[antlr-interest] Difference in the following rules

Paul Johnson gt54-antlr at cyconix.com
Tue Jul 12 01:10:05 PDT 2005


Ric Klaren wrote:
> Hi,
> 
> On 7/11/05, Tarun Khanna <tarunkhanna at gmail.com> wrote:
> 
>>The attached grammar produces a non-determinism warning in the following
>>production
>> factor :
>>      ( ( LPAREN exp RPAREN ) | IDENT )  (DOT  IDENT)*  (DOT  TAB)? 
>>    | 
>>      TAB
>>    ;
> 
> 
> Notice that the (DOT IDENT)* may match the empty word e.g. nothing.
> Add to that that (DOT TAB)? may also match nothing. Add to that that
> the start of both may be a DOT. So antlr has a hard time choosing
> between the closure (DOT IDENT)* and the optional part (DOT TAB)?. 

But what if k is 2, as Tarun said in his original post?

Paul



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