    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.FunctorException;
    023import org.apache.commons.collections4.Predicate;
    024import org.apache.commons.collections4.Transformer;
    025
    026/**
    027 * Predicate implementation that returns the result of a transformer.
    028 *
    029 * @param <T> the type of the input to the predicate.
    030 * @since 3.0
    031 */
    032public final class TransformerPredicate<T> extends AbstractPredicate<T> implements Serializable {
    033
    034    /** Serial version UID */
    035    private static final long serialVersionUID = -2407966402920578741L;
    036
    037    /**
    038     * Creates the predicate.
    039     *
    040     * @param <T> the type that the predicate queries
    041     * @param transformer  the transformer to decorate
    042     * @return the predicate
    043     * @throws NullPointerException if the transformer is null
    044     */
    045    public static <T> Predicate<T> transformerPredicate(final Transformer<? super T, Boolean> transformer) {
    046        return new TransformerPredicate<>(Objects.requireNonNull(transformer, "transformer"));
    047    }
    048
    049    /** The transformer to call */
    050    private final Transformer<? super T, Boolean> iTransformer;
    051
    052    /**
    053     * Constructor that performs no validation.
    054     * Use {@code transformerPredicate} if you want that.
    055     *
    056     * @param transformer  the transformer to decorate
    057     */
    058    public TransformerPredicate(final Transformer<? super T, Boolean> transformer) {
    059        iTransformer = transformer;
    060    }
    061
    062    /**
    063     * Gets the transformer.
    064     *
    065     * @return the transformer
    066     * @since 3.1
    067     */
    068    public Transformer<? super T, Boolean> getTransformer() {
    069        return iTransformer;
    070    }
    071
    072    /**
    073     * Evaluates the predicate returning the result of the decorated transformer.
    074     *
    075     * @param object  the input object
    076     * @return true if decorated transformer returns Boolean.TRUE
    077     * @throws FunctorException if the transformer returns an invalid type
    078     */
    079    @Override
    080    public boolean test(final T object) {
    081        final Boolean result = iTransformer.apply(object);
    082        if (result == null) {
    083            throw new FunctorException(
    084                    "Transformer must return an instanceof Boolean, it was a null object");
    085        }
    086        return result.booleanValue();
    087    }
    088
    089}