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From "Steven Rowe (JIRA)" <j...@apache.org>
Subject [jira] Created: (LUCENE-2747) Deprecate/remove language-specific tokenizers in favor of StandardTokenizer
Date Mon, 08 Nov 2010 20:09:06 GMT
Deprecate/remove language-specific tokenizers in favor of StandardTokenizer
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                 Key: LUCENE-2747
                 URL: https://issues.apache.org/jira/browse/LUCENE-2747
             Project: Lucene - Java
          Issue Type: Improvement
          Components: Analysis
    Affects Versions: 3.1, 4.0
            Reporter: Steven Rowe
             Fix For: 3.1, 4.0


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
PersianAnalyzer.

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