com.healthmarketscience.jackcess.impl

Class IndexData.EntryCursor

java.lang.Object

com.healthmarketscience.jackcess.impl.IndexData.EntryCursor

Enclosing class:

IndexData

public final class IndexData.EntryCursor
extends java.lang.Object

Utility class to traverse the entries in the Index. Remains valid in the face of index entry modifications.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	IndexData.EntryCursor.DirHandler Handles moving the cursor in a given direction.
private class	IndexData.EntryCursor.ForwardDirHandler Handles moving the cursor forward.
private class	IndexData.EntryCursor.ReverseDirHandler Handles moving the cursor backward.

Field Summary

Fields

Modifier and Type	Field and Description
private IndexData.Position	_curPos the current entry
private IndexData.Position	_firstPos the first (exclusive) row id for this cursor
private IndexData.EntryCursor.DirHandler	_forwardDirHandler handler for moving the page cursor forward
private int	_lastModCount the last read modification count on the Index.
private IndexData.Position	_lastPos the last (exclusive) row id for this cursor
private IndexData.Position	_prevPos the previous entry
private IndexData.EntryCursor.DirHandler	_reverseDirHandler handler for moving the page cursor backward

Constructor Summary

Constructors

Modifier	Constructor and Description
private	EntryCursor(IndexData.Position firstPos, IndexData.Position lastPos)

Method Summary

Modifier and Type	Method and Description
void	afterEntry(java.lang.Object[] row) Repositions the cursor so that the previous row will be the first entry <= the given row.
void	afterLast()
void	beforeEntry(java.lang.Object[] row) Repositions the cursor so that the next row will be the first entry >= the given row.
void	beforeFirst()
private void	checkForModification() Checks the index for modifications and updates state accordingly.
private IndexData.Position	getAnotherPosition(boolean moveForward) Gets another entry in the given direction, returning the new entry.
private IndexData.EntryCursor.DirHandler	getDirHandler(boolean moveForward) Returns the DirHandler for the given direction
IndexData.Entry	getFirstEntry() Returns the first entry (exclusive) as defined by this cursor.
IndexData	getIndexData()
private int	getIndexModCount()
IndexData.Entry	getLastEntry() Returns the last entry (exclusive) as defined by this cursor.
IndexData.Entry	getNextEntry()
IndexData.Entry	getPreviousEntry()
boolean	isUpToDate() Returns true if this cursor is up-to-date with respect to its index.
void	reset()
protected void	reset(boolean moveForward)
protected void	restorePosition(IndexData.Entry curEntry) Restores a current position for the cursor (current position becomes previous position).
protected void	restorePosition(IndexData.Entry curEntry, IndexData.Entry prevEntry) Restores a current and previous position for the cursor.
java.lang.String	toString()
private void	updateBounds() Updates any the boundary info (_firstPos/_lastPos).
private IndexData.Position	updatePosition(IndexData.Entry entry) Updates the given position, taking boundaries into account.

Methods inherited from class java.lang.Object

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

Field Detail

_forwardDirHandler

private final IndexData.EntryCursor.DirHandler _forwardDirHandler

handler for moving the page cursor forward

_reverseDirHandler

private final IndexData.EntryCursor.DirHandler _reverseDirHandler

handler for moving the page cursor backward

_firstPos

private IndexData.Position _firstPos

the first (exclusive) row id for this cursor

_lastPos

private IndexData.Position _lastPos

the last (exclusive) row id for this cursor

_curPos

private IndexData.Position _curPos

the current entry

_prevPos

private IndexData.Position _prevPos

the previous entry

_lastModCount

private int _lastModCount

the last read modification count on the Index. we track this so that the cursor can detect updates to the index while traversing and act accordingly

Constructor Detail

EntryCursor

private EntryCursor(IndexData.Position firstPos,
                    IndexData.Position lastPos)

Method Detail

getDirHandler

private IndexData.EntryCursor.DirHandler getDirHandler(boolean moveForward)

Returns the DirHandler for the given direction

getIndexData

public IndexData getIndexData()

getIndexModCount

private int getIndexModCount()

getFirstEntry

public IndexData.Entry getFirstEntry()

Returns the first entry (exclusive) as defined by this cursor.

getLastEntry

public IndexData.Entry getLastEntry()

Returns the last entry (exclusive) as defined by this cursor.

isUpToDate

public boolean isUpToDate()

Returns true if this cursor is up-to-date with respect to its index.

reset

public void reset()

beforeFirst

public void beforeFirst()

afterLast

public void afterLast()

reset

protected void reset(boolean moveForward)

beforeEntry

public void beforeEntry(java.lang.Object[] row)
                 throws java.io.IOException

Repositions the cursor so that the next row will be the first entry >= the given row.

Throws:

java.io.IOException

afterEntry

public void afterEntry(java.lang.Object[] row)
                throws java.io.IOException

Repositions the cursor so that the previous row will be the first entry <= the given row.

Throws:

java.io.IOException

getNextEntry

public IndexData.Entry getNextEntry()
                             throws java.io.IOException

Returns:

valid entry if there was a next entry, #getLastEntry otherwise

Throws:

java.io.IOException

getPreviousEntry

public IndexData.Entry getPreviousEntry()
                                 throws java.io.IOException

Returns:

valid entry if there was a next entry, #getFirstEntry otherwise

Throws:

java.io.IOException

restorePosition

protected void restorePosition(IndexData.Entry curEntry)
                        throws java.io.IOException

Restores a current position for the cursor (current position becomes previous position).

Throws:

java.io.IOException

restorePosition

protected void restorePosition(IndexData.Entry curEntry,
                               IndexData.Entry prevEntry)
                        throws java.io.IOException

Restores a current and previous position for the cursor.

Throws:

java.io.IOException

getAnotherPosition

private IndexData.Position getAnotherPosition(boolean moveForward)
                                       throws java.io.IOException

Gets another entry in the given direction, returning the new entry.

Throws:

java.io.IOException

checkForModification

private void checkForModification()
                           throws java.io.IOException

Checks the index for modifications and updates state accordingly.

Throws:

java.io.IOException

updatePosition

private IndexData.Position updatePosition(IndexData.Entry entry)
                                   throws java.io.IOException

Updates the given position, taking boundaries into account.

Throws:

java.io.IOException

updateBounds

private void updateBounds()
                   throws java.io.IOException

Updates any the boundary info (_firstPos/_lastPos).

Throws:

java.io.IOException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object