1 /*
2
3 dsh-venn Lightweight components for venn diagrams.
4 Copyright (c) 2009-2013 held jointly by the individual authors.
5
6 This library is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published
8 by the Free Software Foundation; either version 3 of the License, or (at
9 your option) any later version.
10
11 This library is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
14 License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with this library; if not, write to the Free Software Foundation,
18 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
19
20 > http://www.fsf.org/licensing/licenses/lgpl.html
21 > http://www.opensource.org/licenses/lgpl-license.php
22
23 */
24 package org.dishevelled.venn.model;
25
26 import java.util.HashSet;
27 import java.util.Set;
28
29 import com.google.common.base.Joiner;
30
31 import org.dishevelled.observable.ObservableSet;
32
33 import org.dishevelled.observable.event.SetChangeEvent;
34 import org.dishevelled.observable.event.SetChangeListener;
35
36 import org.dishevelled.observable.impl.ObservableSetImpl;
37
38 /**
39 * Selection view.
40 *
41 * @param <E> value type
42 * @author Michael Heuer
43 * @version $Revision$ $Date$
44 */
45 final class SelectionView<E>
46 extends ObservableSetImpl<E>
47 {
48 /** Default size. */
49 private static final int DEFAULT_SIZE = 16;
50
51 /** Union view. */
52 private final Set<E> union;
53
54 /** Purge selection. */
55 private final SetChangeListener<E> purgeSelection = new SetChangeListener<E>()
56 {
57 /** {@inheritDoc} */
58 public void setChanged(final SetChangeEvent<E> event)
59 {
60 purgeSelection();
61 }
62 };
63
64
65 /**
66 * Create a new selection view with the specified views.
67 *
68 * @param union union view
69 * @param views variable number of views
70 */
71 SelectionView(final Set<E> union, final ObservableSet<E>... views)
72 {
73 super(new HashSet<E>(Math.max(DEFAULT_SIZE, union == null ? DEFAULT_SIZE : union.size())));
74 this.union = union;
75 for (ObservableSet<E> view : views)
76 {
77 view.addSetChangeListener(purgeSelection);
78 }
79 }
80
81
82 /**
83 * Remove elements from the selection view not present in the union view.
84 */
85 private void purgeSelection()
86 {
87 Set<E> toRemove = new HashSet<E>(Math.max(DEFAULT_SIZE, (int) (size() / 10)));
88 for (E e : this)
89 {
90 if (!union.contains(e))
91 {
92 toRemove.add(e);
93 }
94 }
95 removeAll(toRemove);
96 }
97
98 /** {@inheritDoc} */
99 protected boolean preAdd(final E e)
100 {
101 if (!union.contains(e))
102 {
103 throw new IllegalArgumentException("can not select an element not in union");
104 }
105 return super.preAdd(e);
106 }
107
108 /** {@inheritDoc} */
109 public String toString()
110 {
111 StringBuilder sb = new StringBuilder();
112 sb.append("[");
113 Joiner.on(", ").appendTo(sb, this);
114 sb.append("]");
115 return sb.toString();
116 }
117 }