    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 *      https://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
    020/**
    021 * A functional interface like a {@code ToBooleanFunction} that declares a {@link Throwable}.
    022 *
    023 * @param <T> the type of the argument to the function
    024 * @param <E> The kind of thrown exception or error.
    025 * @since 3.18
    026 */
    027@FunctionalInterface
    028public interface FailableToBooleanFunction<T, E extends Throwable> {
    029
    030    /** NOP singleton */
    031    @SuppressWarnings("rawtypes")
    032    FailableToBooleanFunction NOP = t -> false;
    033
    034    /**
    035     * Gets the NOP singleton.
    036     *
    037     * @param <T> the type of the argument to the function
    038     * @param <E> The kind of thrown exception or error.
    039     * @return The NOP singleton.
    040     */
    041    @SuppressWarnings("unchecked")
    042    static <T, E extends Throwable> FailableToBooleanFunction<T, E> nop() {
    043        return NOP;
    044    }
    045
    046    /**
    047     * Applies this function to the given arguments.
    048     *
    049     * @param t the first function argument
    050     * @return the function result
    051     * @throws E Thrown when the function fails.
    052     */
    053    boolean applyAsBoolean(T t) throws E;
    054}