In this case, just increasing k to k=2 would probably do the trick.
You could also try a semantic predicate like this:
REG_EXP : { LA(2) == COMMON_REG }? '/' COMMON_REG etc.
The trick you used should work, but should probably look like this:
> DIV_OR_REG:
> '/' (
> { $setType(DIV); }
> |
> COMMON_REG (COMMON_REG | INNER_REG)*
> '/'
> ('g' | 'm' | 'i')* { $setType(REG_EXP); }
> );
And instead of declaring DIV and REG_EXP as protected rules you should
simply add them to you parser's tokens{} section.
-Olivier
On 05 Apr 2006 12:42:42 +0300
Anakreon Mendis <anakreonmejdi at yahoo.gr> wrote:
> I have a little problem with a lexer and I hope you could help.
>
> The problem is the two tokens start with the same simbol.
> I have
> DIV : '/';
> and regex:
> REG_EXP :
> '/' COMMON_REG (COMMON_REG | INNER_REG)* '/' ('g' | 'm' | 'i')*
> ;
>
> When the code:
> a = b/c;
> the lexer thinks that '/' starts a regular expression.
> This is wrong ofcourse and the parsing fails.
>
> Any suggestions how to resolve this problem?
>
> This is a failed attemt I've done:
> DIV_OR_REG:
> '/' (
> (' ' | '\t') { _ttype = DIV; $setText("/");}
> | COMMON_REG (COMMON_REG | INNER_REG)*
> '/'
> ('g' | 'm' | 'i')* { _ttype = REG_EXP;}
> | { _ttype = DIV; }
> );
>
>
> protected DIV:;
> protected REG_EXP:;
>
> One thought I had is to create a lexer for regex
> and control would be delivered to it whenever a '/'
> character is found. If that lexer failed to parse
> the input, then the '/' would be set to type DIV.
>
> I hope there is a easier solution.
>
> Anakreon
> --
> Three words describe our society:homo homini lupus
>