Attempt to refactor two "duplicate" functions.

Attempt to extract a generic function `prelude-get-positions-of-line-or-region` from `prelude-duplicate-current-line-or-region` and `prelude-duplicate-and-comment-current-line-or-region`

core/prelude-core.el

@@ -198,50 +198,51 @@ point reaches the beginning or end of the buffer, stop there."
       (kill-new filename)
       (message "Copied buffer file name '%s' to the clipboard." filename))))
 
-(defun prelude-duplicate-current-line-or-region (arg)
-  "Duplicates 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)))
+(defun prelude-get-positions-of-line-or-region ()
+  "Return positions (beg . end) of the current line
+or region."
+  (let (beg end)
     (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)))
-      (-dotimes arg
-                (lambda (n)
-                  (goto-char end)
-                  (newline)
-                  (insert region)
-                  (setq end (point))))
-      (goto-char (+ origin (* (length region) arg) arg)))))
-
-;; TODO: Remove code duplication by extracting something more generic
+    (cons beg end)))
+
+(defun prelude-duplicate-current-line-or-region (arg)
+  "Duplicates 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")
+  (pcase-let* ((origin (point))
+               (`(,beg . ,end) (prelude-get-positions-of-line-or-region))
+               (region (buffer-substring-no-properties beg end)))
+    (-dotimes arg
+      (lambda (n)
+        (goto-char end)
+        (newline)
+        (insert region)
+        (setq end (point))))
+    (goto-char (+ origin (* (length region) arg) arg))))
+
 (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))
+  (pcase-let* ((origin (point))
+               (`(,beg . ,end) (prelude-get-positions-of-line-or-region))
+               (region (buffer-substring-no-properties beg end)))
+    (comment-or-uncomment-region beg end)
     (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)))))
+    (-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."