[O] [PATCH] make comment-dwim in source code blocks more DWIM-ish

[Aaron Ecay]

* lisp/org.el (org-insert-comment, org-comment-or-uncomment-region):
use the relevant language’s major mode comment function if called from
within a source block.

This patch makes it easier to (un)comment lines of babel source.  Now
M-; in a soucre code block should Just Work.

The modification to ‘org-insert-comment’ also fixes a bug, whereby the
function would eat blank lines after it.  The first block, where ! is
the point, would lead to the second instead of the third:

 #+name: orig
 #+begin_src org
 xxxxxxx
 !

 yyyyyy
 #+end_src

 #+name: bad
 #+begin_src org
 xxxxxxx
 #
 yyyyyy
 #+end_src

 #+name: desired
 #+begin_src org
 xxxxxxx
 #

 yyyyyy
 #+end_src

Also, the ‘org-comment-or-uncomment-region’ change results in an
undesirably move of the point after the comment is created.  This is
because ‘comment-region’ wraps the call to ‘comment-region-function’
in a ‘save-excursion’.  The org mode code deletes and reinserts the
whole babel block, which confuses save-excursion.  Org carefully puts
the point back in the proper place, but comment-region’s
save-excursion then substitutes its own erroneous placement.
---
 lisp/org.el | 126 +++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 74 insertions(+), 52 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 43172c8..4aeeada 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -22478,64 +22478,86 @@ non-nil."
 (defun org-insert-comment ()
   "Insert an empty comment above current line.
 If the line is empty, insert comment at its beginning."
-  (beginning-of-line)
-  (if (looking-at "\\s-*$") (replace-match "") (open-line 1))
-  (org-indent-line)
-  (insert "# "))
+  (if (org-in-src-block-p t)
+      (progn
+       (require 'ob-core)
+       (org-babel-do-in-edit-buffer
+        (call-interactively #'comment-dwim)))
+    (beginning-of-line)
+    (if (looking-at "\\s-*$")
+       (delete-region (point) (point-at-eol))
+      (open-line 1))
+    (org-indent-line)
+    (insert "# ")))
 
 (defvar comment-empty-lines)           ; From newcomment.el.
 (defun org-comment-or-uncomment-region (beg end &rest ignore)
   "Comment or uncomment each non-blank line in the region.
 Uncomment each non-blank line between BEG and END if it only
 contains commented lines.  Otherwise, comment them."
-  (save-restriction
-    ;; Restrict region
-    (narrow-to-region (save-excursion (goto-char beg)
-                                     (skip-chars-forward " \r\t\n" end)
-                                     (line-beginning-position))
-                     (save-excursion (goto-char end)
-                                     (skip-chars-backward " \r\t\n" beg)
-                                     (line-end-position)))
-    (let ((uncommentp
-          ;; UNCOMMENTP is non-nil when every non blank line between
-          ;; BEG and END is a comment.
-          (save-excursion
-            (goto-char (point-min))
-            (while (and (not (eobp))
-                        (let ((element (org-element-at-point)))
-                          (and (eq (org-element-type element) 'comment)
-                               (goto-char (min (point-max)
-                                               (org-element-property
-                                                :end element)))))))
-            (eobp))))
-      (if uncommentp
-         ;; Only blank lines and comments in region: uncomment it.
-         (save-excursion
-           (goto-char (point-min))
-           (while (not (eobp))
-             (when (looking-at "[ \t]*\\(#\\(?: \\|$\\)\\)")
-               (replace-match "" nil nil nil 1))
-             (forward-line)))
-       ;; Comment each line in region.
-       (let ((min-indent (point-max)))
-         ;; First find the minimum indentation across all lines.
-         (save-excursion
-           (goto-char (point-min))
-           (while (and (not (eobp)) (not (zerop min-indent)))
-             (unless (looking-at "[ \t]*$")
-               (setq min-indent (min min-indent (current-indentation))))
-             (forward-line)))
-         ;; Then loop over all lines.
-         (save-excursion
-           (goto-char (point-min))
-           (while (not (eobp))
-             (unless (and (not comment-empty-lines) (looking-at "[ \t]*$"))
-               ;; Don't get fooled by invisible text (e.g. link path)
-               ;; when moving to column MIN-INDENT.
-               (let ((buffer-invisibility-spec nil))
-                 (org-move-to-column min-indent t))
-               (insert comment-start))
-             (forward-line))))))))
+  (let* ((pt (point-marker))
+        (head (and (org-in-src-block-p t)
+                   (require 'ob-core)
+                   (org-babel-where-is-src-block-head)))
+        (foot (and head
+                   (save-excursion
+                     (goto-char head)
+                     (looking-at org-babel-src-block-regexp)
+                     (goto-char (match-end 0))
+                     (point-at-bol)))))
+    (if (and head foot
+            (> beg head)
+            (< end foot))
+       (org-babel-do-in-edit-buffer
+        (call-interactively #'comment-dwim))
+      (save-restriction
+       ;; Restrict region
+       (narrow-to-region (save-excursion (goto-char beg)
+                                         (skip-chars-forward " \r\t\n" end)
+                                         (line-beginning-position))
+                         (save-excursion (goto-char end)
+                                         (skip-chars-backward " \r\t\n" beg)
+                                         (line-end-position)))
+       (let ((uncommentp
+              ;; UNCOMMENTP is non-nil when every non blank line between
+              ;; BEG and END is a comment.
+              (save-excursion
+                (goto-char (point-min))
+                (while (and (not (eobp))
+                            (let ((element (org-element-at-point)))
+                              (and (eq (org-element-type element) 'comment)
+                                   (goto-char (min (point-max)
+                                                   (org-element-property
+                                                    :end element)))))))
+                (eobp))))
+         (if uncommentp
+             ;; Only blank lines and comments in region: uncomment it.
+             (save-excursion
+               (goto-char (point-min))
+               (while (not (eobp))
+                 (when (looking-at "[ \t]*\\(#\\(?: \\|$\\)\\)")
+                   (replace-match "" nil nil nil 1))
+                 (forward-line)))
+           ;; Comment each line in region.
+           (let ((min-indent (point-max)))
+             ;; First find the minimum indentation across all lines.
+             (save-excursion
+               (goto-char (point-min))
+               (while (and (not (eobp)) (not (zerop min-indent)))
+                 (unless (looking-at "[ \t]*$")
+                   (setq min-indent (min min-indent (current-indentation))))
+                 (forward-line)))
+             ;; Then loop over all lines.
+             (save-excursion
+               (goto-char (point-min))
+               (while (not (eobp))
+                 (unless (and (not comment-empty-lines) (looking-at "[ \t]*$"))
+                   ;; Don't get fooled by invisible text (e.g. link path)
+                   ;; when moving to column MIN-INDENT.
+                   (let ((buffer-invisibility-spec nil))
+                     (org-move-to-column min-indent t))
+                   (insert comment-start))
+                 (forward-line))))))))))
 
 
 ;;; Planning
-- 
1.8.4.1