emacs/lisp/desktop.el

;;; desktop.el --- save partial status of Emacs when killed

;; Copyright (C) 1993, 1994, 1995, 1997, 2000, 2001
;;   Free Software Foundation, Inc.

;; Author: Morten Welinder <terra@diku.dk>
;; Maintainter: Lars Hansen <larsh@math.ku.dk>
;; Keywords: convenience
;; Favourite-brand-of-beer: None, I hate beer.

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; Save the Desktop, i.e.,
;;	- some global variables
;; 	- the list of buffers with associated files.  For each buffer also
;;		- the major mode
;;		- the default directory
;;		- the point
;;		- the mark & mark-active
;;		- buffer-read-only
;;		- some local variables

;; To use this, use customize to turn on desktop-save-mode or add the
;; following line somewhere in your .emacs file:
;;
;;	(desktop-save-mode 1)
;;
;; For further usage information, look at the section
;; "Saving Emacs Sessions" in the GNU Emacs Manual.

;; When the desktop module is loaded, the function `desktop-kill' is
;; added to the `kill-emacs-hook'. This function is responsible for
;; saving the desktop when Emacs is killed.  Furthermore an anonymous
;; function is added to the `after-init-hook'. This function is
;; responsible for loading the desktop when Emacs is started.

;; Some words on minor modes: Most minor modes are controlled by
;; buffer-local variables, which have a standard save / restore
;; mechanism.  To handle all minor modes, we take the following
;; approach: (1) check whether the variable name from
;; `minor-mode-alist' is also a function; and (2) use translation
;; table `desktop-minor-mode-table' in the case where the two names
;; are not the same.

;; By the way: don't use desktop.el to customize Emacs -- the file .emacs
;; in your home directory is used for that.  Saving global default values
;; for buffers is an example of misuse.

;; PLEASE NOTE: The kill ring can be saved as specified by the variable
;; `desktop-globals-to-save' (by default it isn't).  This may result in saving
;; things you did not mean to keep.  Use M-x desktop-clear RET.

;; Thanks to  hetrick@phys.uva.nl (Jim Hetrick)      for useful ideas.
;;            avk@rtsg.mot.com (Andrew V. Klein)     for a dired tip.
;;            chris@tecc.co.uk (Chris Boucher)       for a mark tip.
;;            f89-kam@nada.kth.se (Klas Mellbourn)   for a mh-e tip.
;;            kifer@sbkifer.cs.sunysb.edu (M. Kifer) for a bug hunt.
;;            treese@lcs.mit.edu (Win Treese)        for ange-ftp tips.
;;            pot@cnuce.cnr.it (Francesco Potorti`)  for misc. tips.
;; ---------------------------------------------------------------------------
;; TODO:
;;
;; Save window configuration.
;; Recognize more minor modes.
;; Save mark rings.

;;; Code:

(defvar desktop-file-version "206"
  "Version number of desktop file format.
Written into the desktop file and used at desktop read to provide
backward compatibility.")

;; ----------------------------------------------------------------------------
;; USER OPTIONS -- settings you might want to play with.
;; ----------------------------------------------------------------------------

(defgroup desktop nil
  "Save status of Emacs when you exit."
  :group 'frames)

;;;###autoload
(define-minor-mode desktop-save-mode
  "Toggle desktop saving mode.
With numeric ARG, turn desktop saving on if ARG is positive, off
otherwise.  See variable `desktop-save' for a description of when the
desktop is saved."
  :global t
  :group 'desktop)

;; Maintained for backward compatibility
(defvaralias 'desktop-enable 'desktop-save-mode)
(make-obsolete-variable 'desktop-enable 'desktop-save-mode)

(defcustom desktop-save 'ask-if-new
  "*Specifies whether the desktop should be saved when it is killed.
A desktop is killed when the user changes desktop or quits Emacs.
Possible values are:
   t             -- always save.
   ask           -- always ask.
   ask-if-new    -- ask if no desktop file exists, otherwise just save.
   ask-if-exists -- ask if desktop file exists, otherwise don't save.
   if-exists     -- save if desktop file exists, otherwise don't save.
   nil           -- never save.
The desktop is never saved when `desktop-save-mode' is nil.
The variables `desktop-directory' and `desktop-base-file-name'
determine where the desktop is saved."
  :type '(choice
    (const :tag "Always save" t)
    (const :tag "Always ask" ask)
    (const :tag "Ask if desktop file is new, else do save" ask-if-new)
    (const :tag "Ask if desktop file exists, else don't save" ask-if-exists)
    (const :tag "Save if desktop file exists, else don't" if-exists)
    (const :tag "Never save" nil))
  :group 'desktop)

