Support bidi reordering of text covered by display properties.

 src/bidi.c (bidi_copy_it): Use offsetof instead of emulating it.
 (bidi_fetch_char, bidi_fetch_char_advance): New functions.
 (bidi_cache_search, bidi_cache_iterator_state)
 (bidi_paragraph_init, bidi_resolve_explicit, bidi_resolve_weak)
 (bidi_level_of_next_char, bidi_move_to_visually_next): Support
 character positions inside a run of characters covered by a
 display string.
 (bidi_paragraph_init, bidi_resolve_explicit_1)
 (bidi_level_of_next_char): Call bidi_fetch_char and
 bidi_fetch_char_advance instead of FETCH_CHAR and
 FETCH_CHAR_ADVANCE.
 (bidi_init_it): Initialize new members.
 (LRE_CHAR, RLE_CHAR, PDF_CHAR, LRO_CHAR, RLO_CHAR): Remove macro
 definitions.
 (bidi_explicit_dir_char): Lookup character type in bidi_type_table,
 instead of using explicit *_CHAR codes.
 (bidi_resolve_explicit, bidi_resolve_weak): Use
 FETCH_MULTIBYTE_CHAR instead of FETCH_CHAR, as reordering of
 bidirectional text is supported only in multibyte buffers.
 (bidi_init_it): Accept additional argument FRAME_WINDOW_P and use
 it to initialize the frame_window_p member of struct bidi_it.
 (bidi_cache_iterator_state, bidi_resolve_explicit_1)
 (bidi_resolve_explicit, bidi_resolve_weak)
 (bidi_level_of_next_char, bidi_move_to_visually_next): Abort if
 bidi_it->nchars is non-positive.
 (bidi_level_of_next_char): Don't try to lookup the cache for the
 next/previous character if nothing is cached there yet, or if we
 were just reseat()'ed to a new position.
 src/xdisp.c (set_cursor_from_row): Set start and stop points
 according to the row's direction when priming the loop that looks
 for the glyph on which to display cursor.
 (single_display_spec_intangible_p): Function deleted.
 (display_prop_intangible_p): Reimplement to call
 handle_display_spec instead of single_display_spec_intangible_p.
 Accept 3 additional arguments needed by handle_display_spec.  This
 fixes incorrect cursor motion across display property with complex
 values: lists, `(when COND...)' forms, etc.
 (single_display_spec_string_p): Support property values that are
 lists with the argument STRING its top-level element.
 (display_prop_string_p): Fix the condition for processing a
 property that is a list to be consistent with handle_display_spec.
 (handle_display_spec): New function, refactored from the
 last portion of handle_display_prop.
 (compute_display_string_pos): Accept additional argument
 FRAME_WINDOW_P.  Call handle_display_spec to determine whether the
 value of a `display' property is a "replacing spec".
 (handle_single_display_spec): Accept 2 additional arguments BUFPOS
 and FRAME_WINDOW_P.  If IT is NULL, don't set up the iterator from
 the display property, but just return a value indicating whether
 the display property will replace the characters it covers.
 (Fcurrent_bidi_paragraph_direction): Initialize the nchars and
 frame_window_p members of struct bidi_it.
 (compute_display_string_pos, compute_display_string_end): New
 functions.
 (push_it): Accept second argument POSITION, where pop_it should
 jump to continue iteration.
 (reseat_1): Initialize bidi_it.disp_pos.
 src/keyboard.c (adjust_point_for_property): Adjust the call to
 display_prop_intangible_p to its new signature.
 src/dispextern.h (struct bidi_it): New member frame_window_p.
 (bidi_init_it): Update prototypes.
 (display_prop_intangible_p): Update prototype.
 (compute_display_string_pos, compute_display_string_end): Declare
 prototypes.
 (struct bidi_it): New members nchars and disp_pos.  ch_len is now
 EMACS_INT.

1 files changed, 13 insertions, 5 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index e612a8b1eba..15e44e0286e 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1816,12 +1816,16 @@ struct bidi_stack {
   bidi_dir_t override;
 };
 
-/* Data type for iterating over bidi text.  */
+/* Data type for reordering bidirectional text.  */
 struct bidi_it {
   EMACS_INT bytepos;		/* iterator's position in buffer */
   EMACS_INT charpos;
-  int ch;			/* character itself */
-  int ch_len;			/* length of its multibyte sequence */
+  int ch;			/* character at that position, or u+FFFC
+				   ("object replacement character") for a run
+				   of characters covered by a display string */
+  EMACS_INT nchars;		/* its "length", usually 1; it's > 1 for a run
+				   of characters covered by a display string */
+  EMACS_INT ch_len;		/* its length in bytes */
   bidi_type_t type;		/* bidi type of this character, after
 				   resolving weak and neutral types */
   bidi_type_t type_after_w1;	/* original type, after overrides and W1 */
@@ -1847,7 +1851,9 @@ struct bidi_it {
   int first_elt;		/* if non-zero, examine current char first */
   bidi_dir_t paragraph_dir;	/* current paragraph direction */
   int new_paragraph;		/* if non-zero, we expect a new paragraph */
+  int frame_window_p;		/* non-zero if displaying on a GUI frame */
   EMACS_INT separator_limit;	/* where paragraph separator should end */
+  EMACS_INT disp_pos;		/* position of display string after ch */
 };
 
 /* Value is non-zero when the bidi iterator is at base paragraph
@@ -2944,7 +2950,7 @@ enum tool_bar_item_image
 
 /* Defined in bidi.c */
 
-extern void bidi_init_it (EMACS_INT, EMACS_INT, struct bidi_it *);
+extern void bidi_init_it (EMACS_INT, EMACS_INT, int, struct bidi_it *);
 extern void bidi_move_to_visually_next (struct bidi_it *);
 extern void bidi_paragraph_init (bidi_dir_t, struct bidi_it *, int);
 extern int  bidi_mirror_char (int);
@@ -2955,7 +2961,7 @@ struct glyph_row *row_containing_pos (struct window *, EMACS_INT,
                                       struct glyph_row *,
                                       struct glyph_row *, int);
 int line_bottom_y (struct it *);
-int display_prop_intangible_p (Lisp_Object);
+int display_prop_intangible_p (Lisp_Object, Lisp_Object, EMACS_INT, EMACS_INT);
 void resize_echo_area_exactly (void);
 int resize_mini_window (struct window *, int);
 #if defined USE_TOOLKIT_SCROLL_BARS && !defined USE_GTK
@@ -3005,6 +3011,8 @@ extern void reseat_at_previous_visible_line_start (struct it *);
 extern Lisp_Object lookup_glyphless_char_display (int, struct it *);
 extern int calc_pixel_width_or_height (double *, struct it *, Lisp_Object,
                                        struct font *, int, int *);
+extern EMACS_INT compute_display_string_pos (EMACS_INT, int);
+extern EMACS_INT compute_display_string_end (EMACS_INT);
 
 #ifdef HAVE_WINDOW_SYSTEM