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17 package org.opensaml.xml.util;
18
19 import java.io.Serializable;
20 import java.util.Collection;
21 import java.util.Collections;
22 import java.util.HashSet;
23 import java.util.Iterator;
24 import java.util.Set;
25
26 import net.jcip.annotations.NotThreadSafe;
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31
32
33 @NotThreadSafe
34 public class LazySet<ElementType> implements Set<ElementType>, Serializable {
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36
37 private static final long serialVersionUID = -1596445680460115174L;
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39
40 private Set<ElementType> delegate = Collections.emptySet();
41
42
43 public boolean add(ElementType element) {
44 if (delegate.isEmpty()) {
45 delegate = Collections.singleton(element);
46 return true;
47 } else {
48 delegate = createImplementation();
49 return delegate.add(element);
50 }
51 }
52
53
54 public boolean addAll(Collection<? extends ElementType> collection) {
55 delegate = createImplementation();
56 return delegate.addAll(collection);
57 }
58
59
60 public void clear() {
61 delegate = Collections.emptySet();
62 }
63
64
65 public boolean contains(Object element) {
66 return delegate.contains(element);
67 }
68
69
70 public boolean containsAll(Collection<?> collection) {
71 return delegate.containsAll(collection);
72 }
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74
75 public boolean isEmpty() {
76 return delegate.isEmpty();
77 }
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79
80 public Iterator<ElementType> iterator() {
81 return delegate.iterator();
82 }
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84
85 public boolean remove(Object element) {
86 delegate = createImplementation();
87 return delegate.remove(element);
88 }
89
90
91 public boolean removeAll(Collection<?> collection) {
92 delegate = createImplementation();
93 return delegate.removeAll(collection);
94 }
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96
97 public boolean retainAll(Collection<?> collection) {
98 delegate = createImplementation();
99 return delegate.retainAll(collection);
100 }
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102
103 public int size() {
104 return delegate.size();
105 }
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108 public Object[] toArray() {
109 return delegate.toArray();
110 }
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113 public <T> T[] toArray(T[] type) {
114 return delegate.toArray(type);
115 }
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122 private Set<ElementType> createImplementation() {
123 if (delegate instanceof HashSet) {
124 return delegate;
125 }
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127 return new HashSet<ElementType>(delegate);
128 }
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130
131 public String toString() {
132 return delegate.toString();
133 }
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136 public int hashCode() {
137 return delegate.hashCode();
138 }
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141 public boolean equals(Object obj) {
142 if (this == obj) {
143 return true;
144 }
145
146 if (obj == null || this.getClass() != obj.getClass()) {
147 return false;
148 }
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150 return delegate.equals(((LazySet<?>) obj).delegate);
151 }
152 }