(defcustom desktop-base-file-name
  (convert-standard-filename ".emacs.desktop")
  "Name of file for Emacs desktop, excluding the directory part."
  :type 'file
  :group 'desktop)
(defvaralias 'desktop-basefilename 'desktop-base-file-name)

(defcustom desktop-path '("." "~")
  "List of directories to search for the desktop file.
The base name of the file is specified in `desktop-base-file-name'."
  :type '(repeat directory)
  :group 'desktop)

(defcustom desktop-missing-file-warning nil
  "*If non-nil then `desktop-read' asks if a non-existent file should be recreated.
Also pause for a moment to display message about errors signaled in
`desktop-buffer-mode-handlers'.

If nil, just print error messages in the message buffer."
  :type 'boolean
  :group 'desktop)

(defcustom desktop-no-desktop-file-hook nil
  "Normal hook run when `desktop-read' can't find a desktop file.
May e.g. be used to show a dired buffer."
  :type 'hook
  :group 'desktop)

(defcustom desktop-after-read-hook nil
  "Normal hook run after a successful `desktop-read'.
May e.g. be used to show a buffer list."
  :type 'hook
  :group 'desktop)

(defcustom desktop-save-hook nil
  "Normal hook run before the desktop is saved in a desktop file.
This is useful for truncating history lists, for example."
  :type 'hook
  :group 'desktop)

(defcustom desktop-globals-to-save
  '(desktop-missing-file-warning
    tags-file-name
    tags-table-list
    search-ring
    regexp-search-ring
    register-alist)
  "List of global variables saved by `desktop-save'.
An element may be variable name (a symbol) or a cons cell of the form
\(VAR . MAX-SIZE), which means to truncate VAR's value to at most
MAX-SIZE elements (if the value is a list) before saving the value.
Feature: Saving `kill-ring' implies saving `kill-ring-yank-pointer'."
  :type '(repeat (restricted-sexp :match-alternatives (symbolp consp)))
  :group 'desktop)

(defcustom desktop-globals-to-clear
  '(kill-ring
    kill-ring-yank-pointer
    search-ring
    search-ring-yank-pointer
    regexp-search-ring
    regexp-search-ring-yank-pointer)
  "List of global variables to clear by `desktop-clear'.
An element may be variable name (a symbol) or a cons cell of the form
\(VAR . FORM). Symbols are set to nil and for cons cells VAR is set
to the value obtained by evaluateing FORM."
  :type '(repeat (restricted-sexp :match-alternatives (symbolp consp)))
  :group 'desktop)

(defcustom desktop-clear-preserve-buffers-regexp
  "^\\(\\*scratch\\*\\|\\*Messages\\*\\|\\*tramp/.+\\*\\)$"
  "Regexp identifying buffers that `desktop-clear' should not delete.
See also `desktop-clear-preserve-buffers'."
  :type 'regexp
  :group 'desktop)

(defcustom desktop-clear-preserve-buffers nil
  "*List of buffer names that `desktop-clear' should not delete.
See also `desktop-clear-preserve-buffers-regexp'."
  :type '(repeat string)
  :group 'desktop)

(defcustom desktop-locals-to-save
  '(desktop-locals-to-save  ; Itself!  Think it over.
    truncate-lines
    case-fold-search
    case-replace
    fill-column
    overwrite-mode
    change-log-default-name
    line-number-mode
    buffer-file-coding-system)
  "List of local variables to save for each buffer.
The variables are saved only when they really are local."
  :type '(repeat symbol)
  :group 'desktop)
(make-variable-buffer-local 'desktop-locals-to-save)

;; We skip .log files because they are normally temporary.
;;         (ftp) files because they require passwords and whatnot.
;;         TAGS files to save time (tags-file-name is saved instead).
(defcustom desktop-buffers-not-to-save
  "\\(^nn\\.a[0-9]+\\|\\.log\\|(ftp)\\|^tags\\|^TAGS\\)$"
  "Regexp identifying buffers that are to be excluded from saving."
  :type 'regexp
  :group 'desktop)

;; Skip tramp and ange-ftp files
(defcustom desktop-files-not-to-save
  "^/[^/:]*:"
  "Regexp identifying files whose buffers are to be excluded from saving."
  :type 'regexp
  :group 'desktop)

(defcustom desktop-modes-not-to-save nil
  "List of major modes whose buffers should not be saved."
  :type '(repeat symbol)
  :group 'desktop)

(defcustom desktop-file-name-format 'absolute
  "*Format in which desktop file names should be saved.
Possible values are:
   absolute -- Absolute file name.
   tilde    -- Relative to ~.
   local    -- Relative to directory of desktop file."
  :type '(choice (const absolute) (const tilde) (const local))
  :group 'desktop)

;;;###autoload
(defvar desktop-save-buffer nil
  "When non-nil, save buffer status in desktop file.
This variable becomes buffer local when set.

