Implement visual-order cursor motion.

 src/xdisp.c (Fmove_point_visually): New function.

 lisp/bindings.el (visual-order-cursor-movement): New defcustom.
 (right-char, left-char): Provide visual-order cursor motion by
 calling move-point-visually.  Update the doc strings.

 doc/emacs/basic.texi (Moving Point): Document visual-order-cursor-movement
 and its effect on right-char and left-char.

 doc/lispref/display.texi (Bidirectional Display): Document move-point-visually.

 etc/NEWS: Document the new feature.

2 files changed, 52 insertions, 12 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 826f270d8f8..1e1fff6fc25 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2013-06-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * bindings.el (visual-order-cursor-movement): New defcustom.
+        (right-char, left-char): Provide visual-order cursor motion by
+        calling move-point-visually.  Update the doc strings.
+
 2013-06-28  Kenichi Handa  <handa@gnu.org>
 
         * international/mule.el (define-coding-system): New coding system
diff --git a/lisp/bindings.el b/lisp/bindings.el
index 2013c079820..7c42cc6c0a8 100644
--- a/lisp/bindings.el
+++ b/lisp/bindings.el
@@ -696,29 +696,63 @@ language you are using."
 (put 'narrow-to-region 'disabled t)
 
 ;; Moving with arrows in bidi-sensitive direction.
+(defcustom visual-order-cursor-movement nil
+  "If non-nil, moving cursor with arrow keys follows the visual order.
+
+When this is non-nil, \\[right-char] will move to the character that is
+to the right of point on display, and \\[left-char] will move to the left,
+disregarding the surrounding bidirectional context.  Depending on the
+bidirectional context of the surrounding characters, this can move point
+many buffer positions away.
+
+When the text is entirely left-to-right, logical-order and visual-order
+cursor movements produce identical results."
+  :type '(choice (const :tag "Logical-order cursor movement" nil)
+                 (const :tag "Visual-order cursor movement" t))
+  :group 'display
+  :version "24.5")
+
 (defun right-char (&optional n)
   "Move point N characters to the right (to the left if N is negative).
 On reaching beginning or end of buffer, stop and signal error.
 
-Depending on the bidirectional context, this may move either forward
-or backward in the buffer.  This is in contrast with \\[forward-char]
-and \\[backward-char], which see."
+If `visual-order-cursor-movement' is non-nil, this always moves
+to the right on display, wherever that is in the buffer.
+Otherwise, depending on the bidirectional context, this may move
+one position either forward or backward in the buffer.  This is
+in contrast with \\[forward-char] and \\[backward-char], which
+see."
   (interactive "^p")
-  (if (eq (current-bidi-paragraph-direction) 'left-to-right)
-      (forward-char n)
-    (backward-char n)))
+  (if visual-order-cursor-movement
+      (dotimes (i (if (numberp n) (abs n) 1))
+        (if (< n 0)
+            (move-point-visually -1)
+          (move-point-visually 1))
+        (sit-for 0))
+    (if (eq (current-bidi-paragraph-direction) 'left-to-right)
+        (forward-char n)
+      (backward-char n))))
 
 (defun left-char ( &optional n)
   "Move point N characters to the left (to the right if N is negative).
 On reaching beginning or end of buffer, stop and signal error.
 
-Depending on the bidirectional context, this may move either backward
-or forward in the buffer.  This is in contrast with \\[backward-char]
-and \\[forward-char], which see."
+If `visual-order-cursor-movement' is non-nil, this always moves
+to the left on display, wherever that is in the buffer.
+Otherwise, depending on the bidirectional context, this may move
+one position either backward or forward in the buffer.  This is
+in contrast with \\[forward-char] and \\[backward-char], which
+see."
   (interactive "^p")
-  (if (eq (current-bidi-paragraph-direction) 'left-to-right)
-      (backward-char n)
-    (forward-char n)))
+  (if visual-order-cursor-movement
+      (dotimes (i (if (numberp n) (abs n) 1))
+        (if (< n 0)
+            (move-point-visually 1)
+          (move-point-visually -1))
+        (sit-for 0))
+    (if (eq (current-bidi-paragraph-direction) 'left-to-right)
+        (backward-char n)
+      (forward-char n))))
 
 (defun right-word (&optional n)
   "Move point N words to the right (to the left if N is negative).