it.unimi.dsi.fastutil.longs
Class Long2ByteOpenHashMap

java.lang.Object
  extended by it.unimi.dsi.fastutil.longs.AbstractLong2ByteFunction
      extended by it.unimi.dsi.fastutil.longs.AbstractLong2ByteMap
          extended by it.unimi.dsi.fastutil.longs.Long2ByteOpenHashMap
All Implemented Interfaces:
Function<Long,Byte>, Hash, Long2ByteFunction, Long2ByteMap, Serializable, Cloneable, Map<Long,Byte>

public class Long2ByteOpenHashMap
extends AbstractLong2ByteMap
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 enlarged as needed when new entries are created, but it is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

The enlargement speed is controlled by the growth factor, a positive number. If the growth factor is p, then the table is enlarged each time roughly by a factor 2p/16. By default, p is Hash.DEFAULT_GROWTH_FACTOR, which means that the table is doubled at each enlargement, but one can easily set more or less aggressive policies by calling growthFactor(int) (note that the growth factor is not serialized: deserialized tables gets the default growth factor).

See Also:
Hash, HashCommon, Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.longs.AbstractLong2ByteMap
AbstractLong2ByteMap.BasicEntry
 
Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash
Hash.Strategy<K>
 
Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.longs.Long2ByteMap
Long2ByteMap.Entry, Long2ByteMap.FastEntrySet
 
Field Summary
static long serialVersionUID
           
 
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
Long2ByteOpenHashMap()
          Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Long2ByteOpenHashMap(int n)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Long2ByteOpenHashMap(int n, float f)
          Creates a new hash map.
Long2ByteOpenHashMap(long[] k, byte[] v)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays.
Long2ByteOpenHashMap(long[] k, byte[] v, float f)
          Creates a new hash map using the elements of two parallel arrays.
Long2ByteOpenHashMap(Long2ByteMap m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.
Long2ByteOpenHashMap(Long2ByteMap m, float f)
          Creates a new hash map copying a given type-specific one.
Long2ByteOpenHashMap(Map<? extends Long,? extends Byte> m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Long2ByteOpenHashMap(Map<? extends Long,? extends Byte> m, float f)
          Creates a new hash map copying a given one.
 
Method Summary
 void clear()
          Removes all associations from this function (optional operation).
 Object clone()
          Returns a deep copy of this map.
 boolean containsKey(long k)
          Checks whether the given value is contained in AbstractLong2ByteMap.keySet().
 boolean containsValue(byte v)
          Checks whether the given value is contained in AbstractLong2ByteMap.values().
 byte get(long k)
          Returns the value to which the given key is mapped.
 Byte get(Long ok)
           
 int growthFactor()
          Gets the growth factor.
 void growthFactor(int growthFactor)
          Sets the growth factor.
 int hashCode()
          Returns a hash code for this map.
 boolean isEmpty()
           
 LongSet keySet()
          Returns a type-specific-set view of the keys of this map.
 Long2ByteMap.FastEntrySet long2ByteEntrySet()
          Returns a type-specific set view of the mappings contained in this map.
 byte put(long k, byte v)
          Adds a pair to the map.
 Byte put(Long ok, Byte ov)
          Delegates to the corresponding type-specific method, taking care of returning null on a missing key.
 boolean rehash()
          Rehashes this map without changing the table size.
 byte remove(long k)
          Removes the mapping with the given key.
 Byte remove(Object ok)
          Delegates to the corresponding type-specific method, taking care of returning null on a missing key.
 int size()
          Returns the intended number of keys in this function, or -1 if no such number exists.
 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.longs.AbstractLong2ByteMap
containsValue, entrySet, equals, putAll, toString
 
Methods inherited from class it.unimi.dsi.fastutil.longs.AbstractLong2ByteFunction
containsKey, defaultReturnValue, defaultReturnValue, get
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.longs.Long2ByteFunction
defaultReturnValue, defaultReturnValue
 
Methods inherited from interface it.unimi.dsi.fastutil.Function
containsKey, get
 
Methods inherited from interface java.util.Map
containsKey, get
 

Field Detail

serialVersionUID

public static final long serialVersionUID
See Also:
Constant Field Values
Constructor Detail

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(int n,
                            float f)
Creates a new hash map. The actual table size is the least available prime greater than n/f.

Parameters:
n - the expected number of elements in the hash map.
f - the load factor.
See Also:
Hash.PRIMES

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(int n)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:
n - the expected number of elements in the hash map.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap()
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.


Long2ByteOpenHashMap

public Long2ByteOpenHashMap(Map<? extends Long,? 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.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(Map<? extends Long,? 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.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(Long2ByteMap 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.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(Long2ByteMap 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.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(long[] 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.

Long2ByteOpenHashMap

public Long2ByteOpenHashMap(long[] 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 Detail

growthFactor

public void growthFactor(int growthFactor)
Sets the growth factor. Subsequent enlargements will increase the table size roughly by a multiplicative factor of 2p/16.

Parameters:
growthFactor - the new growth factor; it must be positive.

growthFactor

public int growthFactor()
Gets the growth factor.