If the value is a function, it called by `desktop-save' with argument
DESKTOP-DIRNAME to obtain auxiliary information to saved in the desktop
file along with the state of the buffer for which it was called.

When file names are returned, they should be formatted using the call
\"(desktop-file-name FILE-NAME DESKTOP-DIRNAME)\".

Later, when `desktop-read' calls a function in `desktop-buffer-mode-handlers'
to restore the buffer, the auxiliary information is passed as the argument
DESKTOP-BUFFER-MISC.")
(make-variable-buffer-local 'desktop-save-buffer)
(make-obsolete-variable 'desktop-buffer-modes-to-save
                        'desktop-save-buffer)
(make-obsolete-variable 'desktop-buffer-misc-functions
                        'desktop-save-buffer)

(defcustom desktop-buffer-mode-handlers
  '((dired-mode . dired-restore-desktop-buffer)
    (rmail-mode . rmail-restore-desktop-buffer)
    (mh-folder-mode . mh-restore-desktop-buffer)
    (Info-mode . Info-restore-desktop-buffer))
  "Alist of major mode specific functions to restore a desktop buffer.
Functions are called by `desktop-read'. List elements must have the form
\(MAJOR-MODE . RESTORE-BUFFER-FUNCTION).

Buffers with a major mode not specified here, are restored by the default
handler `desktop-restore-file-buffer'.

Handlers are called with argument list

   (DESKTOP-BUFFER-FILE-NAME DESKTOP-BUFFER-NAME DESKTOP-BUFFER-MISC)

Furthermore, they may use the following variables:

   desktop-file-version
   desktop-buffer-major-mode
   desktop-buffer-minor-modes
   desktop-buffer-point
   desktop-buffer-mark
   desktop-buffer-read-only
   desktop-buffer-locals

If a handler returns a buffer, then the saved mode settings
and variable values for that buffer are copied into it."
  :type 'alist
  :group 'desktop)

(put 'desktop-buffer-mode-handlers 'risky-local-variable t)
(make-obsolete-variable 'desktop-buffer-handlers
                        'desktop-buffer-mode-handlers)

(defcustom desktop-minor-mode-table
  '((auto-fill-function auto-fill-mode)
    (vc-mode nil))
  "Table mapping minor mode variables to minor mode functions.
Each entry has the form (NAME RESTORE-FUNCTION).
NAME is the name of the buffer-local variable indicating that the minor
mode is active.  RESTORE-FUNCTION is the function to activate the minor mode.
called.  RESTORE-FUNCTION nil means don't try to restore the minor mode.
Only minor modes for which the name of the buffer-local variable
and the name of the minor mode function are different have to be added to
this table."
  :type 'sexp
  :group 'desktop)

;; ----------------------------------------------------------------------------
(defvar desktop-dirname nil
  "The directory in which the desktop file should be saved.")

(defconst desktop-header
";; --------------------------------------------------------------------------
;; Desktop File for Emacs
;; --------------------------------------------------------------------------
" "*Header to place in Desktop file.")

(defvar desktop-delay-hook nil
  "Hooks run after all buffers are loaded; intended for internal use.")

;; ----------------------------------------------------------------------------
(defun desktop-truncate (list n)
  "Truncate LIST to at most N elements destructively."
  (let ((here (nthcdr (1- n) list)))
    (if (consp here)
	(setcdr here nil))))

;; ----------------------------------------------------------------------------
(defun desktop-clear ()
  "Empty the Desktop.
This kills all buffers except for internal ones and those matching
`desktop-clear-preserve-buffers-regexp' or listed in
`desktop-clear-preserve-buffers'.  Furthermore, it clears the
variables listed in `desktop-globals-to-clear'."
  (interactive)
  (dolist (var desktop-globals-to-clear)
    (if (symbolp var)
      (eval `(setq-default ,var nil))
      (eval `(setq-default ,(car var) ,(cdr var)))))
  (let ((buffers (buffer-list)))
    (while buffers
      (let ((bufname (buffer-name (car buffers))))
         (or
           (null bufname)
           (string-match desktop-clear-preserve-buffers-regexp bufname)
           (member bufname desktop-clear-preserve-buffers)
           ;; Don't kill buffers made for internal purposes.
           (and (not (equal bufname "")) (eq (aref bufname 0) ?\ ))
           (kill-buffer (car buffers))))
      (setq buffers (cdr buffers))))
  (delete-other-windows))

