net.sf.jagg.msd
Class ChainedDiscriminator<T>

java.lang.Object
  net.sf.jagg.msd.AbstractDiscriminator<T>
      net.sf.jagg.msd.ChainedDiscriminator<T>

All Implemented Interfaces:

Discriminator<T>

Direct Known Subclasses:

ArrayDiscriminator, CalendarDiscriminator, ClassDiscriminator, CollectionDiscriminator, DateDiscriminator, EnumDiscriminator, PropertiesDiscriminator, RandomAccessListDiscriminator

public abstract class ChainedDiscriminator<T>
extends AbstractDiscriminator<T>

A ChainedDiscriminator relies on another Discriminator to perform its work in a separate step, after this discriminator's work is done.

Since:

0.5.0

Author:

Randy Gettman

Constructor Summary

ChainedDiscriminator()

Method Summary

<E> java.util.List<java.util.List<E>>	discriminate(java.util.List<E> elements, Extractor<E,T> extractor, MsdWorkspace workspace) Partitions the given List of elements into another List, in which all of the elements from the given list exist in the new list, and all elements that compare equal are adjacent to each other, according to the given Extractor.
protected abstract <E> ChainedExtractor<E,?,T>	getChainedExtractor(java.util.List<E> elements, Extractor<E,T> extractor) Returns an Extractor that extracts a label of unknown type from a label of type T, using the given Extractor, which supplies labels of type T.
protected abstract <E> Discriminator<?>	getDiscriminator(java.util.List<E> elements, ChainedExtractor<E,?,T> extractor, int index) Returns a Discriminator that discriminates on an unknown type.

Methods inherited from class net.sf.jagg.msd.AbstractDiscriminator

discriminate

Methods inherited from class java.lang.Object

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

Constructor Detail

ChainedDiscriminator

public ChainedDiscriminator()

Method Detail

discriminate

public <E> java.util.List<java.util.List<E>> discriminate(java.util.List<E> elements,
                                                          Extractor<E,T> extractor,
                                                          MsdWorkspace workspace)

Partitions the given List of elements into another List, in which all of the elements from the given list exist in the new list, and all elements that compare equal are adjacent to each other, according to the given Extractor.

Type Parameters:

E - The type of element that is being discriminated by the type <E>

Parameters:

elements - A List of elements.

extractor - An Extractor that gives labels for each element.

workspace - The MsdWorkspace used in the discrimination process.

Returns:

A List of Lists containing all equivalence classes. Each equivalence class list contains all elements that compare equal to each other. If for any reason, this is unable to discriminate the List, e.g. the elements are non- Discriminable objects, then this returns null.

getChainedExtractor

protected abstract <E> ChainedExtractor<E,?,T> getChainedExtractor(java.util.List<E> elements,
                                                                   Extractor<E,T> extractor)

Returns an Extractor that extracts a label of unknown type from a label of type T, using the given Extractor, which supplies labels of type T. For the same index, the returned Extractor must return labels of the same type as the type discriminated by the Discriminator returned by getDiscriminator.

Type Parameters:

E - The type of element.

Parameters:

elements - The List of elements.

extractor - The Extractor that extracts a label of type T from the element.

Returns:

A ChainedExtractor that extracts a label of unknown type from a label of type T.

See Also:

getDiscriminator(java.util.List, net.sf.jagg.msd.ChainedExtractor, int)

getDiscriminator

protected abstract <E> Discriminator<?> getDiscriminator(java.util.List<E> elements,
                                                         ChainedExtractor<E,?,T> extractor,
                                                         int index)

Returns a Discriminator that discriminates on an unknown type. For the same index, the returned Discriminator must discriminate on the same type as the labels that are returned by the ChainedExtractor that is returned by getChainedExtractor. If it is known that no more loops are necessary, then the returned Discriminator may be null.

Parameters:

elements - The list of elements.

extractor - The ChainedExtractor that was obtained from getChainedExtractor.

index - The index of the loop.

Returns:

A Discriminator, or null if it is known for sure that no more loops are necessary.

See Also:

getChainedExtractor(java.util.List, net.sf.jagg.msd.Extractor)