Re: Returning special EOF token when EOF found in scanner

Nicholas Allen wrote:
> I have a quick question though. I want to return my own token when EOF is 
> matched in the scanner to my parser. The reason is that I gather up all the 
> comments and add them to my own TOKEN object so that each token found also 
> includes the comments that appeared immediately before it.
> 
> So if I can pass my own special EOF token object back to my parser I can get 
> the comments that appear at the end of the file. I tried this:
> 
> <<EOF>>			{
> 				terminate;
> 				last_token := EOF_TK;
> 				matched_token(create {TOKEN}.make(EOF_TK, line, column, line, column, 
> comments)); 
> 				}
> 
> But it seems the parser does not get this token.

In fact the parser might get this EOF_TK token, but it might
not receive the notification from the scanner that the end
of file has been reached.

> Any idea why or how I should  be doing this instead?

I didn't try it, so it might not work, but here is a suggestion:

%x EOF_TOKEN
...
<INITIAL><<EOF>> {
         last_token := EOF_TK
         matched_token (create {TOKEN}.make(EOF_TK, line, column, line, 
column, comments))
         set_start_condition (EOF_TOKEN)
     }

<EOF_TOKEN><<EOF>> {
         set_start_condition (INITIAL)
         terminate
     }


-- 
Eric Bezault
mailto:ericb-D6Qt/9opevxWk0Htik3J/[email protected]
http://www.gobosoft.com



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