[cl-ppcre-devel] Strange parsing

[Edi Weitz]

On Wed, 3 Dec 2008 23:07:26 -0800, "Ken Harris" <kengruven at gmail.com> wrote:

> When playing around with cl-ppcre 2.0.1, I've discovered this:
>
>  (cl-ppcre::parse-string "?") -> :QUESTION-MARK
>
> I found this odd, since :QUESTION-MARK isn't part of the parse-tree
> grammar in the docs.  Two or more ("??", "???", etc.) also leave a
> :QUESTION-MARK in the parse-tree.  I took a quick look at the source
> code, and it looks like :QUESTION-MARK is used by the lexer (with
> other keywords like :CLOSE-PAREN), but that it seems to expect them
> to be replaced by the time you end up with a parse-tree.
>
> In comparison, if you try to use ")", like (cl-ppcre::parse-string
> ")"), it signals a condition in parse-string.  I can't find any way
> to get :CLOSE-PAREN in the output.  It's a little weird that it can
> parse "??" but then signals if you try to use it.
>
> If I try to cl-ppcre:scan anything with one of these, I get a
> ppcre-syntax-error, "Unknown token QUESTION-MARK in parse tree".  I
> don't know if this is a bug or not, and I don't think I'm going to
> run into a situation where this matters, but there you go.  :-)

Yeah, this looks like an oversight.  I'll check.

Thanks for the report,
Edi.