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https://issues.apache.org/jira/browse/LUCENE-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12838081#action_12838081
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Steven Rowe commented on LUCENE-2167:
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I wrote word break rules grammar specifications for JFlex 1.5.0-SNAPSHOT and
both Unicode versions 5.1 and 5.2 - you can see the files here:
http://jflex.svn.sourceforge.net/viewvc/jflex/trunk/testsuite/testcases/src/test/cases/unicode-word-break/
The files are UnicodeWordBreakRules_5_*.* - these are written to: parse the
Unicode test files; run the generated scanner against each composed test
string; output the break opportunities/prohibitions in the same format as the
test files; and then finally compare the output against the test file itself,
looking for a match. (These tests currently pass.)
The .flex files would need to be significantly changed to be used as a
StandardTokenizer replacement, but you can get an idea from them how to
implement the Unicode word break rules in (as yet unreleased version 1.5.0)
JFlex syntax.
> StandardTokenizer Javadoc does not correctly describe tokenization around
> punctuation characters
> ------------------------------------------------------------------------------------------------
>
> Key: LUCENE-2167
> URL: https://issues.apache.org/jira/browse/LUCENE-2167
> Project: Lucene - Java
> Issue Type: Bug
> Affects Versions: 2.4.1, 2.9, 2.9.1, 3.0
> Reporter: Shyamal Prasad
> Priority: Minor
> Attachments: LUCENE-2167.patch, LUCENE-2167.patch
>
> Original Estimate: 0.5h
> Remaining Estimate: 0.5h
>
> The Javadoc for StandardTokenizer states:
> {quote}
> Splits words at punctuation characters, removing punctuation.
> However, a dot that's not followed by whitespace is considered part of a
> token.
> Splits words at hyphens, unless there's a number in the token, in which case
> the whole
> token is interpreted as a product number and is not split.
> {quote}
> This is not accurate. The actual JFlex implementation treats hyphens
> interchangeably with
> punctuation. So, for example "video,mp4,test" results in a *single* token and
> not three tokens
> as the documentation would suggest.
> Additionally, the documentation suggests that "video-mp4-test-again" would
> become a single
> token, but in reality it results in two tokens: "video-mp4-test" and "again".
> IMHO the parser implementation is fine as is since it is hard to keep
> everyone happy, but it is probably
> worth cleaning up the documentation string.
> The patch included here updates the documentation string and adds a few test
> cases to confirm the cases described above.
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