org.apache.lucene.util.collections

Class ObjectToFloatMap<K>

java.lang.Object

org.apache.lucene.util.collections.ObjectToFloatMap<K>

public class ObjectToFloatMap<K>
extends Object

An Array-based hashtable which maps Objects of generic type T to primitive float values.
The hashtable is constructed with a given capacity, or 16 as a default. In case there's not enough room for new pairs, the hashtable grows.
Capacity is adjusted to a power of 2, and there are 2 * capacity entries for the hash. The pre allocated arrays (for keys, values) are at length of capacity + 1, when index 0 is used as 'Ground' or 'NULL'.
The arrays are allocated ahead of hash operations, and form an 'empty space' list, to which the key,value pair is allocated.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor and Description
ObjectToFloatMap() Constructs a map with default capacity.
ObjectToFloatMap(int capacity) Constructs a map with given capacity.

Method Summary

Methods

Modifier and Type	Method and Description
protected int	calcBaseHashIndex(K key) Calculating the baseHash index using the internal hashFactor.
void	clear() Empties the map.
boolean	containsKey(K key) Checks if a given key exists in the map.
boolean	containsValue(float o) Checks if the given object exists in the map. This method iterates over the collection, trying to find an equal object.
boolean	equals(Object o)
protected int	find(K key) Find the actual index of a given key.
float	get(K key) Returns the float mapped with the given key.
protected void	grow() Grows the map.
int	hashCode()
boolean	isEmpty()
FloatIterator	iterator() Returns a new iterator for the mapped floats.
Iterator<K>	keyIterator() Returns an iterator on the map keys.
float	put(K key, float e) Inserts the <key,value> pair into the map.
float	remove(K key) Removes a <key,value> pair from the map and returns the mapped value, or Float.NaN if the none existed.
int	size()
float[]	toArray() Translates the mapped pairs' values into an array of Objects
float[]	toArray(float[] a) Translates the mapped pairs' values into an array of T
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectToFloatMap

public ObjectToFloatMap()

Constructs a map with default capacity.

ObjectToFloatMap

public ObjectToFloatMap(int capacity)

Constructs a map with given capacity. Capacity is adjusted to a native power of 2, with minimum of 16.

Parameters:

capacity - minimum capacity for the map.

Method Detail

calcBaseHashIndex

protected int calcBaseHashIndex(K key)

Calculating the baseHash index using the internal hashFactor.

clear

public void clear()

Empties the map. Generates the "Empty" space list for later allocation.

containsKey

public boolean containsKey(K key)

Checks if a given key exists in the map.

Parameters:

key - that is checked against the map data.

Returns:

true if the key exists in the map. false otherwise.

containsValue

public boolean containsValue(float o)

Checks if the given object exists in the map.
This method iterates over the collection, trying to find an equal object.

Parameters:

o - object that is checked against the map data.

Returns:

true if the object exists in the map (in .equals() meaning). false otherwise.

find

protected int find(K key)

Find the actual index of a given key.

Returns:

index of the key. zero if the key wasn't found.

get

public float get(K key)

Returns the float mapped with the given key.

Parameters:

key - object who's mapped float we're interested in.

Returns:

a float mapped by the given key. Float.NaN if the key wasn't found.

grow

protected void grow()

Grows the map. Allocates a new map of double the capacity, and fast-insert the old key-value pairs.

isEmpty

public boolean isEmpty()

Returns:

true if the map is empty. false otherwise.

iterator

public FloatIterator iterator()

Returns a new iterator for the mapped floats.

keyIterator

public Iterator<K> keyIterator()

Returns an iterator on the map keys.

put

public float put(K key,
        float e)

Inserts the <key,value> pair into the map. If the key already exists, this method updates the mapped value to the given one, returning the old mapped value.

Returns:

the old mapped value, or Float.NaN if the key didn't exist.

remove

public float remove(K key)

Removes a <key,value> pair from the map and returns the mapped value, or Float.NaN if the none existed.

Parameters:

key - used to find the value to remove

Returns:

the removed value or Float.NaN if none existed.

size

public int size()

Returns:

number of pairs currently in the map

toArray

public float[] toArray()

Translates the mapped pairs' values into an array of Objects

Returns:

an object array of all the values currently in the map.

toArray

public float[] toArray(float[] a)

Translates the mapped pairs' values into an array of T

Parameters:

a - the array into which the elements of the list are to be stored, if it is big enough; otherwise, use as much space as it can.

Returns:

an array containing the elements of the list

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object