From kengruven at gmail.com  Thu Dec  4 07:07:26 2008
From: kengruven at gmail.com (Ken Harris)
Date: Wed, 3 Dec 2008 23:07:26 -0800
Subject: [cl-ppcre-devel] Strange parsing
Message-ID: <d97bec7a0812032307n3c328f65naeb26bdeb2fe9410@mail.gmail.com>

Hi, all,

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.  :-)

cheers,


- Ken



From edi at agharta.de  Thu Dec  4 07:30:54 2008
From: edi at agharta.de (Edi Weitz)
Date: Thu, 04 Dec 2008 08:30:54 +0100
Subject: [cl-ppcre-devel] Strange parsing
In-Reply-To: <d97bec7a0812032307n3c328f65naeb26bdeb2fe9410@mail.gmail.com> (Ken
	Harris's message of "Wed, 3 Dec 2008 23:07:26 -0800")
References: <d97bec7a0812032307n3c328f65naeb26bdeb2fe9410@mail.gmail.com>
Message-ID: <u63m0z9ap.fsf@agharta.de>

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.