Retrospective commit from 2009-12-26.

Redesign handle_stop_backwards.
Fix character mirroring for non-ASCII characters.

 xdisp.c (handle_stop_backwards): Call compute_stop_pos in the
 loop, instead of calling handle_stop.  Call handle_stop only once,
 after the loop.
 (next_element_from_buffer): Don't call handle_stop_backwards if at
 stop position.  If base_level_stop is zero, set it to 1.

 term.c (append_glyph): Fill resolved_level and bidi_type slots
 of struct glyph for unidirectional display.

 xdisp.c (set_cursor_from_row): Handle zero-width characters.

 bidi.c (bidi_mirror_char): More efficient code (suggested by
 Ehud Karni <ehud@unix.mvs.co.il>).  Don't even try to mirror
 non-ASCII characters.

5 files changed, 61 insertions, 23 deletions

diff --git a/src/.gdbinit b/src/.gdbinit
index 61e3da6c68c..a500f2532f5 100644
--- a/src/.gdbinit
+++ b/src/.gdbinit
@@ -448,6 +448,9 @@ Pretty print window structure w.
 end
 
 define pbiditype
+  if ($arg0 == 0)
+    printf "UNDEF"
+  end
   if ($arg0 == 1)
     printf "L"
   end
@@ -466,7 +469,7 @@ define pbiditype
   if ($arg0 == 6)
     printf "B"
   end
-  if ($arg0 < 1 || $arg0 > 6)
+  if ($arg0 < 0 || $arg0 > 6)
     printf "%d??", $arg0
   end
 end
diff --git a/src/ChangeLog.bidi b/src/ChangeLog.bidi
index b9fb7457cfd..7e11c6ec024 100644
--- a/src/ChangeLog.bidi
+++ b/src/ChangeLog.bidi
@@ -1,3 +1,20 @@
+2009-12-26  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (handle_stop_backwards): Call compute_stop_pos in the
+        loop, instead of calling handle_stop.  Call handle_stop only once,
+        after the loop.
+        (next_element_from_buffer): Don't call handle_stop_backwards if at
+        stop position.  If base_level_stop is zero, set it to 1.
+
+        * term.c (append_glyph): Fill resolved_level and bidi_type slots
+        of struct glyph for unidirectional display.
+
+        * xdisp.c (set_cursor_from_row): Handle zero-width characters.
+
+        * bidi.c (bidi_mirror_char): More efficient code (suggested by
+        Ehud Karni <ehud@unix.mvs.co.il>).  Don't even try to mirror
+        non-ASCII characters.
+
 2009-12-19  Eli Zaretskii  <eliz@gnu.org>
 
         * buffer.c (Fbuffer_swap_text): Swap the values of
diff --git a/src/bidi.c b/src/bidi.c
index d18629279d6..5abb4ca9f43 100644
--- a/src/bidi.c
+++ b/src/bidi.c
@@ -509,16 +509,13 @@ int
 bidi_mirror_char (int c)
 {
   static const char mirrored_pairs[] = "()<>[]{}";
-  const char *p = strchr (mirrored_pairs, c);
+  const char *p = c > 0 && c < 128 ? strchr (mirrored_pairs, c) : NULL;
 
   if (p)
     {
       size_t i = p - mirrored_pairs;
 
-      if ((i & 1) == 0)
-        return mirrored_pairs[i + 1];
-      else
-        return mirrored_pairs[i - 1];
+      return mirrored_pairs [(i ^ 1)];
     }
   return c;
 }
diff --git a/src/term.c b/src/term.c
index 7c9e05f36b2..51bf7a4aeb7 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1579,8 +1579,15 @@ append_glyph (it)
       if (it->bidi_p)
         {
           glyph->resolved_level = it->bidi_it.resolved_level;
+          if ((it->bidi_it.type & 7) != it->bidi_it.type)
+            abort ();
           glyph->bidi_type = it->bidi_it.type;
         }
+      else
+        {
+          glyph->resolved_level = 0;
+          glyph->bidi_type = UNKNOWN_BT;
+        }
 
       ++it->glyph_row->used[it->area];
       ++glyph;
diff --git a/src/xdisp.c b/src/xdisp.c
index ddd18d502a0..b18b0e04be2 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -6549,8 +6549,8 @@ next_element_from_stretch (it)
 }
 
 /* Scan forward from CHARPOS in the current buffer, until we find a
-   stop position > current IT's position, handling all the stop
-   positions in between.
+   stop position > current IT's position.  Then handle the stop
+   position before that.
 
