[antlr-interest] newbie left-recursive problem

[Frank Smith]

The problem is that everything that you call off of the expression rule
(such as infixexpression) begins with a call to the expression rule again.

The wikipedia entry for fixing left recursion seems to follow the formula
from The Dragon Book (by Al Aho, et al)  and that worked for me in my
grammar:
http://en.wikipedia.org/wiki/Left_recursion

Good luck.

On 7/5/07, ali azimi <aliaazimi at yahoo.com> wrote:
>
> Hi,
>
> I have read some articles about left-recursive problem and managed to
> understand the nature of the problem. However I can not remedy the problem I
> am facing in my grammar. I am hoping you can help me.
>
> You can see left-recursive problems in the followings. how can I remedy
> them?
> variable:fieldmodify|elementmodify|variableidentifier
>  ;
> elementmodify
>  :variable'('expression(','expression)*')'
>  ;
> fieldmodify
>  :variable'!'fieldname
>  ;
> expression
>
>  :literalidentifier|synonymidentifier|variableidentifier|fieldextract|elementextract|infixexpression|parenthesisexpression
>
>  |operatorapplication|valuemake|imperativeoperator|conditionalexpression|forallname|spellingexpression
>  ;
>
> and the followings:
>
> infixexpression
>  :expression dyadicoperator expression
>  |monadicoperator expression
>  ;
> elementextract
>  :expression '('expression (',' expression)*')'
>  ;
> fieldextract
>  :expression '!'fieldname
>  ;
>
>
> Thank you so much in advance,
> Al
>
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