org.apache.directory.server.core.partition.impl.btree
Class IndexCursorAdaptor<K,O>

java.lang.Object
  org.apache.directory.server.core.partition.impl.btree.IndexCursorAdaptor<K,O>

All Implemented Interfaces:

java.lang.Iterable<IndexEntry<K,O>>, Cursor<IndexEntry<K,O>>, IndexCursor<K,O>

public class IndexCursorAdaptor<K,O>
extends java.lang.Object
implements IndexCursor<K,O>

A Cursor which adapts an underlying Tuple based Cursor to one which returns IndexEntry objects rather than tuples.

Version:

$Rev$

Author:

Apache Directory Project

Constructor Summary

IndexCursorAdaptor(Cursor<Tuple> wrappedCursor, boolean forwardIndex)
Creates an IndexCursorAdaptor which wraps and adapts a Cursor from a table to one which returns an IndexEntry.

Method Summary

void	after(IndexEntry<K,O> element) Prepares this Cursor, so a subsequent call to Cursor#previous() with a true return value, will have positioned the Cursor on a dataset element equal to or less than the element argument but not greater.
void	afterLast() Positions this Curser after the last element.
void	afterValue(java.lang.Long id, K key) An alternative to calling after(IndexEntry) which often may require wrapping an id and value in a newly created IndexEntry object that may be an unnecessary object creation.
boolean	available() Determines whether or not a call to get() will succeed.
void	before(IndexEntry<K,O> element) Prepares this Cursor, so a subsequent call to Cursor#next() with a true return value, will have positioned the Cursor on a dataset element equal to or less than the element argument but not greater.
void	beforeFirst() Positions this Curser before the first element.
void	beforeValue(java.lang.Long id, K key) An alternative to calling before(IndexEntry) which often may require wrapping an id and value in a newly created IndexEntry object that may be an unnecessary object creation.
void	close() Closes this Cursor and frees any resources it my have allocated.
void	close(java.lang.Exception reason) Closes this Cursor and frees any resources it my have allocated.
boolean	first() Positions this Curser at the first element.
IndexEntry<K,O>	get() Gets the object at the current position.
boolean	isClosed() Checks if this Curser is closed.
boolean	isElementReused() Gets whether or not this Cursor will return the same element object instance on get() operations for any position of this Cursor.
java.util.Iterator<IndexEntry<K,O>>	iterator()
boolean	last() Positions this Curser at the last element.
boolean	next() Advances this Cursor to the next position.
boolean	previous() Advances this Cursor to the previous position.
void	setClosureMonitor(ClosureMonitor monitor) Sets a non-null closure monitor to associate with this Cursor.

Methods inherited from class java.lang.Object

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

Constructor Detail

IndexCursorAdaptor

public IndexCursorAdaptor(Cursor<Tuple> wrappedCursor,
                          boolean forwardIndex)

Creates an IndexCursorAdaptor which wraps and adapts a Cursor from a table to one which returns an IndexEntry.

Parameters:

wrappedCursor - the Cursor being adapted

forwardIndex - true for a cursor over a forward index, false for one over a reverse index

Method Detail

available

public boolean available()

Description copied from interface: Cursor

Determines whether or not a call to get() will succeed.

Specified by:

available in interface Cursor<IndexEntry<K,O>>

Returns:

true if the cursor is valid get() will succeed, false otherwise

beforeValue

public void beforeValue(java.lang.Long id,
                        K key)
                 throws java.lang.Exception

Description copied from interface: IndexCursor

An alternative to calling before(IndexEntry) which often may require wrapping an id and value in a newly created IndexEntry object that may be an unnecessary object creation. Some implementations may not support this operation and may throw an UnsupportedOperationEception.

Specified by:

beforeValue in interface IndexCursor<K,O>

Parameters:

id - the Long id for the entry

key - the value to advance just before

Throws:

java.lang.Exception - if there are faults peforming this operation

afterValue

public void afterValue(java.lang.Long id,
                       K key)
                throws java.lang.Exception

Description copied from interface: IndexCursor

An alternative to calling after(IndexEntry) which often may require wrapping an id and value in a newly created IndexEntry object that may be an unnecessary object creation. Some implementations may not support this operation and may throw an UnsupportedOperationEception.

Specified by:

afterValue in interface IndexCursor<K,O>

Parameters:

id - the Long id for the entry

key - the value to advance just after the last value

Throws:

java.lang.Exception - if there are faults peforming this operation

before

public void before(IndexEntry<K,O> element)
            throws java.lang.Exception

Description copied from interface: Cursor

Prepares this Cursor, so a subsequent call to Cursor#next() with a true return value, will have positioned the Cursor on a dataset element equal to or less than the element argument but not greater. A call to Cursor#previous() with a true return value will position the Cursor on a dataset element less than the argument. If Cursor#next() returns false then the Cursor is past the last element and so all values in the dataset are less than the argument. If Cursor#previous() returns false then the Cursor is positioned before the first element and all elements in the dataset are greater than the argument.

Specified by:

before in interface Cursor<IndexEntry<K,O>>

Parameters:

element - the element to be positioned before

Throws:

java.lang.Exception - with problems accessing the underlying btree

java.lang.UnsupportedOperationException - if this method is not supported

after

public void after(IndexEntry<K,O> element)
           throws java.lang.Exception

Description copied from interface: Cursor

Prepares this Cursor, so a subsequent call to Cursor#previous() with a true return value, will have positioned the Cursor on a dataset element equal to or less than the element argument but not greater. A call to Cursor#next() with a true return value will position the Cursor on a dataset element greater than the argument. If Cursor#next() returns false then the Cursor is past the last element and so all values in the dataset are less than or equal to the argument. If Cursor#previous() returns false then the Cursor is positioned before the first element and all elements in the dataset are greater than the argument.

