org.basex.util.hash

Class TokenSet

java.lang.Object

org.basex.util.hash.ASet

org.basex.util.hash.TokenSet

All Implemented Interfaces:

Iterable<byte[]>

Direct Known Subclasses:

Names, TokenBoolMap, TokenIntMap, TokenMap, TokenObjMap

public class TokenSet
extends ASet
implements Iterable<byte[]>

This is an efficient and memory-saving hash set for storing tokens. The first entry of the token set (offset 0) is always empty.

Author:

BaseX Team 2005-19, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[][]	keys Hashed keys.

Fields inherited from class org.basex.util.hash.ASet

buckets, next, size

Constructor Summary

Constructors

Constructor and Description
TokenSet() Default constructor.
TokenSet(byte[]... key) Constructor, specifying initial keys.
TokenSet(DataInput in) Constructor, specifying some initial input.

Method Summary

Modifier and Type	Method and Description
boolean	add(byte[] key) Stores the specified key if it has not been stored before.
boolean	add(String key) Stores the specified string as key if it has not been stored before.
void	clear() Resets the data structure.
boolean	contains(byte[] key) Checks if the set contains the specified key.
protected int	hash(int id) Returns the hash value of the element with the specified id.
int	id(byte[] key) Returns the id of the specified key, or 0 if the key does not exist.
Iterator<byte[]>	iterator()
byte[]	key(int id) Returns the key with the specified id.
int	put(byte[] key) Stores the specified key and returns its id.
void	read(DataInput in) Reads the data structure from the specified input.
protected void	rehash(int newSize) Rehashes all entries.
int	remove(byte[] key) Removes the entry with the specified key.
String	toString()
void	write(DataOutput out) Writes the data structure to the specified output.

Methods inherited from class org.basex.util.hash.ASet

checkSize, isEmpty, size, toString, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

keys

protected byte[][] keys

Hashed keys.

Constructor Detail

TokenSet

public TokenSet()

Default constructor.

TokenSet

public TokenSet(byte[]... key)

Constructor, specifying initial keys.

Parameters:

key - initial keys

TokenSet

public TokenSet(DataInput in)
         throws IOException

Constructor, specifying some initial input.

Parameters:

in - input stream

Throws:

IOException - I/O exception

Method Detail

read

public void read(DataInput in)
          throws IOException

Reads the data structure from the specified input.

Parameters:

in - input stream

Throws:

IOException - I/O exception

write

public void write(DataOutput out)
           throws IOException

Writes the data structure to the specified output.

Parameters:

out - output stream

Throws:

IOException - I/O exception

add

public final boolean add(byte[] key)

Stores the specified key if it has not been stored before.

Parameters:

key - key to be added

Returns:

true if the key did not exist yet and was stored

add

public final boolean add(String key)

Stores the specified string as key if it has not been stored before.

Parameters:

key - string to be added

Returns:

true if the key did not exist yet and was stored

put

public final int put(byte[] key)

Stores the specified key and returns its id.

Parameters:

key - key to be added

Returns:

unique id of stored key (larger than zero)

contains

public final boolean contains(byte[] key)

Checks if the set contains the specified key.

Parameters:

key - key to be looked up

Returns:

result of check

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 looked up

Returns:

id, or 0 if key does not exist

key

public final byte[] key(int id)

Returns the key with the specified id. All ids starts with 1 instead of 0.

Parameters:

id - id of the key to return

Returns:

key

remove

public int remove(byte[] key)

Removes the entry with the specified key. The deletion of keys will lead to empty entries. If ASet.size is called after deletions, the original number of entries will be returned.

Parameters:

key - key

Returns:

id of the deleted key, or 0 if the key did not exist

hash

protected int hash(int id)

Description copied from class: ASet

Returns the hash value of the element with the specified id.

Specified by:

hash in class ASet

Parameters:

id - id of the element

Returns:

hash value

rehash

protected void rehash(int newSize)

Description copied from class: ASet

Rehashes all entries.

Specified by:

rehash in class ASet

Parameters:

newSize - new hash size

clear

public void clear()

Description copied from class: ASet

Resets the data structure.

iterator

public final Iterator<byte[]> iterator()

Specified by:

iterator in interface Iterable<byte[]>

toString

public String toString()

Overrides:

toString in class Object