bug#14170: 24.3; linum won't create all overlays after a folding

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Glenn Morris <rgm@gnu.org>,  14170@debbugs.gnu.org
> Date: Sat, 13 Apr 2013 21:21:22 -0400
> 
> >> > nlinum works correctly.
> >> This is the answer to most recent bug reports involving linum, as I
> >> recall. Will nlinum replace linum at some point?
> > Btw, if nlinum is our response to the problems in linum, then nlinum
> > should be a bit more friendly to bidirectional text, and determine
> > whether to put numbers on the left or right margin by looking at what
> > current-bidi-paragraph-direction returns.  (Yes, this means that if
> > some paragraphs are L2R and others R2L, some numbers will be on the
> > left, while others on the right.)
> 
> Patches welcome

Below.  (There's a missing feature in bidi display that causes the
numbers to be displayed backwards in R2L paragraphs; I will fix that
later.)

> but I don't think we need to worry a bout this w.r.t moving from
> linum.el to nlinum.el since linum.el doesn't support R2L paragraphs
> either.

Well, I hope you allow me to worry about that ;-)

=== modified file 'packages/nlinum/nlinum.el'
--- packages/nlinum/nlinum.el   2012-10-24 19:29:40 +0000
+++ packages/nlinum/nlinum.el   2013-04-14 06:09:13 +0000
@@ -35,7 +35,7 @@
 
 ;;;###autoload
 (define-minor-mode nlinum-mode
-  "Toggle display of line numbers in the left margin (Linum mode).
+  "Toggle display of line numbers in the margin (Linum mode).
 With a prefix argument ARG, enable Linum mode if ARG is positive,
 and disable it otherwise.  If called from Lisp, enable the mode
 if ARG is omitted or nil.
@@ -55,9 +55,21 @@ Linum mode is a buffer-local minor mode.
     (jit-lock-register #'nlinum--region t))
   (nlinum--setup-windows))
 
+(defvar margin-side nil)
 (defun nlinum--setup-window ()
-  (set-window-margins nil (if nlinum-mode nlinum--width)
-                      (cdr (window-margins))))
+  (cond ((eq bidi-paragraph-direction 'left-to-right)
+        (set-window-margins nil (if nlinum-mode nlinum--width)
+                            (cdr (window-margins)))
+        (setq-local margin-side 'left))
+       ((eq bidi-paragraph-direction 'right-to-left)
+        (set-window-margins nil (car (window-margins))
+                            (if nlinum-mode nlinum--width))
+        (setq-local margin-side 'right))
+       (t
+        (set-window-margins nil
+                            (if nlinum-mode nlinum--width)
+                            (if nlinum-mode nlinum--width))
+        (setq-local margin-side nil))))
 
 (defun nlinum--setup-windows ()
   (dolist (win (get-buffer-window-list nil nil t))
@@ -157,7 +169,14 @@ Linum mode is a buffer-local minor mode.
             (and (not (eobp)) (< (point) limit)
                  (let* ((ol (make-overlay (point) (1+ (point))))
                         (str (format fmt line))
-                        (width (string-width str)))
+                        (width (string-width str))
+                       (side
+                        (cond ((eq margin-side 'left) 'left-margin)
+                              ((eq margin-side 'right) 'right-margin)
+                              (t (if (eq (current-bidi-paragraph-direction)
+                                         'right-to-left)
+                                     'right-margin
+                                   'left-margin)))))
                    (when (< nlinum--width width)
                      (setq nlinum--width width)
                      (nlinum--new-width))
@@ -165,7 +184,7 @@ Linum mode is a buffer-local minor mode.
                    (overlay-put ol 'evaporate t)
                    (overlay-put ol 'before-string
                                 (propertize " " 'display
-                                            `((margin left-margin)
+                                            `((margin ,side)
                                               ,(propertize str
                                                            'face 'linum))))
                    ;; (setq nlinum--ol-counter (1- nlinum--ol-counter))