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https://issues.apache.org/jira/browse/JENA-966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14604886#comment-14604886
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Andy Seaborne commented on JENA-966:
------------------------------------
In {{Unparser.listSubjects}} the iterator {{firstChoiceCyclic}} is setup with:
{noformat}
Iterator<Resource> firstChoiceCyclic = allInfiniteLeft()
.filterKeep(r -> {
codeCoverage[4]++;
if (r.isAnon())
return false;
Integer cnt = objectTable.get(r);
if (cnt == null || cnt.intValue() <= 1)
return false;
return true;
});
{noformat}
{{allInfiniteLeft}} with the old code, {{LateBindingIterator}} calls
{{NiceIterator.filterKeep}} which itself creates a {{FilterIterator}} and the
unlazy operation is first called at the "hasNext" stage - i.e. first use in the
iterator of iterators, and after {{fakeLazyEvaluator}} which is the
initialization of {{infinite}}.
{{allInfiniteLeft} with the new code, {{LazyIterator}} calls the unlazy
operation during {{LazyIterator.filterKeep}} hence it's called at setup time
assigning to {{firstChoiceCyclic}}.
Temporary fix applied to {{LazyIterator}} : the NiceIterator code for
filterKeep, filterDrop copied to LazyIterator.
NB It looks like {{LazyIterator.mapWith}} is also wrong. Fix applied for
review. It uses {Map1Iterator}}.
Possible proper solutions:
# {{LazyIterator}} extends {{NiceIterator}} and only override hasNext, next,
remove.
# Drop {{LazyIterator}}, use {{LateBindingIterator}} (renamed?)
# Drop both, put a copy of {{LateBindingIterator}} into package-scoped in the
unparser package as {{UnparserLateBindingIterator}} for unparser use only.
Comments?
> LazyIterator
> ------------
>
> Key: JENA-966
> URL: https://issues.apache.org/jira/browse/JENA-966
> Project: Apache Jena
> Issue Type: Bug
> Components: Core
> Affects Versions: Jena 3.0.0
> Reporter: Claude Warren
> Assignee: Claude Warren
>
> LazyIterator is an abstract class. The documentation indicates that the
> create() method needs to be overridden to create an instance. From this I
> would expect that
> now LazyIterator(){
> @Override
> public ExtendedIterator<Model> create() {
> ...
> }};
> Would work however LazyIterator does not override:
> remoteNext(), andThen(), toList(), and toSet().
> I believe these should be implemented in the class.
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