it.unimi.dsi.fastutil.shorts

Class Short2ReferenceOpenCustomHashMap<V>

java.lang.Object

it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceFunction<V>

it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceMap<V>

it.unimi.dsi.fastutil.shorts.Short2ReferenceOpenCustomHashMap<V>

All Implemented Interfaces:

Hash, Short2ReferenceFunction<V>, Short2ReferenceMap<V>, Serializable, Cloneable, Function<Short,V>, IntFunction<V>, Map<Short,V>

public class Short2ReferenceOpenCustomHashMap<V>
extends AbstractShort2ReferenceMap<V>
implements Serializable, Cloneable, Hash

A type-specific hash map with a fast, small-footprint implementation whose hashing strategy is specified at creation time.

Instances of this class use a hash table to represent a map. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size; however, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create maps with a large capacity in which insertions and deletions do not cause immediately rehashing. Moreover, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.

Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceMap

AbstractShort2ReferenceMap.BasicEntry<V>, AbstractShort2ReferenceMap.BasicEntrySet<V>

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash

Hash.Strategy<K>

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.shorts.Short2ReferenceMap

Short2ReferenceMap.Entry<V>, Short2ReferenceMap.FastEntrySet<V>

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	containsNullKey Whether this map contains the key zero.
protected Short2ReferenceMap.FastEntrySet<V>	entries Cached set of entries.
protected float	f The acceptable load factor.
protected short[]	key The array of keys.
protected ShortSet	keys Cached set of keys.
protected int	mask The mask for wrapping a position counter.
protected int	maxFill Threshold after which we rehash.
protected int	minN We never resize below this threshold, which is the construction-time {#n}.
protected int	n The current table size.
protected int	size Number of entries in the set (including the key zero, if present).
protected ShortHash.Strategy	strategy The hash strategy of this custom map.
protected V[]	value The array of values.
protected ReferenceCollection<V>	values Cached collection of values.

Fields inherited from class it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceFunction

defRetValue

Fields inherited from interface it.unimi.dsi.fastutil.Hash

DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR

Constructor Summary

Constructors

Constructor and Description
Short2ReferenceOpenCustomHashMap(int expected, float f, ShortHash.Strategy strategy) Creates a new hash map.
Short2ReferenceOpenCustomHashMap(int expected, ShortHash.Strategy strategy) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Short2ReferenceOpenCustomHashMap(Map<? extends Short,? extends V> m, float f, ShortHash.Strategy strategy) Creates a new hash map copying a given one.
Short2ReferenceOpenCustomHashMap(Map<? extends Short,? extends V> m, ShortHash.Strategy strategy) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Short2ReferenceOpenCustomHashMap(short[] k, V[] v, float f, ShortHash.Strategy strategy) Creates a new hash map using the elements of two parallel arrays.
Short2ReferenceOpenCustomHashMap(short[] k, V[] v, ShortHash.Strategy strategy) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.
Short2ReferenceOpenCustomHashMap(Short2ReferenceMap<V> m, float f, ShortHash.Strategy strategy) Creates a new hash map copying a given type-specific one.
Short2ReferenceOpenCustomHashMap(Short2ReferenceMap<V> m, ShortHash.Strategy strategy) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.
Short2ReferenceOpenCustomHashMap(ShortHash.Strategy strategy) Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all of the mappings from this map (optional operation).
Short2ReferenceOpenCustomHashMap<V>	clone() Returns a deep copy of this map.
V	compute(short k, BiFunction<? super Short,? super V,? extends V> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
V	computeIfAbsent(short k, IntFunction<? extends V> mappingFunction) If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map.
V	computeIfPresent(short k, BiFunction<? super Short,? super V,? extends V> remappingFunction) If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
boolean	containsKey(short k) Returns true if this function contains a mapping for the specified key.
boolean	containsValue(Object v)
V	get(short k) Returns the value to which the given key is mapped.
V	getOrDefault(short k, V defaultValue) Returns the value to which the specified key is mapped, or the defaultValue if this map contains no mapping for the key.
int	hashCode() Returns a hash code for this map.
boolean	isEmpty()
ShortSet	keySet() Returns a type-specific-set view of the keys of this map.
V	merge(short k, V v, BiFunction<? super V,? super V,? extends V> remappingFunction) If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
V	put(short k, V v) Adds a pair to the map (optional operation).
void	putAll(Map<? extends Short,? extends V> m)
V	putIfAbsent(short k, V v) If the specified key is not already associated with a value, associates it with the given value and returns the default return value, else returns the current value.
protected void	rehash(int newN) Rehashes the map.
V	remove(short k) Removes the mapping with the given key (optional operation).
boolean	remove(short k, Object v) Removes the entry for the specified key only if it is currently mapped to the specified value.
V	replace(short k, V v) Replaces the entry for the specified key only if it is currently mapped to some value.
boolean	replace(short k, V oldValue, V v) Replaces the entry for the specified key only if currently mapped to the specified value.
protected void	shiftKeys(int pos) Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
Short2ReferenceMap.FastEntrySet<V>	short2ReferenceEntrySet() Returns a type-specific set view of the mappings contained in this map.
int	size() Returns the number of key/value mappings in this map.
ShortHash.Strategy	strategy() Returns the hashing strategy.
boolean	trim() Rehashes the map, making the table as small as possible.
boolean	trim(int n) Rehashes this map if the table is too large.
ReferenceCollection<V>	values() Returns a type-specific-set view of the values of this map.

