Re: Scheme Mode and Regular Expression Literals

[Eli Zaretskii <eliz@gnu.org>]

> From: Toshi Umehara <toshi@niceume.com>
> Cc: emacs-devel@gnu.org
> Date: Sat, 09 Mar 2024 11:59:10 +0900
> 
> 
> Regular expression literals as exist in Gauche Scheme does not seem to
> work in scheme mode. #/regexp/ is not dealt as a chunk. I looked for its
> solution on the Web, and reached this web page,
> https://ardggy.hatenablog.jp/entry/2015/11/24/143713 (in Japanese).  The
> solution on the page overwrites syntax-propertize-function and adds a
> new rule for regular expression literals. I got a hint from it, and have
> tried to manage backslash slash ( \/ ) not to finish the literal and
> backshashes of even numbers (like \\\\ ) not to work as escapes.
> 
> Currently, the following code in init.el works for me.
> 
> #+BEGIN_SRC
> (add-hook 'scheme-mode-hook
>           (lambda ()
>             (setq-local
>              syntax-propertize-function
>              (lambda (start end)
>                (goto-char start)
>                (funcall
>                 (syntax-propertize-rules
>                  ;; For #/regexp/ syntax
>                  ("\\(#\\)/\\(\\\\/\\|\\\\\\\\\\|.\\)*?\\(/\\)"
>                   (1 "|")
>                   (3 "|"))
>                  ;; For #; comment syntax
>                  ("\\(#\\);"
>                   (1 (prog1 "< cn"
>                        (scheme-syntax-propertize-sexp-comment
>                         (point) end)))))
>                 (point) end))
>              ))
>           )
> #+END_SRC

Thanks.

Stefan, is the below the right fix?  I'm confused by the call to
scheme-syntax-propertize-sexp-comment that scheme-syntax-propertize
does at its very beginning -- what is it for?

diff --git a/lisp/progmodes/scheme.el b/lisp/progmodes/scheme.el
index 67abab6..a83e5dc 100644
--- a/lisp/progmodes/scheme.el
+++ b/lisp/progmodes/scheme.el
@@ -412,6 +412,11 @@ scheme-syntax-propertize
   (scheme-syntax-propertize-sexp-comment (point) end)
   (funcall
    (syntax-propertize-rules
+    ;; For #/regexp/ syntax
+    ("\\(#\\)/\\(\\\\/\\|\\\\\\\\\\|.\\)*?\\(/\\)"
+     (1 "|")
+     (3 "|"))
+    ;; For #; comment syntax
     ("\\(#\\);" (1 (prog1 "< cn"
                      (scheme-syntax-propertize-sexp-comment (point) end)))))
    (point) end))