danbikel.parser
Class ProbabilityCache<K>

java.lang.Object
  java.util.AbstractMap<K,Object>
      danbikel.util.AbstractMapToPrimitive<K>
          danbikel.util.HashMapPrimitive<K>
              danbikel.util.HashMapDouble<K>
                  danbikel.parser.ProbabilityCache<K>

All Implemented Interfaces:

FlexibleMap<K,Object>, MapToPrimitive<K>, Serializable, Cloneable, Map<K,Object>

public class ProbabilityCache<K>
extends HashMapDouble<K>

A cache for storing arbitrary objects with their probabilities. This class uses a hash map, and offers several replacement strategies.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class danbikel.util.HashMapDouble

HashMapDouble.Entry<K>

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

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

Field Summary

static int	BUCKET_LRU Integer to indicate to delete the least-recently used entry in the same bucket as an entry being added after the size limit of this cache has been reached or exceeded.
static int	CLEAR_ALL Integer to indicate to delete all of the elements every time the size limit of this cache has been reached or exceeded.
static int	HALF_LIFE Integer to indicate to delete a random half of the elements every time the size limit of this cache has been reached or exceeded.
static int	RANDOM Integer to indicate to delete a random element every time the size limit of this cache has been exceeded.

Fields inherited from class danbikel.util.HashMapPrimitive

defaultInitialCapacity, defaultLoadFactor, hashCodeBitmask

Constructor Summary

ProbabilityCache(int maxCapacity)
Constructs a ProbabilityCache with the specified maximum capacity and the default replacement strategy.

ProbabilityCache(int maxCapacity, int initialCapacity)
Constructs a ProbabilityCache with the specified maximum capacity, the specified initial capacity and the default replacement strategy.

ProbabilityCache(int maxCapacity, int initialCapacity, float loadFactor)
Constructs a ProbabilityCache with the specified maximum capacity, the specified initial capacity, the specified load factor and the default replacement strategy.

Method Summary

boolean	containsKey(Object key)
Object	get(Object key) Throws an UnsupportedOperationException, as the only way to get values from this specialized cache is through the getProb(Object) method.
MapToPrimitive.Entry	getProb(K key) Returns the Double containing the probability of the specified key, or null if the specified key is not in this cache.
double	put(K key, double probability) Adds the specified key with the specified probability to this cache.
Object	put(Object key, Object value) Throws an UnsupportedOperationException, as the only way to add keys to this specialized cache is through the put(Object,double) method.
double	putAndRemove(K key, double probability) A synonym for putAndRemove(key, key.hashCode(), probability).
double	putAndRemove(K key, int hash, double probability) Puts the specified key into the cache with the specified probability, removing the least-recently used key from this key's bucket if the bucket is not currently empty.
void	removeRandom() Removes a random mapping from this map (optional operation).
void	setMaxCapacity(int maxCapacity) Sets the maximum capacity for this cache.
ProbabilityCache	setStrategy(int strategy) Sets the strategy for replacement when the size limit of this cache has been reached.

Methods inherited from class danbikel.util.HashMapDouble

getNewEntry

Methods inherited from class danbikel.util.HashMapPrimitive

add, add, add, add, add, add, addEntryMRU, entrySet, get, getCapacity, getEntry, getEntry, getEntryMRU, getEntryMRU, getLoadFactor, getOrCreateEntry, getStats, put, put, put, put, put, put, put, remove, removeLRU, removeLRU, removeRandom

Methods inherited from class danbikel.util.AbstractMapToPrimitive

add, add, add, add, add, add, put, put, put, put, put, put, toString

Methods inherited from class java.util.AbstractMap

clear, clone, containsValue, equals, hashCode, isEmpty, keySet, putAll, size, values

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

clear, containsValue, equals, hashCode, isEmpty, keySet, putAll, size, values

Field Detail

RANDOM

public static final int RANDOM

Integer to indicate to delete a random element every time the size limit of this cache has been exceeded.

See Also:

setStrategy(int), put(Object,double), Constant Field Values

BUCKET_LRU

public static final int BUCKET_LRU

Integer to indicate to delete the least-recently used entry in the same bucket as an entry being added after the size limit of this cache has been reached or exceeded. Put another way, after the size limit of the cache has been reached (the size limit is specified at construction), every time an element is cached, if its bucket contains at least one item, then the least-recently used item of that bucket is first deleted and then the current item is added. Thus, this replacement strategy will treat the maximum capacity of this cache as a soft limit, for in instances where the bucket is already empty, this strategy will simply add an item, deleting nothing. A consequence is that the average bucket size can increase over time, but never by more than 1 + the average bucket size at the time the maximum capacity was reached (because only empty buckets can increase in size from 0 to 1).

This strategy is the default.

