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.DoubleUnaryOperator;
22
23 /**
24 * A functional interface like {@link DoubleUnaryOperator} that declares a {@link Throwable}.
25 *
26 * @param <E> The kind of thrown exception or error.
27 * @since 3.11
28 */
29 public interface FailableDoubleUnaryOperator<E extends Throwable> {
30
31 /** NOP singleton */
32 @SuppressWarnings("rawtypes")
33 FailableDoubleUnaryOperator NOP = t -> 0d;
34
35 /**
36 * Returns a unary operator that always returns its input argument.
37 *
38 * @param <E> The kind of thrown exception or error.
39 * @return a unary operator that always returns its input argument
40 */
41 static <E extends Throwable> FailableDoubleUnaryOperator<E> identity() {
42 return t -> t;
43 }
44
45 /**
46 * Returns The NOP singleton.
47 *
48 * @param <E> The kind of thrown exception or error.
49 * @return The NOP singleton.
50 */
51 @SuppressWarnings("unchecked")
52 static <E extends Throwable> FailableDoubleUnaryOperator<E> nop() {
53 return NOP;
54 }
55
56 /**
57 * Returns a composed {@link FailableDoubleUnaryOperator} like
58 * {@link DoubleUnaryOperator#andThen(DoubleUnaryOperator)}.
59 *
60 * @param after the operator to apply after this one.
61 * @return a composed {@link FailableDoubleUnaryOperator} like
62 * {@link DoubleUnaryOperator#andThen(DoubleUnaryOperator)}.
63 * @throws NullPointerException if after is null.
64 * @see #compose(FailableDoubleUnaryOperator)
65 */
66 default FailableDoubleUnaryOperator<E> andThen(final FailableDoubleUnaryOperator<E> after) {
67 Objects.requireNonNull(after);
68 return (final double t) -> after.applyAsDouble(applyAsDouble(t));
69 }
70
71 /**
72 * Applies this operator to the given operand.
73 *
74 * @param operand the operand
75 * @return the operator result
76 * @throws E Thrown when a consumer fails.
77 */
78 double applyAsDouble(double operand) throws E;
79
80 /**
81 * Returns a composed {@link FailableDoubleUnaryOperator} like
82 * {@link DoubleUnaryOperator#compose(DoubleUnaryOperator)}.
83 *
84 * @param before the operator to apply before this one.
85 * @return a composed {@link FailableDoubleUnaryOperator} like
86 * {@link DoubleUnaryOperator#compose(DoubleUnaryOperator)}.
87 * @throws NullPointerException if before is null.
88 * @see #andThen(FailableDoubleUnaryOperator)
89 */
90 default FailableDoubleUnaryOperator<E> compose(final FailableDoubleUnaryOperator<E> before) {
91 Objects.requireNonNull(before);
92 return (final double v) -> applyAsDouble(before.applyAsDouble(v));
93 }
94 }