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;
024
025/**
026 * Predicate implementation that throws an exception if the input is null.
027 *
028 * @param <T> the type of the input to the predicate.
029 * @since 3.0
030 */
031public final class NullIsExceptionPredicate<T> extends AbstractPredicate<T> implements PredicateDecorator<T>, Serializable {
032
033    /** Serial version UID */
034    private static final long serialVersionUID = 3243449850504576071L;
035
036    /**
037     * Creates the null exception predicate.
038     *
039     * @param <T> the type that the predicate queries
040     * @param predicate  the predicate to decorate, not null
041     * @return the predicate
042     * @throws NullPointerException if the predicate is null
043     */
044    public static <T> Predicate<T> nullIsExceptionPredicate(final Predicate<? super T> predicate) {
045        return new NullIsExceptionPredicate<>(Objects.requireNonNull(predicate, "predicate"));
046    }
047
048    /** The predicate to decorate */
049    private final Predicate<? super T> iPredicate;
050
051    /**
052     * Constructor that performs no validation.
053     * Use {@code nullIsExceptionPredicate} if you want that.
054     *
055     * @param predicate  the predicate to call after the null check
056     */
057    public NullIsExceptionPredicate(final Predicate<? super T> predicate) {
058        iPredicate = predicate;
059    }
060
061    /**
062     * Gets the predicate being decorated.
063     *
064     * @return the predicate as the only element in an array
065     * @since 3.1
066     */
067    @Override
068    @SuppressWarnings("unchecked")
069    public Predicate<? super T>[] getPredicates() {
070        return new Predicate[] { iPredicate };
071    }
072
073    /**
074     * Evaluates the predicate returning the result of the decorated predicate
075     * once a null check is performed.
076     *
077     * @param object  the input object
078     * @return true if decorated predicate returns true
079     * @throws FunctorException if input is null
080     */
081    @Override
082    public boolean test(final T object) {
083        if (object == null) {
084            throw new FunctorException("Input Object must not be null");
085        }
086        return iPredicate.test(object);
087    }
088
089}