Regular LALR grammars (Simon Huntington)
Tue, 25 May 1993 14:16:57 GMT

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Regular LALR grammars (1993-05-25)
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Newsgroups: comp.compilers
From: (Simon Huntington)
Keywords: LALR, parse, question
Organization: SoftWare Interrupt Developments
Date: Tue, 25 May 1993 14:16:57 GMT

How are regular parser grammars handled by the parser generator? I know
how a grammar using regular expressions (ie. EBNF) can be converted to
BNF, but does a regular-grammar parser use the regular expressions during
closure? ie.

x -> a*

what would the Closure of: x -> . a*

x -> . a
-> a . ?

If this is correct, I assume + and optional [] are handled similarly:

for x -> .a+

closure of: x -> .a+
is: x -> .a

closure of: x -> a+.
is: x -> a.
-> .a

for x -> [a]
closure of: x -> .[a]
is: x -> .a
-> a.

Is this correct or will it have the same effect as transforming the grammar
to BNF-form only?
Simon Huntington
Software Interrupt Developments. Leeds, UK.

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