;; ----------------------------------------------------------------------------
(add-hook 'kill-emacs-hook 'desktop-kill)

(defun desktop-kill ()
  "If `desktop-save-mode' is non-nil, do what `desktop-save' says to do.
If the desktop should be saved and `desktop-dirname'
is nil, ask the user where to save the desktop."
  (when
    (and
      desktop-save-mode
      (let ((exists (file-exists-p (expand-file-name desktop-base-file-name desktop-dirname))))
        (or
          (eq desktop-save t)
          (and exists (memq desktop-save '(ask-if-new if-exists)))
          (and
            (or
              (memq desktop-save '(ask ask-if-new))
              (and exists (eq desktop-save 'ask-if-exists)))
            (y-or-n-p "Save desktop? ")))))
    (unless desktop-dirname
      (setq desktop-dirname
        (file-name-as-directory
          (expand-file-name
            (call-interactively
              (lambda (dir) (interactive "DDirectory for desktop file: ") dir))))))
    (condition-case err
      (desktop-save desktop-dirname)
      (file-error
        (unless (yes-or-no-p "Error while saving the desktop. Ignore? ")
          (signal (car err) (cdr err)))))))

;; ----------------------------------------------------------------------------
(defun desktop-list* (&rest args)
  (if (null (cdr args))
      (car args)
    (setq args (nreverse args))
    (let ((value (cons (nth 1 args) (car args))))
      (setq args (cdr (cdr args)))
      (while args
	(setq value (cons (car args) value))
	(setq args (cdr args)))
      value)))

;; ----------------------------------------------------------------------------
(defun desktop-internal-v2s (value)
  "Convert VALUE to a pair (QUOTE . TXT); (eval (read TXT)) gives VALUE.
TXT is a string that when read and evaluated yields value.
QUOTE may be `may' (value may be quoted),
`must' (values must be quoted), or nil (value may not be quoted)."
  (cond
   ((or (numberp value) (null value) (eq t value))
    (cons 'may (prin1-to-string value)))
   ((stringp value)
    (let ((copy (copy-sequence value)))
      (set-text-properties 0 (length copy) nil copy)
      ;; Get rid of text properties because we cannot read them
      (cons 'may (prin1-to-string copy))))
   ((symbolp value)
    (cons 'must (prin1-to-string value)))
   ((vectorp value)
    (let* ((special nil)
	   (pass1 (mapcar
		   (lambda (el)
		     (let ((res (desktop-internal-v2s el)))
		       (if (null (car res))
			   (setq special t))
		       res))
		   value)))
      (if special
	  (cons nil (concat "(vector "
			    (mapconcat (lambda (el)
					 (if (eq (car el) 'must)
					     (concat "'" (cdr el))
					   (cdr el)))
				       pass1
				       " ")
			    ")"))
	(cons 'may (concat "[" (mapconcat 'cdr pass1 " ") "]")))))
   ((consp value)
    (let ((p value)
	  newlist
	  use-list*
	  anynil)
      (while (consp p)
	(let ((q.txt (desktop-internal-v2s (car p))))
	  (or anynil (setq anynil (null (car q.txt))))
	  (setq newlist (cons q.txt newlist)))
	(setq p (cdr p)))
      (if p
	  (let ((last (desktop-internal-v2s p))
		(el (car newlist)))
	    (or anynil (setq anynil (null (car last))))
	    (or anynil
		(setq newlist (cons '(must . ".") newlist)))
	    (setq use-list* t)
	    (setq newlist (cons last newlist))))
      (setq newlist (nreverse newlist))
      (if anynil
	  (cons nil
		(concat (if use-list* "(desktop-list* "  "(list ")
			(mapconcat (lambda (el)
				     (if (eq (car el) 'must)
					 (concat "'" (cdr el))
				       (cdr el)))
				   newlist
				   " ")
			")"))
	(cons 'must
	      (concat "(" (mapconcat 'cdr newlist " ") ")")))))
   ((subrp value)
    (cons nil (concat "(symbol-function '"
		      (substring (prin1-to-string value) 7 -1)
		      ")")))
   ((markerp value)
    (let ((pos (prin1-to-string (marker-position value)))
	  (buf (prin1-to-string (buffer-name (marker-buffer value)))))
      (cons nil (concat "(let ((mk (make-marker)))"
			" (add-hook 'desktop-delay-hook"
			" (list 'lambda '() (list 'set-marker mk "
			pos " (get-buffer " buf ")))) mk)"))))
   (t					; save as text
    (cons 'may "\"Unprintable entity\""))))

