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; 18 19 import org.apache.commons.functor.BinaryFunction; 20 import org.apache.commons.functor.BinaryPredicate; 21 import org.apache.commons.functor.adapter.BinaryFunctionBinaryPredicate; 22 import org.apache.commons.functor.adapter.IgnoreLeftFunction; 23 24 /** 25 * Holder class for a right-identity <code>BinaryFunction</code> (evaluates to the right argument) and a right-identity 26 * <code>BinaryPredicate</code> (tests whether right <code>Boolean</code> argument equals <code>Boolean.TRUE</code>). 27 * 28 * @version $Revision: 1160415 $ $Date: 2011-08-22 22:14:38 +0200 (Mon, 22 Aug 2011) $ 29 * @author Rodney Waldhoff 30 * @author Matt Benson 31 */ 32 public final class RightIdentity { 33 34 // static attributes 35 // ------------------------------------------------------------------------ 36 /** 37 * Right-identity function. 38 */ 39 public static final BinaryFunction<Object, Object, Object> FUNCTION = RightIdentity.<Object, Object>function(); 40 41 /** 42 * Right-identity predicate. 43 */ 44 public static final BinaryPredicate<Object, Boolean> PREDICATE = 45 BinaryFunctionBinaryPredicate.adapt(IgnoreLeftFunction.adapt(new Identity<Boolean>())); 46 47 // constructor 48 // ------------------------------------------------------------------------ 49 /** 50 * Create a new RightIdentity. 51 */ 52 public RightIdentity() { 53 } 54 55 // static methods 56 // ------------------------------------------------------------------------ 57 58 /** 59 * Get a typed right-identity BinaryFunction. 60 * @param <L> the left argument type. 61 * @param <R> the right argument type. 62 * @return BinaryFunction<L, R, R> 63 */ 64 public static <L, R> BinaryFunction<L, R, R> function() { 65 return IgnoreLeftFunction.adapt(new Identity<R>()); 66 } 67 68 /** 69 * Get a typed right-identity BinaryPredicate. 70 * @param <L> the left argument type. 71 * @return BinaryPredicate<L, Boolean> 72 */ 73 public static <L> BinaryPredicate<L, Boolean> predicate() { 74 return BinaryFunctionBinaryPredicate.adapt( 75 IgnoreLeftFunction.<L, Boolean, Boolean>adapt(new Identity<Boolean>())); 76 } 77 }