Specified by:

after in interface Cursor<IndexEntry<K,O>>

Parameters:

element - the element to be positioned after

Throws:

java.lang.Exception - if there are problems positioning this cursor or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

beforeFirst

public void beforeFirst()
                 throws java.lang.Exception

Description copied from interface: Cursor

Positions this Curser before the first element.

Specified by:

beforeFirst in interface Cursor<IndexEntry<K,O>>

Throws:

java.lang.Exception - if there are problems positioning this cursor or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

afterLast

public void afterLast()
               throws java.lang.Exception

Description copied from interface: Cursor

Positions this Curser after the last element.

Specified by:

afterLast in interface Cursor<IndexEntry<K,O>>

Throws:

java.lang.Exception - if there are problems positioning this Cursor or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

first

public boolean first()
              throws java.lang.Exception

Description copied from interface: Cursor

Positions this Curser at the first element.

Specified by:

first in interface Cursor<IndexEntry<K,O>>

Returns:

true if the position has been successfully changed to the first element, false otherwise

Throws:

java.lang.Exception - if there are problems positioning this Cursor or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

last

public boolean last()
             throws java.lang.Exception

Description copied from interface: Cursor

Positions this Curser at the last element.

Specified by:

last in interface Cursor<IndexEntry<K,O>>

Returns:

true if the position has been successfully changed to the last element, false otherwise

Throws:

java.lang.Exception - if there are problems positioning this Cursor or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

isClosed

public boolean isClosed()
                 throws java.lang.Exception

Description copied from interface: Cursor

Checks if this Curser is closed. Calls to this operation should not fail with exceptions if and only if the cursor is in the closed state.

Specified by:

isClosed in interface Cursor<IndexEntry<K,O>>

Returns:

true if this Cursor is closed, false otherwise

Throws:

java.lang.Exception - if there are problems determining the cursor's closed state

java.lang.UnsupportedOperationException - if this method is not supported

previous

public boolean previous()
                 throws java.lang.Exception

Description copied from interface: Cursor

Advances this Cursor to the previous position. If called before explicitly positioning this Cursor, the position is presumed to be after the last element and this method moves the cursor back to the last element.

Specified by:

previous in interface Cursor<IndexEntry<K,O>>

Returns:

true if the advance succeeded, false otherwise

Throws:

java.lang.Exception - if there are problems advancing to the next position

java.lang.UnsupportedOperationException - if this method is not supported

next

public boolean next()
             throws java.lang.Exception

Description copied from interface: Cursor

Advances this Cursor to the next position. If called before explicitly positioning this Cursor, the position is presumed to be before the first element and this method moves the cursor forward to the first element.

Specified by:

next in interface Cursor<IndexEntry<K,O>>

Returns:

true if the advance succeeded, false otherwise

Throws:

java.lang.Exception - if there are problems advancing to this Cursor to the next position, or if this Cursor is closed

java.lang.UnsupportedOperationException - if this method is not supported

get

public IndexEntry<K,O> get()
                    throws java.lang.Exception

Description copied from interface: Cursor

Gets the object at the current position. Cursor implementations may choose to reuse element objects by re-populating them on advances instead of creating new objects on each advance.

Specified by:

get in interface Cursor<IndexEntry<K,O>>

Returns:

the object at the current position

Throws:

java.lang.Exception - if the object at this Cursor's current position cannot be retrieved, or if this Cursor is closed

isElementReused

public boolean isElementReused()

Description copied from interface: Cursor

Gets whether or not this Cursor will return the same element object instance on get() operations for any position of this Cursor. Some Cursor implementations may reuse the same element copying values into it for every position rather than creating and emiting new element objects on each advance. Some Cursor implementations may return different elements for each position yet the same element instance is returned for the same position. In these cases this method should return true.

Specified by:

isElementReused in interface Cursor<IndexEntry<K,O>>

Returns:

true if elements are reused by this Cursor

setClosureMonitor

public final void setClosureMonitor(ClosureMonitor monitor)

Description copied from interface: Cursor

Sets a non-null closure monitor to associate with this Cursor.

Specified by:

setClosureMonitor in interface Cursor<IndexEntry<K,O>>

Parameters:

monitor - the monitor to use for detecting Cursor close events

close

public void close()
           throws java.lang.Exception

Description copied from interface: Cursor

Closes this Cursor and frees any resources it my have allocated. Repeated calls to this method after this Cursor has already been called should not fail with exceptions.

Specified by:

close in interface Cursor<IndexEntry<K,O>>

Throws:

java.lang.Exception - if for some reason this Cursor could not be closed

close

public void close(java.lang.Exception reason)
           throws java.lang.Exception

Description copied from interface: Cursor

Closes this Cursor and frees any resources it my have allocated. Repeated calls to this method after this Cursor has already been called should not fail with exceptions. The reason argument is the Exception instance thrown instead of the standard CursorClosedException.

Specified by:

close in interface Cursor<IndexEntry<K,O>>

Parameters:

reason - exception thrown when this Cursor is accessed after close

Throws:

java.lang.Exception - if for some reason this Cursor could not be closed

iterator

public java.util.Iterator<IndexEntry<K,O>> iterator()

Specified by:

iterator in interface java.lang.Iterable<IndexEntry<K,O>>