;; ----------------------------------------------------------------------------
(defun desktop-value-to-string (value)
  "Convert VALUE to a string that when read evaluates to the same value.
Not all types of values are supported."
  (let* ((print-escape-newlines t)
	 (float-output-format nil)
	 (quote.txt (desktop-internal-v2s value))
	 (quote (car quote.txt))
	 (txt (cdr quote.txt)))
    (if (eq quote 'must)
	(concat "'" txt)
      txt)))

;; ----------------------------------------------------------------------------
(defun desktop-outvar (varspec)
  "Output a setq statement for variable VAR to the desktop file.
The argument VARSPEC may be the variable name VAR (a symbol),
or a cons cell of the form  (VAR . MAX-SIZE),
which means to truncate VAR's value to at most MAX-SIZE elements
\(if the value is a list) before saving the value."
  (let (var size)
    (if (consp varspec)
	(setq var (car varspec) size (cdr varspec))
      (setq var varspec))
    (if (boundp var)
	(progn
	  (if (and (integerp size)
		   (> size 0)
		   (listp (eval var)))
	      (desktop-truncate (eval var) size))
	  (insert "(setq "
		  (symbol-name var)
		  " "
		  (desktop-value-to-string (symbol-value var))
		  ")\n")))))

;; ----------------------------------------------------------------------------
(defun desktop-save-buffer-p (filename bufname mode &rest dummy)
  "Return t if buffer should have its state saved in the desktop file.
FILENAME is the visited file name, BUFNAME is the buffer name, and
MODE is the major mode."
  (let ((case-fold-search nil))
    (and (not (string-match desktop-buffers-not-to-save bufname))
         (not (memq mode desktop-modes-not-to-save))
         (or (and filename
                  (not (string-match desktop-files-not-to-save filename)))
             (and (eq mode 'dired-mode)
                  (with-current-buffer bufname
                    (not (string-match desktop-files-not-to-save
                                       default-directory))))
             (and (null filename)
		  (with-current-buffer bufname desktop-save-buffer))))))

;; ----------------------------------------------------------------------------
(defun desktop-file-name (filename dirname)
  "Convert FILENAME to format specified in `desktop-file-name-format'.
DIRNAME must be the directory in which the desktop file will be saved."
  (cond
    ((not filename) nil)
    ((eq desktop-file-name-format 'tilde)
     (let ((relative-name (file-relative-name (expand-file-name filename) "~")))
       (cond
         ((file-name-absolute-p relative-name) relative-name)
         ((string= "./" relative-name) "~/")
         ((string= "." relative-name) "~")
         (t (concat "~/" relative-name)))))
    ((eq desktop-file-name-format 'local) (file-relative-name filename dirname))
    (t (expand-file-name filename))))

;; ----------------------------------------------------------------------------
(defun desktop-save (dirname)
  "Save the desktop in a desktop file.
Parameter DIRNAME specifies where to save the desktop file.
See also `desktop-base-file-name'."
  (interactive "DDirectory to save desktop file in: ")
  (run-hooks 'desktop-save-hook)
  (setq dirname (file-name-as-directory (expand-file-name dirname)))
  (save-excursion
    (let ((filename (expand-file-name desktop-base-file-name dirname))
          (info
            (mapcar
              #'(lambda (b)
                  (set-buffer b)
                  (list
                    (desktop-file-name (buffer-file-name) dirname)
                    (buffer-name)
                    major-mode
                    ;; minor modes
                    (let (ret)
                      (mapc
                        #'(lambda (minor-mode)
                          (and
                            (boundp minor-mode)
                            (symbol-value minor-mode)
                            (let ((special (assq minor-mode desktop-minor-mode-table)))
                              (when (or special (functionp minor-mode))
                                (setq ret
                                  (cons
                                    (if special (cadr special) minor-mode)
                                    ret))))))
                        (mapcar #'car minor-mode-alist))
                      ret)
                    (point)
                    (list (mark t) mark-active)
                    buffer-read-only
                    ;; Auxiliary information
                    (when (functionp desktop-save-buffer)
                      (funcall desktop-save-buffer dirname))
                    (let ((locals desktop-locals-to-save)
                          (loclist (buffer-local-variables))
                          (ll))
                      (while locals
                        (let ((here (assq (car locals) loclist)))
                          (if here
                            (setq ll (cons here ll))
                            (when (member (car locals) loclist)
                              (setq ll (cons (car locals) ll)))))
                        (setq locals (cdr locals)))
                      ll)))
              (buffer-list)))
          (buf (get-buffer-create "*desktop*")))
      (set-buffer buf)
      (erase-buffer)

