter = mExpressions.iterator(); argIter.hasNext();) {

             args.add(((Expression)argIter.next()).bindFunctions(functions));

         }

         // it would be nice if we knew for sure that the operators list

         // was immutable, but we'll just assume so for now.

         return new BinaryOperatorExpression(

                 mExpression.bindFunctions(functions),

                 mOperators,

                 args);

     }

   //-------------------------------------

 }