bug#22873: Can we support multiple Cursors?

[Eli Zaretskii]

> Date: Tue, 08 Mar 2016 22:27:02 -0800
> From: Keith David Bershatsky <esq@lawlist.com>
> Cc: 22873@debbugs.gnu.org
> 
> The second draft of the proposed feature for multiple fake cursors is 
> attached.  For the record, I'm not a programmer -- just a hobbyist -- and the 
> draft patch is not meant to be a proposed official patch -- it is just a 
> working proof concept.  The patch contains a few extra things that I use for 
> debugging and also for drawing my solid vertical line that tracks the cursor 
> position.  It has been tested to some extent on Emacs built for OSX 10.6.8 
> and Windows XP (SP-3).  Different colors for each fake cursor have already 
> been implemented on Emacs for OSX, but I haven't yet looked into how to 
> accomplish that objective on Emacs for Windows.  The draft concept patch is 
> for the master branch as of March 8, 2016 bearing commit 
> "e0400b72a24d67b53f71c8b97915cae599e36c37".  After applying the patch, the 
> new feature can be tested as follows:

Looks like quite a few of the changes in the patch are not really
related to multiple cursors.  Did you produce diffs for all of your
other local changes?

> diff --git a/src/buffer.h b/src/buffer.h
> index 5783bfb..01c3755 100644
> --- a/src/buffer.h
> +++ b/src/buffer.h
> @@ -643,6 +643,15 @@ struct buffer
>       cache are enabled.  See search.c, indent.c and bidi.c for details.  */
>    Lisp_Object cache_long_scans_;
>  
> +  /* The name of the hook.  */
> +  Lisp_Object window_start_end_hook_;
> +
> +  /* The name of list.  */
> +  Lisp_Object posn_list_;
> +
> +  /* The name of list used by multiple cursors for next redisplay.  */
> +  Lisp_Object mc_list_;
> +
>    /* If the width run cache is enabled, this table contains the
>       character widths width_run_cache (see above) assumes.  When we
>       do a thorough redisplay, we compare this against the buffer's
> @@ -885,6 +894,21 @@ struct buffer
>     buffer.  (Some setters that are private to a single .c file are
>     defined as static in those files.)  */
>  INLINE void
> +bset_window_start_end_hook (struct buffer *b, Lisp_Object val)
> +{
> +  b->window_start_end_hook_ = val;
> +}

The above inline function and the corresponding member of struct
buffer seems unrelated.

> diff --git a/src/keyboard.c b/src/keyboard.c
> index 4e1ac15..329cba0 100644
> --- a/src/keyboard.c
> +++ b/src/keyboard.c
> @@ -1244,6 +1244,15 @@ static int read_key_sequence (Lisp_Object *, int, 
> Lisp_Object,
>                                bool, bool, bool, bool);
>  static void adjust_point_for_property (ptrdiff_t, bool);
>  
> +static void
> +set_window_start_end_hook (void)
> +{
> +  Lisp_Object window = (selected_window);
> +  struct window *w = decode_live_window (window);
> +  w->window_start_end_hook_force = true;
> +  w->window_start_end_hook_pending = true;
> +}
> +
>  Lisp_Object
>  command_loop_1 (void)
>  {
> @@ -1269,6 +1278,8 @@ command_loop_1 (void)
>        if (!NILP (Vpost_command_hook) && !NILP (Vrun_hooks))
>       safe_run_hooks (Qpost_command_hook);
>  
> +      set_window_start_end_hook ();
> +
>        /* If displaying a message, resize the echo area window to fit
>        that message's size exactly.  */
>        if (!NILP (echo_area_buffer[0]))
> @@ -1485,6 +1496,8 @@ command_loop_1 (void)
>  
>        safe_run_hooks (Qpost_command_hook);
>  
> +      set_window_start_end_hook ();
> +
>        /* If displaying a message, resize the echo area window to fit
>        that message's size exactly.  */
>        if (!NILP (echo_area_buffer[0]))

Likewise.

> diff --git a/src/xdisp.c b/src/xdisp.c
> index 5b96144..102ac23 100644
> --- a/src/xdisp.c
> +++ b/src/xdisp.c
> @@ -13414,6 +13414,93 @@ do { if (! polling_stopped_here) stop_polling ();    
> \
>  do { if (polling_stopped_here) start_polling ();     \
>         polling_stopped_here = false; } while (false)
>  
> +static void
> +run_window_start_end_hook (Lisp_Object window, struct text_pos startp, 
> EMACS_INT posint, struct it it, char *string, bool force)
> +{

Likewise.

> +    case 'w':
> +      {
> +  ptrdiff_t window_start = marker_position (w->start);
> +  pint2str (decode_mode_spec_buf, width, window_start);
> +  return decode_mode_spec_buf;
> +      }
> +
> +    case 'W':
> +      {
> +  ptrdiff_t window_end = BUF_Z (b) - w->window_end_pos;
> +  pint2str (decode_mode_spec_buf, width, window_end);
> +  return decode_mode_spec_buf;
> +      }
> +

Likewise.

> +static const char *
> +internal_line_number_at_position (struct window *w, register int c, int 
> field_width, Lisp_Object *string)
> +{

Likewise.

> +DEFUN ("line-number-at-position", Fline_number_at_position, 
> Sline_number_at_position, 1, 2, 0,
> +       doc: /* Return line number at position.  */)
> +  (Lisp_Object window, Lisp_Object pos)
> +{

Likewise.

Thanks.