Create a repo for box-comment

packages.el

@@ -10,6 +10,8 @@
 ;;(package! some-package)
 (package! ace-jump-mode
   :recipe (:local-repo "repos/ace-jump-mode"))
+(package! box-comment
+  :recipe (:local-repo "repos/x-lib"))
 (package! deadgrep)
 (package! duplicate-thing)
 (package! treemacs-icons-dired)

repos/x-lib/box-comment.el

@@ -0,0 +1,131 @@
+;;; box-comment.el -*- lexical-binding: t -*-
+
+;;
+;;; Variables:
+
+(defvar box-comment--comment-start-emacs-lisp-mode ";; "
+  "String to begin comment lines in `emacs-lisp-mode'.")
+
+(defvar box-comment--comment-start-lisp-interaction-mode ";; "
+  "String to begin comment lines in `list-interaction-mode'.")
+
+(defvar box-comment--comment-start-scheme-mode ";; "
+  "String to begin comment lines in `scheme-mode'.")
+
+;;
+;;; Code:
+
+(defun +x-box-comment--comment-start ()
+  "Get the string that starts box comments for the current mode."
+  (let ((box-comment-var
+         (intern (format "box-comment--comment-start-%s" major-mode))))
+    (string-trim-right (if (boundp box-comment-var)
+                           (eval box-comment-var)
+                         comment-start)
+                       "[[:space:]]")))
+
+(defun +x-box-comment--box-comment-line-p (box-comment-start)
+  "Return t if point is in a line suitable for box comments."
+  (save-excursion
+    (end-of-line)
+    (search-backward (string-trim-right box-comment-start "[[:space:]]")
+                     (line-beginning-position)
+                     t)))
+
+(defun +x-box-comment--box-comment-boundary-p (box-comment-start)
+  "Return non-nil if point is in a box comment boundary line."
+  (save-excursion
+    (if (/= (- (line-end-position) (line-beginning-position)) fill-column)
+        nil
+      (end-of-line)
+      (re-search-backward (format "^[[:space:]]*%s -+$" box-comment-start)
+                          (line-beginning-position)
+                          t))))
+
+(defun +x-box-comment--insert-box-boundary (box-comment-start indent len)
+  "Insert a box comment boundary line."
+  (indent-line-to indent)
+  (insert box-comment-start " " (make-string len ?-)))
+
+(defun +x-box-comment--re-search (re beg end)
+  "Return non-nil if RE is between BEG and END."
+  (save-excursion
+    (goto-char beg)
+    (re-search-forward re end t)))
+
+;;;###autoload
+(defun +x-box-comment/box-comment ()
+  "Format the comment at point into a box comment.
+
+If the comment at point is already a box comment, this command
+will update and fix the box comment format (if necessary)."
+  (interactive)
+  (let ((box-comment-start (+x-box-comment--comment-start))
+        (use-region (use-region-p))
+        offset region-len indent len)
+
+    ;; If we are not in a comment, create a comment.
+    (unless (+x-box-comment--box-comment-line-p box-comment-start)
+      (if (and (not use-region)
+               (+x-box-comment--re-search "^[[:space:]]*$"
+                                          (line-beginning-position)
+                                          (line-end-position)))
+          (comment-dwim nil)
+        (comment-line nil)
+        ;; `comment-line' behaves differently whether its invoked on a region or
+        ;; not. In a region, the point ends up within the comment, unless the
+        ;; region ended on an empty line in which case the point ends up on the
+        ;; next line. Outside of a region, the point ends up on the next line.
+        (if use-region
+            (progn
+              (unless (or (+x-box-comment--box-comment-line-p box-comment-start)
+                          (not (+x-box-comment--re-search box-comment-start
+                                                          (region-beginning)
+                                                          (region-end))))
+                (forward-line -1))
+              (end-of-line)
+              (setq region-len (- (region-end) (region-beginning))))
+          (forward-line -1)
+          (end-of-line))))
+
+    (save-excursion
+      (end-of-line)
+      (when (search-backward box-comment-start (line-beginning-position) t)
+
+        ;; Get the variables.
+        (setq indent (current-column))
+        (setq len (- (- fill-column (+ (length box-comment-start) 1)) indent))
+
+        ;; Find the first line.
+        (if use-region
+            (progn
+              (goto-char (region-beginning))
+              (setq offset (- (current-column) indent)))
+          (while (+x-box-comment--box-comment-line-p box-comment-start)
+            (forward-line -1))
+          (forward-line +1))
+
+        ;; If not a box comment boundary, insert it.
+        (unless (+x-box-comment--box-comment-boundary-p box-comment-start)
+          (beginning-of-line)
+          (+x-box-comment--insert-box-boundary box-comment-start indent len)
+          (newline)
+          (indent-line-to indent))
+
+        ;; Now find the last line
+        (if use-region
+            (forward-char (+ offset region-len))
+          (while (+x-box-comment--box-comment-line-p box-comment-start)
+            (forward-line +1))
+          (forward-line -1))
+
+        ;; If not a box comment boundary, insert it.
+        (unless (+x-box-comment--box-comment-boundary-p box-comment-start)
+          (end-of-line)
+          (newline)
+          (+x-box-comment--insert-box-boundary box-comment-start
+                                               indent
+                                               len))))))
+
+(provide 'box-comment)
+;;; box-comment.el ends here