lisp/resume.el

   1 ;;; resume.el --- process command line args from within a suspended Emacs job
   2
   3 ;; Copyright (C) 1992, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4
   5 ;; Author: Joe Wells <jbw@bucsf.bu.edu>
   6 ;; Adapted-By: ESR
   7 ;; Keywords: processes
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; The purpose of this library is to handle command line arguments
  29 ;; when you resume an existing Emacs job.
  30
  31 ;; In order to use it, you must put this code in your .emacs file.
  32
  33 ;; (add-hook 'suspend-hook 'resume-suspend-hook)
  34 ;; (add-hook 'suspend-resume-hook 'resume-process-args)
  35
  36 ;; You can't get the benefit of this library by using the `emacs' command,
  37 ;; since that always starts a new Emacs job.  Instead you must use a
  38 ;; command called `edit' which knows how to resume an existing Emacs job
  39 ;; if you have one, or start a new Emacs job if you don't have one.
  40
  41 ;; To define the `edit' command, run the script etc/emacs.csh (if you use CSH),
  42 ;; or etc/emacs.bash if you use BASH.  You would normally do this in your
  43 ;; login script.
  44
  45 ;; Stephan Gildea suggested bug fix (gildea@bbn.com).
  46 ;; Ideas from Michael DeCorte and other people.
  47
  48 ;;; Code:
  49
  50 (defvar resume-emacs-args-file (expand-file-name "~/.emacs_args")
  51   "*This file is where arguments are placed for a suspended emacs job.")
  52
  53 (defvar resume-emacs-args-buffer " *Command Line Args*"
  54   "Buffer that is used by resume-process-args.")
  55
  56 (defun resume-process-args ()
  57   "Handler for command line args given when Emacs is resumed."
  58   (let ((start-buffer (current-buffer))
  59         (args-buffer (get-buffer-create resume-emacs-args-buffer))
  60         length args
  61         (command-line-default-directory default-directory))
  62     (unwind-protect
  63         (progn
  64           (set-buffer args-buffer)
  65           (erase-buffer)
  66           ;; get the contents of resume-emacs-args-file
  67           (condition-case ()
  68               (let ((result (insert-file-contents resume-emacs-args-file)))
  69                 (setq length (car (cdr result))))
  70             ;; the file doesn't exist, ergo no arguments
  71             (file-error
  72               (erase-buffer)
  73               (setq length 0)))
  74           (if (<= length 0)
  75               (setq args nil)
  76             ;; get the arguments from the buffer
  77             (goto-char (point-min))
  78             (while (not (eobp))
  79               (skip-chars-forward " \t\n")
  80               (let ((begin (point)))
  81                 (skip-chars-forward "^ \t\n")
  82                 (setq args (cons (buffer-substring begin (point)) args)))
  83               (skip-chars-forward " \t\n"))
  84             ;; arguments are now in reverse order
  85             (setq args (nreverse args))
  86             ;; make sure they're not read again
  87             (erase-buffer))
  88           (resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)
  89           ;; if nothing was in buffer, args will be null
  90           (or (null args)
  91               (setq command-line-default-directory
  92                     (file-name-as-directory (car args))
  93                     args (cdr args)))
  94           ;; actually process the arguments
  95           (command-line-1 args))
  96       ;; If the command line args don't result in a find-file, the
  97       ;; buffer will be left in args-buffer.  So we change back to the
  98       ;; original buffer.  The reason I don't just use
  99       ;; (let ((default-directory foo))
 100       ;;    (command-line-1 args))
 101       ;; in the context of the original buffer is because let does not
 102       ;; work properly with buffer-local variables.
 103       (if (eq (current-buffer) args-buffer)
 104           (set-buffer start-buffer)))))
 105
 106 ;;;###autoload
 107 (defun resume-suspend-hook ()
 108   "Clear out the file used for transmitting args when Emacs resumes."
 109   (save-excursion
 110     (set-buffer (get-buffer-create resume-emacs-args-buffer))
 111     (erase-buffer)
 112     (resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)))
 113
 114 (defun resume-write-buffer-to-file (buffer file)
 115   "Writes the contents of BUFFER into FILE, if permissions allow."
 116   (if (not (file-writable-p file))
 117       (error "No permission to write file %s" file))
 118   (save-excursion
 119     (set-buffer buffer)
 120     (clear-visited-file-modtime)
 121     (save-restriction
 122       (widen)
 123       (write-region (point-min) (point-max) file nil 'quiet))
 124     (set-buffer-modified-p nil)))
 125
 126 (provide 'resume)
 127
 128 ;;; arch-tag: c90b2761-4803-4e58-a0ae-c4721368b628
 129 ;;; resume.el ends here