Re: Scheme Mode and Regular Expression Literals

[Toshi Umehara <toshi@niceume.com>]

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

Hope this helps.

--
Toshi (Toshihiro Umehara)