=?gb2312?q?=BB=D8=B8=B4=A3=BA=20Re:=20[antlr-interest]=20a=20left=20recur?= =?gb2312?q?sive=20walker=20rule?=

[=?gb2312?q?=CB=EF=BC=CD=B8=D5=20Jigang=20(Robert)=20Sun?=]

Sorry I had a few days off.

The corresponding parser rule is A : ("("A")" |B)+ C, I turned off "(" and ")", thus caused the
problem in tree walker.

Jigang

--- Loring Craymer <lgcraymer at yahoo.com>дµÀ:

> This looks very weird--you have no termination condition for the recursion.  Normally, recursive
> rules have termination conditions and the recursion-to-iteration conversion is relatively
> straightforward.  I cannot easily imaging how you got to this form.  What did the annotated
> parser rule look like that got you here?
> 
> --Loring
> 
> "��͸￁ Jigang (Robert) Sun" <sunjigang1965 at yahoo.com.cn> wrote: Hi,
> I have a rule in tree walker, which is left recursive:  A : (A|B)+ C ,
> 
> so I am trying to eliminate it 
> 
> A : (A|B)+ C
> => A : ( A(A|B)* | B(A|B)*) C
> => A : A(A|B)* C | B(A|B)* C
> => A : B(A|B)* C  ((A|B)* C)*
> => A : B ( (A|B)* C )+
> => A : B ( ( B((A|B)* C)+ |B )* C )+ //replace A with " B ( (A|B)* C )+ "
> => A : B( ( B [((A|B)* C)+ | ]* C)+ // need to replace A with " B ( (A|B)* C )+ " again
> => A : ... //then again and again forever, never ends
> 
> Any better solution?
> 
> Thanks
> 
> Jigang
> 
> 
> 
> 
> 
>   
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