com.bigdata.btree.filter
Class Advancer<E>

java.lang.Object
  com.bigdata.btree.filter.Advancer<E>

Type Parameters:

E - The type of the objects visited by the source iterator.

All Implemented Interfaces:

ITupleFilter<E>, cutthecrap.utils.striterators.IFilter, Serializable

Direct Known Subclasses:

DistinctTermAdvancer

public abstract class Advancer<E>
extends Object
implements ITupleFilter<E>

Used to write logic that advances an ITupleCursor to another key after it visits some element. For example, the "distinct term scan" for the RDF DB is written in this manner.

Version:

$Id: Advancer.java 2265 2009-10-26 12:51:06Z thompsonbry $

Author:

Bryan Thompson

See Also:

Serialized Form

TODO:

write test for remove(). in order for remove() to work we must note the key for the last visited tuple and then issue remove(key) against the underlying index.

Field Summary

protected static boolean	INFO
protected static org.apache.log4j.Logger	log
protected ITupleCursor<E>	src Set by #filter(ITupleCursor).

Constructor Summary

protected

Advancer()

Method Summary

protected abstract void	advance(ITuple<E> tuple) Offers an opportunity to advance the source ITupleCursor to a new key using {@link ITupleCursor#seek(byte[]).
ITupleIterator<E>	filter(Iterator src) Strengthened return type.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final transient org.apache.log4j.Logger log

INFO

protected static final transient boolean INFO

src

protected ITupleCursor<E> src

Set by #filter(ITupleCursor).

Constructor Detail

Advancer

protected Advancer()

Method Detail

filter

public final ITupleIterator<E> filter(Iterator src)

Description copied from interface: ITupleFilter

Strengthened return type.

Specified by:

filter in interface ITupleFilter<E>

Specified by:

filter in interface cutthecrap.utils.striterators.IFilter

Parameters:

src - The source iterator (MUST be an ITupleCursor).

Returns:

advance

protected abstract void advance(ITuple<E> tuple)

Offers an opportunity to advance the source ITupleCursor to a new key using {@link ITupleCursor#seek(byte[]).

Parameters:

tuple - The current value.