org.apache.directory.server.core.partition.impl.btree.jdbm
Class DupsContainerCursor<K,V>

java.lang.Object
  org.apache.directory.server.xdbm.AbstractTupleCursor<K,DupsContainer<V>>
      org.apache.directory.server.core.partition.impl.btree.jdbm.DupsContainerCursor<K,V>

All Implemented Interfaces:

java.lang.Iterable<Tuple<K,DupsContainer<V>>>, Cursor<Tuple<K,DupsContainer<V>>>, TupleCursor<K,DupsContainer<V>>

public class DupsContainerCursor<K,V>
extends AbstractTupleCursor<K,DupsContainer<V>>

A cursor for browsing tables with duplicates which returns the container for values rather than just the value.

Version:

$$Rev$$

Author:

Apache Directory Project

Constructor Summary

DupsContainerCursor(JdbmTable<K,V> table)
Creates a Cursor over the tuples of a JDBM table.

Method Summary

void	after(Tuple<K,DupsContainer<V>> 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	afterKey(K key) An alternative to calling after(Tuple) which often may require wrapping a key in a newly created Tuple object that may be unnecessary.
void	afterLast() Positions this Curser after the last element.
void	afterValue(K key, DupsContainer<V> value) An alternative to calling after(Tuple) which often may require wrapping a key and a value in a newly created Tuple object that may be unnecessary.
boolean	available() Determines whether or not a call to get() will succeed.
void	before(Tuple<K,DupsContainer<V>> element) Positions this Cursor before the key of the supplied tuple.
void	beforeFirst() Positions this Curser before the first element.
void	beforeKey(K key) An alternative to calling before(Tuple) which often may require wrapping a key in a newly created Tuple object that may be unnecessary.
void	beforeValue(K key, DupsContainer<V> value) An alternative to calling before(Tuple) which often may require wrapping a key and a value in a newly created Tuple object that may be unnecessary.
boolean	first() Positions this Curser at the first element.
Tuple<K,DupsContainer<V>>	get() Gets the object at the current position.
boolean	isElementReused() Gets whether or not this Cursor will return the same element object instance on get() operations for any position of this Cursor.
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.

Methods inherited from class org.apache.directory.server.xdbm.AbstractTupleCursor

checkNotClosed, close, close, isClosed, iterator, setClosureMonitor

Methods inherited from class java.lang.Object

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

Constructor Detail

DupsContainerCursor

public DupsContainerCursor(JdbmTable<K,V> table)
                    throws java.io.IOException

Creates a Cursor over the tuples of a JDBM table.

Parameters:

table - the JDBM Table to build a Cursor over

Throws:

java.io.IOException - of there are problems accessing the BTree

Method Detail

available

public boolean available()

Description copied from interface: Cursor

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

Returns:

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

beforeKey

public void beforeKey(K key)
               throws java.lang.Exception

Description copied from interface: TupleCursor

An alternative to calling before(Tuple) which often may require wrapping a key in a newly created Tuple object that may be unnecessary. This method behaves just like before(Tuple) except it advances to just before the first value of the key.

Parameters:

key - the key to advance just before

Throws:

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

afterKey

public void afterKey(K key)
              throws java.lang.Exception

Description copied from interface: TupleCursor

An alternative to calling after(Tuple) which often may require wrapping a key in a newly created Tuple object that may be unnecessary. This method behaves just like after(Tuple) except it advances to just after the last value of the key.

Parameters:

key - the key to advance just after the last value

Throws:

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

beforeValue

public void beforeValue(K key,
                        DupsContainer<V> value)
                 throws java.lang.Exception

Description copied from interface: TupleCursor

An alternative to calling before(Tuple) which often may require wrapping a key and a value in a newly created Tuple object that may be unnecessary. This method behaves just like before(Tuple) except it advances to just before the value of the key which may still be of the same key. This method will not be supported if duplicate keys are not supported. In this case an UnsupportedOperationException will be thrown.

Parameters:

key - the key of the value to advance just before

value - the value to advance just before

Throws:

java.lang.UnsupportedOperationException - if duplicate keys not supporrted

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

afterValue

public void afterValue(K key,
                       DupsContainer<V> value)
                throws java.lang.Exception

Description copied from interface: TupleCursor

An alternative to calling after(Tuple) which often may require wrapping a key and a value in a newly created Tuple object that may be unnecessary. This method behaves just like after(Tuple) except it advances to just after the value with the specified key. This method will not be supported if duplicate keys are not supported. In this case an UnsupportedOperationException will be thrown.

Parameters:

key - the key of the value to advance just after

value - the value to advance just after

Throws:

java.lang.UnsupportedOperationException - if duplicate keys not supporrted

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

before

public void before(Tuple<K,DupsContainer<V>> element)
            throws java.lang.Exception

Positions this Cursor before the key of the supplied tuple.

Parameters:

element - the tuple who's key is used to position this Cursor

Throws:

java.io.IOException - if there are failures to position the Cursor

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

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

after

public void after(Tuple<K,DupsContainer<V>> 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.

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.

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.

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.

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.

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

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.

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.

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 Tuple<K,DupsContainer<V>> 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.

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.

Returns:

true if elements are reused by this Cursor