Re: Buffer listing in multiple frames/ttys

[Károly Lőrentey]

Juri Linkov <address@hidden> writes:
>> I note that `bury-buffer' removes the buffer from the frame-local
>> buffer lists of all frames, not just the selected one.  This is an
>> unwanted side-effect in this case, as we want the effects of
>> `next-buffer' to remain frame-local.  I propose to add an optional
>> parameter to `bury-buffer' to support this.
>
> I think this change should be made for all invocations of
> `bury-buffer', not only from `next-buffer'. [...] And so there is no
> need for a new optional parameter.

That's fine by me.

> Also I think recoding a buffer to the new frame parameter should be
> made in `bury-buffer' instead of `next-buffer'.    Some commands call 
> `bury-buffer'
> directly, and it would be good to record their buffers in the
> frame-local parameter.

Ah, good idea.  I implemented this in the patch at the end of this
message.  It involves adding a new element to the frame struct, and
changing switch-to-buffer, bury-buffer and kill-buffer etc. to
maintain the list.

> Instead of introducing a new frame parameter `previous-buffer-list'
> what do you think about reusing the existing frame parameter `buffer-list'?
> It could have a special marker delimiting a list of frame's "next" visited
> buffers and "previous" visited buffers.  A nil value could serve as
> such special marker.  So for example, (frame-parameter nil 'buffer-list)
> could contain:
>
> (#<buffer *b+1*> #<buffer *b+2*> nil #<buffer *b-2*> #<buffer *b-1*>)

I thought of this as well, but it would be an incompatible change that
is not strictly necessary.  The 'buffer-list frame parameter has been
in Emacs since (I think) 1997; some external packages may rely on its
current contents.  Also, using a special marker seems a bit less clean
to me than using a separate parameter.  (It is also less efficient.)

The below patch also renames `prev-buffer' to `previous-buffer', and
extends it to support the buffer-predicate frame parameter.  It
incorporates all fixes that have been suggested in this thread, except
for the customization option for disabling frame-local behaviour.
(`other-buffer' has been unconditionally using the frame-local buffer
list for years; I don't see a point in making it configurable for
next-buffer/previous-buffer either.)

If there are no objections, I will document the changes and install
them in CVS.

Index: lisp/bindings.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/bindings.el,v
retrieving revision 1.154
diff -u -3 -p -r1.154 bindings.el
*** lisp/bindings.el    28 Oct 2005 16:19:16 -0000      1.154
--- lisp/bindings.el    7 Dec 2005 14:46:48 -0000
***************
*** 338,364 ****
  (defvar mode-line-buffer-identification-keymap nil "\
  Keymap for what is displayed by `mode-line-buffer-identification'.")
  
! (defun last-buffer () "\
! Return the last non-hidden buffer in the buffer list."
!   ;; This logic is more or less copied from bury-buffer,
!   ;; except that we reverse the buffer list.
!   (let ((list (nreverse (buffer-list (selected-frame))))
!       (pred (frame-parameter nil 'buffer-predicate))
!       found notsogood)
!     (while (and list (not found))
!       (unless (or (eq (aref (buffer-name (car list)) 0) ? )
!                 ;; If the selected frame has a buffer_predicate,
!                 ;; disregard buffers that don't fit the predicate.
!                 (and pred (not (funcall pred (car list)))))
!       (if (get-buffer-window (car list) 'visible)
!           (or notsogood (eq (car list) (current-buffer)))
!         (setq found (car list))))
!       (pop list))
!     (or found notsogood
!       (get-buffer "*scratch*")
        (progn
!         (set-buffer-major-mode
!          (get-buffer-create "*scratch*"))
          (get-buffer "*scratch*")))))
  
  (defun unbury-buffer () "\
--- 338,372 ----
  (defvar mode-line-buffer-identification-keymap nil "\
  Keymap for what is displayed by `mode-line-buffer-identification'.")
  
! (defun last-buffer (&optional buffer visible-ok frame) "\
! Return the last non-hidden buffer in the buffer list.
! If BUFFER is non-nil, last-buffer will ignore that buffer.
! Buffers not visible in windows are preferred to visible buffers,
! unless optional argument VISIBLE-OK is non-nil.
! If the optional third argument FRAME is non-nil, use that frame's
! buffer list instead of the selected frame's buffer list.
! If no other buffer exists, the buffer `*scratch*' is returned."
!   (setq frame (or frame (selected-frame)))
!   ;; This logic is more or less copied from other-buffer.
!   (let ((search-list
!        #'(lambda (list)
!            "Search LIST for a valid buffer to display."
!            (let ((pred (frame-parameter frame 'buffer-predicate))
!                  found buf)
!              (while (and (not found) list)
!                (setq buf (car list))
!                (if (and (not (eq buffer buf))
!                         (buffer-live-p buf)
!                         (or (null pred) (funcall pred buf))
!                         (not (eq (aref (buffer-name buf) 0) ?\s))
!                         (or visible-ok (null (get-buffer-window buf 
'visible))))
!                    (setq found buf)
!                  (setq list (cdr list))))
!              list))))
!     (or (car (funcall search-list (frame-parameter frame 
'buried-buffer-list)))
!       (car (funcall search-list (nreverse (buffer-list frame))))
        (progn
!         (set-buffer-major-mode (get-buffer-create "*scratch*"))
          (get-buffer "*scratch*")))))
  
