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    /** The closure to wrap */
036    private final Predicate<? super T> iPredicate;
037
038    /**
039     * Factory method that performs validation.
040     *
041     * @param <T>  the input type
042     * @param predicate  the predicate to call, not null
043     * @return the <code>predicate</code> transformer
044     * @throws IllegalArgumentException if the predicate is null
045     */
046    public static <T> Transformer<T, Boolean> predicateTransformer(final Predicate<? super T> predicate) {
047        if (predicate == null) {
048            throw new IllegalArgumentException("Predicate must not be null");
049        }
050        return new PredicateTransformer<>(predicate);
051    }
052
053    /**
054     * Constructor that performs no validation.
055     * Use <code>predicateTransformer</code> if you want that.
056     *
057     * @param predicate  the predicate to call, not null
058     */
059    public PredicateTransformer(final Predicate<? super T> predicate) {
060        super();
061        iPredicate = predicate;
062    }
063
064    /**
065     * Transforms the input to result by calling a predicate.
066     *
067     * @param input  the input object to transform
068     * @return the transformed result
069     */
070    @Override
071    public Boolean transform(final T input) {
072        return Boolean.valueOf(iPredicate.evaluate(input));
073    }
074
075    /**
076     * Gets the predicate.
077     *
078     * @return the predicate
079     * @since 3.1
080     */
081    public Predicate<? super T> getPredicate() {
082        return iPredicate;
083    }
084
085}