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32
33 package jbet;
34 import java.util.*;
35
36 public class InternSet implements Collection
37 {
38 Hashtable h;
39
40 public InternSet() { h = new Hashtable(); }
41 public InternSet (InternSet in) { h = new Hashtable (in.h); }
42 public InternSet (Object  o) { this(); add (o); }
43
44 public Iterator iterator () { return h.values().iterator(); }
45 public int size() { return h.size(); }
46 public boolean isEmpty() { return h.isEmpty(); }
47 public boolean contains (Object o) { return h.get (o) != null; }
48 public boolean add (Object o) { if (o == null) throw new IllegalStateException ("add(null)"); return null == h.put (o, o); }
49 public boolean remove (Object o) { return null != h.remove (o); }
50 public void clear() { h.clear (); }
51 public Object clone () throws CloneNotSupportedException {
52 throw new CloneNotSupportedException ("no InternSet.clone");
53 }
54
55 public boolean addAll (Collection c) {
56 boolean change = false;
57 for (Iterator i = c.iterator(); i.hasNext(); )
58 if (add (i.next()))
59 change = true;
60 return change;
61 }
62
63 public boolean removeAll (Collection c) {
64 boolean change = false;
65 for (Iterator i = c.iterator(); i.hasNext(); )
66 if (remove (i.next()))
67 change = true;
68 return change;
69 }
70
71 public boolean retainAll (Collection c) {
72 boolean change = false;
73 for (Iterator i = h.values().iterator(); i.hasNext(); ) {
74 Object o = i.next();
75 if (!c.contains (o)) {
76 remove (o);
77 change = true;
78 }
79 }
80 return change;
81 }
82
83 public boolean containsAll (Collection c) {
84 boolean all = true;
85 for (Iterator i = c.iterator(); i.hasNext(); )
86 all &= contains (i.next());
87 return all;
88 }
89
90 public Object [] toArray () {
91 Object [] a = new Object [size()];
92 int n = 0;
93 for (Iterator i = h.values().iterator(); i.hasNext(); )
94 a[n++] = i.next();
95 if (n != a.length)
96 throw new IllegalStateException ("InternSet.toArray failed");
97 return a;
98 }
99
100 public Object [] toArray (Object [] a) {
101 if (a.length < size()) {
102 a = (Object [])
103 java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size());
104 }
105 int n = 0;
106 for (Iterator i = h.values().iterator(); i.hasNext(); )
107 a[n++] = i.next();
108 if (n != a.length)
109 throw new IllegalStateException ("InternSet.toArray failed");
110 return a;
111 }
112
113 public Object add2 (Object in) {
114 Object o = h.get (in);
115 if (o != null)
116 return o;
117
118 h.put (in, in);
119 return in;
120 }
121
122 public java.io.ObjectOutputStream writeObject () { throw new IllegalStateException ("no InternSet.writeObject"); }
123 public void readObject (java.io.ObjectInputStream o) { throw new IllegalStateException ("no InternSet.readObject"); }
124
125 public static InternSet EMPTY = new InternSet();
126 }
127 |
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