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; 020import java.util.Objects; 021 022import org.apache.commons.collections4.Predicate; 023import org.apache.commons.collections4.Transformer; 024 025/** 026 * Predicate implementation that transforms the given object before invoking 027 * another {@code Predicate}. 028 * 029 * @since 3.1 030 */ 031public final class TransformedPredicate<T> implements PredicateDecorator<T>, Serializable { 032 033 /** Serial version UID */ 034 private static final long serialVersionUID = -5596090919668315834L; 035 036 /** 037 * Factory to create the predicate. 038 * 039 * @param <T> the type that the predicate queries 040 * @param transformer the transformer to call 041 * @param predicate the predicate to call with the result of the transform 042 * @return the predicate 043 * @throws NullPointerException if the transformer or the predicate is null 044 */ 045 public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer, 046 final Predicate<? super T> predicate) { 047 return new TransformedPredicate<>(Objects.requireNonNull(transformer, "transformer"), 048 Objects.requireNonNull(predicate, "predicate")); 049 } 050 051 /** The transformer to call */ 052 private final Transformer<? super T, ? extends T> iTransformer; 053 054 /** The predicate to call */ 055 private final Predicate<? super T> iPredicate; 056 057 /** 058 * Constructor that performs no validation. 059 * Use {@code transformedPredicate} if you want that. 060 * 061 * @param transformer the transformer to use 062 * @param predicate the predicate to decorate 063 */ 064 public TransformedPredicate(final Transformer<? super T, ? extends T> transformer, 065 final Predicate<? super T> predicate) { 066 iTransformer = transformer; 067 iPredicate = predicate; 068 } 069 070 /** 071 * Evaluates the predicate returning the result of the decorated predicate 072 * once the input has been transformed 073 * 074 * @param object the input object which will be transformed 075 * @return true if decorated predicate returns true 076 */ 077 @Override 078 public boolean evaluate(final T object) { 079 final T result = iTransformer.transform(object); 080 return iPredicate.evaluate(result); 081 } 082 083 /** 084 * Gets the predicate being decorated. 085 * 086 * @return the predicate as the only element in an array 087 * @since 3.1 088 */ 089 @Override 090 @SuppressWarnings("unchecked") 091 public Predicate<? super T>[] getPredicates() { 092 return new Predicate[] {iPredicate}; 093 } 094 095 /** 096 * Gets the transformer in use. 097 * 098 * @return the transformer 099 */ 100 public Transformer<? super T, ? extends T> getTransformer() { 101 return iTransformer; 102 } 103 104}