/*

  * 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.algorithm;

 import java.io.Serializable;

 import java.util.Iterator;

 import org.apache.commons.functor.BinaryProcedure;

 import org.apache.commons.functor.UnaryPredicate;

 import org.apache.commons.functor.core.composite.UnaryNot;

 /**

  * Retain elements in left Iterator that match right UnaryPredicate.

  *

  * @version $Revision: 1166328 $ $Date: 2011-09-07 21:32:26 +0200 (Wed, 07 Sep 2011) $

  */

 public final class RetainMatching<T>

     implements BinaryProcedure<Iterator<? extends T>, UnaryPredicate<? super T>>, Serializable {

     /**

      * serialVersionUID declaration.

      */

     private static final long serialVersionUID = 6760018011875465469L;

     private static final RetainMatching<Object> INSTANCE = new RetainMatching<Object>();

     private RemoveMatching<T> removeMatching = new RemoveMatching<T>();

     /**

      * {@inheritDoc}

      * @param left {@link Iterator}

      * @param right {@link UnaryPredicate}

      */

     public void run(Iterator<? extends T> left, UnaryPredicate<? super T> right) {

         removeMatching.run(left, UnaryNot.not(right));

     }

     /**

      * {@inheritDoc}

      */

     public boolean equals(Object obj) {

         return obj == this || obj != null && obj.getClass().equals(getClass());

     }

     /**

      * {@inheritDoc}

      */

     public int hashCode() {

         return System.identityHashCode(INSTANCE);

     }

     /**

      * Get a static {@link RetainMatching} instance.

      * @return {@link RetainMatching}

      */

     public static RetainMatching<Object> instance() {

         return INSTANCE;

     }

 }