4.4BSD/usr/src/contrib/emacs-18.57/lisp/server.el
;; Lisp code for GNU Emacs running as server process.
;; Copyright (C) 1986, 1987, 1990 Free Software Foundation, Inc.
;; Author William Sommerfeld, wesommer@athena.mit.edu.
;; Changes by peck@sun.com and by rms.
;; 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 1, 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, 675 Mass Ave, Cambridge, MA 02139, USA.
;;; This Lisp code is run in Emacs when it is to operate as
;;; a server for other processes.
;;; Load this library and do M-x server-edit to enable Emacs as a server.
;;; Emacs runs the program ../etc/server as a subprocess
;;; for communication with clients. If there are no client buffers to edit,
;;; server-edit acts like (switch-to-buffer (other-buffer))
;;; When some other program runs "the editor" to edit a file,
;;; "the editor" can be the Emacs client program ../etc/emacsclient.
;;; This program transmits the file names to Emacs through
;;; the server subprocess, and Emacs visits them and lets you edit them.
;;; Note that any number of clients may dispatch files to emacs to be edited.
;;; When you finish editing a Server buffer, again call server-edit
;;; to mark that buffer as done for the client and switch to the next
;;; Server buffer. When all the buffers for a client have been edited
;;; and exited with server-edit, the client "editor" will return
;;; to the program that invoked it.
;;; Your editing commands and Emacs's display output go to and from
;;; the terminal in the usual way. Thus, server operation is possible
;;; only when Emacs can talk to the terminal at the time you invoke
;;; the client. This is possible in two cases:
;;; 1. On a window system, where Emacs runs in one window and the
;;; program that wants to use "the editor" runs in another.
;;; 2. When the program that wants to use "the editor" is running
;;; as a subprocess of Emacs.
;;; The buffer local variable "server-buffer-clients" lists
;;; the clients who are waiting for this buffer to be edited.
;;; The global variable "server-clients" lists all the waiting clients,
;;; and which files are yet to be edited for each.
(defvar server-program "server"
"*The program to use as the edit server")
(defvar server-process nil
"the current server process")
(defvar server-previous-string "")
(defvar server-clients nil
"List of current server clients.
Each element is (CLIENTID FILES...) where CLIENTID is a string
that can be given to the server process to identify a client.
When a buffer is marked as \"done\", it is removed from this list.")
(defvar server-buffer-clients nil
"List of clientids for clients requesting editing of current buffer.")
(make-variable-buffer-local 'server-buffer-clients)
(setq-default server-buffer-clients nil)
(or (assq 'server-buffer-clients minor-mode-alist)
(setq minor-mode-alist (cons '(server-buffer-clients " Server") minor-mode-alist)))
;; If a *server* buffer exists,
;; write STRING to it for logging purposes.
(defun server-log (string)
(if (get-buffer "*server*")
(save-excursion
(set-buffer "*server*")
(goto-char (point-max))
(insert string)
(or (bobp) (newline)))))
(defun server-sentinel (proc msg)
(cond ((eq (process-status proc) 'exit)
(server-log (message "Server subprocess exited")))
((eq (process-status proc) 'signal)
(server-log (message "Server subprocess killed")))))
(defun server-start (&optional leave-dead)
"Allow this Emacs process to be a server for client processes.
This starts a server communications subprocess through which
client \"editors\" can send your editing commands to this Emacs job.
To use the server, set up the program `etc/emacsclient' in the
Emacs distribution as your standard \"editor\".
Prefix arg means just kill any existing server communications subprocess."
(interactive "P")
;; kill it dead!
(if server-process
(progn
(set-process-sentinel server-process nil)
(condition-case () (delete-process server-process) (error nil))))
(condition-case () (delete-file "~/.emacs_server") (error nil))
;; If we already had a server, clear out associated status.
(while server-clients
(let ((buffer (nth 1 (car server-clients))))
(server-buffer-done buffer)))
(if leave-dead
nil
(if server-process
(server-log (message "Restarting server")))
(setq server-process (start-process "server" nil server-program))
(set-process-sentinel server-process 'server-sentinel)
(set-process-filter server-process 'server-process-filter)
(process-kill-without-query server-process)))
;Process a request from the server to edit some files.
