org.apache.lucene.util.collections
Class IntToDoubleMap

java.lang.Object
  org.apache.lucene.util.collections.IntToDoubleMap

public class IntToDoubleMap
extends Object

An Array-based hashtable which maps primitive int to a primitive double.
The hashtable is constracted 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.

Field Summary

static double

GROUND

Constructor Summary

IntToDoubleMap()
Constructs a map with default capacity.

IntToDoubleMap(int capacity)
Constructs a map with given capacity.

Method Summary

protected int	calcBaseHashIndex(int key) Calculating the baseHash index using the internal hashFactor .
void	clear() Empties the map.
boolean	containsKey(int key) Checks if a given key exists in the map.
boolean	containsValue(double value) Checks if the given value exists in the map. This method iterates over the collection, trying to find an equal object.
boolean	equals(Object o)
protected int	find(int key) Find the actual index of a given key.
double	get(int key) Returns the value mapped with the given key.
protected void	grow() Grows the map.
int	hashCode()
boolean	isEmpty()
DoubleIterator	iterator() Returns a new iterator for the mapped double values.
IntIterator	keyIterator() Returns an iterator on the map keys.
double	put(int key, double v) Inserts the <key,value> pair into the map.
double	remove(int key) Removes a <key,value> pair from the map and returns the mapped value, or Double.NaN if the none existed.
int	size()
double[]	toArray() Translates the mapped pairs' values into an array of Objects
double[]	toArray(double[] 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

Field Detail

GROUND

public static final double GROUND

See Also:

Constant Field Values

Constructor Detail

IntToDoubleMap

public IntToDoubleMap()

Constructs a map with default capacity.

IntToDoubleMap

public IntToDoubleMap(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(int key)

Calculating the baseHash index using the internal hashFactor .

Parameters:

key -

clear

public void clear()

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

containsKey

public boolean containsKey(int 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(double value)

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

Parameters:

value - double value that is checked against the map data.

Returns:

true if the value exists in the map, false otherwise.

find

protected int find(int key)

Find the actual index of a given key.

Parameters:

key -

Returns:

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

get

public double get(int key)

Returns the value mapped with the given key.

Parameters:

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

Returns:

a double value mapped by the given key. Double.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 DoubleIterator iterator()

Returns a new iterator for the mapped double values.

keyIterator

public IntIterator keyIterator()

Returns an iterator on the map keys.

put

public double put(int key,
                  double v)

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 Double.NaN if the key didn't exist.

remove

public double remove(int key)

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

Parameters:

key - used to find the value to remove

Returns:

the removed value or Double.NaN if none existed.

size

public int size()

Returns:

number of pairs currently in the map

toArray

public double[] toArray()

Translates the mapped pairs' values into an array of Objects

Returns:

a double array of all the values currently in the map.

toArray

public double[] toArray(double[] 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 use whatever space we need, setting the one after the true data as Double.NaN.

Returns:

an array containing the elements of the list, using the given parameter if big enough, otherwise allocate an appropriate array and return it.

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