Re: EBNF conflict avoidance

"Clint Olsen" <clint@0lsen.net>
24 Nov 2002 01:25:47 -0500

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From: "Clint Olsen" <clint@0lsen.net>
Newsgroups: comp.compilers
Date: 24 Nov 2002 01:25:47 -0500
Organization: AT&T Broadband
References: 02-11-118
Keywords: parse, LL(1)
Posted-Date: 24 Nov 2002 01:25:47 EST

SLK Parsers wrote:
> The conflict avoidance properties of EBNF LL(k) grammars seem
> exaggerated. Of the ten LL(1) conflicts in my C grammar, none appear to
> be avoidable by using EBNF. Can anyone provide references or example
> grammars that illustrate conflict avoidance by using EBNF in top-down
> parsing techniques?


I think you need to consider the fact that you're not naive when it
comes to LL(1) parsing. EBNF saves you from the traditional crap
like:


list : item more_items
          ;


more_items : item
                      |
                      ;


Whereas you'd rather write:


list : items+
          ;


So, I think when they say conflicts I think they are also including
accidental use of left recursion.


-Clint

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