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.composite; 018 019 import java.io.Serializable; 020 021 import org.apache.commons.functor.BinaryFunction; 022 import org.apache.commons.functor.BinaryPredicate; 023 024 /** 025 * A {@link BinaryFunction BinaryFunction} 026 * similiar to Java's "ternary" 027 * or "conditional" operator (<code>? :</code>). 028 * Given a {@link BinaryPredicate predicate} 029 * <i>p</i> and {@link BinaryFunction functions} 030 * <i>f</i> and <i>g</i>, {@link #evaluate evaluates} 031 * to 032 * <code>p.test(x,y) ? f.evaluate(x,y) : g.evaluate(x,y)</code>. 033 * <p> 034 * Note that although this class implements 035 * {@link Serializable}, a given instance will 036 * only be truly <code>Serializable</code> if all the 037 * underlying functors are. Attempts to serialize 038 * an instance whose delegates are not all 039 * <code>Serializable</code> will result in an exception. 040 * </p> 041 * @version $Revision: 1166381 $ $Date: 2011-09-07 22:19:48 +0200 (Wed, 07 Sep 2011) $ 042 * @author Rodney Waldhoff 043 */ 044 public final class ConditionalBinaryFunction<L, R, T> implements BinaryFunction<L, R, T>, Serializable { 045 /** 046 * serialVersionUID declaration. 047 */ 048 private static final long serialVersionUID = -994698971284481482L; 049 050 /** Base hash integer used to shift hash */ 051 private static final int HASH_SHIFT = 4; 052 // attributes 053 // ------------------------------------------------------------------------ 054 private final BinaryPredicate<? super L, ? super R> ifPred; 055 private final BinaryFunction<? super L, ? super R, ? extends T> thenFunc; 056 private final BinaryFunction<? super L, ? super R, ? extends T> elseFunc; 057 058 // constructor 059 // ------------------------------------------------------------------------ 060 /** 061 * Create a new ConditionalBinaryFunction. 062 * @param ifPred if 063 * @param thenFunc then 064 * @param elseFunc else 065 */ 066 public ConditionalBinaryFunction(BinaryPredicate<? super L, ? super R> ifPred, 067 BinaryFunction<? super L, ? super R, ? extends T> thenFunc, 068 BinaryFunction<? super L, ? super R, ? extends T> elseFunc) { 069 if (ifPred == null) { 070 throw new IllegalArgumentException("BinaryPredicate argument was null"); 071 } 072 if (thenFunc == null || elseFunc == null) { 073 throw new IllegalArgumentException("One or more BinaryFunction arguments was null"); 074 } 075 this.ifPred = ifPred; 076 this.thenFunc = thenFunc; 077 this.elseFunc = elseFunc; 078 } 079 080 // predicate interface 081 // ------------------------------------------------------------------------ 082 /** 083 * {@inheritDoc} 084 */ 085 public T evaluate(L left, R right) { 086 if (ifPred.test(left, right)) { 087 return thenFunc.evaluate(left, right); 088 } else { 089 return elseFunc.evaluate(left, right); 090 } 091 } 092 093 /** 094 * {@inheritDoc} 095 */ 096 public boolean equals(Object that) { 097 return that == this || (that instanceof ConditionalBinaryFunction<?, ?, ?> 098 && equals((ConditionalBinaryFunction<?, ?, ?>) that)); 099 } 100 101 /** 102 * Learn whether another ConditionalBinaryFunction is equal to this. 103 * @param that ConditionalBinaryFunction to test 104 * @return boolean 105 */ 106 public boolean equals(ConditionalBinaryFunction<?, ?, ?> that) { 107 return null != that 108 && (null == ifPred ? null == that.ifPred : ifPred.equals(that.ifPred)) 109 && (null == thenFunc ? null == that.thenFunc : thenFunc.equals(that.thenFunc)) 110 && (null == elseFunc ? null == that.elseFunc : elseFunc.equals(that.elseFunc)); 111 } 112 113 /** 114 * {@inheritDoc} 115 */ 116 public int hashCode() { 117 int hash = "ConditionalBinaryFunction".hashCode(); 118 if (null != ifPred) { 119 hash <<= HASH_SHIFT; 120 hash ^= ifPred.hashCode(); 121 } 122 if (null != thenFunc) { 123 hash <<= HASH_SHIFT; 124 hash ^= thenFunc.hashCode(); 125 } 126 if (null != elseFunc) { 127 hash <<= HASH_SHIFT; 128 hash ^= elseFunc.hashCode(); 129 } 130 return hash; 131 } 132 133 /** 134 * {@inheritDoc} 135 */ 136 public String toString() { 137 return "ConditionalBinaryFunction<" + ifPred + "?" + thenFunc + ":" + elseFunc + ">"; 138 } 139 140 }