org.planx.msd.lang
Class PolymorphicDiscriminator<T>

java.lang.Object
  org.planx.msd.util.AbstractDiscriminator<T>
      org.planx.msd.lang.PolymorphicDiscriminator<T>

All Implemented Interfaces:

Discriminator<T>

public class PolymorphicDiscriminator<T>
extends AbstractDiscriminator<T>

A Discriminator capable of discriminating objects of different types. Discriminators for types to be handled are added using addDiscriminator(java.lang.Class, org.planx.msd.Discriminator). When discriminating a list of input values, the values are first separated by type. That is, by the specific Class they are instance of. This is done using a ClassDiscriminator. Next, objects of each type are discriminated by looking up a discriminator for the type based on the class. Note, that a discriminator is associated with a specific Class and not subclasses.

Author:

Thomas Ambus

Constructor Summary

PolymorphicDiscriminator()

Method Summary

<E extends T> void	addDiscriminator(Class<E> cls, Discriminator<? super E> d)
<U,S> Collection<List<S>>	discriminate(List<? extends U> values, Extractor<U,? extends T,S> e) Discriminates a List of values using an Extractor, and returns a Collection of Lists, each representing an equivalence class containing elements from values that are equivalent.

Methods inherited from class org.planx.msd.util.AbstractDiscriminator

discriminate

Methods inherited from class java.lang.Object

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

Constructor Detail

PolymorphicDiscriminator

public PolymorphicDiscriminator()

Method Detail

addDiscriminator

public <E extends T> void addDiscriminator(Class<E> cls,
                                           Discriminator<? super E> d)

discriminate

public <U,S> Collection<List<S>> discriminate(List<? extends U> values,
                                              Extractor<U,? extends T,S> e)

Description copied from interface: Discriminator

Discriminates a List of values using an Extractor, and returns a Collection of Lists, each representing an equivalence class containing elements from values that are equivalent. The Extractor performs the task of extracting two kinds of objects from the input values: The label which is the object equivalence is defined upon, and the value which is the object that will be returned. That is, the label determines which equivalence class the value goes into.

The Collection of Lists returned should be considered unmodifiable (though, in some cases they might actually be modifiable, but this behaviour should not be relied upon).

Specified by:

discriminate in interface Discriminator<T>

Specified by:

discriminate in class AbstractDiscriminator<T>

Throws:

NonDiscriminableObjectException - if an object was encountered for which no discriminator was registered