Retrospective commit from 2009-10-05.

Continue working on paragraph base direction.
Support per-buffer default paragraph direction.

 buffer.h (struct buffer): New member paragraph_direction.
 buffer.c (init_buffer_once): Initialize it.
 (syms_of_buffer): Declare Lisp variables
 default-paragraph-direction and paragraph-direction.
 dispextern.h (struct it): New member paragraph_embedding.
 xdisp.c (init_iterator): Initialize it from the buffer's value
 of paragraph-direction.
 <Qright_to_left, Qleft_to_right>: New variables.
 (syms_of_xdisp): Initialize and staticpro them.
 (set_iterator_to_next, next_element_from_buffer): Use the value of
 paragraph_embedding to determine the paragraph direction.
 bidi.c (bidi_line_init): Fix second argument to
 bidi_set_sor_type.
 (bidi_init_it): Initialize paragraph_dir to NEUTRAL_DIR.
 (bidi_get_next_char_visually): Record the last character of the
 separator in separator_limit, not the character after that.
 (bidi_find_paragraph_start): Accept character and byte positions
 instead of the whole iterator stricture.  All callers changed.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 2930465834d..8484abcdbb5 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5188,6 +5188,7 @@ init_buffer_once ()
   buffer_defaults.ctl_arrow = Qt;
   buffer_defaults.bidi_display_reordering = Qnil;
   buffer_defaults.direction_reversed = Qnil;
+  buffer_defaults.paragraph_direction = Qnil;
   buffer_defaults.cursor_type = Qt;
   buffer_defaults.extra_line_spacing = Qnil;
   buffer_defaults.cursor_in_non_selected_windows = Qt;
@@ -5274,6 +5275,7 @@ init_buffer_once ()
   XSETFASTINT (buffer_local_flags.category_table, idx); ++idx;
   XSETFASTINT (buffer_local_flags.bidi_display_reordering, idx); ++idx;
   XSETFASTINT (buffer_local_flags.direction_reversed, idx); ++idx;
+  XSETFASTINT (buffer_local_flags.paragraph_direction, idx); ++idx;
   XSETFASTINT (buffer_local_flags.buffer_file_coding_system, idx);
   /* Make this one a permanent local.  */
   buffer_permanent_local_flags[idx++] = 1;
@@ -5545,6 +5547,11 @@ This is the same as (default-value 'direction-reversed).  */);
                      doc: /* *Default value of `enable-multibyte-characters' for buffers not overriding it.
 This is the same as (default-value 'enable-multibyte-characters).  */);
 
+  DEFVAR_LISP_NOPRO ("default-paragraph-direction",
+                     &buffer_defaults.paragraph_direction,
+                     doc: /* Default value of `paragraph-direction' for buffers that do not override it.
+This is the same as (default-value 'paragraph-direction).  */);
+
   DEFVAR_LISP_NOPRO ("default-buffer-file-coding-system",
                      &buffer_defaults.buffer_file_coding_system,
                      doc: /* Default value of `buffer-file-coding-system' for buffers not overriding it.
@@ -5806,6 +5813,18 @@ See also the variable `bidi-display-reordering'.  */);
                      doc: /*Non-nil means reorder bidirectional text for display in the visual order.
 See also the variable `direction-reversed'.  */);
 
+  DEFVAR_PER_BUFFER ("paragraph-direction",
+                     &current_buffer->paragraph_direction, Qnil,
+                     doc: /* *If non-nil, forces directionality of text paragraphs in the buffer.
+                             
+If this is nil (the default), the direction of each paragraph is
+determined by the first strong directional character of its text.
+The values of `right-to-left' and `left-to-right' override that.
+Any other value is treated as nil.
+                             
+This variable has no effect unless the buffer's value of
+\`bidi-display-reordering' is non-nil.  */);
+
  DEFVAR_PER_BUFFER ("truncate-lines", &current_buffer->truncate_lines, Qnil,
                      doc: /* *Non-nil means do not display continuation lines.
 Instead, give each line of text just one screen line.