Methods inherited from class it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceMap

equals, toString

Methods inherited from class it.unimi.dsi.fastutil.shorts.AbstractShort2ReferenceFunction

defaultReturnValue, defaultReturnValue

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.dsi.fastutil.shorts.Short2ReferenceMap

compute, computeIfAbsent, computeIfAbsentPartial, computeIfPresent, containsKey, defaultReturnValue, defaultReturnValue, entrySet, get, getOrDefault, merge, put, putIfAbsent, remove, remove, replace, replace

Methods inherited from interface it.unimi.dsi.fastutil.shorts.Short2ReferenceFunction

apply

Methods inherited from interface it.unimi.dsi.fastutil.Function

apply

Methods inherited from interface java.util.function.Function

andThen, compose, identity

Methods inherited from interface java.util.Map

forEach, replaceAll

Field Detail

key

protected transient short[] key

The array of keys.

value

protected transient V[] value

The array of values.

mask

protected transient int mask

The mask for wrapping a position counter.

containsNullKey

protected transient boolean containsNullKey

Whether this map contains the key zero.

strategy

protected ShortHash.Strategy strategy

The hash strategy of this custom map.

n

protected transient int n

The current table size.

maxFill

protected transient int maxFill

Threshold after which we rehash. It must be the table size times f.

minN

protected final transient int minN

We never resize below this threshold, which is the construction-time {#n}.

size

protected int size

Number of entries in the set (including the key zero, if present).

f

protected final float f

The acceptable load factor.

entries

protected transient Short2ReferenceMap.FastEntrySet<V> entries

Cached set of entries.

keys

protected transient ShortSet keys

Cached set of keys.

values

protected transient ReferenceCollection<V> values

Cached collection of values.

Constructor Detail

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(int expected,
                                        float f,
                                        ShortHash.Strategy strategy)

Creates a new hash map.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash map.

f - the load factor.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(int expected,
                                        ShortHash.Strategy strategy)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

expected - the expected number of elements in the hash map.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(ShortHash.Strategy strategy)

Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(Map<? extends Short,? extends V> m,
                                        float f,
                                        ShortHash.Strategy strategy)

Creates a new hash map copying a given one.

Parameters:

m - a Map to be copied into the new hash map.

f - the load factor.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(Map<? extends Short,? extends V> m,
                                        ShortHash.Strategy strategy)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.

Parameters:

m - a Map to be copied into the new hash map.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(Short2ReferenceMap<V> m,
                                        float f,
                                        ShortHash.Strategy strategy)

Creates a new hash map copying a given type-specific one.

Parameters:

m - a type-specific map to be copied into the new hash map.

f - the load factor.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(Short2ReferenceMap<V> m,
                                        ShortHash.Strategy strategy)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.

Parameters:

m - a type-specific map to be copied into the new hash map.

strategy - the strategy.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(short[] k,
                                        V[] v,
                                        float f,
                                        ShortHash.Strategy strategy)

Creates a new hash map using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

f - the load factor.

strategy - the strategy.

Throws:

IllegalArgumentException - if k and v have different lengths.

Short2ReferenceOpenCustomHashMap

public Short2ReferenceOpenCustomHashMap(short[] k,
                                        V[] v,
                                        ShortHash.Strategy strategy)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.

Parameters:

k - the array of keys of the new hash map.

v - the array of corresponding values in the new hash map.

strategy - the strategy.

Throws:

IllegalArgumentException - if k and v have different lengths.

Method Detail

strategy

public ShortHash.Strategy strategy()

Returns the hashing strategy.

