1 cananian 1.1.2.1 // SortedMapComparator.java, created Mon Sep 17 16:57:49 2001 by cananian
2 cananian 1.1.2.1 // Copyright (C) 2000 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.Util;
5 cananian 1.1.2.1
6 cananian 1.1.2.1 import java.util.Comparator;
7 cananian 1.1.2.1 import java.util.Iterator;
8 cananian 1.1.2.1 import java.util.Map;
9 cananian 1.1.2.1 import java.util.Set;
10 cananian 1.1.2.1 import java.util.SortedMap;
11 cananian 1.3
12 cananian 1.3 import net.cscott.jutil.Default;
13 cananian 1.1.2.1 /**
14 cananian 1.1.2.1 * A <code>SortedMapComparator</code> compares two sorted maps
15 cananian 1.1.2.1 * entry-by-entry (treating the map as a sorted pair list).
16 cananian 1.1.2.1 *
17 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
18 cananian 1.3 * @version $Id: SortedMapComparator.java,v 1.3 2004/02/08 01:56:15 cananian Exp $
19 cananian 1.1.2.1 */
20 cananian 1.3 public class SortedMapComparator<K,V> implements Comparator<SortedMap<K,V>> {
21 cananian 1.3 final Comparator<? super K> keyComparator;
22 cananian 1.3 final Comparator<? super V> valueComparator;
23 cananian 1.1.2.1
24 cananian 1.1.2.1 /** Creates a <code>SortedMapComparator</code> which compares
25 cananian 1.1.2.1 * entries in the order defined by the <code>SortedMap</code> and
26 cananian 1.1.2.1 * compares keys before values.
27 cananian 1.1.2.1 * All keys and values must implement <code>java.lang.Comparable</code>.
28 cananian 1.1.2.1 */
29 cananian 1.1.2.1 public SortedMapComparator() { this(null, null); }
30 cananian 1.1.2.1 /** Creates a <code>SortedMapComparator</code> which compares
31 cananian 1.1.2.1 * entries in the order defined by the <code>SortedMap</code>
32 cananian 1.1.2.1 * and compares keys (using <code>keyComparator</code>) before values
33 cananian 1.1.2.1 * (using <code>valueComparator</code>).
34 cananian 1.1.2.1 * If <code>keyComparator</code> is <code>null</code>, then all
35 cananian 1.1.2.1 * keys must implement <code>java.lang.Comparable</code>.
36 cananian 1.1.2.1 * If <code>valueComparator</code> is <code>null</code>, then all
37 cananian 1.1.2.1 * values must implement <code>java.lang.Comparable</code>.
38 cananian 1.1.2.1 */
39 cananian 1.3 public SortedMapComparator(Comparator<? super K> keyComparator,
40 cananian 1.3 Comparator<? super V> valueComparator) {
41 cananian 1.1.2.1 this.keyComparator = (keyComparator==null) ?
42 cananian 1.3 Default.<K>comparator() : keyComparator;
43 cananian 1.1.2.1 this.valueComparator = (valueComparator==null) ?
44 cananian 1.3 Default.<V>comparator() : valueComparator;
45 cananian 1.1.2.1 }
46 cananian 1.1.2.1
47 cananian 1.3 public int compare(SortedMap<K,V> sm1, SortedMap<K,V> sm2) {
48 cananian 1.1.2.1 // throws ClassCastException if objects are not the proper types.
49 cananian 1.3 Iterator<Map.Entry<K,V>> it1 = sm1.entrySet().iterator();
50 cananian 1.3 Iterator<Map.Entry<K,V>> it2 = sm2.entrySet().iterator();
51 cananian 1.1.2.1 while (it1.hasNext() && it2.hasNext()) {
52 cananian 1.3 Map.Entry<K,V> me1 = it1.next();
53 cananian 1.3 Map.Entry<K,V> me2 = it2.next();
54 cananian 1.1.2.1 int kcmp = keyComparator.compare(me1.getKey(), me2.getKey());
55 cananian 1.1.2.1 if (kcmp!=0) return kcmp;
56 cananian 1.1.2.1 int vcmp = valueComparator.compare(me1.getValue(), me2.getValue());
57 cananian 1.1.2.1 if (vcmp!=0) return vcmp;
58 cananian 1.1.2.1 }
59 cananian 1.1.2.1 // for maps of unequal size, the shorter is the smaller.
60 cananian 1.1.2.1 return it1.hasNext() ? 1 : it2.hasNext() ? -1 : 0;
61 cananian 1.1.2.1 }
62 cananian 1.2 }