[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Why token are numbered from 258?
|
From: |
Pavel Stehule |
|
Subject: |
Re: Why token are numbered from 258? |
|
Date: |
Thu, 7 Feb 2019 20:38:54 +0100 |
čt 7. 2. 2019 v 20:35 odesílatel Christian Schoenebeck <
address@hidden> napsal:
> On Donnerstag, 7. Februar 2019 11:33:38 CET Peng Yu wrote:
> > I don't quite understand why tokens are numbered starting from 258.
> > What are 256 and 257 for? Thanks.
>
>
the one byte encodings like ASCII can has 256 chars. The gramatic can be
mix of special chars like ();, ... and words (tokens).
You don't need to declare special tokens for one char symbols.
Regards
Pavel
> It's been a while, but as far as I can remember those extra 2 are always
> automatically used for the special built-in terminals YYEOF and YYEMPTY.
>
> Best regards,
> Christian Schoenebeck
>
> _______________________________________________
> address@hidden https://lists.gnu.org/mailman/listinfo/help-bison
>