org.grouplens.lenskit.collections

Interface FastCollection<E>

Type Parameters:

E - The type of value in the fast collection.

All Superinterfaces:

Collection<E>, Iterable<E>

All Known Implementing Classes:

CopyingFastCollection, PackedScoredIdList

public interface FastCollection<E>
extends Collection<E>

Collection supporting fast iteration.

A fast collection is a collection that may support fast iteration — iteration where the same object is returned each time, having been mutated to represent the next state. It can save greatly in object allocation overhead in some circumstances. Using a fast iterator is only possible if the looping code doesn't allow objects returned by the iterator to escape the loop (e.g. it doesn't save them away in other objects or something), but many loops only observe the object and then discard it before the next iteration. Those loops benefit from fast iterators.

Author:

GroupLens Research

Method Summary

Methods

Modifier and Type	Method and Description
Iterator<E>	fastIterator() Return a fast iterator.

Methods inherited from interface java.util.Collection

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray

Method Detail

fastIterator

Iterator<E> fastIterator()

Return a fast iterator. The iterator may not actually be fast; if the underlying structure does not support fast iteration, the iterator may return distinct objects every time. However, that is usually in cases where the underlying collection is storing distinct objects anyway so no overhead is introduced.

Returns:

An iterator that may not return distinct objects.