    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}