1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.functor.core.composite; 18 19 import java.io.Serializable; 20 21 import org.apache.commons.functor.BinaryProcedure; 22 23 /** 24 * Transposes (swaps) the arguments to some other 25 * {@link BinaryProcedure procedure}. 26 * For example, given a procedure <i>p</i> 27 * and the ordered pair of arguments <i>a</i>, 28 * <i>b</i>. 29 * {@link #run runs} 30 * <code>p.run(b,a)</code>. 31 * <p> 32 * Note that although this class implements 33 * {@link Serializable}, a given instance will 34 * only be truly <code>Serializable</code> if the 35 * underlying functor is. Attempts to serialize 36 * an instance whose delegate is not 37 * <code>Serializable</code> will result in an exception. 38 * </p> 39 * @version $Revision: 1156320 $ $Date: 2011-08-10 21:14:50 +0200 (Wed, 10 Aug 2011) $ 40 * @author Rodney Waldhoff 41 */ 42 public class TransposedProcedure<L, R> implements BinaryProcedure<L, R>, Serializable { 43 /** 44 * serialVersionUID declaration. 45 */ 46 private static final long serialVersionUID = 4472683678460290015L; 47 // attributes 48 // ------------------------------------------------------------------------ 49 private final BinaryProcedure<? super R, ? super L> procedure; 50 51 // constructor 52 // ------------------------------------------------------------------------ 53 /** 54 * Create a new TransposedProcedure. 55 * @param procedure BinaryProcedure to transpose 56 */ 57 public TransposedProcedure(BinaryProcedure<? super R, ? super L> procedure) { 58 if (procedure == null) { 59 throw new IllegalArgumentException("BinaryProcedure argument was null"); 60 } 61 this.procedure = procedure; 62 } 63 64 // functor interface 65 // ------------------------------------------------------------------------ 66 /** 67 * {@inheritDoc} 68 */ 69 public void run(L left, R right) { 70 procedure.run(right, left); 71 } 72 73 /** 74 * {@inheritDoc} 75 */ 76 public boolean equals(Object that) { 77 return that == this || (that instanceof TransposedProcedure<?, ?> && equals((TransposedProcedure<?, ?>) that)); 78 } 79 80 /** 81 * Learn whether another TransposedProcedure is equal to this. 82 * @param that TransposedPredicate to test 83 * @return boolean 84 */ 85 public boolean equals(TransposedProcedure<?, ?> that) { 86 return null != that && (null == procedure ? null == that.procedure : procedure.equals(that.procedure)); 87 } 88 89 /** 90 * {@inheritDoc} 91 */ 92 public int hashCode() { 93 int hash = "TransposedProcedure".hashCode(); 94 if (null != procedure) { 95 hash ^= procedure.hashCode(); 96 } 97 return hash; 98 } 99 100 /** 101 * {@inheritDoc} 102 */ 103 public String toString() { 104 return "TransposedProcedure<" + procedure + ">"; 105 } 106 107 // static 108 // ------------------------------------------------------------------------ 109 /** 110 * Transpose a BinaryProcedure. 111 * @param p to transpose 112 * @return TransposedProcedure 113 */ 114 public static <L, R> TransposedProcedure<R, L> transpose(BinaryProcedure<? super L, ? super R> p) { 115 return null == p ? null : new TransposedProcedure<R, L>(p); 116 } 117 118 }