See Also:

setStrategy(int), put(Object,double), Constant Field Values

HALF_LIFE

public static final int HALF_LIFE

Integer to indicate to delete a random half of the elements every time the size limit of this cache has been reached or exceeded.

See Also:

setStrategy(int), put(Object,double), Constant Field Values

CLEAR_ALL

public static final int CLEAR_ALL

Integer to indicate to delete all of the elements every time the size limit of this cache has been reached or exceeded.

See Also:

setStrategy(int), put(Object,double), Constant Field Values

Constructor Detail

ProbabilityCache

public ProbabilityCache(int maxCapacity)

Constructs a ProbabilityCache with the specified maximum capacity and the default replacement strategy.

Parameters:

maxCapacity - the maximum number of elements held by this cache

See Also:

BUCKET_LRU, setStrategy(int)

ProbabilityCache

public ProbabilityCache(int maxCapacity,
                        int initialCapacity)

Constructs a ProbabilityCache with the specified maximum capacity, the specified initial capacity and the default replacement strategy.

Parameters:

maxCapacity - the maximum number of elements held by this cache

initialCapacity - the initial capacity of the underlying hash map

See Also:

BUCKET_LRU, setStrategy(int)

ProbabilityCache

public ProbabilityCache(int maxCapacity,
                        int initialCapacity,
                        float loadFactor)

Constructs a ProbabilityCache with the specified maximum capacity, the specified initial capacity, the specified load factor and the default replacement strategy.

Parameters:

maxCapacity - the maximum number of elements held by this cache

initialCapacity - the initial capacity of the underlying hash map

loadFactor - the load factor of the underlying hash map

See Also:

BUCKET_LRU, setStrategy(int)

Method Detail

setStrategy

public ProbabilityCache setStrategy(int strategy)

Sets the strategy for replacement when the size limit of this cache has been reached.

Parameters:

strategy - the integer id for the caching strategy to set for this cache

Returns:

this probability cache object

See Also:

RANDOM, BUCKET_LRU, HALF_LIFE, CLEAR_ALL

setMaxCapacity

public void setMaxCapacity(int maxCapacity)

Sets the maximum capacity for this cache.

Parameters:

maxCapacity - the new maximum capacity of this cache

Throws:

IllegalArgumentException - if the specified maximum capacity is zero or negative

put

public Object put(Object key,
                  Object value)

Throws an UnsupportedOperationException, as the only way to add keys to this specialized cache is through the put(Object,double) method.

Specified by:

put in interface Map<K,Object>

Overrides:

put in class HashMapPrimitive<K>

Parameters:

key - ignored

value - ignored

Returns:

nothing

See Also:

put(Object,double)

put

public double put(K key,
                  double probability)

Adds the specified key with the specified probability to this cache. As a side effect, if the maximum capacity of this cache has been reached or exceeded at the time this method is invoked, then one or more cached elements may be removed, depending on the cache strategy being used.

Specified by:

put in interface MapToPrimitive<K>

Overrides:

put in class AbstractMapToPrimitive<K>

Parameters:

key - the key to add to this cache

probability - the probability of the specified key to be cached

Returns:

the old value associated with key, or null if there was no mapping for this key

See Also:

setStrategy(int)

putAndRemove

public final double putAndRemove(K key,
                                 double probability)

A synonym for putAndRemove(key, key.hashCode(), probability).

Parameters:

key - the key to be inserted into this cache

probability - the probability of the key

Returns:

the old probability of the specified key, or Double.NaN if the key did not exist in this map

putAndRemove

public final double putAndRemove(K key,
                                 int hash,
                                 double probability)

Puts the specified key into the cache with the specified probability, removing the least-recently used key from this key's bucket if the bucket is not currently empty.

Parameters:

key - the key to be inserted into this cache

hash - the hash value of the specified key

probability - the probability of the specified key

Returns:

the old probability of the specified key, or Double.NaN if the key did not exist in this map

get

public Object get(Object key)

Throws an UnsupportedOperationException, as the only way to get values from this specialized cache is through the getProb(Object) method.

Specified by:

get in interface Map<K,Object>

Overrides:

get in class AbstractMap<K,Object>

See Also:

getProb(Object)

getProb

public MapToPrimitive.Entry getProb(K key)

Returns the Double containing the probability of the specified key, or null if the specified key is not in this cache.

Parameters:

key - the key to look up in this cache

Returns:

the probability of the specified key or null if it is not in this cache

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,Object>

Overrides:

containsKey in class HashMapPrimitive<K>

removeRandom

public void removeRandom()

Description copied from class: AbstractMapToPrimitive

Removes a random mapping from this map (optional operation).

Specified by:

removeRandom in interface MapToPrimitive<K>

Overrides:

removeRandom in class AbstractMapToPrimitive<K>