Returns:
the growth factor of this set.
See Also:
growthFactor(int)

put

public byte put(long k,
                byte v)
Description copied from interface: Long2ByteFunction
Adds a pair to the map.

Specified by:
put in interface Long2ByteFunction
Overrides:
put in class AbstractLong2ByteFunction
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)

put

public Byte put(Long ok,
                Byte ov)
Description copied from class: AbstractLong2ByteFunction
Delegates to the corresponding type-specific method, taking care of returning null on a missing key.

This method must check whether the provided key is in the map using containsKey(). Thus, it probes the map twice. Implementors of subclasses should override it with a more efficient method.

Specified by:
put in interface Function<Long,Byte>
Specified by:
put in interface Map<Long,Byte>
Overrides:
put in class AbstractLong2ByteFunction
Parameters:
ok - the key.
ov - the value.
Returns:
the old value, or null if no value was present for the given key.
See Also:
Map.put(Object,Object)

containsValue

public boolean containsValue(byte v)
Description copied from class: AbstractLong2ByteMap
Checks whether the given value is contained in AbstractLong2ByteMap.values().

Specified by:
containsValue in interface Long2ByteMap
Overrides:
containsValue in class AbstractLong2ByteMap
See Also:
Map.containsValue(Object)

clear

public void clear()
Description copied from interface: Function
Removes all associations from this function (optional operation).

Specified by:
clear in interface Function<Long,Byte>
Specified by:
clear in interface Map<Long,Byte>
Overrides:
clear in class AbstractLong2ByteFunction
See Also:
Map.clear()

containsKey

public boolean containsKey(long k)
Description copied from class: AbstractLong2ByteMap
Checks whether the given value is contained in AbstractLong2ByteMap.keySet().

Specified by:
containsKey in interface Long2ByteFunction
Overrides:
containsKey in class AbstractLong2ByteMap
See Also:
Function.containsKey(Object)

size

public int size()
Description copied from interface: Function
Returns the intended number of keys in this function, or -1 if no such number exists.

Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible.

Specified by:
size in interface Function<Long,Byte>
Specified by:
size in interface Map<Long,Byte>
Returns:
the intended number of keys in this function, or -1 if that number is not available.

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Map<Long,Byte>
Overrides:
isEmpty in class AbstractLong2ByteMap

get

public byte get(long k)
Description copied from interface: Long2ByteFunction
Returns the value to which the given key is mapped.

Specified by:
get in interface Long2ByteFunction
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)

remove

public byte remove(long k)
Description copied from interface: Long2ByteFunction
Removes the mapping with the given key.

Specified by:
remove in interface Long2ByteFunction
Overrides:
remove in class AbstractLong2ByteFunction
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 Byte get(Long ok)

remove

public Byte remove(Object ok)
Description copied from class: AbstractLong2ByteFunction
Delegates to the corresponding type-specific method, taking care of returning null on a missing key.

This method must check whether the provided key is in the map using containsKey(). Thus, it probes the map twice. Implementors of subclasses should override it with a more efficient method.

Specified by:
remove in interface Function<Long,Byte>
Specified by:
remove in interface Map<Long,Byte>
Overrides:
remove in class AbstractLong2ByteFunction
Returns:
the old value, or null if no value was present for the given key.
See Also:
Map.remove(Object)

long2ByteEntrySet

public Long2ByteMap.FastEntrySet long2ByteEntrySet()
Description copied from interface: Long2ByteMap
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 Long2ByteMap.entrySet() so that it returns an ObjectSet of objects of type Long2ByteMap.Entry (the latter makes it possible to access keys and values with type-specific methods).

Specified by:
long2ByteEntrySet in interface Long2ByteMap
Returns:
a type-specific set view of the mappings contained in this map.
See Also:
Long2ByteMap.entrySet()

keySet

public LongSet keySet()
Description copied from class: AbstractLong2ByteMap
Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by AbstractLong2ByteMap.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 Long2ByteMap
Specified by:
keySet in interface Map<Long,Byte>
Overrides:
keySet in class AbstractLong2ByteMap
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: AbstractLong2ByteMap
Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by AbstractLong2ByteMap.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 Long2ByteMap
Specified by:
values in interface Map<Long,Byte>
Overrides:
values in class AbstractLong2ByteMap
Returns:
a set view of the values of this map; it may be safely cast to a type-specific interface.
See Also:
Map.values()

rehash

public boolean rehash()
Rehashes this map without changing the table size.

This method should be called when the map underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.

If you need to reduce the table siza to fit exactly this map, you must use trim().

Returns:
true if there was enough memory to rehash the map, false otherwise.
See Also:
trim()

trim

public boolean trim()
Rehashes the map, making the table as small as possible.

This method rehashes to the smallest size satisfying the load factor. It can be used when the map will not be changed anymore, so to optimize access speed (by collecting deleted entries) and size.

If the table size is already the minimum possible, this method does nothing. If you want to guarantee rehashing, use rehash().

Returns:
true if there was enough memory to trim the map.
See Also:
trim(int), rehash()

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()

clone

public Object 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<Long,Byte>
Overrides:
hashCode in class AbstractLong2ByteMap
Returns:
a hash code for this map.