1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.lang3.function;
19
20 import java.util.Objects;
21 import java.util.function.BiFunction;
22 import java.util.function.Function;
23
24 /**
25 * A functional interface like {@link BiFunction} that declares a {@link Throwable}.
26 *
27 * @param <T> Input type 1.
28 * @param <U> Input type 2.
29 * @param <R> Return type.
30 * @param <E> The kind of thrown exception or error.
31 * @since 3.11
32 */
33 @FunctionalInterface
34 public interface FailableBiFunction<T, U, R, E extends Throwable> {
35
36 /** NOP singleton */
37 @SuppressWarnings("rawtypes")
38 FailableBiFunction NOP = (t, u) -> null;
39
40 /**
41 * Returns The NOP singleton.
42 *
43 * @param <T> Consumed type 1.
44 * @param <U> Consumed type 2.
45 * @param <R> Return type.
46 * @param <E> The kind of thrown exception or error.
47 * @return The NOP singleton.
48 */
49 @SuppressWarnings("unchecked")
50 static <T, U, R, E extends Throwable> FailableBiFunction<T, U, R, E> nop() {
51 return NOP;
52 }
53
54 /**
55 * Returns a composed {@link FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
56 *
57 * @param <V> the output type of the {@code after} function, and of the composed function.
58 * @param after the operation to perform after this one.
59 * @return a composed {@link FailableBiFunction} that like {@link BiFunction#andThen(Function)}.
60 * @throws NullPointerException when {@code after} is null.
61 */
62 default <V> FailableBiFunction<T, U, V, E> andThen(final FailableFunction<? super R, ? extends V, E> after) {
63 Objects.requireNonNull(after);
64 return (final T t, final U u) -> after.apply(apply(t, u));
65 }
66
67 /**
68 * Applies this function.
69 *
70 * @param input1 the first input for the function
71 * @param input2 the second input for the function
72 * @return the result of the function
73 * @throws E Thrown when the function fails.
74 */
75 R apply(T input1, U input2) throws E;
76 }