1package org.antlr.runtime.misc;
2
3import java.util.*;
4
5/** Sometimes we need to map a key to a value but key is two pieces of data.
6 *  This nested hash table saves creating a single key each time we access
7 *  map; avoids mem creation.
8 */
9public class DoubleKeyMap<Key1, Key2, Value> {
10	Map<Key1, Map<Key2, Value>> data = new LinkedHashMap<Key1, Map<Key2, Value>>();
11
12	public Value put(Key1 k1, Key2 k2, Value v) {
13		Map<Key2, Value> data2 = data.get(k1);
14		Value prev = null;
15		if ( data2==null ) {
16			data2 = new LinkedHashMap<Key2, Value>();
17			data.put(k1, data2);
18		}
19		else {
20			prev = data2.get(k2);
21		}
22		data2.put(k2, v);
23		return prev;
24	}
25
26	public Value get(Key1 k1, Key2 k2) {
27		Map<Key2, Value> data2 = data.get(k1);
28		if ( data2==null ) return null;
29		return data2.get(k2);
30	}
31
32	public Map<Key2, Value> get(Key1 k1) { return data.get(k1); }
33
34	/** Get all values associated with primary key */
35	public Collection<Value> values(Key1 k1) {
36		Map<Key2, Value> data2 = data.get(k1);
37		if ( data2==null ) return null;
38		return data2.values();
39	}
40
41	/** get all primary keys */
42	public Set<Key1> keySet() {
43		return data.keySet();
44	}
45
46	/** get all secondary keys associated with a primary key */
47	public Set<Key2> keySet(Key1 k1) {
48		Map<Key2, Value> data2 = data.get(k1);
49		if ( data2==null ) return null;
50		return data2.keySet();
51	}
52
53	public Collection<Value> values() {
54		Set<Value> s = new HashSet<Value>();
55		for (Map<Key2, Value> k2 : data.values()) {
56			for (Value v : k2.values()) {
57				s.add(v);
58			}
59		}
60		return s;
61	}
62}
63