  (defun unbury-buffer () "\
***************
*** 673,680 ****
  
  (define-key global-map [?\C-x right] 'next-buffer)
  (define-key global-map [?\C-x C-right] 'next-buffer)
! (define-key global-map [?\C-x left] 'prev-buffer)
! (define-key global-map [?\C-x C-left] 'prev-buffer)
  
  (let ((map minibuffer-local-map))
    (define-key map "\en"   'next-history-element)
--- 681,688 ----
  
  (define-key global-map [?\C-x right] 'next-buffer)
  (define-key global-map [?\C-x C-right] 'next-buffer)
! (define-key global-map [?\C-x left] 'previous-buffer)
! (define-key global-map [?\C-x C-left] 'previous-buffer)
  
  (let ((map minibuffer-local-map))
    (define-key map "\en"   'next-history-element)
Index: lisp/menu-bar.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/menu-bar.el,v
retrieving revision 1.282
diff -u -3 -p -r1.282 menu-bar.el
*** lisp/menu-bar.el    19 Nov 2005 11:23:04 -0000      1.282
--- lisp/menu-bar.el    7 Dec 2005 14:46:48 -0000
***************
*** 1662,1671 ****
                             "Next Buffer"
                             'next-buffer
                             :help "Switch to the \"next\" buffer in a cyclic 
order")
!                      (list 'prev-buffer
                             'menu-item
                             "Previous Buffer"
!                            'prev-buffer
                             :help "Switch to the \"previous\" buffer in a 
cyclic order")
                       (list 'select-named-buffer
                             'menu-item
--- 1662,1671 ----
                             "Next Buffer"
                             'next-buffer
                             :help "Switch to the \"next\" buffer in a cyclic 
order")
!                      (list 'previous-buffer
                             'menu-item
                             "Previous Buffer"
!                            'previous-buffer
                             :help "Switch to the \"previous\" buffer in a 
cyclic order")
                       (list 'select-named-buffer
                             'menu-item
Index: lisp/simple.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/simple.el,v
retrieving revision 1.777
diff -u -3 -p -r1.777 simple.el
*** lisp/simple.el      4 Dec 2005 02:42:29 -0000       1.777
--- lisp/simple.el      7 Dec 2005 14:46:48 -0000
***************
*** 56,76 ****
    "Switch to the next buffer in cyclic order."
    (interactive)
    (let ((buffer (current-buffer)))
!     (switch-to-buffer (other-buffer buffer))
      (bury-buffer buffer)))
  
! (defun prev-buffer ()
    "Switch to the previous buffer in cyclic order."
    (interactive)
!   (let ((list (nreverse (buffer-list)))
!       found)
!     (while (and (not found) list)
!       (let ((buffer (car list)))
!       (if (and (not (get-buffer-window buffer))
!                (not (string-match "\\` " (buffer-name buffer))))
!           (setq found buffer)))
!       (setq list (cdr list)))
!     (switch-to-buffer found)))
  
  ;;; next-error support framework
  
--- 56,69 ----
    "Switch to the next buffer in cyclic order."
    (interactive)
    (let ((buffer (current-buffer)))
!     (switch-to-buffer (other-buffer buffer t))
      (bury-buffer buffer)))
  
! (defun previous-buffer ()
    "Switch to the previous buffer in cyclic order."
    (interactive)
!   (switch-to-buffer (last-buffer (current-buffer) t)))
! 
  
  ;;; next-error support framework
  
Index: src/alloc.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/alloc.c,v
retrieving revision 1.384
diff -u -3 -p -r1.384 alloc.c
*** src/alloc.c 30 Nov 2005 00:04:51 -0000      1.384
--- src/alloc.c 7 Dec 2005 14:46:48 -0000
***************
*** 5370,5375 ****
--- 5370,5376 ----
          mark_object (ptr->menu_bar_vector);
          mark_object (ptr->buffer_predicate);
          mark_object (ptr->buffer_list);
+         mark_object (ptr->buried_buffer_list);
          mark_object (ptr->menu_bar_window);
          mark_object (ptr->tool_bar_window);
          mark_face_cache (ptr->face_cache);
Index: src/buffer.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/buffer.c,v
retrieving revision 1.496
diff -u -3 -p -r1.496 buffer.c
*** src/buffer.c        6 Dec 2005 07:37:47 -0000       1.496
--- src/buffer.c        7 Dec 2005 14:46:48 -0000
***************
*** 212,236 ****
       (frame)
       Lisp_Object frame;
  {
!   Lisp_Object framelist, general;
    general = Fmapcar (Qcdr, Vbuffer_alist);
  
    if (FRAMEP (frame))
      {
!       Lisp_Object tail;
  
