Mercurial > hg > blitz_condensed
comparison src/com/go/trove/util/MapBackedSet.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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-1:000000000000 | 0:3dc0c5604566 |
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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 } |