/*

  * 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 javax.servlet.jsp.el.ELException;

 import javax.servlet.jsp.el.FunctionMapper;

 import javax.servlet.jsp.el.VariableResolver;

 /**

  *

  * <p>Represents a conditional expression.  I've decided not to produce an

  * abstract base "TernaryOperatorExpression" class since (a) future ternary

  * operators are unlikely and (b) it's not clear that there would be a

  * meaningful way to abstract them.  (For instance, would they all be right-

  * associative?  Would they all have two fixed operator symbols?)

  * 

  * @author Shawn Bayern

  **/

 public class ConditionalExpression

   extends Expression

 {

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

   // Properties

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

   // property condition

   Expression mCondition;

   public Expression getCondition ()

   { return mCondition; }

   public void setCondition (Expression pCondition)

   { mCondition = pCondition; }

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

   // property trueBranch

   Expression mTrueBranch;

   public Expression getTrueBranch ()

   { return mTrueBranch; }

   public void setTrueBranch (Expression pTrueBranch)

   { mTrueBranch = pTrueBranch; }

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

   // property falseBranch

   Expression mFalseBranch;

   public Expression getFalseBranch ()

   { return mFalseBranch; }

   public void setFalseBranch (Expression pFalseBranch)

   { mFalseBranch = pFalseBranch; }

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

   /**

    *

    * Constructor

    **/

   public ConditionalExpression (Expression pCondition,

                                 Expression pTrueBranch,

                                 Expression pFalseBranch)

   {

     mCondition = pCondition;

     mTrueBranch = pTrueBranch;

     mFalseBranch = pFalseBranch;

   }

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

   // Expression methods

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

   /**

    *

    * Returns the expression in the expression language syntax

    **/

   public String getExpressionString ()

   {

     return

       "( " + mCondition.getExpressionString() + " ? " + 

       mTrueBranch.getExpressionString() + " : " +

       mFalseBranch.getExpressionString() + " )";

   }

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

   /**

    *

    * Evaluates the conditional expression and returns the literal result

    **/

   public Object evaluate (VariableResolver vr,

                           FunctionMapper f)

     throws ELException

   {

     // first, evaluate the condition (and coerce the result to a boolean value)

     boolean condition =

       Coercions.coerceToBoolean(

         mCondition.evaluate(vr, f)).booleanValue();

     // then, use this boolean to branch appropriately

     if (condition)

       return mTrueBranch.evaluate(vr, f);

     else

       return mFalseBranch.evaluate(vr, f);

   }

   public Expression bindFunctions(final FunctionMapper functions) throws ELException {

        return new ConditionalExpression(

                mCondition.bindFunctions(functions),

                mTrueBranch.bindFunctions(functions),

                mFalseBranch.bindFunctions(functions));

   }

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

 }