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.functor.core.algorithm; 018 019 import java.io.Serializable; 020 import java.util.Iterator; 021 022 import org.apache.commons.functor.BinaryProcedure; 023 import org.apache.commons.functor.UnaryPredicate; 024 import org.apache.commons.functor.core.composite.UnaryNot; 025 026 /** 027 * Retain elements in left Iterator that match right UnaryPredicate. 028 * 029 * @version $Revision: 1166328 $ $Date: 2011-09-07 21:32:26 +0200 (Wed, 07 Sep 2011) $ 030 */ 031 public final class RetainMatching<T> 032 implements BinaryProcedure<Iterator<? extends T>, UnaryPredicate<? super T>>, Serializable { 033 /** 034 * serialVersionUID declaration. 035 */ 036 private static final long serialVersionUID = 6760018011875465469L; 037 038 private static final RetainMatching<Object> INSTANCE = new RetainMatching<Object>(); 039 040 private RemoveMatching<T> removeMatching = new RemoveMatching<T>(); 041 042 /** 043 * {@inheritDoc} 044 * @param left {@link Iterator} 045 * @param right {@link UnaryPredicate} 046 */ 047 public void run(Iterator<? extends T> left, UnaryPredicate<? super T> right) { 048 removeMatching.run(left, UnaryNot.not(right)); 049 } 050 051 /** 052 * {@inheritDoc} 053 */ 054 public boolean equals(Object obj) { 055 return obj == this || obj != null && obj.getClass().equals(getClass()); 056 } 057 058 /** 059 * {@inheritDoc} 060 */ 061 public int hashCode() { 062 return System.identityHashCode(INSTANCE); 063 } 064 065 /** 066 * Get a static {@link RetainMatching} instance. 067 * @return {@link RetainMatching} 068 */ 069 public static RetainMatching<Object> instance() { 070 return INSTANCE; 071 } 072 }