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3926Re: [antlr-interest] Re: how do i skip unmatched characters?

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  • Stdiobe
    Jul 2, 2001
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      Ric,

      > Doh! What version of antlr are you using one of my snapshots? According to
      > the docs it should be on by default?

      I'm using standard 2.7.1, but it's also turned off in the patched versions
      (and also in version 2.6.0).

      I just checked the documentation again and it seems the documentation
      doesn't literally say it's "on" but it does suggest it in "err.html" under
      "Default
      Exception Handling in the Lexer":

      "Normally you want the lexer to keep trying to get a valid token upon
      lexical error. That way, the parser doesn't have to deal with lexical
      errors
      and ask for another token ...... To get ANTLR to generate lexers that
      pass on RecognitionException's to the parser as TokenStreamException's,
      use the defaultErrorHandler=false grammar option."

      However, the documentation in "options.html" mentions that "ANTLR
      will generate default exception handling code for a parser or tree-parser
      rule".
      It doesn't say that a default error handler is generated for lexers, so it
      seems I was wrong with my assumption that Antlr will also generate
      a default error handler for lexers (although I still think the current
      behaviour
      is not logical).

      Note that the lexer of Antlr itself (in antlr.g) doesn't use a default
      error handler. Sometimes I get unmatched character exceptions with
      ANTLR where it doesn't report the linenumber. Turning error handling
      on would solve that problem.

      Again, thanks for your advise!

      Stdiobe.
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