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From: "Uwe Schindler" <uwe@thetaphi.de>
To: <java-user@lucene.apache.org>
References: <4B714F5C.2040709@deri.org>
In-Reply-To: <4B714F5C.2040709@deri.org>
Subject: RE: Flex & Docs/AndPositionsEnum
Date: Tue, 9 Feb 2010 13:16:28 +0100
Message-ID: <002701caa981$b5400ef0$1fc02cd0$@de>
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Hi Renaud,

In flex the correct way to add additional posting data to these classes =
would be the usage of custom attributes, registered in the attributes() =
AttributeSource.

Due to some limitations, there is currently no working support in =
MultiReaders to have a "view" on the underlying Enums, but we are =
working on that.

In general what you do (if it works in future):
Define an interface for your extensions based on the Attribute interface =
and also provide the implementation class. Then call =
YourEnums.attributes().addAttribute(YourInterface.class) in the ctor of =
your enum, store a local reference to the attribute and fill this on =
iteration. Any consumer of this Enum can check using =
TermPositions.attributes().hasAttribute/getAttribute/addAttribute for =
the existence of the the same and then read the attributes during =
iteration. There is no need to change the Enum class API at all.

It works in the same way like the TokenStreams since 2.9/3.0.

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: Renaud Delbru [mailto:renaud.delbru@deri.org]
> Sent: Tuesday, February 09, 2010 1:05 PM
> To: java-user
> Cc: Michael McCandless
> Subject: Flex & Docs/AndPositionsEnum
>=20
> Hi Michael,
>=20
> I have updated my lucene-1458, and I discovered there was big
> modifications in the StandardCodec interface.
> I updated my own codecs to this new interface, but I encounter a
> problem. My codecs are creating DocsAndPositionsEnum subclasses that
> allow to access more information than simply the doc, freq and =
position
> (I have other information encoded into the Prox file).
> In the code, to be able to manipulate the additional interface that my
> classes provide, I was casting the DocsAndPositionsEnum object =
returned
> by IndexReader#termPositionsEnum() into the correct subclass. While
> this
> approach was working in the previous flewx branch, this does not work
> anymore with the last committed changes. In certain cases, the
> IndexReader#termPositionsEnum() does not return the
> DocsAndPositionsEnum
> created by the StandardPostingsReader, but a =
MultiDocsAndPositionsEnum.
> However, I am not able either to subclass the =
MultiDocsAndPositionsEnum
> or to wrap it into a decorator because it is declared as 'private
> static
> final' in DirectoryReader.
>=20
> Are these classes (MultiTermEnum, MultiDocsAndPositionsEnum, etc.)
> hidden in a voluntary manner ? Or is there is another way to extends
> StandardCodec without having to deal with these classes ?
>=20
> Cheers
> --
> Renaud Delbru
>=20
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