jdbm.btree

Class BPage.Browser

java.lang.Object

jdbm.helper.TupleBrowser<K,V>

jdbm.btree.BPage.Browser

Enclosing class:

BPage<K,V>

class BPage.Browser
extends TupleBrowser<K,V>

PRIVATE INNER CLASS Browser to traverse leaf BPages.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) ActionContext	context context used to track browsing action
private int	index Current index in the page.
private BPage<K,V>	page Current page.

Constructor Summary

Constructors

Constructor and Description
Browser(BPage<K,V> page, int index, ActionContext context) Create a browser.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the browser and deallocates any resources it might have allocated.
boolean	getNext(Tuple<K,V> tuple) Get the next Tuple in the current BTree.
boolean	getPrevious(Tuple<K,V> tuple) Get the previous tuple.

Methods inherited from class java.lang.Object

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

Field Detail

page

private BPage<K,V> page

Current page.

context

ActionContext context

context used to track browsing action

index

private int index

Current index in the page. The index positionned on the next tuple to return.

Constructor Detail

Browser

Browser(BPage<K,V> page,
        int index,
        ActionContext context)

Create a browser.

Parameters:

page - Current page

context - context in case of action capable record manager

index - Position of the next tuple to return.

Method Detail

getNext

public boolean getNext(Tuple<K,V> tuple)
                throws java.io.IOException

Get the next Tuple in the current BTree. We have 3 cases to deal with : 1) we are at the end of the btree. We will return false, the tuple won't be set. 2) we are in the middle of a page : grab the values and store them into the tuple 3) we are at the end of the page : grab the next page, and get the tuple from it.

Specified by:

getNext in class TupleBrowser<K,V>

Parameters:

tuple - Tuple into which values are copied.

Returns:

true if we have found a tumple, false otherwise.

Throws:

java.io.IOException

getPrevious

public boolean getPrevious(Tuple<K,V> tuple)
                    throws java.io.IOException

Description copied from class: TupleBrowser

Get the previous tuple.

Specified by:

getPrevious in class TupleBrowser<K,V>

Parameters:

tuple - Tuple into which values are copied.

Returns:

True if values have been copied in tuple, or false if there is no previous tuple.

Throws:

java.io.IOException

close

public void close()

Description copied from class: TupleBrowser

Closes the browser and deallocates any resources it might have allocated. Repeated calls of close are OK.

Overrides:

close in class TupleBrowser<K,V>