Package it.unimi.dsi.fastutil.objects

Class Reference2ByteOpenHashMap<K>

java.lang.Object

it.unimi.dsi.fastutil.objects.AbstractReference2ByteFunction<K>

it.unimi.dsi.fastutil.objects.AbstractReference2ByteMap<K>

it.unimi.dsi.fastutil.objects.Reference2ByteOpenHashMap<K>

All Implemented Interfaces:

Function<K,Byte>, Hash, Reference2ByteFunction<K>, Reference2ByteMap<K>, Serializable, Cloneable, Function<K,Byte>, ToIntFunction<K>, Map<K,Byte>

public class Reference2ByteOpenHashMap<K>
extends AbstractReference2ByteMap<K>
implements Serializable, Cloneable, Hash

A type-specific hash map with a fast, small-footprint implementation.

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.

Entries returned by the type-specific Reference2ByteMap.entrySet() method implement the suitable type-specific Pair interface; only values are mutable.

See Also:

• Hash
• HashCommon
• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.objects.AbstractReference2ByteMap

AbstractReference2ByteMap.BasicEntry<K>, AbstractReference2ByteMap.BasicEntrySet<K>

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

Hash.Strategy<K>

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.objects.Reference2ByteMap

Reference2ByteMap.Entry<K>, Reference2ByteMap.FastEntrySet<K>

Field Summary

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	Description
Reference2ByteOpenHashMap()	Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Reference2ByteOpenHashMap(int expected)	Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Reference2ByteOpenHashMap(int expected, float f)	Creates a new hash map.
Reference2ByteOpenHashMap(Reference2ByteMap<K> m)	Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.
Reference2ByteOpenHashMap(Reference2ByteMap<K> m, float f)	Creates a new hash map copying a given type-specific one.
Reference2ByteOpenHashMap(Map<? extends K,? extends Byte> m)	Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Reference2ByteOpenHashMap(Map<? extends K,? extends Byte> m, float f)	Creates a new hash map copying a given one.
Reference2ByteOpenHashMap(K[] k, byte[] v)	Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.
Reference2ByteOpenHashMap(K[] k, byte[] v, float f)	Creates a new hash map using the elements of two parallel arrays.

Method Summary

Modifier and Type	Method	Description
byte	addTo(K k, byte incr)	Adds an increment to value currently associated with a key.
void	clear()	Removes all of the mappings from this map (optional operation).
Reference2ByteOpenHashMap<K>	clone()	Returns a deep copy of this map.
byte	computeByte(K k, BiFunction<? super K,? super Byte,? extends Byte> remappingFunction)	Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
byte	computeByteIfPresent(K k, BiFunction<? super K,? super Byte,? extends Byte> remappingFunction)	If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
byte	computeIfAbsent(K key, Reference2ByteFunction<? super K> 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, unless the key is not present in the given mapping function.
byte	computeIfAbsent(K k, ToIntFunction<? super K> 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.
boolean	containsKey(Object k)	Returns true if this function contains a mapping for the specified key.
boolean	containsValue(byte v)	Returns true if this map maps one or more keys to the specified value.
void	ensureCapacity(int capacity)	Ensures that this map can hold a certain number of keys without rehashing.
byte	getByte(Object k)	Returns the value to which the given key is mapped.
byte	getOrDefault(Object k, byte 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()
ReferenceSet<K>	keySet()	Returns a type-specific-set view of the keys of this map.
byte	merge(K k, byte v, BiFunction<? super Byte,? super Byte,? extends Byte> remappingFunction)	If the specified key is not already associated with a value, associates it with the given value.
byte	put(K k, byte v)	Adds a pair to the map (optional operation).
void	putAll(Map<? extends K,? extends Byte> m)
byte	putIfAbsent(K k, byte 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.
Reference2ByteMap.FastEntrySet<K>	reference2ByteEntrySet()	Returns a type-specific set view of the mappings contained in this map.
boolean	remove(Object k, byte v)	Removes the entry for the specified key only if it is currently mapped to the specified value.
byte	removeByte(Object k)	Removes the mapping with the given key (optional operation).
byte	replace(K k, byte v)	Replaces the entry for the specified key only if it is currently mapped to some value.
boolean	replace(K k, byte oldValue, byte v)	Replaces the entry for the specified key only if currently mapped to the specified value.
int	size()	Returns the number of key/value mappings in this map.
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.
ByteCollection	values()	Returns a type-specific-set view of the values of this map.

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractReference2ByteMap

equals, toString

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractReference2ByteFunction

defaultReturnValue, defaultReturnValue

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

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

apply

Methods inherited from interface java.util.function.Function

compose

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, replaceAll

Methods inherited from interface it.unimi.dsi.fastutil.objects.Reference2ByteFunction

andThen, andThenByte, andThenChar, andThenDouble, andThenFloat, andThenInt, andThenLong, andThenObject, andThenReference, andThenShort, applyAsInt, composeByte, composeChar, composeDouble, composeFloat, composeInt, composeLong, composeObject, composeReference, composeShort

Methods inherited from interface it.unimi.dsi.fastutil.objects.Reference2ByteMap

computeByteIfAbsent, computeByteIfAbsentPartial, containsValue, defaultReturnValue, defaultReturnValue, entrySet, forEach, get, getOrDefault, merge, mergeByte, mergeByte, mergeByte, put, putIfAbsent, remove, remove, replace, replace

Constructor Details

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(int expected,
 float f)

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.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(int expected)

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

Parameters:

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

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap()

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

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(Map<? extends K,? extends Byte> m,
 float f)

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.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(Map<? extends K,? extends Byte> m)

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.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(Reference2ByteMap<K> m,
 float f)

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.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(Reference2ByteMap<K> m)

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.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(K[] k,
 byte[] v,
 float f)

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.

