[antlr-interest] Re: antlr-interest@antlr.org
Joseph Goettgens
jg at pcCFD.com
Tue Mar 28 15:40:29 PST 2006
Karl,
> succeded with the grammar before, ...
> Basically I'm trying to use Antlr as a natrual language parser.
you seem to put a lot of (read: too much) stuff into the lexer. The grammar
is probaly the center for organizing things since it is more "capable" than
a lexer, though antlr blurs this difference to some degree. The grammar
eventually will tell you which token types you need to
distinguish---shouldn't be too many as natural languages don't have things
like reserved words or other constructs derived from regular expressions.
Have a look at http://en.wikipedia.org/wiki/Formal_language . I guess you
are still dealing with a formal languange and not a natural one (e.g. see
http://en.wikipedia.org/wiki/Noam_Chomsky). If you were really dealing with
a natural language you'd be dealing with ungrammatical things sooner or
later. Kalle, für den Fall, dass Du zuviel Bier trinkts, the lexer will
become a real challenge, Prost and indeed.
Even if you were able to specify a description of your language with a
single meta-language you are giving up one level of abstraction, since
grammars give rules for types of words and lexers give rules on how to form
words from elements of a vocabulary. In algebraic terms, you would avoid
factoring out common terms and are punished by dealing with unnecessarily
complex expression, subsequently.
jg
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