      (insert
        ";; -*- coding: emacs-mule; -*-\n"
        desktop-header
        ";; Created " (current-time-string) "\n"
        ";; Desktop file format version " desktop-file-version "\n"
        ";; Emacs version " emacs-version "\n\n"
        ";; Global section:\n")
      (mapcar (function desktop-outvar) desktop-globals-to-save)
      (if (memq 'kill-ring desktop-globals-to-save)
        (insert
          "(setq kill-ring-yank-pointer (nthcdr "
          (int-to-string (- (length kill-ring) (length kill-ring-yank-pointer)))
          " kill-ring))\n"))

      (insert "\n;; Buffer section -- buffers listed in same order as in buffer list:\n")
      (mapcar #'(lambda (l)
                  (if (apply 'desktop-save-buffer-p l)
                      (progn
                        (insert "(desktop-create-buffer " desktop-file-version)
                        (mapcar #'(lambda (e)
                                    (insert "\n  " (desktop-value-to-string e)))
                                l)
                        (insert ")\n\n"))))
              info)
      (setq default-directory dirname)
      (when (file-exists-p filename) (delete-file filename))
      (let ((coding-system-for-write 'emacs-mule))
        (write-region (point-min) (point-max) filename nil 'nomessage))))
  (setq desktop-dirname dirname))

;; ----------------------------------------------------------------------------
(defun desktop-remove ()
  "Delete desktop file in `desktop-dirname'.
This function also sets `desktop-dirname' to nil."
  (interactive)
  (when desktop-dirname
    (let ((filename (expand-file-name desktop-base-file-name desktop-dirname)))
      (setq desktop-dirname nil)
      (when (file-exists-p filename)
        (delete-file filename)))))

;; ----------------------------------------------------------------------------
;;;###autoload
(defun desktop-read (&optional dirname)
  "Read and process the desktop file in directory DIRNAME.
Look for a desktop file in DIRNAME, or if DIRNAME is omitted, look in
directories listed in `desktop-path'.  If a desktop file is found, it
is processed and `desktop-after-read-hook' is run. If no desktop file
is found, clear the desktop and run `desktop-no-desktop-file-hook'.
This function is a no-op when Emacs is running in batch mode.
It returns t if a desktop file was loaded, nil otherwise."
  (interactive)
  (unless noninteractive
    (setq desktop-dirname
      (file-name-as-directory
        (expand-file-name
          (or
            ;; If DIRNAME is specified, use it.
            (and (< 0 (length dirname)) dirname)
            ;; Otherwise search desktop file in desktop-path.
            (let ((dirs desktop-path))
              (while
                (and
                  dirs
                  (not
                    (file-exists-p (expand-file-name desktop-base-file-name (car dirs)))))
                (setq dirs (cdr dirs)))
              (and dirs (car dirs)))
            ;; If not found and `desktop-path' is non-nil, use its first element.
            (and desktop-path (car desktop-path))
            ;; Default: Home directory.
            "~"))))
    (if (file-exists-p (expand-file-name desktop-base-file-name desktop-dirname))
      ;; Desktop file found, process it.
      (let ((desktop-first-buffer nil)
            (desktop-buffer-ok-count 0)
            (desktop-buffer-fail-count 0))
        ;; Evaluate desktop buffer.
        (load (expand-file-name desktop-base-file-name desktop-dirname) t t t)
        ;; `desktop-create-buffer' puts buffers at end of the buffer list.
        ;; We want buffers existing prior to evaluating the desktop (and not reused)
        ;; to be placed at the end of the buffer list, so we move them here.
        (mapcar 'bury-buffer
                (nreverse (cdr (memq desktop-first-buffer (nreverse (buffer-list))))))
        (switch-to-buffer (car (buffer-list)))
        (run-hooks 'desktop-delay-hook)
        (setq desktop-delay-hook nil)
        (run-hooks 'desktop-after-read-hook)
        (message "Desktop: %d buffer%s restored%s."
                 desktop-buffer-ok-count
                 (if (= 1 desktop-buffer-ok-count) "" "s")
                 (if (< 0 desktop-buffer-fail-count)
                     (format ", %d failed to restore" desktop-buffer-fail-count)
                   ""))
        t)
      ;; No desktop file found.
      (desktop-clear)
      (let ((default-directory desktop-dirname))
        (run-hooks 'desktop-no-desktop-file-hook))
      (message "No desktop file.")
      nil)))

