public class PatriciaTrie<E> extends AbstractBitwiseTrie<K,V> implements Trie<java.lang.String,E>
A 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
'prefixMap', '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.
This PATRICIA Trie supports both variable length & fixed length
keys. Some methods, such as prefixMap(Object) are suited only
to variable length keys.
| Modifier and Type | Class and Description |
|---|---|
protected static class |
AbstractPatriciaTrie.TrieEntry<K,V>
A
Trie is a set of AbstractPatriciaTrie.TrieEntry nodes. |
| Modifier and Type | Field and Description |
|---|---|
protected int |
modCount
The number of times this
Trie has been modified. |
| Constructor and Description |
|---|
PatriciaTrie() |
PatriciaTrie(java.util.Map<? extends java.lang.String,? extends E> 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()
Gets the first key currently in this map.
|
V |
get(java.lang.Object k) |
int |
hashCode()
Gets the standard Map hashCode.
|
java.util.SortedMap<K,V> |
headMap(K toKey) |
java.util.Set<K> |
keySet() |
K |
lastKey()
Gets the last key currently in this map.
|
OrderedMapIterator<K,V> |
mapIterator()
Obtains an
OrderedMapIterator over the map. |
K |
nextKey(K key)
Gets the next key after the one specified.
|
java.util.SortedMap<K,V> |
prefixMap(K key)
Returns a view of this
Trie of all elements that are prefixed
by the given key. |
K |
previousKey(K key)
Gets the previous key before the one specified.
|
V |
put(K key,
V value)
Note that the return type is Object, rather than V as in the Map interface.
|
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. |
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.util.Collection<V> |
values() |
getKeyAnalyzer, toStringclone, containsValue, equals, isEmpty, putAll, sizefinalize, getClass, notify, notifyAll, wait, wait, waitcomparator, entrySet, firstKey, headMap, keySet, lastKey, subMap, tailMap, valuesfirstKey, lastKey, mapIterator, nextKey, previousKeyclear, containsKey, containsValue, equals, get, hashCode, isEmpty, put, putAll, remove, sizecontainsKey, containsValue, entrySet, get, isEmpty, keySet, remove, size, valuesprotected transient int modCount
Trie has been modified.
It's used to detect concurrent modifications and fail-fast the Iterators.public PatriciaTrie()
public PatriciaTrie(java.util.Map<? extends java.lang.String,? extends E> m)
public void clear()
public int size()
public V put(K key,
V value)
Putpublic V get(java.lang.Object k)
public java.util.Map.Entry<K,V> select(K key)
Map.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.key - the key to use in the searchMap.Entry whose key is closest in a bitwise XOR metric
to the provided keypublic K selectKey(K key)
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.key - the key to use in the searchpublic V selectValue(K key)
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.key - the key to use in the searchpublic boolean containsKey(java.lang.Object k)
containsKey in interface java.util.Map<K,V>containsKey in interface Get<K,V>containsKey in class java.util.AbstractMap<K,V>Map.containsKey(Object)public java.util.Set<java.util.Map.Entry<K,V>> entrySet()
public java.util.Set<K> keySet()
public java.util.Collection<V> values()
public V remove(java.lang.Object k)
public int hashCode()
hashCode in interface java.util.Map<K,V>hashCode in class java.util.AbstractMap<K,V>public java.util.Comparator<? super K> comparator()
comparator in interface java.util.SortedMap<K,V>public K firstKey()
OrderedMapfirstKey in interface java.util.SortedMap<K,V>firstKey in interface OrderedMap<K,V>public K lastKey()
OrderedMaplastKey in interface java.util.SortedMap<K,V>lastKey in interface OrderedMap<K,V>public K nextKey(K key)
OrderedMapnextKey in interface OrderedMap<K,V>key - the key to search for next frompublic K previousKey(K key)
OrderedMappreviousKey in interface OrderedMap<K,V>key - the key to search for previous frompublic OrderedMapIterator<K,V> mapIterator()
OrderedMapOrderedMapIterator over the map.
A ordered map iterator is an efficient way of iterating over maps in both directions.
mapIterator in interface IterableGet<K,V>mapIterator in interface OrderedMap<K,V>public java.util.SortedMap<K,V> prefixMap(K key)
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 java.util.SortedMap<K,V> headMap(K toKey)
headMap in interface java.util.SortedMap<K,V>public java.util.SortedMap<K,V> subMap(K fromKey,
K toKey)
subMap in interface java.util.SortedMap<K,V>public java.util.SortedMap<K,V> tailMap(K fromKey)
tailMap in interface java.util.SortedMap<K,V>Copyright © 2001-2013. All Rights Reserved.