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 {@link Throwable}.
025 *
026 * @param <T> Predicate type.
027 * @param <E> The kind of thrown exception or error.
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> The kind of thrown exception or error.
046     * @return The NOP singleton.
047     */
048    @SuppressWarnings("unchecked")
049    static <T, E extends Throwable> FailablePredicate<T, E> falsePredicate() {
050        return FALSE;
051    }
052
053    /**
054     * Returns The TRUE singleton.
055     *
056     * @param <T> Predicate type.
057     * @param <E> The kind of thrown exception or error.
058     * @return The NOP singleton.
059     */
060    @SuppressWarnings("unchecked")
061    static <T, E extends Throwable> FailablePredicate<T, E> truePredicate() {
062        return TRUE;
063    }
064
065    /**
066     * Returns a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
067     *
068     * @param other a predicate that will be logically-ANDed with this predicate.
069     * @return a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
070     * @throws NullPointerException if other is null
071     */
072    default FailablePredicate<T, E> and(final FailablePredicate<? super T, E> other) {
073        Objects.requireNonNull(other);
074        return t -> test(t) && other.test(t);
075    }
076
077    /**
078     * Returns a predicate that negates this predicate.
079     *
080     * @return a predicate that negates this predicate.
081     */
082    default FailablePredicate<T, E> negate() {
083        return t -> !test(t);
084    }
085
086    /**
087     * Returns a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
088     *
089     * @param other a predicate that will be logically-ORed with this predicate.
090     * @return a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
091     * @throws NullPointerException if other is null
092     */
093    default FailablePredicate<T, E> or(final FailablePredicate<? super T, E> other) {
094        Objects.requireNonNull(other);
095        return t -> test(t) || other.test(t);
096    }
097
098    /**
099     * Tests the predicate.
100     *
101     * @param object the object to test the predicate on
102     * @return the predicate's evaluation
103     * @throws E if the predicate fails
104     */
105    boolean test(T object) throws E;
106}