;; ----------------------------------------------------------------------------
;; Maintained for backward compatibility
;;;###autoload
(defun desktop-load-default ()
  "Load the `default' start-up library manually.
Also inhibit further loading of it."
  (if (not inhibit-default-init)	; safety check
      (progn
	(load "default" t t)
	(setq inhibit-default-init t))))
(make-obsolete 'desktop-load-default 'desktop-save-mode)

;; ----------------------------------------------------------------------------
;;;###autoload
(defun desktop-change-dir (dirname)
  "Change to desktop saved in DIRNAME.
Kill the desktop as specified by variables `desktop-save-mode' and
`desktop-save', then clear the desktop and load the desktop file in
directory DIRNAME."
  (interactive "DChange to directory: ")
  (setq dirname (file-name-as-directory (expand-file-name dirname desktop-dirname)))
  (desktop-kill)
  (desktop-clear)
  (desktop-read dirname))
  
;; ----------------------------------------------------------------------------
;;;###autoload
(defun desktop-save-in-desktop-dir ()
  "Save the desktop in directory `desktop-dirname'."
  (interactive)
  (if desktop-dirname
    (desktop-save desktop-dirname)
    (call-interactively 'desktop-save))
  (message "Desktop saved in %s" desktop-dirname))

;; ----------------------------------------------------------------------------
;;;###autoload
(defun desktop-revert ()
  "Revert to the last loaded desktop."
  (interactive)
  (unless desktop-dirname
    (error "Unknown desktop directory"))
  (unless (file-exists-p (expand-file-name desktop-base-file-name desktop-dirname))
    (error "No desktop file found"))
  (desktop-clear)
  (desktop-read desktop-dirname))

;; ----------------------------------------------------------------------------
(defun desktop-restore-file-buffer (desktop-buffer-file-name
                                    desktop-buffer-name
                                    desktop-buffer-misc)
  "Restore a file buffer."
  (eval-when-compile ; Just to silence the byte compiler
    (defvar desktop-buffer-major-mode)
    (defvar desktop-buffer-locals))
  (if desktop-buffer-file-name
      (if (or (file-exists-p desktop-buffer-file-name)
              (let ((msg (format "Desktop: File \"%s\" no longer exists."
                                 desktop-buffer-file-name)))
                 (if desktop-missing-file-warning
		     (y-or-n-p (concat msg " Re-create? "))
                   (message msg)
                   nil)))
	  (let* ((auto-insert nil) ; Disable auto insertion
		 (coding-system-for-read
		  (or coding-system-for-read
		      (cdr (assq 'buffer-file-coding-system
				 desktop-buffer-locals))))
		 (buf (find-file-noselect desktop-buffer-file-name)))
	    (condition-case nil
		(switch-to-buffer buf)
	      (error (pop-to-buffer buf)))
	    (and (not (eq major-mode desktop-buffer-major-mode))
		 (functionp desktop-buffer-major-mode)
		 (funcall desktop-buffer-major-mode))
	    buf)
	nil)))

;; ----------------------------------------------------------------------------
;; Create a buffer, load its file, set its mode, ...;
;; called from Desktop file only.

(eval-when-compile ; Just to silence the byte compiler
   (defvar desktop-first-buffer) ;; Dynamically bound in `desktop-read'
)

