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 package org.apache.hc.core5.http.protocol;
29
30 import java.util.Collection;
31 import java.util.HashMap;
32 import java.util.LinkedList;
33 import java.util.Map;
34
35
36
37
38
39
40
41
42
43 final class ChainBuilder<E> {
44
45 private final LinkedList<E> list;
46 private final Map<Class<?>, E> uniqueClasses;
47
48 public ChainBuilder() {
49 this.list = new LinkedList<>();
50 this.uniqueClasses = new HashMap<>();
51 }
52
53 private void ensureUnique(final E e) {
54 final E previous = this.uniqueClasses.remove(e.getClass());
55 if (previous != null) {
56 this.list.remove(previous);
57 }
58 this.uniqueClasses.put(e.getClass(), e);
59 }
60
61 public ChainBuilder<E> addFirst(final E e) {
62 if (e == null) {
63 return this;
64 }
65 ensureUnique(e);
66 this.list.addFirst(e);
67 return this;
68 }
69
70 public ChainBuilder<E> addLast(final E e) {
71 if (e == null) {
72 return this;
73 }
74 ensureUnique(e);
75 this.list.addLast(e);
76 return this;
77 }
78
79 public ChainBuilder<E> addAllFirst(final Collection<E> c) {
80 if (c == null) {
81 return this;
82 }
83 for (final E e: c) {
84 addFirst(e);
85 }
86 return this;
87 }
88
89 @SafeVarargs
90 public final ChainBuilder<E> addAllFirst(final E... c) {
91 if (c == null) {
92 return this;
93 }
94 for (final E e: c) {
95 addFirst(e);
96 }
97 return this;
98 }
99
100 public ChainBuilder<E> addAllLast(final Collection<E> c) {
101 if (c == null) {
102 return this;
103 }
104 for (final E e: c) {
105 addLast(e);
106 }
107 return this;
108 }
109
110 @SafeVarargs
111 public final ChainBuilder<E> addAllLast(final E... c) {
112 if (c == null) {
113 return this;
114 }
115 for (final E e: c) {
116 addLast(e);
117 }
118 return this;
119 }
120
121 public LinkedList<E> build() {
122 return new LinkedList<>(this.list);
123 }
124
125 }