        CHECK_FRAME (frame);
  
        framelist = Fcopy_sequence (XFRAME (frame)->buffer_list);
  
!       /* Remove from GENERAL any buffer that duplicates one in FRAMELIST.  */
        tail = framelist;
!       while (! NILP (tail))
        {
          general = Fdelq (XCAR (tail), general);
          tail = XCDR (tail);
        }
!       return nconc2 (framelist, general);
      }
  
    return general;
--- 212,249 ----
       (frame)
       Lisp_Object frame;
  {
!   Lisp_Object general;
    general = Fmapcar (Qcdr, Vbuffer_alist);
  
    if (FRAMEP (frame))
      {
!       Lisp_Object framelist, prevlist, tail;
!       Lisp_Object args[3];
  
        CHECK_FRAME (frame);
  
        framelist = Fcopy_sequence (XFRAME (frame)->buffer_list);
+       prevlist = Fcopy_sequence (XFRAME (frame)->buried_buffer_list);
  
!       /* Remove from GENERAL any buffer that duplicates one in
!          FRAMELIST or PREVLIST.  */
        tail = framelist;
!       while (CONSP (tail))
        {
          general = Fdelq (XCAR (tail), general);
          tail = XCDR (tail);
        }
!       tail = prevlist;
!       while (CONSP (tail))
!       {
!         general = Fdelq (XCAR (tail), general);
!         tail = XCDR (tail);
!       }
! 
!       args[0] = framelist;
!       args[1] = general;
!       args[2] = prevlist;
!       return Fnconc (3, args);
      }
  
    return general;
***************
*** 1545,1550 ****
--- 1558,1580 ----
    XSETCDR (link, Vbuffer_alist);
    Vbuffer_alist = link;
  
+   /* Effectively do a delq on buried_buffer_list.  */
+   
+   prev = Qnil;
+   for (link = XFRAME (frame)->buried_buffer_list; CONSP (link);
+        link = XCDR (link))
+     {
+       if (EQ (XCAR (link), buf))
+         {
+           if (NILP (prev))
+             XFRAME (frame)->buried_buffer_list = XCDR (link);
+           else
+             XSETCDR (prev, XCDR (XCDR (prev)));
+           break;
+         }
+       prev = link;
+     }
+ 
    /* Now move this buffer to the front of frame_buffer_list also.  */
  
    prev = Qnil;
***************
*** 2016,2025 ****
        XSETCDR (link, Qnil);
        Vbuffer_alist = nconc2 (Vbuffer_alist, link);
  
!       /* Removing BUFFER from frame-specific lists
!        has the effect of putting BUFFER at the end
!        of the combined list in each frame.  */
!       frames_discard_buffer (buffer);
      }
  
    return Qnil;
--- 2046,2055 ----
        XSETCDR (link, Qnil);
        Vbuffer_alist = nconc2 (Vbuffer_alist, link);
  
!       XFRAME (selected_frame)->buffer_list
!         = Fdelq (buffer, XFRAME (selected_frame)->buffer_list);
!       XFRAME (selected_frame)->buried_buffer_list
!         = Fcons (buffer, XFRAME (selected_frame)->buried_buffer_list);
      }
  
    return Qnil;
Index: src/frame.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/frame.c,v
retrieving revision 1.322
diff -u -3 -p -r1.322 frame.c
*** src/frame.c 10 Oct 2005 14:52:50 -0000      1.322
--- src/frame.c 7 Dec 2005 14:46:48 -0000
***************
*** 104,110 ****
  Lisp_Object Qunsplittable;
  Lisp_Object Qmenu_bar_lines, Qtool_bar_lines;
  Lisp_Object Qleft_fringe, Qright_fringe;
! Lisp_Object Qbuffer_predicate, Qbuffer_list;
  Lisp_Object Qtty_color_mode;
  
  Lisp_Object Qfullscreen, Qfullwidth, Qfullheight, Qfullboth;
--- 104,110 ----
  Lisp_Object Qunsplittable;
  Lisp_Object Qmenu_bar_lines, Qtool_bar_lines;
  Lisp_Object Qleft_fringe, Qright_fringe;
! Lisp_Object Qbuffer_predicate, Qbuffer_list, Qburied_buffer_list;
  Lisp_Object Qtty_color_mode;
  
