/*

  * 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.functor.core.composite;

 import java.io.Serializable;

 import org.apache.commons.functor.BinaryPredicate;

 import org.apache.commons.functor.BinaryProcedure;

 import org.apache.commons.functor.core.NoOp;

 /**

  * A {@link BinaryProcedure BinaryProcedure}

  * similiar to Java's "ternary"

  * or "conditional" operator (<code>&#x3F; &#x3A;</code>).

  * Given a {@link BinaryPredicate predicate}

  * <i>p</i> and {@link BinaryProcedure procedures}

  * <i>q</i> and <i>r</i>, {@link #run runs}

  * <code>if (p.test(x,y)) { q.run(x,y); } else { r.run(x,y); }</code>.

  * <p>

  * Note that although this class implements

  * {@link Serializable}, a given instance will

  * only be truly <code>Serializable</code> if all the

  * underlying functors are.  Attempts to serialize

  * an instance whose delegates are not all

  * <code>Serializable</code> will result in an exception.

  * </p>

  * @version $Revision: 1166384 $ $Date: 2011-09-07 22:22:00 +0200 (Wed, 07 Sep 2011) $

  * @author Rodney Waldhoff

  */

 public final class ConditionalBinaryProcedure<L, R> implements BinaryProcedure<L, R>, Serializable {

     /**

      * serialVersionUID declaration.

      */

     private static final long serialVersionUID = -3521992036791188475L;

     /** Base hash integer used to shift hash */

     private static final int HASH_SHIFT = 4;

     // attributes

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

     private final BinaryPredicate<? super L, ? super R> ifPred;

     private final BinaryProcedure<? super L, ? super R> thenProc;

     private final BinaryProcedure<? super L, ? super R> elseProc;

     // constructor

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

     /**

      * Create a new ConditionalBinaryProcedure.

      * @param ifPred to evaluate

      * @param thenProc if <code>ifPred</code> yields <code>true</code>

      */

     public ConditionalBinaryProcedure(BinaryPredicate<? super L, ? super R> ifPred,

             BinaryProcedure<? super L, ? super R> thenProc) {

         this(ifPred, thenProc, NoOp.instance());

     }

     /**

      * Create a new ConditionalBinaryProcedure.

      * @param ifPred to evaluate

      * @param thenProc if <code>ifPred</code> yields <code>true</code>

      * @param elseProc if <code>ifPred</code> yields <code>false</code>

      */

     public ConditionalBinaryProcedure(BinaryPredicate<? super L, ? super R> ifPred,

             BinaryProcedure<? super L, ? super R> thenProc, BinaryProcedure<? super L, ? super R> elseProc) {

         if (ifPred == null) {

             throw new IllegalArgumentException("BinaryPredicate argument was null");

         }

         this.ifPred = ifPred;

         if (thenProc == null || elseProc == null) {

             throw new IllegalArgumentException("One or more BinaryProcedure arguments was null");

         }

         this.thenProc = thenProc;

         this.elseProc = elseProc;

     }

     // predicate interface

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

     /**

      * {@inheritDoc}

      */

     public void run(L left, R right) {

         if (ifPred.test(left, right)) {

             thenProc.run(left, right);

         } else {

             elseProc.run(left, right);

         }

     }

     /**

      * {@inheritDoc}

      */

     public boolean equals(Object that) {

         return that == this || (that instanceof ConditionalBinaryProcedure<?, ?>

                                     && equals((ConditionalBinaryProcedure<?, ?>) that));

     }

     /**

      * Learn whether a given ConditionalBinaryProcedure is equal to this.

      * @param that compared object

      * @return boolean

      */

     public boolean equals(ConditionalBinaryProcedure<?, ?> that) {

         return null != that

                 && (null == ifPred ? null == that.ifPred : ifPred.equals(that.ifPred))

                 && (null == thenProc ? null == that.thenProc : thenProc.equals(that.thenProc))

                 && (null == elseProc ? null == that.elseProc : elseProc.equals(that.elseProc));

     }

     /**

      * {@inheritDoc}

      */

     public int hashCode() {

         int hash = "ConditionalBinaryProcedure".hashCode();

         if (null != ifPred) {

             hash <<= HASH_SHIFT;

             hash ^= ifPred.hashCode();

         }

         if (null != thenProc) {

             hash <<= HASH_SHIFT;

             hash ^= thenProc.hashCode();

         }

         if (null != elseProc) {

             hash <<= HASH_SHIFT;

             hash ^= elseProc.hashCode();

         }

         return hash;

     }

     /**

      * {@inheritDoc}

      */

     public String toString() {

         return "ConditionalBinaryProcedure<" + ifPred + "?" + thenProc + ":" + elseProc + ">";

     }

 }