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Re: GLR: modification of $1
From: |
Paul Eggert |
Subject: |
Re: GLR: modification of $1 |
Date: |
01 Oct 2003 21:32:37 -0700 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 |
Frank Heckenbach <address@hidden> writes:
> Perhaps a stupid question, but are the `$1' etc. variables read-only
> (in particular, in mid-rule actions)?
Traditionally, they were read-write. The POSIX spec is muddled in
this area. However, even if it clearly stated that they are
read-write, that requirement would apply only to the traditional
yacc.c template; it wouldn't apply to the GLR template.
> The examples in the documentation don't seem to modify
> them, but other parsers do (e.g., the gcc C parser does so for
> handling `&&' etc.).
(Blush.) I'm responsible for some of those contorted grammars.
> If modification is actually allowed, there seems to be a bug in the
> GLR parser (tested with 1.875b since I can't easily build the CVS
> versions).
If modification is not allowed in GLR parsers, perhaps glr.c should be
changed so that $1 expands to a const-qualified object; that way,
errors will be caught at compile-time.
- GLR: modification of $1, Frank Heckenbach, 2003/10/01
- Re: GLR: modification of $1,
Paul Eggert <=
- Re: GLR: modification of $1, Frank Heckenbach, 2003/10/02
- Re: GLR: modification of $1, Paul Hilfinger, 2003/10/02
- Re: GLR: modification of $1, Frank Heckenbach, 2003/10/02
- Re: GLR: modification of $1, Paul Eggert, 2003/10/03
- Re: GLR: modification of $1, Frank Heckenbach, 2003/10/04
- Re: GLR: modification of $1, Paul Eggert, 2003/10/05
- Re: GLR: modification of $1, Frank Heckenbach, 2003/10/05
- Re: GLR: modification of $1, Hans Aberg, 2003/10/04
- Re: GLR: modification of $1, Frank Heckenbach, 2003/10/04
- Re: GLR: modification of $1, Hans Aberg, 2003/10/05