[ragel-users] Testing beginning of line in a scanner

[Adrian Thurston]

Hey Mitchell, I just checked in a fix for this. Also, you might want to
try "when !starts_line" to enforce the negative sense of a condition.
This will prevent not_starts_line from being executed right after
starts_line to get the same info only negated.

-Adrian

mitchell wrote:
> Hi,
> 
> I'm trying to test for a character that occurs only at the beginning
> of a line in a scanner:
> 
>   special = '!' when starts_line @callback;
>   line := |*
>     [\t ]+ => callback;
>     special;
>     newline => callback;
>     '!' when not_starts_line => callback;
>     ^(space | '!') => callback;
>   *|;
> 
> I get a
>   ragel: fsmgraph.h:385: TransAp::TransAp(const TransAp&): Assertion
>   `lmActionTable.length() == 0 && other.lmActionTable.length() == 0'
> failed
> error.
> 
> If I remove the "'!' when not_starts_line" line, Ragel compiles, but I
> cannot detect any '!'s in a place other than the beginning of a line
> which is no good.
> 
> Any ideas?
> 
> Thanks,
> -Mitchell;
> > 
>