    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.BiFunction;
    022import java.util.function.Function;
    023
    024/**
    025 * A functional interface like {@link BiFunction} that declares a {@code Throwable}.
    026 *
    027 * @param <T> Input type 1.
    028 * @param <U> Input type 2.
    029 * @param <R> Return type.
    030 * @param <E> Thrown exception.
    031 * @since 3.11
    032 */
    033@FunctionalInterface
    034public interface FailableBiFunction<T, U, R, E extends Throwable> {
    035
    036    /** NOP singleton */
    037    @SuppressWarnings("rawtypes")
    038    FailableBiFunction NOP = (t, u) -> null;
    039
    040    /**
    041     * Returns The NOP singleton.
    042     *
    043     * @param <T> Consumed type 1.
    044     * @param <U> Consumed type 2.
    045     * @param <R> Return type.
    046     * @param <E> Thrown exception.
    047     * @return The NOP singleton.
    048     */
    049    static <T, U, R, E extends Throwable> FailableBiFunction<T, U, R, E> nop() {
    050        return NOP;
    051    }
    052
    053    /**
    054     * Returns a composed {@code FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
    055     *
    056     * @param <V> the output type of the {@code after} function, and of the composed function.
    057     * @param after the operation to perform after this one.
    058     * @return a composed {@code FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
    059     * @throws NullPointerException when {@code after} is null.
    060     */
    061    default <V> FailableBiFunction<T, U, V, E> andThen(final FailableFunction<? super R, ? extends V, E> after) {
    062        Objects.requireNonNull(after);
    063        return (final T t, final U u) -> after.apply(apply(t, u));
    064    }
    065
    066    /**
    067     * Applies this function.
    068     *
    069     * @param input1 the first input for the function
    070     * @param input2 the second input for the function
    071     * @return the result of the function
    072     * @throws E Thrown when the function fails.
    073     */
    074    R apply(T input1, U input2) throws E;
    075}