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https://issues.apache.org/jira/browse/LUCENE-1126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12627943#action_12627943
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Michael McCandless commented on LUCENE-1126:
--------------------------------------------

Hmm -- I'm now seeing an failure with this patch, in TestThaiAnalyzer (in 
contrib/analyzers):

{code}
    [junit] Testcase: 
testAnalyzer(org.apache.lucene.analysis.th.TestThaiAnalyzer):     FAILED
    [junit] expected:<?[]> but was:<?[??]>
    [junit] junit.framework.ComparisonFailure: expected:<?[]> but was:<?[??]>
    [junit]     at 
org.apache.lucene.analysis.th.TestThaiAnalyzer.assertAnalyzesTo(TestThaiAnalyzer.java:43)
    [junit]     at 
org.apache.lucene.analysis.th.TestThaiAnalyzer.testAnalyzer(TestThaiAnalyzer.java:54)
    [junit] 
{code}

Does anyone else see this?

> Simplify StandardTokenizer JFlex grammar
> ----------------------------------------
>
>                 Key: LUCENE-1126
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1126
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Analysis
>    Affects Versions: 2.2
>            Reporter: Steven Rowe
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.4
>
>         Attachments: LUCENE-1126.patch
>
>
> Summary of thread entitled "Fullwidth alphanumeric characters, plus a 
> question on Korean ranges" begun by Daniel Noll on java-user, and carried 
> over to java-dev:
> On 01/07/2008 at 5:06 PM, Daniel Noll wrote:
> > I wish the tokeniser could just use Character.isLetter and
> > Character.isDigit instead of having to know all the ranges itself, since
> > the JRE already has all this information.  Character.isLetter does
> > return true for CJK characters though, so the ranges would still come in
> > handy for determining what kind of letter they are.  I don't support
> > JFlex has a way to do this...
> The DIGIT macro could be replaced by JFlex's predefined character class 
> [:digit:], which has the same semantics as java.lang.Character.isDigit().
> Although JFlex's predefined character class [:letter:] (same semantics as 
> java.lang.Character.isLetter()) includes CJK characters, there is a way to 
> handle this using JFlex's regex negation syntax {{!}}.  From [the JFlex 
> documentation|http://jflex.de/manual.html]:
> bq. [T]he expression that matches everything of {{a}} not matched by {{b}} is 
> !(!{{a}}|{{b}}) 
> So to exclude CJ characters from the LETTER macro:
> {code}
>     LETTER = ! ( ! [:letter:] | {CJ} )
> {code}
>  
> Since [:letter:] includes all of the Korean ranges, there's no reason 
> (AFAICT) to treat them separately; unlike Chinese and Japanese characters, 
> which are individually tokenized, the Korean characters should participate in 
> the same token boundary rules as all of the other letters.
> I looked at some of the differences between Unicode 3.0.0, which Java 1.4.2 
> supports, and Unicode 5.0, the latest version, and there are lots of new and 
> modified letter and digit ranges.  This stuff gets tweaked all the time, and 
> I don't think Lucene should be in the business of trying to track it, or take 
> a position on which Unicode version users' data should conform to.  
> Switching to using JFlex's [:letter:] and [:digit:] predefined character 
> classes ties (most of) these decisions to the user's choice of JVM version, 
> and this seems much more reasonable to me than the current status quo.
> I will attach a patch shortly.

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