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Re: User Token Numbers
From: |
Akim Demaille |
Subject: |
Re: User Token Numbers |
Date: |
08 Apr 2002 23:27:06 +0200 |
User-agent: |
Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Common Lisp) |
>>>>> "Paul" == Paul Eggert <address@hidden> writes:
Paul> That is a clear violation of POSIX, I'm afraid.
Ok, thanks.
>> But I would like to know more from POSIX, in particular, I would
>> like to make sure that EOF (= 0) is the only number that is
>> reserved.
Paul> It depends on what you mean by "reserved". If you you mean
Paul> "yacc cannot assign these token numbers", then POSIX reserves
Paul> all nonpositive integers, all token numbers used for literals in
Paul> the grammar, and all user-assigned token numbers.
Bison does not use negative numbers, so...
Paul> Here are the relevant quotes:
Paul> * "All token numbers assigned by yacc shall be unique and
Paul> distinct from the token numbers used for literals and
Paul> user-assigned tokens."
Paul> Other things from POSIX include:
Paul> * User-defined assigned token numbers must be positive.
ISTR that the first user token number should be 257, so, now that I
have $undefined moved, I must put it past the user tokens, right? 256
is `error', 257 is the last user token, so (unless I find a hole
somewhere, which I don't plan to do), it means pushing it till the end.
Paul> * Yacc can assign a token number immediately when it sees a
Paul> %token declaration. However, in my opinion it'd be a bit nicer
Paul> if it waits till end of grammar, so that it doesn't assign a
Paul> token number that collides with a later user-defined token
Paul> number.
That's what I plan to do for $undefined.
Thanks!
- User Token Numbers, Akim Demaille, 2002/04/08
- Re: User Token Numbers, Paul Eggert, 2002/04/08
- Re: User Token Numbers,
Akim Demaille <=
- Re: User Token Numbers, Paul Eggert, 2002/04/08
- Re: User Token Numbers, Akim Demaille, 2002/04/09
- Re: User Token Numbers, Paul Eggert, 2002/04/09
- Re: User Token Numbers, Akim Demaille, 2002/04/10
- Re: User Token Numbers, Hans Aberg, 2002/04/10
- Re: User Token Numbers, Paul Eggert, 2002/04/10
Re: User Token Numbers, Florian Krohm, 2002/04/08
Re: POSIX and reduce/reduce conflicts, Paul Eggert, 2002/04/08