[Xapian-tickets] [Xapian] #473: Add a posting source returning the documents matching a Query

[Xapian]

#473: Add a posting source returning the documents matching a Query
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 Reporter:  richard      |             Owner:  nobody
     Type:  enhancement  |            Status:  new
 Priority:  normal       |         Milestone:
Component:  Library API  |           Version:  git master
 Severity:  normal       |        Resolution:
 Keywords:               |        Blocked By:
 Blocking:               |  Operating System:  All
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Changes (by olly):

 * version:  SVN trunk => git master


Comment:

 This is an interesting idea, and I'm sure has potential uses, but I wonder
 if we want to come up with a set of use cases so we can consider if this
 is the best solution.

 We have several features which between them can do some of the things this
 could:

 * `MatchSpy` allows looking at the matching documents in a stream-like
 fashion, but it's "look but don't touch" - you can't modify and pass them
 on.

 * `MatchDecider` allows veto-ing potential matches, which allows
 filtering, but not modification of weight contributions.

 * `PostingSource` combined with the query via various operators allows
 contributing extra weight and filtering, but it's "on the side" not "in
 the flow".

 The attached patch seems incomplete - a number of methods which should
 return values have empty implementations.  It also would likely need some
 updates due changes in the underlying code.

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Ticket URL: <https://trac.xapian.org/ticket/473#comment:1>
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