it.unimi.dsi.fastutil.objects
Class Object2IntLinkedOpenHashMap

java.lang.Object
  extended byit.unimi.dsi.fastutil.objects.AbstractObject2IntMap
      extended byit.unimi.dsi.fastutil.objects.Object2IntLinkedOpenHashMap
All Implemented Interfaces:
Cloneable, Hash, Map, Object2IntMap, Object2IntSortedMap, Serializable, SortedMap

public class Object2IntLinkedOpenHashMap
extends AbstractObject2IntMap
implements Serializable, Cloneable, Hash, Object2IntSortedMap

A type-specific linked hash map with 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 serialised: deserialised tables gets the default growth factor).

This class implements the interface of a sorted map, so to allow easy access of the iteration order: for instance, you can get the first key in iteration order with firstKey() without having to create an iterator; however, this class partially violates the SortedMap contract because all submap methods throw an exception and comparator() returns always null.

The iterators provided by the views of this class using are type-specific list iterators. However, creation of an iterator using a starting point is going to be very expensive, as the chosen starting point must be linearly searched for, unless it is lastKey(), in which case the iterator is created in constant time.

Note that deletions in a linked table require scanning the list until the element to be removed is found. The only exceptions are the first element, the last element, and deletions performed using an iterator.

See Also:
Hash, HashCommon, Serialized Form

Field Summary
static long serialVersionUID
           
 
Fields inherited from interface it.unimi.dsi.fastutil.Hash
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED
 
Constructor Summary
Object2IntLinkedOpenHashMap()
          Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Object2IntLinkedOpenHashMap(int n)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Object2IntLinkedOpenHashMap(int n, float f)
          Creates a new hash map.
Object2IntLinkedOpenHashMap(Map m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Object2IntLinkedOpenHashMap(Map m, float f)
          Creates a new hash map copying a given one.
Object2IntLinkedOpenHashMap(Object2IntMap m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.
Object2IntLinkedOpenHashMap(Object2IntMap m, float f)
          Creates a new hash map copying a given type-specific one.
 
Method Summary
 void clear()
           
 Object clone()
          Returns a deep copy of this map.
 Comparator comparator()
           
 boolean containsKey(Object k)
           
 boolean containsValue(int v)
           
 Set entrySet()
           
 Object firstKey()
          Returns the first key of this map in iteration order.
 Object get(Object ok)
           
 int getInt(Object k)
          Returns the value to which the given key is mapped.
 int growthFactor()
          Gets the growth factor.
 void growthFactor(int growthFactor)
          Sets the growth factor.
 int hashCode()
          Returns a hash code for this map.
 SortedMap headMap(Object oto)
           
 boolean isEmpty()
           
 Set keySet()
           
 Object lastKey()
          Returns the last key of this map in iteration order.
 int put(Object k, int v)
          Adds a pair to the map.
 Object put(Object ok, Object ov)
           
 boolean rehash()
          Rehashes this map without changing the table size.
 Object remove(Object ok)
           
 int removeInt(Object ok)
          Removes the mapping with the given key.
 int size()
           
 SortedMap subMap(Object ofrom, Object oto)
           
 SortedMap tailMap(Object ofrom)
           
 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.
 Collection values()
           
 
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2IntMap
containsValue, defaultReturnValue, defaultReturnValue, equals, getDefRetValue, putAll, setDefRetValue, toString
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2IntMap
defaultReturnValue, defaultReturnValue, getDefRetValue, setDefRetValue
 
Methods inherited from interface java.util.Map
containsValue, equals, putAll
 

Field Detail

serialVersionUID

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

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(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

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(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.

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap()
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.


Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(Map 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.

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(Map 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.

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(Object2IntMap 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.

Object2IntLinkedOpenHashMap

public Object2IntLinkedOpenHashMap(Object2IntMap 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.
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.

put

public Object put(Object ok,
                  Object ov)
Specified by:
put in interface Map

put

public int put(Object k,
               int v)
Description copied from interface: Object2IntMap
Adds a pair to the map.

Specified by:
put in interface Object2IntMap
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:
Map.put(Object,Object)

remove

public Object remove(Object ok)
Specified by:
remove in interface Map

containsValue

public boolean containsValue(int v)
Specified by:
containsValue in interface Object2IntMap
See Also:
Map.containsValue(Object)

clear

public void clear()
Specified by:
clear in interface Map

firstKey

public final Object firstKey()
Returns the first key of this map in iteration order.

Specified by:
firstKey in interface SortedMap
Returns:
the first key in iteration order.

lastKey

public final Object lastKey()
Returns the last key of this map in iteration order.

Specified by:
lastKey in interface SortedMap
Returns:
the last key in iteration order.

tailMap

public final SortedMap tailMap(Object ofrom)
Specified by:
tailMap in interface SortedMap

headMap

public final SortedMap headMap(Object oto)
Specified by:
headMap in interface SortedMap

subMap

public final SortedMap subMap(Object ofrom,
                              Object oto)
Specified by:
subMap in interface SortedMap

comparator

public final Comparator comparator()
Specified by:
comparator in interface SortedMap

containsKey

public boolean containsKey(Object k)
Specified by:
containsKey in interface Map

size

public int size()
Specified by:
size in interface Map

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Map

get

public Object get(Object ok)
Specified by:
get in interface Map

getInt

public int getInt(Object k)
Description copied from interface: Object2IntMap
Returns the value to which the given key is mapped.

Specified by:
getInt in interface Object2IntMap
Parameters:
k - the key.
Returns:
the corresponding value, or the default return value if no value was present for the given key.
See Also:
Map.get(Object)

removeInt

public int removeInt(Object ok)
Description copied from interface: Object2IntMap
Removes the mapping with the given key.

Specified by:
removeInt in interface Object2IntMap
Parameters:
ok -
Returns:
the old value, or the default return value if no value was present for the given key.
See Also:
Map.remove(Object)

entrySet

public Set entrySet()
Specified by:
entrySet in interface Map

keySet

public Set keySet()
Specified by:
keySet in interface Map

values

public Collection values()
Specified by:
values in interface Map

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 optimise 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 n entries, still satisfying the load factor. If the current table size is smaller than or equal to N, or if the number of elements of this map is larger than 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.

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
Overrides:
hashCode in class AbstractObject2IntMap
Returns:
a hash code for this map.