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https://issues.apache.org/jira/browse/LUCENE-1614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714457#action_12714457
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Michael McCandless commented on LUCENE-1614:
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Let's decouple the two things we are talking about...
First off, Scorer.score(Collector, int) (and also BooleanScorer2)
require that nextDoc has already been called. So we should not add
the "if" into those methods; if anything, we should do the opposite
(add an assert).
Second, the semantics of calling docID() before nextDoc/advance have
been called... on this I think your proposal is good, except: in the
event that the Scorer will not match any docs, it's also fine if it
returns -1. Ie we do not require all Scorers to up-front determine
whether they will match docs or not. Said another way, if a Scorer
will not match any docs, docID() may return either -1 or NO_MORE_DOCS
before nextDoc/advance have been called.
bq. Note that I also wrote that this method should not throw any exception, but
I think of relaxing that either, and say "it is better if the implementation
does not throw any exception in case there are no more documents to return".
The reason is, we cannot force "don't throw exception" in the code ... What do
you think?
I don't think we need to allow for docID() to throw an exception?
(doc() doesn't today and I haven't heard complaints, I think).
If there are no more documents to return, docID() should return
NO_MORE_DOCS.
> Add next() and skipTo() variants to DocIdSetIterator that return the current
> doc, instead of boolean
> ----------------------------------------------------------------------------------------------------
>
> Key: LUCENE-1614
> URL: https://issues.apache.org/jira/browse/LUCENE-1614
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Search
> Reporter: Shai Erera
> Fix For: 2.9
>
> Attachments: LUCENE-1614.patch, LUCENE-1614.patch, LUCENE-1614.patch,
> LUCENE-1614.patch, LUCENE-1614.patch, LUCENE-1614.patch, LUCENE-1614.patch
>
>
> See
> http://www.nabble.com/Another-possible-optimization---now-in-DocIdSetIterator-p23223319.html
> for the full discussion. The basic idea is to add variants to those two
> methods that return the current doc they are at, to save successive calls to
> doc(). If there are no more docs, return -1. A summary of what was discussed
> so far:
> # Deprecate those two methods.
> # Add nextDoc() and skipToDoc(int) that return doc, with default impl in DISI
> (calls next() and skipTo() respectively, and will be changed to abstract in
> 3.0).
> #* I actually would like to propose an alternative to the names: advance()
> and advance(int) - the first advances by one, the second advances to target.
> # Wherever these are used, do something like '(doc = advance()) >= 0' instead
> of comparing to -1 for improved performance.
> I will post a patch shortly
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