org.basex.data
Class MemData

java.lang.Object
  org.basex.data.Data
      org.basex.data.MemData

public class MemData
extends Data

This class stores and organizes the database table and the index structures for textual content in a compressed memory structure. Each node occupies 64 bits. The current storage layout looks like follows:

 ELEMENTS:
 - Byte     0: Node kind (TAG)
 - Byte     1: Tag Reference
 - Byte     2: Number of attributes
 - Byte  4- 7: Number of descendants (size)
 - Byte  4- 7: Relative parent reference
 TEXT NODES:
 - Byte     0: Node kind (TEXT/PI/COMM)
 - Byte  0- 3: Text reference
 - Byte  4- 7: Parent Reference
 ATTRIBUTE NODES:
 - Byte     0: Node kind (ATTR)
 - Byte     1: Attribute name reference
 - Byte     2: Relative parent reference
 - Byte  4- 7: Attribute value Reference
 

Author:

Workgroup DBIS, University of Konstanz 2005-07, ISC License, Christian Gruen

Field Summary

Fields inherited from class org.basex.data.Data

ATTR, atts, COMM, contentID, deepfs, dirID, DOC, ELEM, fileID, meta, nameID, PI, size, sizeID, suffixID, tags, TEXT, timeID

Constructor Summary

MemData(int cap, Names tag, Names att)
Constructor.

Method Summary

void	addAtt(byte[] a, byte[] v, int p) Convenience method for adding an attribute.
void	addAtt(int a, byte[] v, int d) Adds an attribute.
void	addElem(byte[] t, int d, int a, int s, int k) Convenience method for adding an element.
void	addElem(int t, int d, int a, int s, int k) Adds an element.
void	addText(byte[] t, int d, int k) Adds a text node.
void	append(MemData d, int p) Copies some data.
int	attID(byte[] v) Returns the id for the specified attribute value.
int	attNameID(int pre) Returns an attribute name id (reference to the attribute name index).
double	attNum(int pre) Returns an attribute value as double value.
int	attSize(int pre, int kind) Returns a number of attributes.
byte[]	attToken(int id) Returns the index value for the specified attribute value id.
byte[]	attValue(int pre) Returns an attribute value.
void	close() Closes the current database.
void	closeIndex(Index.TYPE index) Closes the specified index.
void	delete(int pre) Deletes a node and its descendants.
void	finishTag(int pre) Adds the size value to the table.
void	flush() Flushes the table data.
int[][]	ftIDs(byte[] word, FTOption ftOption) Returns the indexed id references for the specified fulltext token.
int	id(int pre) Returns a unique node id.
void	info(PrintOutput out) Returns info on the index structures.
void	insert(int pre, int par, byte[] tag, byte kind) Inserts a tag name, text node, comment or processing instruction.
void	insert(int pre, int par, byte[] name, byte[] v) Inserts an attribute.
void	insert(int pre, int par, Data d) Insert a data instance at the specified pre value.
void	insert(MemData d, int pos) Inserts a data instance at the specified position.
int	kind(int pre) Returns a node kind.
int	nrFTIDs(byte[] token) Returns the number of indexed id references for the specified token.
void	openIndex(Index.TYPE type, Index ind) Opens the specified index.
int	parent(int pre, int kind) Returns a pre value of the parent node.
int	pre(int id) Returns a pre value.
int	size(int pre, int kind) Returns a size value (number of descendant table entries).
int	tagID(int pre) Returns a tag id (reference to the tag index).
byte[]	text(int pre) Returns a text.
int	textLen(int pre) Returns a text length.
double	textNum(int pre) Returns a text as double value.
byte[]	textToken(int id) Returns the index value for the specified index id.
void	update(int pre, byte[] text) Updates a tag name, text node, comment or processing instruction.
void	update(int pre, byte[] attName, byte[] attValue) Updates an attribute name and value.

Methods inherited from class org.basex.data.Data

atom, atomNum, attName, attNameID, attValue, ids, initNames, noLeaf, nrIDs, nrTags, tag, tagID

Methods inherited from class java.lang.Object

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

Constructor Detail

MemData

public MemData(int cap,
               Names tag,
               Names att)

Constructor.

Parameters:

cap - initial array capacity

tag - tag index

att - attribute name index

Method Detail

addAtt

public final void addAtt(byte[] a,
                         byte[] v,
                         int p)

Convenience method for adding an attribute.

Parameters:

a - attribute name

v - attribute value

p - parent

addAtt

public final void addAtt(int a,
                         byte[] v,
                         int d)

Adds an attribute.

Parameters:

a - attribute name

v - attribute value

d - distance

addElem

public final void addElem(byte[] t,
                          int d,
                          int a,
                          int s,
                          int k)

Convenience method for adding an element.

Parameters:

t - tag

d - distance

a - number of attributes

s - node size

k - node kind

addElem

public final void addElem(int t,
                          int d,
                          int a,
                          int s,
                          int k)

Adds an element.

Parameters:

t - tag

d - distance

a - number of attributes

s - node size

k - node kind

addText

public final void addText(byte[] t,
                          int d,
                          int k)

Adds a text node.

Parameters:

t - text to be added

d - distance

k - node kind

append

public final void append(MemData d,
                         int p)

Copies some data.

Parameters:

d - data reference

p - position

attID

public final int attID(byte[] v)

Returns the id for the specified attribute value.

