Add prelude-duplicate-and-comment-current-line-or-region (fixes #348)

README.md

@@ -227,6 +227,7 @@ Keybinding         | Description
 <kbd>C-c e</kbd> | Eval a bit of Emacs Lisp code and replace it with its result.
 <kbd>C-c s</kbd> | Swap two active windows.
 <kbd>C-c d</kbd> | Duplicate the current line (or region).
+<kbd>C-c M-d</kbd> | Duplicate and comment the current line (or region).
 <kbd>C-c r</kbd> | Rename the currently visited file and buffer.
 <kbd>C-c t</kbd> | Open a terminal emulator (`ansi-term`).
 <kbd>C-c k</kbd> | Kill all open buffers except the one you're currently in.

core/prelude-core.el

@@ -222,6 +222,30 @@ there's a region, all lines that region covers will be duplicated."
                   (setq end (point))))
       (goto-char (+ origin (* (length region) arg) arg)))))
 
+;; TODO: Remove code duplication by extracting something more generic
+(defun prelude-duplicate-and-comment-current-line-or-region (arg)
+  "Duplicates and comments the current line or region ARG times.
+If there's no region, the current line will be duplicated.  However, if
+there's a region, all lines that region covers will be duplicated."
+  (interactive "p")
+  (let (beg end (origin (point)))
+    (if (and mark-active (> (point) (mark)))
+        (exchange-point-and-mark))
+    (setq beg (line-beginning-position))
+    (if mark-active
+        (exchange-point-and-mark))
+    (setq end (line-end-position))
+    (let ((region (buffer-substring-no-properties beg end)))
+      (comment-or-uncomment-region beg end)
+      (setq end (line-end-position))
+      (-dotimes arg
+                (lambda (n)
+                  (goto-char end)
+                  (newline)
+                  (insert region)
+                  (setq end (point))))
+      (goto-char (+ origin (* (length region) arg) arg)))))
+
 (defun prelude-rename-file-and-buffer ()
   "Renames current buffer and file it is visiting."
   (interactive)

core/prelude-mode.el

@@ -54,6 +54,7 @@
     (define-key map (kbd "C-c s") 'prelude-swap-windows)
     (define-key map (kbd "C-c D") 'prelude-delete-file-and-buffer)
     (define-key map (kbd "C-c d") 'prelude-duplicate-current-line-or-region)
+    (define-key map (kbd "C-c M-d") 'prelude-duplicate-and-comment-current-line-or-region)
     (define-key map (kbd "C-c r") 'prelude-rename-file-and-buffer)
     (define-key map (kbd "C-c t") 'prelude-visit-term-buffer)
     (define-key map (kbd "C-c k") 'prelude-kill-other-buffers)