Is it possible to configure multi-line comments to comment/uncomment selected text?
For example C/C++'s preprocessor could be toggled like this.
eg:
Before:
// a comment Some(code); /* some comment */ After:
#if 0 // a comment Some(code); /* some comment */ #endif Since C/C++ don't support nested comments, I find this preferable behavior to quickly disable chunks of code.
This can be done by matching the beginning & end of the region, removing when found, adding when not found.
The following example is a generic function which takes arguments which can be set for each major-mode.
(defun my-comment-multi-line-toggle--impl (head tail head-regex tail-regex) "Utility for toggling multi-line comments. Argument HEAD Start of multi-line comment. Argument TAIL End of multi-line comment. Argument HEAD-REGEX Match the start of a multi-line comment. Argument TAIL-REGEX Match the end of a multi-line comment." (unless (use-region-p) (user-error "No active region")) (let ((beg (region-beginning)) (end (region-end)) (match-head nil) (match-tail nil) ;; Prevent local language settings ;; impacting basic space stepping. (syntax-table (make-syntax-table))) (save-excursion (with-syntax-table syntax-table ;; True when we have multi-line comments. (if (and (setq match-head (save-match-data (goto-char beg) (skip-chars-forward "[:blank:]") (when (looking-at head-regex) (match-data)))) (setq match-tail (save-match-data (goto-char end) (skip-chars-backward "[:blank:]") (when (looking-back tail-regex) (match-data)))) ;; Double check there is no overlap. (<= (save-match-data (set-match-data match-head) (match-end 0)) (save-match-data (set-match-data match-tail) (match-beginning 0)))) ;; Remove multi-line comment. (dolist (match (list match-tail match-head)) (save-match-data (set-match-data match) (goto-char (match-beginning 0)) (replace-match "" t nil nil)) (beginning-of-line) (when (looking-at-p "[[:blank:]]*$") (kill-whole-line))) ;; Add multi-line comment. (goto-char end) (insert tail) (indent-according-to-mode) (insert "\n") (goto-char beg) (insert head) (indent-according-to-mode) (insert "\n")))))) (defun my-comment-multi-line-toggle (&optional head tail head-regex tail-regex) "Toggle multi-line comments for various languages." (interactive) (cond ;; Support optionally passing in arguments. ((and head tail head-regex tail-regex) (my-comment-multi-line-toggle--impl head tail head-regex tail-regex)) ((memq major-mode '(c-mode c++-mode glsl-mode)) (my-comment-multi-line-toggle--impl "#if 0" "#endif" "^[[:blank:]]*#[[:blank:]]*if[[:blank:]]+0[[:blank:]]*$" "^[[:blank:]]*#[[:blank:]]*endif[[:blank:]]*$")) ((memq major-mode '(lua-mode)) (my-comment-multi-line-toggle--impl "--[[" "]]" "^[[:blank:]]*\\-\\-\\[\\[[[:blank:]]*$" "^[[:blank:]]*\\]\\][[:blank:]]*$")) ((memq major-mode '(cmake-mode)) (my-comment-multi-line-toggle--impl "#[[" "]]" "^[[:blank:]]*#\\[\\[[[:blank:]]*$" "^[[:blank:]]*\\]\\][[:blank:]]*$")) ((memq major-mode '(python-mode)) (my-comment-multi-line-toggle--impl "'''" "'''" "^[[:blank:]]*\\('''\\|\"\"\"\\)[[:blank:]]*$" "^[[:blank:]]*\\('''\\|\"\"\"\\)[[:blank:]]*$")) (t (user-error "Multi-line comment unsupported major mode '%s'" major-mode))))