Module org.apache.jena.core

Package org.apache.jena.mem.store.indexed

Class IndexListsIterator

java.lang.Object

org.apache.jena.util.iterator.NiceIterator<Triple>

org.apache.jena.mem.store.indexed.IndexListsIterator

All Implemented Interfaces:

Iterator<Triple>, org.apache.jena.atlas.iterator.IteratorCloseable<Triple>, org.apache.jena.atlas.lib.Closeable, ClosableIterator<Triple>, ExtendedIterator<Triple>

public class IndexListsIterator
extends NiceIterator<Triple>

Iterator over the intersection of two IndexLists, used by the eager indexing strategy to answer two-key patterns (e.g. subject-and-predicate or predicate-and-object).

The intersection is computed lazily: the iterator walks the shorter of the two lists and probes each candidate triple index against the larger list's reverse-index array. This gives expected O(min(|A|, |B|)) cost without any explicit set-allocation.

Detects concurrent modifications by snapshotting triples.size() at construction time and rechecking it on each call to next() / forEachRemaining(Consumer); throws ConcurrentModificationException if the size has changed.

Constructor Summary

Constructors

Constructor	Description
IndexListsIterator(IndexedTripleSource source, IndexList indexListA, int[] reverseIndicesA, IndexList indexListB, int[] reverseIndicesB)	Creates an iterator over the triples whose indices appear in both indexListA and indexListB.

Method Summary

Modifier and Type	Method	Description
void	forEachRemaining(Consumer<? super Triple> action)
boolean	hasNext()	default hasNext: no elements, return false.
Triple	next()	default next: throw an exception.

Methods inherited from class org.apache.jena.util.iterator.NiceIterator

andThen, andThen, asList, asSet, close, close, emptyIterator, filterDrop, filterKeep, mapWith, remove, removeNext, toList, toSet

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jena.util.iterator.ExtendedIterator

forEach, nextOptional

Constructor Details

IndexListsIterator

public IndexListsIterator(IndexedTripleSource source,
 IndexList indexListA,
 int[] reverseIndicesA,
 IndexList indexListB,
 int[] reverseIndicesB)

Creates an iterator over the triples whose indices appear in both indexListA and indexListB.

Parameters:

source - the canonical triple set to dereference indices against

indexListA - one of the index lists to intersect

reverseIndicesA - reverse-index array for indexListA

indexListB - the other index list to intersect

reverseIndicesB - reverse-index array for indexListB

Method Details

hasNext

public boolean hasNext()

Description copied from class: NiceIterator

default hasNext: no elements, return false.

Specified by:

hasNext in interface Iterator<Triple>

Overrides:

hasNext in class NiceIterator<Triple>

next

public Triple next()

Description copied from class: NiceIterator

default next: throw an exception.

Specified by:

next in interface Iterator<Triple>

Overrides:

next in class NiceIterator<Triple>

forEachRemaining

public void forEachRemaining(Consumer<? super Triple> action)