(defun desktop-create-buffer
  (desktop-file-version
   desktop-buffer-file-name
   desktop-buffer-name
   desktop-buffer-major-mode
   desktop-buffer-minor-modes
   desktop-buffer-point
   desktop-buffer-mark
   desktop-buffer-read-only
   desktop-buffer-misc
   &optional
   desktop-buffer-locals)
  ;; Just to silence the byte compiler. Bound locally in `desktop-read'.
  (eval-when-compile
    (defvar desktop-buffer-ok-count)
    (defvar desktop-buffer-fail-count))
  ;; To make desktop files with relative file names possible, we cannot
  ;; allow `default-directory' to change. Therefore we save current buffer.
  (save-current-buffer
    (let ((buffer-list (buffer-list))
          (result
           (condition-case err
               (funcall (or (cdr (assq desktop-buffer-major-mode
                                       desktop-buffer-mode-handlers))
                            'desktop-restore-file-buffer)
                        desktop-buffer-file-name
                        desktop-buffer-name
                        desktop-buffer-misc)
             (error
              (message "Desktop: Can't load buffer %s: %s"
                       desktop-buffer-name
                       (error-message-string err))
              (when desktop-missing-file-warning (sit-for 1))
              nil))))
      (if (bufferp result)
          (setq desktop-buffer-ok-count (1+ desktop-buffer-ok-count))
        (setq desktop-buffer-fail-count (1+ desktop-buffer-fail-count))
        (setq result nil))
      (unless (bufferp result) (setq result nil))
      ;; Restore buffer list order with new buffer at end. Don't change
      ;; the order for old desktop files (old desktop module behaviour).
      (unless (< desktop-file-version 206)
        (mapcar 'bury-buffer buffer-list)
        (when result (bury-buffer result)))
      (when result
        (unless (or desktop-first-buffer (< desktop-file-version 206))
          (setq desktop-first-buffer result))
        (set-buffer result)
        (unless (equal (buffer-name) desktop-buffer-name)
          (rename-buffer desktop-buffer-name))
        ;; minor modes
        (cond ((equal '(t) desktop-buffer-minor-modes) ; backwards compatible
               (auto-fill-mode 1))
              ((equal '(nil) desktop-buffer-minor-modes) ; backwards compatible
               (auto-fill-mode 0))
              (t
               (mapcar #'(lambda (minor-mode)
                           (when (functionp minor-mode) (funcall minor-mode 1)))
                       desktop-buffer-minor-modes)))
        ;; Even though point and mark are non-nil when written by `desktop-save'
        ;; they may be modified by handlers wanting to set point or mark themselves.
        (when desktop-buffer-point
          (goto-char
            (condition-case err
                ;; Evaluate point. Thus point can be something like '(search-forward ...
                (eval desktop-buffer-point)
              (error (message "%s" (error-message-string err)) 1))))
        (when desktop-buffer-mark
          (if (consp desktop-buffer-mark)
            (progn
              (set-mark (car desktop-buffer-mark))
              (setq mark-active (car (cdr desktop-buffer-mark))))
            (set-mark desktop-buffer-mark)))
        ;; Never override file system if the file really is read-only marked.
        (if desktop-buffer-read-only (setq buffer-read-only desktop-buffer-read-only))
        (while desktop-buffer-locals
          (let ((this (car desktop-buffer-locals)))
            (if (consp this)
              ;; an entry of this form `(symbol . value)'
              (progn
                (make-local-variable (car this))
                (set (car this) (cdr this)))
              ;; an entry of the form `symbol'
              (make-local-variable this)
              (makunbound this)))
          (setq desktop-buffer-locals (cdr desktop-buffer-locals)))))))

;; ----------------------------------------------------------------------------
;; Backward compatibility -- update parameters to 205 standards.
(defun desktop-buffer (desktop-buffer-file-name desktop-buffer-name
		       desktop-buffer-major-mode
		       mim pt mk ro tl fc cfs cr desktop-buffer-misc)
  (desktop-create-buffer 205 desktop-buffer-file-name desktop-buffer-name
			 desktop-buffer-major-mode (cdr mim) pt mk ro
			 desktop-buffer-misc
			 (list (cons 'truncate-lines tl)
			       (cons 'fill-column fc)
			       (cons 'case-fold-search cfs)
			       (cons 'case-replace cr)
			       (cons 'overwrite-mode (car mim)))))

;; ----------------------------------------------------------------------------
;; When `desktop-save-mode' is non-nil and "--no-desktop" is not specified on the
;; command line, we do the rest of what it takes to use desktop, but do it
;; after finishing loading the init file.
;; We cannot use `command-switch-alist' to process "--no-desktop" because these
;; functions are processed after `after-init-hook'.
(add-hook
  'after-init-hook
  '(lambda ()
    (let ((key "--no-desktop"))
      (if (member key command-line-args)
        (delete key command-line-args)
        (when desktop-save-mode (desktop-read))))))

(provide 'desktop)

;;; arch-tag: 221907c3-1771-4fd3-9c2e-c6f700c6ede9
;;; desktop.el ends here