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.Predicate;
22
23 /**
24 * A functional interface like {@link Predicate} that declares a {@link Throwable}.
25 *
26 * @param <T> Predicate type.
27 * @param <E> The kind of thrown exception or error.
28 * @since 3.11
29 */
30 @FunctionalInterface
31 public interface FailablePredicate<T, E extends Throwable> {
32
33 /** FALSE singleton */
34 @SuppressWarnings("rawtypes")
35 FailablePredicate FALSE = t -> false;
36
37 /** TRUE singleton */
38 @SuppressWarnings("rawtypes")
39 FailablePredicate TRUE = t -> true;
40
41 /**
42 * Returns The FALSE singleton.
43 *
44 * @param <T> Predicate type.
45 * @param <E> The kind of thrown exception or error.
46 * @return The NOP singleton.
47 */
48 @SuppressWarnings("unchecked")
49 static <T, E extends Throwable> FailablePredicate<T, E> falsePredicate() {
50 return FALSE;
51 }
52
53 /**
54 * Returns The TRUE singleton.
55 *
56 * @param <T> Predicate type.
57 * @param <E> The kind of thrown exception or error.
58 * @return The NOP singleton.
59 */
60 @SuppressWarnings("unchecked")
61 static <T, E extends Throwable> FailablePredicate<T, E> truePredicate() {
62 return TRUE;
63 }
64
65 /**
66 * Returns a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
67 *
68 * @param other a predicate that will be logically-ANDed with this predicate.
69 * @return a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
70 * @throws NullPointerException if other is null
71 */
72 default FailablePredicate<T, E> and(final FailablePredicate<? super T, E> other) {
73 Objects.requireNonNull(other);
74 return t -> test(t) && other.test(t);
75 }
76
77 /**
78 * Returns a predicate that negates this predicate.
79 *
80 * @return a predicate that negates this predicate.
81 */
82 default FailablePredicate<T, E> negate() {
83 return t -> !test(t);
84 }
85
86 /**
87 * Returns a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
88 *
89 * @param other a predicate that will be logically-ORed with this predicate.
90 * @return a composed {@link FailablePredicate} like {@link Predicate#and(Predicate)}.
91 * @throws NullPointerException if other is null
92 */
93 default FailablePredicate<T, E> or(final FailablePredicate<? super T, E> other) {
94 Objects.requireNonNull(other);
95 return t -> test(t) || other.test(t);
96 }
97
98 /**
99 * Tests the predicate.
100 *
101 * @param object the object to test the predicate on
102 * @return the predicate's evaluation
103 * @throws E if the predicate fails
104 */
105 boolean test(T object) throws E;
106 }