Returns:

the hashing strategy of this custom hash map.

putAll

public void putAll(Map<? extends Short,? extends V> m)

Description copied from class: AbstractShort2ReferenceMap

Specified by:

putAll in interface Map<Short,V>

Overrides:

putAll in class AbstractShort2ReferenceMap<V>

put

public V put(short k,
             V v)

Description copied from interface: Short2ReferenceFunction

Adds a pair to the map (optional operation).

Specified by:

put in interface Short2ReferenceFunction<V>

Parameters:

k - the key.

v - the value.

Returns:

the old value, or the default return value if no value was present for the given key.

See Also:

Function.put(Object,Object)

shiftKeys

protected final void shiftKeys(int pos)

Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.

Parameters:

pos - a starting position.

remove

public V remove(short k)

Description copied from interface: Short2ReferenceFunction

Removes the mapping with the given key (optional operation).

Specified by:

remove in interface Short2ReferenceFunction<V>

Parameters:

k - the key.

Returns:

the old value, or the default return value if no value was present for the given key.

See Also:

Function.remove(Object)

get

public V get(short k)

Description copied from interface: Short2ReferenceFunction

Returns the value to which the given key is mapped.

Specified by:

get in interface Short2ReferenceFunction<V>

Parameters:

k - the key.

Returns:

the corresponding value, or the default return value if no value was present for the given key.

See Also:

Function.get(Object)

containsKey

public boolean containsKey(short k)

Description copied from interface: Short2ReferenceMap

Returns true if this function contains a mapping for the specified key.

Specified by:

containsKey in interface Short2ReferenceFunction<V>

Specified by:

containsKey in interface Short2ReferenceMap<V>

Overrides:

containsKey in class AbstractShort2ReferenceMap<V>

Parameters:

k - the key.

Returns:

true if this function associates a value to key.

See Also:

Map.containsKey(Object)

containsValue

public boolean containsValue(Object v)

Specified by:

containsValue in interface Map<Short,V>

Overrides:

containsValue in class AbstractShort2ReferenceMap<V>

getOrDefault

public V getOrDefault(short k,
                      V defaultValue)

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

Specified by:

getOrDefault in interface Short2ReferenceMap<V>

Parameters:

k - the key.

defaultValue - the default mapping of the key.

Returns:

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

See Also:

Map.getOrDefault(Object, Object)

putIfAbsent

public V putIfAbsent(short k,
                     V v)

If the specified key is not already associated with a value, associates it with the given value and returns the default return value, else returns the current value.

Specified by:

putIfAbsent in interface Short2ReferenceMap<V>

Parameters:

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

v - value to be associated with the specified key.

Returns:

the previous value associated with the specified key, or the default return value if there was no mapping for the key.

See Also:

Map.putIfAbsent(Object, Object)

remove

public boolean remove(short k,
                      Object v)

Removes the entry for the specified key only if it is currently mapped to the specified value.

Specified by:

remove in interface Short2ReferenceMap<V>

Parameters:

k - key with which the specified value is associated.

v - value expected to be associated with the specified key.

Returns:

true if the value was removed.

See Also:

Map.remove(Object, Object)

replace

public boolean replace(short k,
                       V oldValue,
                       V v)

Replaces the entry for the specified key only if currently mapped to the specified value.

Specified by:

replace in interface Short2ReferenceMap<V>

Parameters:

k - key with which the specified value is associated.

oldValue - value expected to be associated with the specified key.

v - value to be associated with the specified key.

Returns:

true if the value was replaced.

See Also:

Map.replace(Object, Object, Object)

replace

public V replace(short k,
                 V v)

Replaces the entry for the specified key only if it is currently mapped to some value.

Specified by:

replace in interface Short2ReferenceMap<V>

Parameters:

k - key with which the specified value is associated.

v - value to be associated with the specified key.

Returns:

the previous value associated with the specified key, or the default return value if there was no mapping for the key.

See Also:

Map.replace(Object, Object)

computeIfAbsent

public V computeIfAbsent(short k,
                         IntFunction<? extends V> mappingFunction)

If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map.

Note that contrarily to the default computeIfAbsent(), it is not possible to not add a value for a given key, since the mappingFunction cannot return null. If such a behavior is needed, please use the corresponding nullable version.

Specified by:

computeIfAbsent in interface Short2ReferenceMap<V>

Parameters:

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

mappingFunction - the function to compute a value.

Returns:

the current (existing or computed) value associated with the specified key.

