Re: [Tracker] Using tracker extractors from other applications

[Nikolaus Rath <Nikolaus rath org>]

Ivan Frade <ivan frade-Re5JQEeQqe8AvxtiuMwx3w public gmane org> writes:
> Hi,
>
> On Sat, Nov 20, 2010 at 12:21 AM, Nikolaus Rath <Nikolaus-BTH8mxji4b0 public gmane org> wrote:
>
> > Nikolaus Rath <Nikolaus-BTH8mxji4b0-XMD5yJDbdMReXY1tMh2IBg public gmane org> writes:
> > > > extractor = ExtractorHelper ()
> > > > results = extractor.get_metadata (filename)
> > Upon closer investigation, get_metadata() fails whenever it encounters a
> > text/plain file that contains a '['. Looking at the code, this does not
> > seem surprising.
> >
> > Is the format of the string that's returned by GetMetadata() described
> > somewhere? Then I could try to fix the parser.
>
> GetMetadata() returns triplets in "turtle" format, with the subject missing
> (because the caller should know it and probably wants to add more
> information). That python "parser" (if you can call it that) uses just
> regular expressions to parse those triplets and handle the anonymous nodes
> (those "[ xxx ]") in a tricky way to form a single key for the dictionary.
>
> Nodes like:
> A slo:location [a slo:GeoLocation; slo:city "Helsinki"]
> Are translated in the dictionary to:
> slo:location:city "Helsinki"
>
> Not nice, but good enough for our testing. Remember that this code is just
> an internal utility and not a public API. Patches are welcome if you find
> issues,

Well, I would be quite happy to submit patches. But at the moment I
still have absolutely no idea what GetMetadata() returns. What is a
"turtle format"? What is a "subject"? What defines a node? I think you
are assuming that I know something which I actually don't..


Btw, if tracker itself does not use ExtractorHelper, how does e.g.
tracker-miner make sense of the metadata? Maybe I could use that code as
a start instead. I tried to follow the invocation of
get_metadata_fast_async but could not really identify the part where the
metadata is parsed.


Thanks,

   -Nikolaus

-- 
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