E - the type of the values in this mappublic class PatriciaTrie<E> extends AbstractBitwiseTrie<K,V>
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. |
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>| Modifier and Type | Field and Description |
|---|---|
protected int |
modCount
The number of times this
Trie has been modified. |
| Constructor and Description |
|---|
PatriciaTrie() |
PatriciaTrie(Map<? extends String,? extends E> m) |
| Modifier and Type | Method and Description |
|---|---|
void |
clear() |
Comparator<? super K> |
comparator() |
boolean |
containsKey(Object k) |
Set<Map.Entry<K,V>> |
entrySet() |
K |
firstKey()
Gets the first key currently in this map.
|
V |
get(Object k) |
SortedMap<K,V> |
headMap(K toKey) |
Set<K> |
keySet() |
K |
lastKey()
Gets the last key currently in this map.
|
OrderedMapIterator<K,V> |
mapIterator()
Obtains a
MapIterator over the map. |
K |
nextKey(K key)
Gets the next key after the one specified.
|
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(Object k) |
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() |
SortedMap<K,V> |
subMap(K fromKey,
K toKey) |
SortedMap<K,V> |
tailMap(K fromKey) |
Collection<V> |
values() |
getKeyAnalyzer, toStringclone, containsValue, equals, hashCode, isEmpty, putAllfinalize, getClass, notify, notifyAll, wait, wait, waitcompute, computeIfAbsent, computeIfPresent, containsValue, equals, forEach, getOrDefault, hashCode, isEmpty, merge, putAll, putIfAbsent, remove, replace, replace, replaceAllcontainsValue, isEmptyprotected transient int modCount
public PatriciaTrie()
public PatriciaTrie(Map<? extends String,? extends E> m)
public void clear()
clear in interface Map<K,V>clear in interface Put<K,V>clear in class AbstractMap<K,V>Map.clear()public int size()
size in interface Map<K,V>size in interface Get<K,V>size in class AbstractMap<K,V>Map.size()public V put(K key, V value)
Putput in interface Map<K,V>put in interface Put<K,V>put in class AbstractMap<K,V>key - key with which the specified value is to be associatedvalue - value to be associated with the specified keykey, or
null if there was no mapping for key.
(A null return can also indicate that the map
previously associated null with key,
if the implementation supports null values.)Map.put(Object, Object)public V get(Object k)
get in interface Map<K,V>get in interface Get<K,V>get in class AbstractMap<K,V>k - the key whose associated value is to be returnednull if this map contains no mapping for the keyMap.get(Object)public 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(Object k)
containsKey in interface Map<K,V>containsKey in interface Get<K,V>containsKey in class AbstractMap<K,V>k - key whose presence in this map is to be testedtrue if this map contains a mapping for the specified
keyMap.containsKey(Object)public Set<Map.Entry<K,V>> entrySet()
entrySet in interface Map<K,V>entrySet in interface SortedMap<K,V>entrySet in interface Get<K,V>entrySet in class AbstractMap<K,V>Map.entrySet()public Set<K> keySet()
keySet in interface Map<K,V>keySet in interface SortedMap<K,V>keySet in interface Get<K,V>keySet in class AbstractMap<K,V>Map.keySet()public Collection<V> values()
values in interface Map<K,V>values in interface SortedMap<K,V>values in interface Get<K,V>values in class AbstractMap<K,V>Map.values()public V remove(Object k)
remove in interface Map<K,V>remove in interface Get<K,V>remove in class AbstractMap<K,V>k - key whose mapping is to be removed from the mapkey, or
null if there was no mapping for key.ClassCastException - if provided key is of an incompatible typeMap.remove(Object)public Comparator<? super K> comparator()
public K firstKey()
OrderedMappublic K lastKey()
OrderedMappublic K nextKey(K key)
OrderedMapkey - the key to search for next frompublic K previousKey(K key)
OrderedMapkey - the key to search for previous frompublic OrderedMapIterator<K,V> mapIterator()
IterableGetMapIterator over the map.
A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or use Map Entry objects.
IterableMap<String,Integer> map = new HashedMap<String,Integer>();
MapIterator<String,Integer> it = map.mapIterator();
while (it.hasNext()) {
String key = it.next();
Integer value = it.getValue();
it.setValue(value + 1);
}
public 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'.
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