Parameters:

v - attribute value

Returns:

id

attNameID

public final int attNameID(int pre)

Description copied from class: Data

Returns an attribute name id (reference to the attribute name index).

Specified by:

attNameID in class Data

Parameters:

pre - pre value

Returns:

token reference

attNum

public final double attNum(int pre)

Description copied from class: Data

Returns an attribute value as double value.

Specified by:

attNum in class Data

Parameters:

pre - pre value

Returns:

numeric value

attSize

public final int attSize(int pre,
                         int kind)

Description copied from class: Data

Returns a number of attributes.

Specified by:

attSize in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

number of attributes

attToken

public final byte[] attToken(int id)

Returns the index value for the specified attribute value id.

Parameters:

id - index id

Returns:

value

attValue

public final byte[] attValue(int pre)

Description copied from class: Data

Returns an attribute value.

Specified by:

attValue in class Data

Parameters:

pre - pre value

Returns:

atomized value

close

public void close()

Description copied from class: Data

Closes the current database.

Specified by:

close in class Data

closeIndex

public void closeIndex(Index.TYPE index)

Description copied from class: Data

Closes the specified index.

Specified by:

closeIndex in class Data

Parameters:

index - index to be closed

delete

public final void delete(int pre)

Description copied from class: Data

Deletes a node and its descendants.

Specified by:

delete in class Data

Parameters:

pre - pre value of the node to delete

finishTag

public final void finishTag(int pre)

Adds the size value to the table.

Parameters:

pre - closing pre tag

flush

public void flush()

Description copied from class: Data

Flushes the table data.

Specified by:

flush in class Data

ftIDs

public int[][] ftIDs(byte[] word,
                     FTOption ftOption)

Description copied from class: Data

Returns the indexed id references for the specified fulltext token.

Specified by:

ftIDs in class Data

Parameters:

word - token to be looked up

ftOption - fulltext options

Returns:

id array

id

public final int id(int pre)

Description copied from class: Data

Returns a unique node id.

Specified by:

id in class Data

Parameters:

pre - pre value

Returns:

node id

info

public final void info(PrintOutput out)

Description copied from class: Data

Returns info on the index structures.

Specified by:

info in class Data

Parameters:

out - output stream

insert

public final void insert(int pre,
                         int par,
                         byte[] tag,
                         byte kind)

Description copied from class: Data

Inserts a tag name, text node, comment or processing instruction.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

tag - value to be inserted

kind - node kind

insert

public void insert(int pre,
                   int par,
                   byte[] name,
                   byte[] v)

Description copied from class: Data

Inserts an attribute.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

name - attribute name

v - attribute value

insert

public final void insert(int pre,
                         int par,
                         Data d)

Description copied from class: Data

Insert a data instance at the specified pre value. Note that the specified data instance must differ from this instance.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

d - data instance to copy from

insert

public final void insert(MemData d,
                         int pos)

Inserts a data instance at the specified position. Attention: get sure that both data instances are based on the same indexes as the references are simply copied and not checked at all...

Parameters:

d - data instance

pos - insertion position

kind

public final int kind(int pre)

Description copied from class: Data

Returns a node kind.

Specified by:

kind in class Data

Parameters:

pre - pre value

Returns:

node kind

nrFTIDs

public final int nrFTIDs(byte[] token)

Description copied from class: Data

Returns the number of indexed id references for the specified token.

Specified by:

nrFTIDs in class Data

Parameters:

token - token to be looked up

Returns:

id array

openIndex

public void openIndex(Index.TYPE type,
                      Index ind)

Description copied from class: Data

Opens the specified index.

Specified by:

openIndex in class Data

Parameters:

type - index to be opened

ind - index instance

parent

public final int parent(int pre,
                        int kind)

Description copied from class: Data

Returns a pre value of the parent node.

Specified by:

parent in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

pre value of the parent node

pre

public final int pre(int id)

Description copied from class: Data

Returns a pre value.

Specified by:

pre in class Data

Parameters:

id - unique node id

Returns:

pre value or -1 if id was not found

size

public final int size(int pre,
                      int kind)

Description copied from class: Data

Returns a size value (number of descendant table entries).

Specified by:

size in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

size value

tagID

public final int tagID(int pre)

Description copied from class: Data

Returns a tag id (reference to the tag index).

Specified by:

tagID in class Data

Parameters:

pre - pre value

Returns:

token reference

text

public final byte[] text(int pre)

Description copied from class: Data

Returns a text.

Specified by:

text in class Data

Parameters:

pre - pre value

Returns:

atomized value

textLen

public final int textLen(int pre)

Description copied from class: Data

Returns a text length.

Specified by:

textLen in class Data

Parameters:

pre - pre value

Returns:

atomized value

textNum

public final double textNum(int pre)

Description copied from class: Data

Returns a text as double value.

Specified by:

textNum in class Data

Parameters:

pre - pre value

Returns:

numeric value

textToken

public final byte[] textToken(int id)

Returns the index value for the specified index id.

Parameters:

id - index id

Returns:

value

update

public final void update(int pre,
                         byte[] text)

Description copied from class: Data

Updates a tag name, text node, comment or processing instruction.

Specified by:

update in class Data

Parameters:

pre - pre of the text node to change

text - value to be updated

update

public final void update(int pre,
                         byte[] attName,
                         byte[] attValue)

Description copied from class: Data

Updates an attribute name and value.

Specified by:

update in class Data

Parameters:

pre - pre of node to insert after

attName - attribute name

attValue - attribute value