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.collections4.functors; 018 019import java.io.Serializable; 020 021import org.apache.commons.collections4.Predicate; 022import org.apache.commons.collections4.Transformer; 023 024/** 025 * Transformer implementation that calls a Predicate using the input object 026 * and then returns the result. 027 * 028 * @since 3.0 029 */ 030public class PredicateTransformer<T> implements Transformer<T, Boolean>, Serializable { 031 032 /** Serial version UID */ 033 private static final long serialVersionUID = 5278818408044349346L; 034 035 /** 036 * Factory method that performs validation. 037 * 038 * @param <T> the input type 039 * @param predicate the predicate to call, not null 040 * @return the {@code predicate} transformer 041 * @throws IllegalArgumentException if the predicate is null 042 */ 043 public static <T> Transformer<T, Boolean> predicateTransformer(final Predicate<? super T> predicate) { 044 if (predicate == null) { 045 throw new IllegalArgumentException("Predicate must not be null"); 046 } 047 return new PredicateTransformer<>(predicate); 048 } 049 050 /** The closure to wrap */ 051 private final Predicate<? super T> iPredicate; 052 053 /** 054 * Constructor that performs no validation. 055 * Use {@code predicateTransformer} if you want that. 056 * 057 * @param predicate the predicate to call, not null 058 */ 059 public PredicateTransformer(final Predicate<? super T> predicate) { 060 iPredicate = predicate; 061 } 062 063 /** 064 * Gets the predicate. 065 * 066 * @return the predicate 067 * @since 3.1 068 */ 069 public Predicate<? super T> getPredicate() { 070 return iPredicate; 071 } 072 073 /** 074 * Transforms the input to result by calling a predicate. 075 * 076 * @param input the input object to transform 077 * @return the transformed result 078 */ 079 @Override 080 public Boolean transform(final T input) { 081 return Boolean.valueOf(iPredicate.evaluate(input)); 082 } 083 084}