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https://issues.apache.org/jira/browse/LUCENE-3842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13465778#comment-13465778
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Michael McCandless commented on LUCENE-3842:
--------------------------------------------
Thanks Rob, good feedback ... I'll post new patch changing that posInc check to
an assert, and removing that obsolete NOTE.
{quote}
As far as the limitations, i feel like if the last token's endOffset != length
of input
that might be pretty safe in general (e.g. standardtokenizer) because of how
unicode
works... i have to think about it.
{quote}
I think we should try that! This way the suggester can "guess" whether the
input text is still inside the last token.
But this won't help the StopFilter case, ie if user types 'a' then StopFilter
will still delete it even though the token isn't "done" (ie maybe user intends
to type 'apple').
Still it's progress so I think we should try it ...
I'm not sure why FST is so much larger ... the outputs should share very well
with KeywordTokenizer ... hmm what weights do we use for the benchmark?
> Analyzing Suggester
> -------------------
>
> Key: LUCENE-3842
> URL: https://issues.apache.org/jira/browse/LUCENE-3842
> Project: Lucene - Core
> Issue Type: New Feature
> Components: modules/spellchecker
> Affects Versions: 3.6, 4.0-ALPHA
> Reporter: Robert Muir
> Attachments: LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch,
> LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch,
> LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch,
> LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch, LUCENE-3842.patch,
> LUCENE-3842.patch, LUCENE-3842-TokenStream_to_Automaton.patch
>
>
> Since we added shortest-path wFSA search in LUCENE-3714, and generified the
> comparator in LUCENE-3801,
> I think we should look at implementing suggesters that have more capabilities
> than just basic prefix matching.
> In particular I think the most flexible approach is to integrate with
> Analyzer at both build and query time,
> such that we build a wFST with:
> input: analyzed text such as ghost0christmas0past <-- byte 0 here is an
> optional token separator
> output: surface form such as "the ghost of christmas past"
> weight: the weight of the suggestion
> we make an FST with PairOutputs<weight,output>, but only do the shortest path
> operation on the weight side (like
> the test in LUCENE-3801), at the same time accumulating the output (surface
> form), which will be the actual suggestion.
> This allows a lot of flexibility:
> * Using even standardanalyzer means you can offer suggestions that ignore
> stopwords, e.g. if you type in "ghost of chr...",
> it will suggest "the ghost of christmas past"
> * we can add support for synonyms/wdf/etc at both index and query time (there
> are tradeoffs here, and this is not implemented!)
> * this is a basis for more complicated suggesters such as Japanese
> suggesters, where the analyzed form is in fact the reading,
> so we would add a TokenFilter that copies ReadingAttribute into term text
> to support that...
> * other general things like offering suggestions that are more "fuzzy" like
> using a plural stemmer or ignoring accents or whatever.
> According to my benchmarks, suggestions are still very fast with the
> prototype (e.g. ~ 100,000 QPS), and the FST size does not
> explode (its short of twice that of a regular wFST, but this is still far
> smaller than TST or JaSpell, etc).
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