gnu.kawa.util

Class IntHashTable

java.lang.Object

gnu.kawa.util.IntHashTable

public class IntHashTable
extends java.lang.Object

A hash table that maps Object to int. This is a custom hash table optimised for Object-to-int maps. This is done to avoid unnecessary object allocation in the image set.

See Also:

OutPort

Field Summary

Fields

Modifier and Type	Field and Description
protected int[]	ints
protected int	mask
protected int	num_bindings
protected java.lang.Object[]	objs

Constructor Summary

Constructors

Constructor and Description
IntHashTable() Construct an Object-to-int hash table.
IntHashTable(int capacity) Construct an Object-to-int hash table with a specified amount of mappings.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all mappings from this map.
int	getFromIndex(int index) Return the value stored at the specified index in the table.
int	hash(java.lang.Object key) Compute the hash code of a given object.
int	lookup(java.lang.Object key) Lookup a given key's value in the hash table.
int	lookup(java.lang.Object key, int hash) Find either the index of a key's value, or the index of an available space.
int	putAtIndex(java.lang.Object key, int value, int index) Associates the specified key with the specified value in this map.
protected void	rehash() Expand the hash table when it exceeds the load factor.
int	remove(java.lang.Object key)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

objs

protected java.lang.Object[] objs

ints

protected int[] ints

mask

protected int mask

num_bindings

protected int num_bindings

Constructor Detail

IntHashTable

public IntHashTable()

Construct an Object-to-int hash table. The default size of the hash table is 64 mappings.

IntHashTable

public IntHashTable(int capacity)

Construct an Object-to-int hash table with a specified amount of mappings.

Parameters:

capacity - The number of default mappings in this hash table.

Method Detail

hash

public int hash(java.lang.Object key)

Compute the hash code of a given object.

Parameters:

key - The object whose hash code is to be computed.

Returns:

zero if the object is null, otherwise the identityHashCode

lookup

public int lookup(java.lang.Object key,
                  int hash)

Find either the index of a key's value, or the index of an available space.

Parameters:

key - The key to whose value you want to find.

hash - The hash code of this key.

Returns:

Either the index of the key's value, or an index pointing to unoccupied space.

lookup

public int lookup(java.lang.Object key)

Lookup a given key's value in the hash table.

Parameters:

key - The key whose value you want to find.

Returns:

Either the index of the key's value, or an index pointing to unoccupied space.

getFromIndex

public int getFromIndex(int index)

Return the value stored at the specified index in the table.

Parameters:

index - The index to inspect, as returned from lookup(java.lang.Object, int)

Returns:

A non-negative integer if the index contains a non-null value, or -1 if it does.

putAtIndex

public int putAtIndex(java.lang.Object key,
                      int value,
                      int index)

Associates the specified key with the specified value in this map.

Parameters:

key - key with which the specified value is to be associated.

value - value to be associated with the specified key.

index - the index at which to place this binding, as returned from lookup(java.lang.Object, int).

Returns:

previous value associated with specified key, or -1 if there was no mapping for key.

remove

public int remove(java.lang.Object key)

rehash

protected void rehash()

Expand the hash table when it exceeds the load factor. Rehash the existing objects.

clear

public void clear()

Removes all mappings from this map.