    This is called when we are reordering bidirectional text.  The
    caller should save and restore IT and in particular the bidi_p
@@ -6563,6 +6563,7 @@ handle_stop_backwards (it, charpos)
 {
   struct text_pos pos1;
   EMACS_INT where_we_are = IT_CHARPOS (*it);
+  EMACS_INT next_stop;
 
   /* Scan in strict logical order.  */
   it->bidi_p = 0;
@@ -6571,12 +6572,18 @@ handle_stop_backwards (it, charpos)
       it->prev_stop = charpos;
       SET_TEXT_POS (pos1, charpos, CHAR_TO_BYTE (charpos));
       reseat_1 (it, pos1, 0);
-      handle_stop (it);
+      compute_stop_pos (it);
       /* We must advance forward, right?  */
       if (it->stop_charpos <= it->prev_stop)
         abort ();
+      charpos = it->stop_charpos;
     }
-  while (it->stop_charpos <= where_we_are);
+  while (charpos <= where_we_are);
+
+  next_stop = it->stop_charpos;
+  it->stop_charpos = it->prev_stop;
+  handle_stop (it);
+  it->stop_charpos = next_stop;
 }
 
 /* Load IT with the next display element from current_buffer.  Value
@@ -6668,26 +6675,31 @@ next_element_from_buffer (it)
               success_p = 0;
             }
         }
-      else if (it->bidi_p && !BIDI_AT_BASE_LEVEL (it->bidi_it))
+      else if (!(!it->bidi_p
+                 || BIDI_AT_BASE_LEVEL (it->bidi_it)
+                 || IT_CHARPOS (*it) == it->stop_charpos))
         {
           /* With bidi non-linear iteration, we could find ourselves
              far beyond the last computed stop_charpos, with several
              other stop positions in between that we missed.  Scan
-             them all now, in buffer's logical order.  */
+             them all now, in buffer's logical order, until we find
+             and handle the last stop_charpos that precedes our
+             current position.  */
           struct it save_it = *it;
 
           handle_stop_backwards (it, it->stop_charpos);
-          save_it.stop_charpos = it->stop_charpos;
-          save_it.prev_stop = it->prev_stop;
-          *it = save_it;
+          it->bidi_p = 1;
+          it->current = save_it.current;
+          it->position = save_it.position;
           return GET_NEXT_DISPLAY_ELEMENT (it);
         }
       else
         {
+          /* If we are at base paragraph embedding level, take note of
+             the last stop position seen at this level.  */
+          if (BIDI_AT_BASE_LEVEL (it->bidi_it))
+            it->base_level_stop = it->stop_charpos;
           handle_stop (it);
-          /* We are at base paragraph embedding level, so take note of
-             the last stop_pos seen at this level.  */
-          it->base_level_stop = it->stop_charpos;
           return GET_NEXT_DISPLAY_ELEMENT (it);
         }
     }
@@ -6696,15 +6708,15 @@ next_element_from_buffer (it)
       struct it save_it = *it;
 
       if (it->base_level_stop <= 0)
-        abort ();
+        it->base_level_stop = 1;
       if (IT_CHARPOS (*it) < it->base_level_stop)
         abort ();
       if (BIDI_AT_BASE_LEVEL (it->bidi_it))
         abort ();
       handle_stop_backwards (it, it->base_level_stop);
-      save_it.stop_charpos = it->stop_charpos;
-      save_it.prev_stop = it->prev_stop;
-      *it = save_it;
+      it->bidi_p = 1;
+      it->current = save_it.current;
+      it->position = save_it.position;
       return GET_NEXT_DISPLAY_ELEMENT (it);
     }
   else
@@ -12771,7 +12783,9 @@ set_cursor_from_row (w, row, matrix, delta, delta_bytes, dy, dvpos)
               glyph--;
             }
         }
-      else if (match_with_avoid_cursor)
+      else if (match_with_avoid_cursor
+               /* zero-width characters produce no glyphs */
+               || eabs (glyph_after - glyph_before) == 1)
         {
           cursor = glyph_after;
           x = -1;