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}