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From "DM Smith (JIRA)" <>
Subject [jira] Commented: (LUCENE-2747) Deprecate/remove language-specific tokenizers in favor of StandardTokenizer
Date Wed, 10 Nov 2010 12:45:14 GMT


DM Smith commented on LUCENE-2747:

Robert, Let me ask another way. How about implementing StandardTokenizer using jflex to be
UAX29Tokenizer minus NUM and ALPHANUM?

> Deprecate/remove language-specific tokenizers in favor of StandardTokenizer
> ---------------------------------------------------------------------------
>                 Key: LUCENE-2747
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Analysis
>    Affects Versions: 3.1, 4.0
>            Reporter: Steven Rowe
>             Fix For: 3.1, 4.0
>         Attachments: LUCENE-2747.patch, LUCENE-2747.patch
> As of Lucene 3.1, StandardTokenizer implements UAX#29 word boundary rules to provide
language-neutral tokenization.  Lucene contains several language-specific tokenizers that
should be replaced by UAX#29-based StandardTokenizer (deprecated in 3.1 and removed in 4.0).
 The language-specific *analyzers*, by contrast, should remain, because they contain language-specific
post-tokenization filters.  The language-specific analyzers should switch to StandardTokenizer
in 3.1.
> Some usages of language-specific tokenizers will need additional work beyond just replacing
the tokenizer in the language-specific analyzer.  
> For example, PersianAnalyzer currently uses ArabicLetterTokenizer, and depends on the
fact that this tokenizer breaks tokens on the ZWNJ character (zero-width non-joiner; U+200C),
but in the UAX#29 word boundary rules, ZWNJ is not a word boundary.  Robert Muir has suggested
using a char filter converting ZWNJ to spaces prior to StandardTokenizer in the converted

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