--- Begin Message ---
Subject: |
26.1; Incomplete ? and ?? handling in rx |
Date: |
Wed, 16 Jan 2019 12:39:58 +0100 |
In rx, the ? and ?? operators can be written verbatim as ? and ?? (space and ?
character), or by using symbols whose leading character needs to be escaped, \?
and \?? respectively. The names come from Olin Shivers's SRE, but ? is not a
special character in Scheme syntax, hence the character syntax hack.
However, the symbols only partially work:
(rx (\? "x") (\?? "y")) --> "x?y?" ; expected "x?y??"
(rx (minimal-match (\? "x"))) --> "x??" ; expected "x?"
While it could be argued that only the character-based syntax should be used,
the fact is that the symbols are accepted and seem to work, just in a subtly
broken way.
The documentation is also not clear on this point, and a programmer knowing the
elisp syntax might very well assume that the symbols are the ones to use.
Suggested fix:
diff --git a/lisp/emacs-lisp/rx.el b/lisp/emacs-lisp/rx.el
index a39fe55c32..8b4551d0d3 100644
--- a/lisp/emacs-lisp/rx.el
+++ b/lisp/emacs-lisp/rx.el
@@ -733,8 +733,8 @@
is non-nil."
(rx-check form)
(setq form (rx-trans-forms form))
- (let ((suffix (cond ((memq (car form) '(* + ?\s)) "")
- ((memq (car form) '(*? +? ??)) "?")
+ (let ((suffix (cond ((memq (car form) '(* + \? ?\s)) "")
+ ((memq (car form) '(*? +? \?? ??)) "?")
(rx-greedy-flag "")
(t "?")))
(op (cond ((memq (car form) '(* *? 0+ zero-or-more)) "*")
--- End Message ---
--- Begin Message ---
Subject: |
Re: bug#34100: Acknowledgement (26.1; Incomplete ? and ?? handling in rx) |
Date: |
Fri, 01 Feb 2019 11:44:20 +0200 |
> From: Michael Heerdegen <address@hidden>
> Date: Mon, 28 Jan 2019 16:53:28 +0100
> Cc: address@hidden
>
> Mattias EngdegÄrd <address@hidden> writes:
>
> > Anything more I can do? I thought this one would be rather
> > straightforward. I do understand that there are more pressing
> > matters.
>
> I guess you just have to be patient until someone has a look. That can
> sometimes take some time, there are a lot of open bug reports...
>
> For me what you suggest looks like a good idea btw.
Sorry for the long delay, Mattias. I've now pushed your changes to
the master branch, and I'm marking this bug done.
Thanks.
--- End Message ---