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
020import java.util.Objects;
021import java.util.function.Consumer;
022import java.util.function.Function;
023
024/**
025 * A functional interface like {@link Consumer} that declares a {@link Throwable}.
026 *
027 * <p>
028 * This is a functional interface whose functional method is {@link #accept(Object)}.
029 * </p>
030 *
031 * @param <T> The type of the argument the consumer accepts.
032 * @param <E> The thrown exception type.
033 * @since 3.11
034 */
035@FunctionalInterface
036public interface FailableConsumer<T, E extends Throwable> {
037
038    /** NOP singleton */
039    @SuppressWarnings("rawtypes")
040    FailableConsumer NOP = Function.identity()::apply;
041
042    /**
043     * Applies the given {@link FailableConsumer} action to the object if the consumer is not {@code null}. Otherwise, does nothing.
044     *
045     * @param consumer The consumer to consume.
046     * @param object   The object to be consumed.
047     * @param <T>      the type of the argument the consumer accepts.
048     * @param <E>      The thrown exception type.
049     * @throws E Thrown when the consumer fails.
050     * @since 3.21.0
051     */
052    static <T, E extends Throwable> void accept(final FailableConsumer<T, E> consumer, final T object) throws E {
053        if (consumer != null) {
054            consumer.accept(object);
055        }
056    }
057
058    /**
059     * Gets the NOP singleton.
060     *
061     * @param <T> The type of the argument the consumer accepts.
062     * @param <E> The thrown exception type.
063     * @return The NOP singleton.
064     */
065    @SuppressWarnings("unchecked")
066    static <T, E extends Throwable> FailableConsumer<T, E> nop() {
067        return NOP;
068    }
069
070    /**
071     * Accepts the given arguments.
072     *
073     * @param object The parameter for the consumable to accept
074     * @throws E Thrown when the consumer fails.
075     */
076    void accept(T object) throws E;
077
078    /**
079     * Returns a composed {@link Consumer} like {@link Consumer#andThen(Consumer)}.
080     *
081     * @param after The operation to perform after this operation
082     * @return A composed {@link Consumer} like {@link Consumer#andThen(Consumer)}.
083     * @throws NullPointerException Thrown when {@code after} is null.
084     */
085    default FailableConsumer<T, E> andThen(final FailableConsumer<? super T, E> after) {
086        Objects.requireNonNull(after, "after");
087        return (final T t) -> {
088            accept(t);
089            after.accept(t);
090        };
091    }
092}