    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 */
    017
    018package org.apache.commons.lang3.function;
    019
    020import java.util.Objects;
    021import java.util.function.Predicate;
    022
    023/**
    024 * A functional interface like {@link Predicate} that declares a {@code Throwable}.
    025 *
    026 * @param <T> Predicate type.
    027 * @param <E> Thrown exception.
    028 * @since 3.11
    029 */
    030@FunctionalInterface
    031public interface FailablePredicate<T, E extends Throwable> {
    032
    033    /** FALSE singleton */
    034    @SuppressWarnings("rawtypes")
    035    FailablePredicate FALSE = t -> false;
    036
    037    /** TRUE singleton */
    038    @SuppressWarnings("rawtypes")
    039    FailablePredicate TRUE = t -> true;
    040
    041    /**
    042     * Returns The FALSE singleton.
    043     *
    044     * @param <T> Predicate type.
    045     * @param <E> Thrown exception.
    046     * @return The NOP singleton.
    047     */
    048    static <T, E extends Throwable> FailablePredicate<T, E> falsePredicate() {
    049        return FALSE;
    050    }
    051
    052    /**
    053     * Returns The FALSE TRUE.
    054     *
    055     * @param <T> Predicate type.
    056     * @param <E> Thrown exception.
    057     * @return The NOP singleton.
    058     */
    059    static <T, E extends Throwable> FailablePredicate<T, E> truePredicate() {
    060        return TRUE;
    061    }
    062
    063    /**
    064     * Returns a composed {@code FailablePredicate} like {@link Predicate#and(Predicate)}.
    065     *
    066     * @param other a predicate that will be logically-ANDed with this predicate.
    067     * @return a composed {@code FailablePredicate} like {@link Predicate#and(Predicate)}.
    068     * @throws NullPointerException if other is null
    069     */
    070    default FailablePredicate<T, E> and(final FailablePredicate<? super T, E> other) {
    071        Objects.requireNonNull(other);
    072        return t -> test(t) && other.test(t);
    073    }
    074
    075    /**
    076     * Returns a predicate that negates this predicate.
    077     *
    078     * @return a predicate that negates this predicate.
    079     */
    080    default FailablePredicate<T, E> negate() {
    081        return t -> !test(t);
    082    }
    083
    084    /**
    085     * Returns a composed {@code FailablePredicate} like {@link Predicate#and(Predicate)}.
    086     *
    087     * @param other a predicate that will be logically-ORed with this predicate.
    088     * @return a composed {@code FailablePredicate} like {@link Predicate#and(Predicate)}.
    089     * @throws NullPointerException if other is null
    090     */
    091    default FailablePredicate<T, E> or(final FailablePredicate<? super T, E> other) {
    092        Objects.requireNonNull(other);
    093        return t -> test(t) || other.test(t);
    094    }
    095
    096    /**
    097     * Tests the predicate.
    098     *
    099     * @param object the object to test the predicate on
    100     * @return the predicate's evaluation
    101     * @throws E if the predicate fails
    102     */
    103    boolean test(T object) throws E;
    104}