org.basex.util.hash

Class TokenSet

java.lang.Object

org.basex.util.hash.TokenSet

All Implemented Interfaces:

java.lang.Iterable<byte[]>

Direct Known Subclasses:

Functions, MemValues, Names, StopWords, TokenBoolMap, TokenIntMap, TokenMap, TokenObjMap

public class TokenSet
extends java.lang.Object
implements java.lang.Iterable<byte[]>

This is an efficient hash set, storing keys in byte arrays. The TokenMap class extends it to a hash map.

Author:

BaseX Team 2005-12, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	CAP Initial hash capacity.
byte[][]	keys Hashed keys.
int	size Hash entries.

Constructor Summary

Constructors

Constructor and Description
TokenSet() Constructor.
TokenSet(byte[]... init) Constructor.
TokenSet(DataInput in) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	add(byte[] key) Indexes the specified key and returns the offset of the added key.
int	delete(byte[] key) Deletes the specified key.
int	id(byte[] key) Returns the id of the specified key or 0 if the key does not exist.
java.util.Iterator<byte[]>	iterator()
byte[]	key(int i) Returns the specified key.
byte[][]	keys() Returns the hash keys.
protected void	read(DataInput in) Reads the token set from the specified input.
protected void	rehash() Resizes the hash table.
int	size() Returns the number of entries.
java.lang.String	toString()
void	write(DataOutput out) Writes the token set to the specified output.

Methods inherited from class java.lang.Object

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

Field Detail

CAP

protected static final int CAP

Initial hash capacity.

See Also:

Constant Field Values

size

public int size

Hash entries. Note: actual number of entries is size - 1.

keys

public byte[][] keys

Hashed keys.

Constructor Detail

TokenSet

public TokenSet()

Constructor.

TokenSet

public TokenSet(byte[]... init)

Constructor.

Parameters:

init - initial tokens

TokenSet

public TokenSet(DataInput in)
         throws java.io.IOException

Constructor.

Parameters:

in - input stream

Throws:

java.io.IOException - I/O exception

Method Detail

read

protected void read(DataInput in)
             throws java.io.IOException

Reads the token set from the specified input.

Parameters:

in - input stream

Throws:

java.io.IOException - I/O exception

write

public void write(DataOutput out)
           throws java.io.IOException

Writes the token set to the specified output.

Parameters:

out - output stream

Throws:

java.io.IOException - I/O exception

add

public final int add(byte[] key)

Indexes the specified key and returns the offset of the added key. If the key already exists, a negative offset is returned.

Parameters:

key - key

Returns:

offset of added key, negative offset otherwise

delete

public int delete(byte[] key)

Deletes the specified key. Warning: After a deletion, the key array will have null entries, and the total number of entries will not reflect the number of valid entries anymore.

Parameters:

key - key

Returns:

deleted key or 0

id

public final int id(byte[] key)

Returns the id of the specified key or 0 if the key does not exist.

Parameters:

key - key to be found

Returns:

id or 0 if nothing was found

key

public final byte[] key(int i)

Returns the specified key.

Parameters:

i - key index

Returns:

key

keys

public final byte[][] keys()

Returns the hash keys.

Returns:

keys

size

public final int size()

Returns the number of entries.

Returns:

number of entries

rehash

protected void rehash()

Resizes the hash table.

iterator

public final java.util.Iterator<byte[]> iterator()

Specified by:

iterator in interface java.lang.Iterable<byte[]>

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object