Re: Why LL(1) Parsers do not support left recursion?

"SLK Parsers" <parsersinc@earthlink.net>
4 Aug 2006 16:39:36 -0400

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[29 earlier articles]
Re: Why LL(1) Parsers do not support left recursion? ajo@andrew.cmu.edu (Arthur J. O'Dwyer) (2006-07-29)
Re: Why LL(1) Parsers do not support left recursion? DrDiettrich1@aol.com (Hans-Peter Diettrich) (2006-07-29)
Re: Why LL(1) Parsers do not support left recursion? parsersinc@earthlink.net (SLK Parsers) (2006-07-31)
Re: Why LL(1) Parsers do not support left recursion? wyrmwif@tsoft.org (SM Ryan) (2006-08-01)
Re: Why LL(1) Parsers do not support left recursion? DrDiettrich1@aol.com (Hans-Peter Diettrich) (2006-08-03)
Re: Why LL(1) Parsers do not support left recursion? parsersinc@earthlink.net (SLK Parsers) (2006-08-03)
Re: Why LL(1) Parsers do not support left recursion? parsersinc@earthlink.net (SLK Parsers) (2006-08-04)
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From: "SLK Parsers" <parsersinc@earthlink.net>
Newsgroups: comp.compilers
Date: 4 Aug 2006 16:39:36 -0400
Organization: Parsers Inc.
References: 06-07-11506-08-011
Keywords: parse

>Hmmm, how can you ever be sure, that the solution for the dangling else
>always will be correct, also in other ambiguous situations?


It is well-known to be correct, and is explained in compiler texts. It
is a very special case. In general, ambiguity is to be avoided unless
you know what you are doing, and probably even then. That said, I used
the technique seven times in a recent translator, and am confident
that it is correct. This was verified by use on about 1000 real
programs.


The SLK parser generator: http://home.earthlink.net/~slkpg/
[My rule of thumb has been that it's OK to use disambiguation for
if/then/else and operator precedence in expressions. Anywhere else
you're likely to get into trouble. -John]



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