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https://issues.apache.org/jira/browse/LUCENE-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13556367#comment-13556367
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Alan Woodward commented on LUCENE-2878:
---------------------------------------

I want to get this moving again - will get the branch up to date tomorrow and 
then iterate from there.
                
> Allow Scorer to expose positions and payloads aka. nuke spans 
> --------------------------------------------------------------
>
>                 Key: LUCENE-2878
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2878
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/search
>    Affects Versions: Positions Branch
>            Reporter: Simon Willnauer
>            Assignee: Simon Willnauer
>              Labels: gsoc2011, gsoc2012, lucene-gsoc-11, lucene-gsoc-12, 
> mentor
>             Fix For: Positions Branch
>
>         Attachments: LUCENE-2878-OR.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878.patch, LUCENE-2878.patch, LUCENE-2878.patch, 
> LUCENE-2878_trunk.patch, LUCENE-2878_trunk.patch, LUCENE-2878-vs-trunk.patch, 
> PosHighlighter.patch, PosHighlighter.patch
>
>
> Currently we have two somewhat separate types of queries, the one which can 
> make use of positions (mainly spans) and payloads (spans). Yet Span*Query 
> doesn't really do scoring comparable to what other queries do and at the end 
> of the day they are duplicating lot of code all over lucene. Span*Queries are 
> also limited to other Span*Query instances such that you can not use a 
> TermQuery or a BooleanQuery with SpanNear or anthing like that. 
> Beside of the Span*Query limitation other queries lacking a quiet interesting 
> feature since they can not score based on term proximity since scores doesn't 
> expose any positional information. All those problems bugged me for a while 
> now so I stared working on that using the bulkpostings API. I would have done 
> that first cut on trunk but TermScorer is working on BlockReader that do not 
> expose positions while the one in this branch does. I started adding a new 
> Positions class which users can pull from a scorer, to prevent unnecessary 
> positions enums I added ScorerContext#needsPositions and eventually 
> Scorere#needsPayloads to create the corresponding enum on demand. Yet, 
> currently only TermQuery / TermScorer implements this API and other simply 
> return null instead. 
> To show that the API really works and our BulkPostings work fine too with 
> positions I cut over TermSpanQuery to use a TermScorer under the hood and 
> nuked TermSpans entirely. A nice sideeffect of this was that the Position 
> BulkReading implementation got some exercise which now :) work all with 
> positions while Payloads for bulkreading are kind of experimental in the 
> patch and those only work with Standard codec. 
> So all spans now work on top of TermScorer ( I truly hate spans since today ) 
> including the ones that need Payloads (StandardCodec ONLY)!!  I didn't bother 
> to implement the other codecs yet since I want to get feedback on the API and 
> on this first cut before I go one with it. I will upload the corresponding 
> patch in a minute. 
> I also had to cut over SpanQuery.getSpans(IR) to 
> SpanQuery.getSpans(AtomicReaderContext) which I should probably do on trunk 
> first but after that pain today I need a break first :).
> The patch passes all core tests 
> (org.apache.lucene.search.highlight.HighlighterTest still fails but I didn't 
> look into the MemoryIndex BulkPostings API yet)

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