1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
/*
* Copyright (C) 2014-2021 Brian L. Browning
*
* This file is part of Beagle
*
* Beagle is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Beagle is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package blbutil;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
/**
* <p>A filter for accepting or rejecting objects.
* </p>
* Instances of class {@code Filter} are required to be immutable.
*
* @param <E> the type of object that is filtered.
*
* @author Brian L. Browning {@code <browning@uw.edu>}
*/
public interface Filter<E> {
/**
* Returns a filter that accepts all non-null objects.
* @param <E> the type of object that is filtered
* @return a filter that accepts all non-null objects
*/
static <E> Filter<E> acceptAllFilter() {
return (E e) -> {
if (e == null) {
throw new NullPointerException("e==null");
}
return true;
};
}
/**
* Returns a filter that accepts all non-null objects that are
* contained in the specified collection.
* @param <E> the type of object that is filtered
* @param include the collection of objects that will be accepted by
* the filter
* @return a filter that accepts all non-null objects that are
* contained in the specified collection
* @throws NullPointerException if {@code include == null}
*/
static <E> Filter<E> includeFilter(Collection<E> include) {
final Set<E> includeSet = new HashSet<>(include);
return (E e) -> {
if (e == null) {
throw new NullPointerException("e==null");
}
return includeSet.contains(e);
};
}
/**
* Returns a filter that accepts all non-null objects that are not
* contained in the specified collection.
* @param <E> the type of object that is filtered
* @param exclude the collection of objects that will be rejected
* by the filter
* @return a filter that accepts all non-null objects that are not
* contained in the specified collection
* @throws NullPointerException if {@code exclude == null}
*/
static <E> Filter<E> excludeFilter(Collection<E> exclude) {
final Set<E> excludeSet = new HashSet<>(exclude);
return (E e) -> {
if (e == null) {
throw new NullPointerException("e==null");
}
return excludeSet.contains(e)==false;
};
}
/**
* Returns {@code true} if the specified object is
* accepted and returns {@code false} if the specified object
* is rejected.
* @param e the object to be filtered
* @return {@code true} if the specified object is
* accepted
* @throws NullPointerException if {@code e==null}
*/
boolean accept(E e);
}
|
