public class PatriciaTrie<K,V>
extends java.util.AbstractMap<K,V>
implements java.io.Serializable
TrieA PATRICIA Trie is a compressed Trie. Instead of storing
all data at the edges of the Trie (and having empty internal nodes),
PATRICIA stores data in every node. This allows for very efficient traversal,
insert, delete, predecessor, successor, prefix, range, and select(Object)
operations. All operations are performed at worst in O(K) time, where K
is the number of bits in the largest item in the tree. In practice,
operations actually take O(A(K)) time, where A(K) is the average number of
bits of all items in the tree.
Most importantly, PATRICIA requires very few comparisons to keys while doing any operation. While performing a lookup, each comparison (at most K of them, described above) will perform a single bit comparison against the given key, instead of comparing the entire key to another key.
The Trie can return operations in lexicographical order using the
traverse(Cursor), 'prefix', 'submap', or 'iterator' methods. The
Trie can also scan for items that are 'bitwise' (using an XOR
metric) by the 'select' method. Bitwise closeness is determined by the
KeyAnalyzer returning true or false for a bit being set or not in
a given key.
Any methods here that take an Object argument may throw a
ClassCastException if the method is expecting an instance of K
and it isn't K.
| Modifier and Type | Field and Description |
|---|---|
protected KeyAnalyzer<? super K> |
keyAnalyzer
The
KeyAnalyzer that's being used to build the
PATRICIA Trie |
| Constructor and Description |
|---|
PatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer) |
PatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer,
java.util.Map<? extends K,? extends V> m) |
| Modifier and Type | Method and Description |
|---|---|
void |
clear() |
java.util.Comparator<? super K> |
comparator() |
boolean |
containsKey(java.lang.Object k) |
java.util.Set<java.util.Map.Entry<K,V>> |
entrySet() |
K |
firstKey() |
V |
get(java.lang.Object k) |
java.util.SortedMap<K,V> |
headMap(K toKey) |
java.util.Set<K> |
keySet() |
K |
lastKey() |
java.util.SortedMap<K,V> |
prefixMap(K prefix)
Returns a view of this
Trie of all elements that are prefixed
by the given key. |
V |
put(K key,
V value) |
V |
remove(java.lang.Object k) |
java.util.Map.Entry<K,V> |
select(K key)
Returns the
Map.Entry whose key is closest in a bitwise XOR
metric to the given key. |
java.util.Map.Entry<K,V> |
select(K key,
Cursor<? super K,? super V> cursor)
Iterates through the
Trie, starting with the entry whose bitwise
value is closest in an XOR metric to the given key. |
K |
selectKey(K key)
Returns the key that is closest in a bitwise XOR metric to the
provided key.
|
V |
selectValue(K key)
Returns the value whose key is closest in a bitwise XOR metric to
the provided key.
|
int |
size() |
java.util.SortedMap<K,V> |
subMap(K fromKey,
K toKey) |
java.util.SortedMap<K,V> |
tailMap(K fromKey) |
java.lang.String |
toString() |
java.util.Map.Entry<K,V> |
traverse(Cursor<? super K,? super V> cursor)
Traverses the
Trie in lexicographical order. |
java.util.Collection<V> |
values() |
clone, containsValue, equals, hashCode, isEmpty, putAllprotected final KeyAnalyzer<? super K> keyAnalyzer
KeyAnalyzer that's being used to build the
PATRICIA Triepublic PatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer)
public PatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer, java.util.Map<? extends K,? extends V> m)
public java.util.Comparator<? super K> comparator()
public java.util.SortedMap<K,V> prefixMap(K prefix)
TrieTrie of all elements that are prefixed
by the given key.
In a Trie with fixed size keys, this is essentially a
Map.get(Object) operation.
For example, if the Trie contains 'Anna', 'Anael',
'Analu', 'Andreas', 'Andrea', 'Andres', and 'Anatole', then
a lookup of 'And' would return 'Andreas', 'Andrea', and 'Andres'.
public void clear()
clear in interface java.util.Map<K,V>clear in class java.util.AbstractMap<K,V>public int size()
size in interface java.util.Map<K,V>size in class java.util.AbstractMap<K,V>public V put(K key,
V value)
put in interface java.util.Map<K,V>put in class java.util.AbstractMap<K,V>public V get(java.lang.Object k)
get in interface java.util.Map<K,V>get in class java.util.AbstractMap<K,V>public java.util.Map.Entry<K,V> select(K key)
TrieMap.Entry whose key is closest in a bitwise XOR
metric to the given key. This is NOT lexicographic closeness.
For example, given the keys:
Trie contained 'H' and 'L', a lookup of 'D' would
return 'L', because the XOR distance between D & L is smaller
than the XOR distance between D & H.Map.Entry whose key is closest in a bitwise XOR metric
to the provided key.public java.util.Map.Entry<K,V> select(K key,
Cursor<? super K,? super V> cursor)
TrieTrie, starting with the entry whose bitwise
value is closest in an XOR metric to the given key. After the closest
entry is found, the Trie will call select on that entry and continue
calling select for each entry (traversing in order of XOR closeness,
NOT lexicographically) until the cursor returns Cursor.Decision.EXIT.
The cursor can return Cursor.Decision.CONTINUE to continue traversing.
Cursor.Decision.REMOVE_AND_EXIT is used to remove the current element
and stop traversing.
Note: The Cursor.Decision.REMOVE operation is not supported.
Cursor.Decision.EXIT on, or null
if it continued till the end.public java.util.Map.Entry<K,V> traverse(Cursor<? super K,? super V> cursor)
TrieTrie in lexicographical order.
Cursor.select(java.util.Map.Entry) will be called on each entry.
The traversal will stop when the cursor returns Cursor.Decision.EXIT,
Cursor.Decision.CONTINUE is used to continue traversing and
Cursor.Decision.REMOVE is used to remove the element that was selected
and continue traversing.
Cursor.Decision.REMOVE_AND_EXIT is used to remove the current element
and stop traversing.
Cursor.Decision.EXIT on, or null
if it continued till the end.public boolean containsKey(java.lang.Object k)
containsKey in interface java.util.Map<K,V>containsKey in class java.util.AbstractMap<K,V>public java.util.Set<java.util.Map.Entry<K,V>> entrySet()
entrySet in interface java.util.Map<K,V>entrySet in interface java.util.SortedMap<K,V>entrySet in class java.util.AbstractMap<K,V>public java.util.Set<K> keySet()
keySet in interface java.util.Map<K,V>keySet in interface java.util.SortedMap<K,V>keySet in class java.util.AbstractMap<K,V>public java.util.Collection<V> values()
values in interface java.util.Map<K,V>values in interface java.util.SortedMap<K,V>values in class java.util.AbstractMap<K,V>public V remove(java.lang.Object k)
remove in interface java.util.Map<K,V>remove in class java.util.AbstractMap<K,V>java.lang.ClassCastException - if provided key is of an incompatible typepublic K selectKey(K key)
TrieTrie contained 'H' and 'L', a lookup of 'D' would
return 'L', because the XOR distance between D & L is smaller
than the XOR distance between D & H.public V selectValue(K key)
TrieTrie contained 'H' and 'L', a lookup of 'D' would
return 'L', because the XOR distance between D & L is smaller
than the XOR distance between D & H.selectValue in interface Trie<K,V>public java.lang.String toString()
toString in class java.util.AbstractMap<K,V>Copyright © 2009- The Apache Software Foundation