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.