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1
4
5 package polyglot.util;
6
7 import java.util.Map  ;
8 import java.util.Collection ;
9 import java.util.Collections ;
10 import java.util.Set ;
11
12
15 public final class NilMap implements Map {
16 public static final NilMap EMPTY_MAP = new NilMap();
17
18 private NilMap() {}
19
20 public boolean containsKey(Object key) { return false; }
21 public boolean containsValue(Object val) { return false; }
22 public Set entrySet() { return Collections.EMPTY_SET; }
23 public int hashCode() { return 0; }
24 public boolean isEmpty() { return true; }
25 public Set keySet() { return Collections.EMPTY_SET; }
26 public int size() { return 0; }
27 public Collection values() { return Collections.EMPTY_SET; }
28 public Object get(Object k) { return null; }
29 public boolean equals(Object o)
30 { return (o instanceof Map ) && ((Map ) o).size() == 0 ; }
31
32
33 public void clear() { throw new UnsupportedOperationException (); }
34 public void putAll(Map t) { throw new UnsupportedOperationException (); }
35 public Object remove(Object o) { throw new UnsupportedOperationException (); }
36 public Object put(Object o1, Object o2)
37 { throw new UnsupportedOperationException (); }
38 }
39
40 |
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