    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 * @param <T> the type of the input to the predicate.
    030 * @since 3.1
    031 */
    032public final class TransformedPredicate<T> extends AbstractPredicate<T> implements PredicateDecorator<T>, Serializable {
    033
    034    /** Serial version UID */
    035    private static final long serialVersionUID = -5596090919668315834L;
    036
    037    /**
    038     * Creates the predicate.
    039     *
    040     * @param <T> the type that the predicate queries
    041     * @param transformer  the transformer to call
    042     * @param predicate  the predicate to call with the result of the transform
    043     * @return the predicate
    044     * @throws NullPointerException if the transformer or the predicate is null
    045     */
    046    public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer,
    047                                                        final Predicate<? super T> predicate) {
    048        return new TransformedPredicate<>(Objects.requireNonNull(transformer, "transformer"),
    049                Objects.requireNonNull(predicate, "predicate"));
    050    }
    051
    052    /** The transformer to call */
    053    private final Transformer<? super T, ? extends T> iTransformer;
    054
    055    /** The predicate to call */
    056    private final Predicate<? super T> iPredicate;
    057
    058    /**
    059     * Constructor that performs no validation.
    060     * Use {@code transformedPredicate} if you want that.
    061     *
    062     * @param transformer  the transformer to use
    063     * @param predicate  the predicate to decorate
    064     */
    065    public TransformedPredicate(final Transformer<? super T, ? extends T> transformer,
    066                                final Predicate<? super T> predicate) {
    067        iTransformer = transformer;
    068        iPredicate = predicate;
    069    }
    070
    071    /**
    072     * Gets the predicate being decorated.
    073     *
    074     * @return the predicate as the only element in an array
    075     * @since 3.1
    076     */
    077    @Override
    078    @SuppressWarnings("unchecked")
    079    public Predicate<? super T>[] getPredicates() {
    080        return new Predicate[] {iPredicate};
    081    }
    082
    083    /**
    084     * Gets the transformer in use.
    085     *
    086     * @return the transformer
    087     */
    088    public Transformer<? super T, ? extends T> getTransformer() {
    089        return iTransformer;
    090    }
    091
    092    /**
    093     * Evaluates the predicate returning the result of the decorated predicate
    094     * once the input has been transformed
    095     *
    096     * @param object  the input object which will be transformed
    097     * @return true if decorated predicate returns true
    098     */
    099    @Override
    100    public boolean test(final T object) {
    101        final T result = iTransformer.apply(object);
    102        return iPredicate.test(result);
    103    }
    104
    105}