    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 * Predicate implementation that transforms the given object before invoking
    026 * another <code>Predicate</code>.
    027 *
    028 * @since 3.1
    029 */
    030public final class TransformedPredicate<T> implements PredicateDecorator<T>, Serializable {
    031
    032    /** Serial version UID */
    033    private static final long serialVersionUID = -5596090919668315834L;
    034
    035    /** The transformer to call */
    036    private final Transformer<? super T, ? extends T> iTransformer;
    037
    038    /** The predicate to call */
    039    private final Predicate<? super T> iPredicate;
    040
    041    /**
    042     * Factory to create the predicate.
    043     *
    044     * @param <T> the type that the predicate queries
    045     * @param transformer  the transformer to call
    046     * @param predicate  the predicate to call with the result of the transform
    047     * @return the predicate
    048     * @throws NullPointerException if the transformer or the predicate is null
    049     */
    050    public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer,
    051                                                        final Predicate<? super T> predicate) {
    052        if (transformer == null) {
    053            throw new NullPointerException("The transformer to call must not be null");
    054        }
    055        if (predicate == null) {
    056            throw new NullPointerException("The predicate to call must not be null");
    057        }
    058        return new TransformedPredicate<>(transformer, predicate);
    059    }
    060
    061    /**
    062     * Constructor that performs no validation.
    063     * Use <code>transformedPredicate</code> if you want that.
    064     *
    065     * @param transformer  the transformer to use
    066     * @param predicate  the predicate to decorate
    067     */
    068    public TransformedPredicate(final Transformer<? super T, ? extends T> transformer,
    069                                final Predicate<? super T> predicate) {
    070        iTransformer = transformer;
    071        iPredicate = predicate;
    072    }
    073
    074    /**
    075     * Evaluates the predicate returning the result of the decorated predicate
    076     * once the input has been transformed
    077     *
    078     * @param object  the input object which will be transformed
    079     * @return true if decorated predicate returns true
    080     */
    081    @Override
    082    public boolean evaluate(final T object) {
    083        final T result = iTransformer.transform(object);
    084        return iPredicate.evaluate(result);
    085    }
    086
    087    /**
    088     * Gets the predicate being decorated.
    089     *
    090     * @return the predicate as the only element in an array
    091     * @since 3.1
    092     */
    093    @Override
    094    @SuppressWarnings("unchecked")
    095    public Predicate<? super T>[] getPredicates() {
    096        return new Predicate[] {iPredicate};
    097    }
    098
    099    /**
    100     * Gets the transformer in use.
    101     *
    102     * @return the transformer
    103     */
    104    public Transformer<? super T, ? extends T> getTransformer() {
    105        return iTransformer;
    106    }
    107
    108}