com.bigdata.striterator

Class ChunkedConvertingIterator<E,F>

java.lang.Object

com.bigdata.striterator.ChunkedConvertingIterator<E,F>

Type Parameters:

E - The generic type of the source elements.

F - The generic type of the converted elements.

All Implemented Interfaces:

IChunkedIterator<F>, IChunkedOrderedIterator<F>, ICloseable, ICloseableIterator<F>, Iterator<F>

public class ChunkedConvertingIterator<E,F>
extends Object
implements IChunkedOrderedIterator<F>

Supports the chunk-at-a-time filter and conversion operations. Chunk-at-a-time operations are potentially much more efficient as they allow for ordered reads and ordered writes on IIndexs.

Version:

$Id$

See Also:

IChunkConverter

Field Summary

Fields inherited from interface com.bigdata.striterator.IChunkedIterator

DEFAULT_CHUNK_SIZE

Constructor Summary

Constructors

Constructor and Description
ChunkedConvertingIterator(IChunkedOrderedIterator<E> src, IChunkConverter<E,F> converter) Ctor when the element type is NOT being changed during conversion.
ChunkedConvertingIterator(IChunkedOrderedIterator<E> src, IChunkConverter<E,F> converter, IKeyOrder<F> keyOrder) Variant ctor when you are also converting the element type.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the iterator, releasing any associated resources.
protected F[]	convert(IChunkedOrderedIterator<E> src) Applies the chunk-at-a-time converter.
IKeyOrder<F>	getKeyOrder() The natural order in which elements are being visited.
boolean	hasNext()
F	next() The next element available from the iterator.
F[]	nextChunk() Return the next "chunk" from the iterator.
F[]	nextChunk(IKeyOrder<F> keyOrder) Return the next "chunk" of elements.
void	remove() Not supported.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChunkedConvertingIterator

public ChunkedConvertingIterator(IChunkedOrderedIterator<E> src,
                         IChunkConverter<E,F> converter)

Ctor when the element type is NOT being changed during conversion. This ctor uses the IKeyOrder reported by the source IChunkedOrderedIterator. This will result in runtime exceptions if the generic types of the source and converted iterators differ.

Parameters:

src - The source iterator.

converter - The chunk-at-a-time converter.

ChunkedConvertingIterator

public ChunkedConvertingIterator(IChunkedOrderedIterator<E> src,
                         IChunkConverter<E,F> converter,
                         IKeyOrder<F> keyOrder)

Variant ctor when you are also converting the element type.

Parameters:

src - The source iterator.

converter - The chunk-at-a-time converter.

keyOrder - The IKeyOrder for the converted chunks -or- null iff not known.

Method Detail

convert

protected F[] convert(IChunkedOrderedIterator<E> src)

Applies the chunk-at-a-time converter. The converted chunk MAY contain a different number of elements. If it does not contain any elements then another chunk will be fetched from the source iterator by hasNext().

Parameters:

src - A chunk of elements from the source iterator.

Returns:

A converted chunk of elements.

close

public void close()

Description copied from interface: ICloseableIterator

Closes the iterator, releasing any associated resources. This method MAY be invoked safely if the iterator is already closed. Implementations of this interface MUST invoke ICloseableIterator.close() if Iterator.hasNext() method returns false to ensure that the iterator is closed (and its resources release) as soon as it is exhausted.

Note: Implementations that support Iterator.remove() MUST NOT eagerly close the iterator when it is exhausted since that would make it impossible to remove the last visited statement. Instead they MUST wait for an explicit ICloseableIterator.close() by the application.

Specified by:

close in interface ICloseable

Specified by:

close in interface ICloseableIterator<F>

next

public F next()

Description copied from interface: IChunkedIterator

The next element available from the iterator.

Specified by:

next in interface IChunkedIterator<F>

Specified by:

next in interface Iterator<F>

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<F>

getKeyOrder

public IKeyOrder<F> getKeyOrder()

Description copied from interface: IChunkedOrderedIterator

The natural order in which elements are being visited.

Specified by:

getKeyOrder in interface IChunkedOrderedIterator<F>

Returns:

The natural order in which the elements are being visited -or- null if not known.

nextChunk

public F[] nextChunk()

Description copied from interface: IChunkedIterator

Return the next "chunk" from the iterator.

Specified by:

nextChunk in interface IChunkedIterator<F>

Returns:

The next chunk.

nextChunk

public F[] nextChunk(IKeyOrder<F> keyOrder)

Description copied from interface: IChunkedOrderedIterator

Return the next "chunk" of elements. The elements will be in the specified order. If IChunkedOrderedIterator.getKeyOrder() would return non-null and the request order corresponds to the value that would be returned by IChunkedOrderedIterator.getKeyOrder() then the elements in the next chunk are NOT sorted. Otherwise the elements in the next chunk are sorted before they are returned. The size of the chunk is up to the implementation.

Specified by:

nextChunk in interface IChunkedOrderedIterator<F>

Parameters:

keyOrder - The natural order for the elements in the chunk.

Returns:

The next chunk of elements in the specified order.

remove

public void remove()

Not supported.

Specified by:

remove in interface IChunkedIterator<F>

Specified by:

remove in interface Iterator<F>

Throws:

UnsupportedOperationException - always.