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.function.ToDoubleBiFunction;
021
022/**
023 * A functional interface like {@link ToDoubleBiFunction} that declares a {@link Throwable}.
024 *
025 * @param <T> the type of the first argument to the function
026 * @param <U> the type of the second argument to the function
027 * @param <E> The kind of thrown exception or error.
028 * @since 3.11
029 */
030@FunctionalInterface
031public interface FailableToDoubleBiFunction<T, U, E extends Throwable> {
032
033    /** NOP singleton */
034    @SuppressWarnings("rawtypes")
035    FailableToDoubleBiFunction NOP = (t, u) -> 0d;
036
037    /**
038     * Returns The NOP singleton.
039     *
040     * @param <T> the type of the first argument to the function
041     * @param <U> the type of the second argument to the function
042     * @param <E> The kind of thrown exception or error.
043     * @return The NOP singleton.
044     */
045    @SuppressWarnings("unchecked")
046    static <T, U, E extends Throwable> FailableToDoubleBiFunction<T, U, E> nop() {
047        return NOP;
048    }
049
050    /**
051     * Applies this function to the given arguments.
052     *
053     * @param t the first function argument
054     * @param u the second function argument
055     * @return the function result
056     * @throws E Thrown when the function fails.
057     */
058    double applyAsDouble(T t, U u) throws E;
059}