Use region cache to speedup bidi_find_paragraph_start.

* src/buffer.h (struct buffer): New member bidi_paragraph_cache.
Rename cache_long_line_scans to cache_long_scans.
* src/buffer.c (bset_cache_long_line_scans): Rename to
bset_cache_long_scans.
(Fget_buffer_create, Fmake_indirect_buffer, Fkill_buffer)
(Fbuffer_swap_text, init_buffer_once): Take bidi_paragraph_cache
into account.
(syms_of_buffer): Rename cache-long-line-scans to
cache-long-scans.  Adjust docstring.
* src/search.c (newline_cache_on_off):
* src/indent.c (width_run_cache_on_off): Adjust users.
* src/bidi.c (bidi_paragraph_cache_on_off): New function.
(bidi_find_paragraph_start): Use bidi_paragraph_cache if needed.
* src/insdel.c (prepare_to_modify_buffer): Invalidate
bidi_paragraph_cache if enabled.
* doc/lispref/positions.texi (Motion by Screen Lines):
* doc/lispref/display.texi (Truncation): Rename `cache-long-line-scans'
to `cache-long-scans'.

1 files changed, 7 insertions, 4 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 646f8f72232..221db39329a 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -632,9 +632,9 @@ struct buffer
   /* List of symbols naming the file format used for auto-save file.  */
   Lisp_Object INTERNAL_FIELD (auto_save_file_format);
 
-  /* True if the newline position cache and width run cache are
-     enabled.  See search.c and indent.c.  */
-  Lisp_Object INTERNAL_FIELD (cache_long_line_scans);
+  /* True if the newline position cache, width run cache and BIDI paragraph
+     cache are enabled.  See search.c, indent.c and bidi.c for details.  */
+  Lisp_Object INTERNAL_FIELD (cache_long_scans);
 
   /* If the width run cache is enabled, this table contains the
      character widths width_run_cache (see above) assumes.  When we
@@ -839,9 +839,12 @@ struct buffer
      the character's width; if it maps a character to zero, we don't
      know what its width is.  This allows compute_motion to process
      such regions very quickly, using algebra instead of inspecting
-     each character.   See also width_table, below.  */
+     each character.   See also width_table, below.
+
+     The latter cache is used to speedup bidi_find_paragraph_start.  */
   struct region_cache *newline_cache;
   struct region_cache *width_run_cache;
+  struct region_cache *bidi_paragraph_cache;
 
   /* Non-zero means don't use redisplay optimizations for
      displaying this buffer.  */