Re: set flex start conditions from bison?

[Akim Demaille]

Le 25 août 09 à 12:19, Rui Maciel a écrit :

> Is it possible to set the flex start conditions from within bison?  
> I've set a couple of lexer start
> conditions in the flex file and added yy_push_state() to the bison  
> file, which already includes a flex-
> generated header. Nonetheless, the compiler still complains that the  
> start condition symbol (named s_element)
> is undeclared. As the start condition symbol is described in the  
> flex file as:
>
> #ifdef YY_HEADER_EXPORT_START_CONDITIONS
> #define INITIAL 0
> #define s_element 1
>
> #endif
>
> That leads me to believe that some other tweaking is needed to at  
> least define
> YY_HEADER_EXPORT_START_CONDITIONS and therefore declare the start  
> condition symbol.
>
> So, how do we set flex start conditions from within a bison file?

AFAIK, Flex does not generate a header file with its definitions such  
as start conditions, so you probably need to write a small wrapper  
around flex that extracts it from the generated scanner *.c file.   
Then, from the grammar file, just include that extracted file from  
like any other.