Throws:

IllegalArgumentException - if k and v have different lengths.

Reference2ByteOpenHashMap

public Reference2ByteOpenHashMap(K[] k,
 byte[] v)

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.

Throws:

IllegalArgumentException - if k and v have different lengths.

Method Details

ensureCapacity

public void ensureCapacity(int capacity)

Ensures that this map can hold a certain number of keys without rehashing.

Parameters:

capacity - a number of keys; there will be no rehashing unless the map size exceeds this number.

putAll

public void putAll(Map<? extends K,? extends Byte> m)

Description copied from class: AbstractReference2ByteMap

Specified by:

putAll in interface Map<K,Byte>

Overrides:

putAll in class AbstractReference2ByteMap<K>

put

public byte put(K k,
 byte v)

Description copied from interface: Reference2ByteFunction

Adds a pair to the map (optional operation).

Specified by:

put in interface Reference2ByteFunction<K>

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)

addTo

public byte addTo(K k,
 byte incr)

Adds an increment to value currently associated with a key.

Note that this method respects the default return value semantics: when called with a key that does not currently appears in the map, the key will be associated with the default return value plus the given increment.

Parameters:

k - the key.

incr - the increment.

Returns:

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

removeByte

public byte removeByte(Object k)

Description copied from interface: Reference2ByteFunction

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

Specified by:

removeByte in interface Reference2ByteFunction<K>

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)

getByte

public byte getByte(Object k)

Description copied from interface: Reference2ByteFunction

Returns the value to which the given key is mapped.

Specified by:

getByte in interface Reference2ByteFunction<K>

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(Object k)

Description copied from class: AbstractReference2ByteMap

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

Specified by:

containsKey in interface Function<K,Byte>

Specified by:

containsKey in interface Map<K,Byte>

Specified by:

containsKey in interface Reference2ByteMap<K>

Overrides:

containsKey in class AbstractReference2ByteMap<K>

Parameters:

k - the key.

Returns:

true if this function associates a value to key.

See Also:

• Map.containsKey(Object)

containsValue

public boolean containsValue(byte v)

Description copied from class: AbstractReference2ByteMap

Returns true if this map maps one or more keys to the specified value.

Specified by:

containsValue in interface Reference2ByteMap<K>

Overrides:

containsValue in class AbstractReference2ByteMap<K>

See Also:

• Map.containsValue(Object)

getOrDefault

public byte getOrDefault(Object k,
 byte 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 Reference2ByteFunction<K>

Specified by:

getOrDefault in interface Reference2ByteMap<K>

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 byte putIfAbsent(K k,
 byte 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 Reference2ByteMap<K>

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(Object k,
 byte v)

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

Specified by:

remove in interface Reference2ByteMap<K>

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(K k,
 byte oldValue,
 byte v)

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

Specified by:

replace in interface Reference2ByteMap<K>

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 byte replace(K k,
 byte v)

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

Specified by:

replace in interface Reference2ByteMap<K>

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 byte computeIfAbsent(K k,
 ToIntFunction<? super K> 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 Reference2ByteMap<K>

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)

computeIfAbsent

public byte computeIfAbsent(K key,
 Reference2ByteFunction<? super K> 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, unless the key is not present in the given mapping function.

This version of computeIfAbsent() uses a type-specific version of fastutil's Function. Since Function has a containsKey() method, it is possible to avoid adding a key by having containsKey() return false for that key.

Specified by:

computeIfAbsent in interface Reference2ByteMap<K>

Parameters:

key - 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)

computeByteIfPresent

public byte computeByteIfPresent(K k,
 BiFunction<? super K,? super Byte,? extends Byte> 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:

computeByteIfPresent in interface Reference2ByteMap<K>

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)

computeByte

public byte computeByte(K k,
 BiFunction<? super K,? super Byte,? extends Byte> 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:

computeByte in interface Reference2ByteMap<K>

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 byte merge(K k,
 byte v,
 BiFunction<? super Byte,? super Byte,? extends Byte> remappingFunction)

If the specified key is not already associated with a value, associates it with the given 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 Reference2ByteMap<K>

Parameters:

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

v - the 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: Reference2ByteMap

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

Specified by:

clear in interface Function<K,Byte>

Specified by:

clear in interface Map<K,Byte>

Specified by:

clear in interface Reference2ByteMap<K>

See Also:

• Map.clear()

size

public int size()

Description copied from interface: Reference2ByteMap

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 Function<K,Byte>

Specified by:

size in interface Map<K,Byte>

Specified by:

size in interface Reference2ByteMap<K>

Returns:

the number of key-value mappings in this map.

See Also:

• Size64

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,Byte>

Overrides:

isEmpty in class AbstractReference2ByteMap<K>

reference2ByteEntrySet

public Reference2ByteMap.FastEntrySet<K> reference2ByteEntrySet()

Description copied from interface: Reference2ByteMap

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:

reference2ByteEntrySet in interface Reference2ByteMap<K>

Returns:

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

See Also:

• Map.entrySet()

keySet

public ReferenceSet<K> keySet()

Description copied from class: AbstractReference2ByteMap

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 Map<K,Byte>

Specified by:

keySet in interface Reference2ByteMap<K>

Overrides:

keySet in class AbstractReference2ByteMap<K>

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 ByteCollection values()

Description copied from class: AbstractReference2ByteMap

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 Map<K,Byte>

Specified by:

values in interface Reference2ByteMap<K>

Overrides:

values in class AbstractReference2ByteMap<K>

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()

clone

public Reference2ByteOpenHashMap<K> 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.

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<K,Byte>

Overrides:

hashCode in class AbstractReference2ByteMap<K>

Returns:

a hash code for this map.