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Re: Lexer woes
From: |
Ben Pfaff |
Subject: |
Re: Lexer woes |
Date: |
Wed, 24 Sep 2008 08:34:59 -0700 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) |
John Darrington <address@hidden> writes:
> On Tue, Sep 23, 2008 at 09:19:26PM -0700, Ben Pfaff wrote:
>
> I also think this would be nice to have. It is a problem that I
> did some work on a few years ago. It is not too hard to write a
> parser generator that accepts a context-free grammar for PSPP
> syntax and outputs C code to parse it, and in fact I did most of
> the work necessary for that.
>
> Really? As I understand it, the example that I've given means that the
> grammar is not context-free.
The grammars for many languages are not strictly context-free,
but compiler writers still write context-free grammars for them
and work around them in various ways. The C language, for
example, famously is not context-free due to the syntax for
"typedef", but that does not stop us from using yacc to parse it.
(Usually, you add a little bit of intelligence to the lexer, and
that's what I planned to do too.)
--
Ben Pfaff
http://benpfaff.org