01: /*
02: * <copyright>
03: *
04: * Copyright 2002-2004 BBNT Solutions, LLC
05: * under sponsorship of the Defense Advanced Research Projects
06: * Agency (DARPA).
07: *
08: * You can redistribute this software and/or modify it under the
09: * terms of the Cougaar Open Source License as published on the
10: * Cougaar Open Source Website (www.cougaar.org).
11: *
12: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
13: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
14: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
15: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
16: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
17: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
18: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
22: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: *
24: * </copyright>
25: */
26:
27: package org.cougaar.util;
28:
29: import java.io.Serializable;
30: import java.util.AbstractSet;
31: import java.util.Collection;
32: import java.util.IdentityHashMap;
33: import java.util.Iterator;
34: import java.util.Map;
35: import java.util.Set;
36:
37: /**
38: * Hash set based upon object "==" identity.
39: * <p>
40: * Should be in "java.util.": Sun bug 4479578.
41: */
42: public class IdentityHashSet extends AbstractSet implements Set,
43: Cloneable, Serializable {
44: private static final Object PRESENT = new Object();
45: private final Map map;
46:
47: public IdentityHashSet() {
48: this (16);
49: }
50:
51: public IdentityHashSet(int initialCapacity) {
52: map = new IdentityHashMap(initialCapacity);
53: }
54:
55: public IdentityHashSet(Collection c) {
56: this (Math.max((int) (c.size() * 1.1) + 1, 16));
57: addAll(c);
58: }
59:
60: public Iterator iterator() {
61: return map.keySet().iterator();
62: }
63:
64: public int size() {
65: return map.size();
66: }
67:
68: public boolean isEmpty() {
69: return map.isEmpty();
70: }
71:
72: public boolean contains(Object o) {
73: return map.containsKey(o);
74: }
75:
76: public boolean add(Object o) {
77: return map.put(o, PRESENT) == null;
78: }
79:
80: public boolean remove(Object o) {
81: return map.remove(o) == PRESENT;
82: }
83:
84: public void clear() {
85: map.clear();
86: }
87: }
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