See Also:

Map.computeIfAbsent(Object, java.util.function.Function)

computeIfPresent

public V computeIfPresent(short k,
                          BiFunction<? super Short,? super V,? extends V> remappingFunction)

If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.

Specified by:

computeIfPresent in interface Short2ReferenceMap<V>

Parameters:

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

remappingFunction - the function to compute a value.

Returns:

the new value associated with the specified key, or the default return value if none.

See Also:

Map.computeIfPresent(Object, java.util.function.BiFunction)

compute

public V compute(short k,
                 BiFunction<? super Short,? super V,? extends V> remappingFunction)

Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).

If the function returns null, the mapping is removed (or remains absent if initially absent). If the function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

Specified by:

compute in interface Short2ReferenceMap<V>

Parameters:

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

remappingFunction - the function to compute a value.

Returns:

the new value associated with the specified key, or the default return value if none.

See Also:

Map.compute(Object, java.util.function.BiFunction)

merge

public V merge(short k,
               V v,
               BiFunction<? super V,? super V,? extends V> remappingFunction)

If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result is null.

Specified by:

merge in interface Short2ReferenceMap<V>

Parameters:

k - key with which the resulting value is to be associated.

v - the non-null value to be merged with the existing value associated with the key or, if no existing value is associated with the key, to be associated with the key.

remappingFunction - the function to recompute a value if present.

Returns:

the new value associated with the specified key, or the default return value if no value is associated with the key.

See Also:

Map.merge(Object, Object, java.util.function.BiFunction)

clear

public void clear()

Description copied from interface: Short2ReferenceMap

Removes all of the mappings from this map (optional operation). The map will be empty after this call returns.

Specified by:

clear in interface Short2ReferenceMap<V>

Specified by:

clear in interface Map<Short,V>

See Also:

Map.clear()

size

public int size()

Description copied from interface: Short2ReferenceMap

Returns the number of key/value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Specified by:

size in interface Short2ReferenceMap<V>

Specified by:

size in interface Map<Short,V>

Returns:

the number of key-value mappings in this map.

See Also:

Size64

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<Short,V>

Overrides:

isEmpty in class AbstractShort2ReferenceMap<V>

short2ReferenceEntrySet

public Short2ReferenceMap.FastEntrySet<V> short2ReferenceEntrySet()

Description copied from interface: Short2ReferenceMap

Returns a type-specific set view of the mappings contained in this map.

This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen Map.entrySet() so that it returns an ObjectSet of type-specific entries (the latter makes it possible to access keys and values with type-specific methods).

Specified by:

short2ReferenceEntrySet in interface Short2ReferenceMap<V>

Returns:

a type-specific set view of the mappings contained in this map.

See Also:

Map.entrySet()

keySet

public ShortSet keySet()

Description copied from class: AbstractShort2ReferenceMap

Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

keySet in interface Short2ReferenceMap<V>

Specified by:

keySet in interface Map<Short,V>

Overrides:

keySet in class AbstractShort2ReferenceMap<V>

Returns:

a set view of the keys of this map; it may be safely cast to a type-specific interface.

See Also:

Map.keySet()

values

public ReferenceCollection<V> values()

Description copied from class: AbstractShort2ReferenceMap

Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by Map.entrySet(). Note that no attempt is made at caching the result of this method, as this would require adding some attributes that lightweight implementations would not need. Subclasses may easily override this policy by calling this method and caching the result, but implementors are encouraged to write more efficient ad-hoc implementations.

Specified by:

values in interface Short2ReferenceMap<V>

Specified by:

values in interface Map<Short,V>

Overrides:

values in class AbstractShort2ReferenceMap<V>

Returns:

a set view of the values of this map; it may be safely cast to a type-specific interface.

See Also:

Map.values()

trim

public boolean trim()

Rehashes the map, making the table as small as possible.

This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.

Returns:

true if there was enough memory to trim the map.

See Also:

trim(int)

trim

public boolean trim(int n)

Rehashes this map if the table is too large.

Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.

This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the map.

See Also:

trim()

rehash

protected void rehash(int newN)

Rehashes the map.

This method implements the basic rehashing strategy, and may be overridden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.

Parameters:

newN - the new size

clone

public Short2ReferenceOpenCustomHashMap<V> clone()

Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

Overrides:

clone in class Object

Returns:

a deep copy of this map.

hashCode

public int hashCode()

Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:

hashCode in interface Map<Short,V>

Overrides:

hashCode in class AbstractShort2ReferenceMap<V>

Returns:

a hash code for this map.