  Lisp_Object Qfullscreen, Qfullwidth, Qfullheight, Qfullboth;
***************
*** 276,281 ****
--- 276,282 ----
    f->menu_bar_items_used = 0;
    f->buffer_predicate = Qnil;
    f->buffer_list = Qnil;
+   f->buried_buffer_list = Qnil;
  #ifdef MULTI_KBOARD
    f->kboard = initial_kboard;
  #endif
***************
*** 1900,1906 ****
    XFRAME (frame)->buffer_list = list;
  }
  
! /* Discard BUFFER from the buffer-list of each frame.  */
  
  void
  frames_discard_buffer (buffer)
--- 1901,1907 ----
    XFRAME (frame)->buffer_list = list;
  }
  
! /* Discard BUFFER from the buffer-list and buried-buffer-list of each frame.  
*/
  
  void
  frames_discard_buffer (buffer)
***************
*** 1912,1917 ****
--- 1913,1920 ----
      {
        XFRAME (frame)->buffer_list
        = Fdelq (buffer, XFRAME (frame)->buffer_list);
+       XFRAME (frame)->buried_buffer_list
+         = Fdelq (buffer, XFRAME (frame)->buried_buffer_list);
      }
  }
  
***************
*** 1999,2011 ****
  {
    register Lisp_Object old_alist_elt;
  
!   /* The buffer-alist parameter is stored in a special place and is
!      not in the alist.  */
    if (EQ (prop, Qbuffer_list))
      {
        f->buffer_list = val;
        return;
      }
  
    /* If PROP is a symbol which is supposed to have frame-local values,
       and it is set up based on this frame, switch to the global
--- 2002,2019 ----
  {
    register Lisp_Object old_alist_elt;
  
!   /* The buffer-list parameters are stored in a special place and not
!      in the alist.  */
    if (EQ (prop, Qbuffer_list))
      {
        f->buffer_list = val;
        return;
      }
+   if (EQ (prop, Qburied_buffer_list))
+     {
+       f->buried_buffer_list = val;
+       return;
+     }
  
    /* If PROP is a symbol which is supposed to have frame-local values,
       and it is set up based on this frame, switch to the global
***************
*** 2145,2150 ****
--- 2153,2159 ----
                   : FRAME_MINIBUF_WINDOW (f)));
    store_in_alist (&alist, Qunsplittable, (FRAME_NO_SPLIT_P (f) ? Qt : Qnil));
    store_in_alist (&alist, Qbuffer_list, frame_buffer_list (frame));
+   store_in_alist (&alist, Qburied_buffer_list, XFRAME 
(frame)->buried_buffer_list);
  
    /* I think this should be done with a hook.  */
  #ifdef HAVE_WINDOW_SYSTEM
***************
*** 3965,3970 ****
--- 3974,3981 ----
    staticpro (&Qbuffer_predicate);
    Qbuffer_list = intern ("buffer-list");
    staticpro (&Qbuffer_list);
+   Qburied_buffer_list = intern ("buried-buffer-list");
+   staticpro (&Qburied_buffer_list);
    Qdisplay_type = intern ("display-type");
    staticpro (&Qdisplay_type);
    Qbackground_mode = intern ("background-mode");
Index: src/frame.h
===================================================================
RCS file: /cvsroot/emacs/emacs/src/frame.h,v
retrieving revision 1.112
diff -u -3 -p -r1.112 frame.h
*** src/frame.h 8 Sep 2005 22:30:08 -0000       1.112
--- src/frame.h 7 Dec 2005 14:46:48 -0000
***************
*** 182,187 ****
--- 182,191 ----
    /* List of buffers viewed in this frame, for other-buffer.  */
    Lisp_Object buffer_list;
  
+   /* List of buffers that were viewed, then buried in this frame.  The
+      most recently buried buffer is first.  For previous-buffer.  */
+   Lisp_Object buried_buffer_list;
+   
    /* A dummy window used to display menu bars under X when no X
       toolkit support is available.  */
    Lisp_Object menu_bar_window;
***************
*** 994,1000 ****
  
  extern Lisp_Object Qauto_raise, Qauto_lower;
  extern Lisp_Object Qborder_color, Qborder_width;
! extern Lisp_Object Qbuffer_predicate, Qbuffer_list;
  extern Lisp_Object Qcursor_color, Qcursor_type;
  extern Lisp_Object Qfont;
  extern Lisp_Object Qbackground_color, Qforeground_color;
--- 998,1004 ----
  
  extern Lisp_Object Qauto_raise, Qauto_lower;
  extern Lisp_Object Qborder_color, Qborder_width;
! extern Lisp_Object Qbuffer_predicate, Qbuffer_list, Qburied_buffer_list;
  extern Lisp_Object Qcursor_color, Qcursor_type;
  extern Lisp_Object Qfont;
  extern Lisp_Object Qbackground_color, Qforeground_color;

-- 
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