    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}