Add code to initialize bidi iterator for displaying strings.

For now, ifdef'ed away.  Some more testing.

 src/bidi.c (bidi_level_of_next_char): Allow the sentinel "position"
 to pass the test for valid cached positions.
 src/xdisp.c (init_iterator): Call bidi_init_it only of a valid
 buffer position was specified.  Initialize paragraph_embedding to L2R.
 (reseat_to_string): Initialize the bidi iterator (for now ifdef'ed out).
 (display_string): If we need to ignore text properties of
 LISP_STRING, set IT->stop_charpos to IT->end_charpos.  (The
 original value of -1 will not work with bidi.)
 src/dispextern.h (struct bidi_string_data): New member lstring.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/bidi.c b/src/bidi.c
index ac950a9000a..a0a57b4c681 100644
--- a/src/bidi.c
+++ b/src/bidi.c
@@ -1679,7 +1679,11 @@ bidi_level_of_next_char (struct bidi_it *bidi_it)
 	    abort ();
 	  next_char_pos = bidi_it->charpos + bidi_it->nchars;
 	}
-      else if (bidi_it->charpos > (bidi_it->string.s ? 0 : 1))
+      else if (bidi_it->charpos >= (bidi_it->string.s ? 0 : 1))
+	/* Implementation note: we allow next_char_pos to be as low as
+	   0 for buffers or -1 for strings, and that is okay because
+	   that's the "position" of the sentinel iterator state we
+	   cached at the beginning of the iteration.  */
 	next_char_pos = bidi_it->charpos - 1;
       if (next_char_pos >= 0)
 	type = bidi_cache_find (next_char_pos, -1, bidi_it);