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comparison src/com/go/trove/util/MapBackedSet.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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1 /* ====================================================================
2 * Trove - Copyright (c) 1997-2000 Walt Disney Internet Group
3 * ====================================================================
4 * The Tea Software License, Version 1.1
5 *
6 * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. The end-user documentation included with the redistribution,
21 * if any, must include the following acknowledgment:
22 * "This product includes software developed by the
23 * Walt Disney Internet Group (http://opensource.go.com/)."
24 * Alternately, this acknowledgment may appear in the software itself,
25 * if and wherever such third-party acknowledgments normally appear.
26 *
27 * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must
28 * not be used to endorse or promote products derived from this
29 * software without prior written permission. For written
30 * permission, please contact opensource@dig.com.
31 *
32 * 5. Products derived from this software may not be called "Tea",
33 * "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet",
34 * "Kettle", "Trove" or "BeanDoc" appear in their name, without prior
35 * written permission of the Walt Disney Internet Group.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS
41 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
42 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
43 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
44 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
45 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
46 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
47 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 * For more information about Tea, please see http://opensource.go.com/.
51 */
52
53 package com.go.trove.util;
54
55 import java.util.*;
56
57 /******************************************************************************
58 * A set implementation that is backed by any map.
59 *
60 * @author Brian S O'Neill
61 * @version
62 * <!--$$Revision: 1.1 $-->, <!--$$JustDate:--> 9/07/00 <!-- $-->
63 */
64 public class MapBackedSet extends AbstractSet implements java.io.Serializable {
65 // Dummy value to associate with an Object in the backing Map
66 private static final Object PRESENT = new Object();
67
68 protected final Map mMap;
69
70 /**
71 * @param map The map to back this set.
72 */
73 public MapBackedSet(Map map) {
74 mMap = map;
75 }
76
77 /**
78 * Returns an iterator over the elements in this set. The elements
79 * are returned in the order determined by the backing map.
80 *
81 * @return an Iterator over the elements in this set.
82 * @see ConcurrentModificationException
83 */
84 public Iterator iterator() {
85 return mMap.keySet().iterator();
86 }
87
88 /**
89 * Returns the number of elements in this set (its cardinality).
90 *
91 * @return the number of elements in this set (its cardinality).
92 */
93 public int size() {
94 return mMap.size();
95 }
96
97 /**
98 * Returns true if this set contains no elements.
99 *
100 * @return true if this set contains no elements.
101 */
102 public boolean isEmpty() {
103 return mMap.isEmpty();
104 }
105
106 /**
107 * Returns true if this set contains the specified element.
108 *
109 * @return true if this set contains the specified element.
110 */
111 public boolean contains(Object obj) {
112 return mMap.containsKey(obj);
113 }
114
115 /**
116 * Adds the specified element to this set if it is not already
117 * present.
118 *
119 * @param obj element to be added to this set.
120 * @return true if the set did not already contain the specified element.
121 */
122 public boolean add(Object obj) {
123 return mMap.put(obj, PRESENT) == null;
124 }
125
126 /**
127 * Removes the given element from this set if it is present.
128 *
129 * @param obj object to be removed from this set, if present.
130 * @return true if the set contained the specified element.
131 */
132 public boolean remove(Object obj) {
133 return mMap.remove(obj) == PRESENT;
134 }
135
136 /**
137 * Removes all of the elements from this set.
138 */
139 public void clear() {
140 mMap.clear();
141 }
142 }