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 */ 017package org.apache.commons.functor.core.collection; 018 019import java.lang.reflect.Array; 020import java.util.Collection; 021 022import org.apache.commons.functor.BinaryPredicate; 023import org.apache.commons.functor.Predicate; 024import org.apache.commons.functor.adapter.RightBoundPredicate; 025import org.apache.commons.lang3.Validate; 026 027/** 028 * A {@link BinaryPredicate} that checks to see if the 029 * specified object is an element of the specified 030 * Collection. 031 * 032 * @param <L> the left argument type. 033 * @param <R> the right argument type. 034 * @since 1.0 035 * @version $Revision: 1537909 $ $Date: 2013-11-01 13:24:41 +0100 (Fr, 01 Nov 2013) $ 036 */ 037public final class IsElementOf<L, R> implements BinaryPredicate<L, R> { 038 // static members 039 //--------------------------------------------------------------- 040 041 /** 042 * A static {@link IsElementOf} instance reference. 043 */ 044 private static final IsElementOf<Object, Object> INSTANCE = new IsElementOf<Object, Object>(); 045 046 // constructors 047 //--------------------------------------------------------------- 048 /** 049 * Create a new IsElementOf. 050 */ 051 public IsElementOf() { 052 } 053 054 // instance methods 055 //--------------------------------------------------------------- 056 /** 057 * {@inheritDoc} 058 */ 059 public boolean test(L obj, R col) { 060 Validate.notNull(col, "Right side argument must not be null."); 061 if (col instanceof Collection<?>) { 062 return testCollection(obj, (Collection<?>) col); 063 } 064 if (col.getClass().isArray()) { 065 return testArray(obj, col); 066 } 067 throw new IllegalArgumentException("Expected Collection or Array, found " + col.getClass()); 068 } 069 070 /** 071 * {@inheritDoc} 072 */ 073 @Override 074 public boolean equals(Object obj) { 075 return (obj instanceof IsElementOf<?, ?>); 076 } 077 078 /** 079 * {@inheritDoc} 080 */ 081 @Override 082 public int hashCode() { 083 return "IsElementOf".hashCode(); 084 } 085 086 /** 087 * {@inheritDoc} 088 */ 089 @Override 090 public String toString() { 091 return "IsElementOf"; 092 } 093 094 /** 095 * Test a collection. 096 * @param obj to find 097 * @param col to search 098 * @return boolean 099 */ 100 private boolean testCollection(Object obj, Collection<?> col) { 101 return col.contains(obj); 102 } 103 104 /** 105 * Test an array. 106 * @param obj to find 107 * @param array to search 108 * @return boolean 109 */ 110 private boolean testArray(Object obj, Object array) { 111 for (int i = 0, m = Array.getLength(array); i < m; i++) { 112 Object value = Array.get(array, i); 113 if (obj == value) { 114 return true; 115 } 116 if (obj != null && obj.equals(value)) { 117 return true; 118 } 119 } 120 return false; 121 } 122 123 // static methods 124 //--------------------------------------------------------------- 125 /** 126 * Get an IsElementOf instance. 127 * @return IsElementOf 128 */ 129 public static IsElementOf<Object, Object> instance() { 130 return INSTANCE; 131 } 132 133 /** 134 * Get an IsElementOf(collection|array) Predicate. 135 * 136 * @param <A> the Predicate argument generic type 137 * @param obj collection/array to search 138 * @return Predicate 139 */ 140 public static <A> Predicate<A> instance(Object obj) { 141 if (null == obj) { 142 throw new NullPointerException("Argument must not be null"); 143 } else if (obj instanceof Collection<?>) { 144 return new RightBoundPredicate<A>(new IsElementOf<A, Object>(), obj); 145 } else if (obj.getClass().isArray()) { 146 return new RightBoundPredicate<A>(new IsElementOf<A, Object>(), obj); 147 } else { 148 throw new IllegalArgumentException("Expected Collection or Array, found " + obj.getClass()); 149 } 150 } 151 152}