Package org.apache.commons.collections4.trie

Class AbstractPatriciaTrie<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

org.apache.commons.collections4.trie.AbstractBitwiseTrie<K,V>

org.apache.commons.collections4.trie.AbstractPatriciaTrie<K,V>

Type Parameters:

K - the type of the keys in this map

V - the type of the values in this map

All Implemented Interfaces:

Serializable, Map<K,V>, SortedMap<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, IterableSortedMap<K,V>, OrderedMap<K,V>, Put<K,V>, Trie<K,V>

Direct Known Subclasses:

PatriciaTrie

public abstract class AbstractPatriciaTrie<K,V>
extends AbstractBitwiseTrie<K,V>

This class implements the base PATRICIA algorithm and everything that is related to the Map interface.

Since:

4.0

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractPatriciaTrie.TrieEntry<K,V>	A Trie is a set of AbstractPatriciaTrie.TrieEntry nodes.

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K extends Object,V extends Object>, AbstractMap.SimpleImmutableEntry<K extends Object,V extends Object>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Field Summary

Fields

Modifier and Type	Field	Description
protected int	modCount	The number of times this Trie has been modified.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractPatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer)	Constructs a new Trie using the given KeyAnalyzer.
protected	AbstractPatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer, Map<? extends K,? extends V> map)	Constructs a new Trie using the given KeyAnalyzer and initializes the Trie with the values from the provided Map.

Method Summary

Modifier and Type	Method	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 an OrderedMapIterator 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()

Methods inherited from class org.apache.commons.collections4.trie.AbstractBitwiseTrie

getKeyAnalyzer, toString

Methods inherited from class java.util.AbstractMap

clone, containsValue, equals, hashCode, isEmpty, putAll

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.collections4.Get

containsValue, isEmpty

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsValue, equals, forEach, getOrDefault, hashCode, isEmpty, merge, putAll, putIfAbsent, remove, replace, replace, replaceAll

Methods inherited from interface org.apache.commons.collections4.Put

putAll

Field Details

modCount

protected transient int modCount

The number of times this Trie has been modified. It's used to detect concurrent modifications and fail-fast the Iterators.

Constructor Details

AbstractPatriciaTrie

protected AbstractPatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer)

Constructs a new Trie using the given KeyAnalyzer.

Parameters:

keyAnalyzer - the KeyAnalyzer to use

AbstractPatriciaTrie

protected AbstractPatriciaTrie(KeyAnalyzer<? super K> keyAnalyzer,
 Map<? extends K,? extends V> map)

Constructs a new Trie using the given KeyAnalyzer and initializes the Trie with the values from the provided Map.

Method Details

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Specified by:

clear in interface Put<K,V>

Overrides:

clear in class AbstractMap<K,V>

See Also:

• Map.clear()

comparator

public Comparator<? super K> comparator()

containsKey

public boolean containsKey(Object k)

Specified by:

containsKey in interface Get<K,V>

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractMap<K,V>

Parameters:

k - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

See Also:

• Map.containsKey(Object)

entrySet

public Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Get<K,V>

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in interface SortedMap<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

Returns:

a set view of the mappings contained in this map

See Also:

• Map.entrySet()

firstKey

public K firstKey()

Description copied from interface: OrderedMap

Gets the first key currently in this map.

Returns:

the first key currently in this map

get

public V get(Object k)

Specified by:

get in interface Get<K,V>

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

Parameters:

k - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped, or null if this map contains no mapping for the key

See Also:

• Map.get(Object)

headMap

public SortedMap<K,V> headMap(K toKey)

keySet

public Set<K> keySet()

Specified by:

keySet in interface Get<K,V>

Specified by:

keySet in interface Map<K,V>

Specified by:

keySet in interface SortedMap<K,V>

Overrides:

keySet in class AbstractMap<K,V>

Returns:

a set view of the keys contained in this map

See Also:

• Map.keySet()

lastKey

public K lastKey()

Description copied from interface: OrderedMap

Gets the last key currently in this map.

Returns:

the last key currently in this map

mapIterator

public OrderedMapIterator<K,V> mapIterator()

Description copied from interface: OrderedMap

Obtains an OrderedMapIterator over the map.

An ordered map iterator is an efficient way of iterating over maps in both directions.

Returns:

a map iterator

nextKey

public K nextKey(K key)

Description copied from interface: OrderedMap

Gets the next key after the one specified.

Parameters:

key - the key to search for next from

Returns:

the next key, null if no match or at end

prefixMap

public SortedMap<K,V> prefixMap(K key)

Description copied from interface: Trie

Returns a view of this Trie 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'.

Parameters:

key - the key used in the search

Returns:

a SortedMap view of this Trie with all elements whose key is prefixed by the search key

previousKey

public K previousKey(K key)

Description copied from interface: OrderedMap

Gets the previous key before the one specified.

Parameters:

key - the key to search for previous from

Returns:

the previous key, null if no match or at start

put

public V put(K key,
 V value)

Description copied from interface: Put

Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.

Specified by:

put in interface Map<K,V>

Specified by:

put in interface Put<K,V>

Overrides:

put in class AbstractMap<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, 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.)

See Also:

• Map.put(Object, Object)

remove

public V remove(Object k)

Specified by:

remove in interface Get<K,V>

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

Parameters:

k - key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key.

Throws:

ClassCastException - if provided key is of an incompatible type

See Also:

• Map.remove(Object)

select

public Map.Entry<K,V> select(K key)

Returns the 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:

1. D = 1000100
2. H = 1001000
3. L = 1001100

If the 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.

Parameters:

key - the key to use in the search

Returns:

the Map.Entry whose key is closest in a bitwise XOR metric to the provided key

selectKey

public K selectKey(K key)

Returns the key that is closest in a bitwise XOR metric to the provided key. This is NOT lexicographic closeness! For example, given the keys:

1. D = 1000100
2. H = 1001000
3. L = 1001100

If the 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.

Parameters:

key - the key to use in the search

Returns:

the key that is closest in a bitwise XOR metric to the provided key

selectValue

public V selectValue(K key)

Returns the value whose key is closest in a bitwise XOR metric to the provided key. This is NOT lexicographic closeness! For example, given the keys:

1. D = 1000100
2. H = 1001000
3. L = 1001100

If the 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.

Parameters:

key - the key to use in the search

Returns:

the value whose key is closest in a bitwise XOR metric to the provided key

size

public int size()

Specified by:

size in interface Get<K,V>

Specified by:

size in interface Map<K,V>

Overrides:

size in class AbstractMap<K,V>

Returns:

the number of key-value mappings in this map

See Also:

• Map.size()

subMap

public SortedMap<K,V> subMap(K fromKey,
 K toKey)

tailMap

public SortedMap<K,V> tailMap(K fromKey)

values

public Collection<V> values()

Specified by:

values in interface Get<K,V>

Specified by:

values in interface Map<K,V>

Specified by:

values in interface SortedMap<K,V>

Overrides:

values in class AbstractMap<K,V>

Returns:

a collection view of the values contained in this map

See Also:

• Map.values()