;Format of STRING is "Client: CLIENTID PATH PATH PATH... \n"
(defun server-process-filter (proc string)
(server-log string)
(setq string (concat server-previous-string string))
(if (not (and (eq ?\n (aref string (1- (length string))))
(eq 0 (string-match "Client: " string))))
;; If input is not complete, save it for later.
(setq server-previous-string string)
;; If it is complete, process it now, and discard what was saved.
(setq string (substring string (match-end 0)))
(setq server-previous-string "")
(let ((client (list (substring string 0 (string-match " " string))))
(files nil)
(lineno 1))
(setq string (substring string (match-end 0)))
(while (string-match "[^ ]+ " string)
(let ((arg
(substring string (match-beginning 0) (1- (match-end 0)))))
(setq string (substring string (match-end 0)))
(if (string-match "\\`\\+[0-9]+\\'" arg)
(setq lineno (read (substring arg 1)))
(setq files
(cons (list arg lineno)
files))
(setq lineno 1))))
(server-visit-files files client)
;; CLIENT is now a list (CLIENTNUM BUFFERS...)
(setq server-clients (cons client server-clients))
(switch-to-buffer (nth 1 client))
(message (substitute-command-keys
"When done with a buffer, type \\[server-edit].")))))
(defun server-visit-files (files client)
"Finds FILES and returns the list CLIENT with the buffers nconc'd.
FILES is an alist whose elements are (FILENAME LINENUMBER)."
(let (client-record)
(while files
(save-excursion
;; If there is an existing buffer modified or the file is modified,
;; revert it.
;; If there is an existing buffer with deleted file, offer to write it.
(let* ((filen (car (car files)))
(obuf (get-file-buffer filen)))
(if (and obuf (set-buffer obuf))
(if (file-exists-p filen)
(if (or (not (verify-visited-file-modtime obuf))
(buffer-modified-p obuf))
(revert-buffer t nil))
(if (y-or-n-p
(concat "File no longer exists: "
filen
", write buffer to file? "))
(write-file filen)))
(set-buffer (find-file-noselect filen))))
(goto-line (nth 1 (car files)))
(setq server-buffer-clients (cons (car client) server-buffer-clients))
(setq client-record (cons (current-buffer) client-record)))
(setq files (cdr files)))
(nconc client client-record)))
(defun server-buffer-done (buffer)
"Mark BUFFER as \"done\" for its client(s).
Buries the buffer, and returns another server buffer
as a suggestion for what to select next."
(let ((running (eq (process-status server-process) 'run))
(next-buffer nil)
(old-clients server-clients))
(while old-clients
(let ((client (car old-clients)))
(or next-buffer
(setq next-buffer (nth 1 (memq buffer client))))
(delq buffer client)
;; If client now has no pending buffers,
;; tell it that it is done, and forget it entirely.
(if (cdr client) nil
(if running
(progn
(send-string server-process
(format "Close: %s Done\n" (car client)))
(server-log (format "Close: %s Done\n" (car client)))))
(setq server-clients (delq client server-clients))))
(setq old-clients (cdr old-clients)))
(if (buffer-name buffer)
(save-excursion
(set-buffer buffer)
(setq server-buffer-clients nil)))
(bury-buffer buffer)
next-buffer))
(defun mh-draft-p (buffer)
"Return non-nil if this BUFFER is an mh <draft> file.
Since MH deletes draft *BEFORE* it is edited, the server treats them specially."
;; This may not be appropriately robust for all cases.
(string= (buffer-name buffer) "draft"))
(defun server-done ()
"Offer to save current buffer, mark it as \"done\" for clients,
bury it, and return a suggested buffer to select next."
(let ((buffer (current-buffer)))
(if server-buffer-clients
(progn
(if (mh-draft-p buffer)
(progn (save-buffer)
(write-region (point-min) (point-max)
(concat buffer-file-name "~"))
(kill-buffer buffer))
(if (and (buffer-modified-p)
(y-or-n-p (concat "Save file " buffer-file-name "? ")))
(save-buffer buffer)))
(server-buffer-done buffer)))))
(defun server-edit (&optional arg)
"Switch to next server editing buffer; say \"Done\" for current buffer.
If a server buffer is current, it is marked \"done\" and optionally saved.
MH <draft> files are always saved and backed up, no questions asked.
When all of a client's buffers are marked as \"done\", the client is notified.
If invoked with a prefix argument, or if there is no server process running,
starts server process and that is all. Invoked by \\[server-edit]."
(interactive "P")
(if (or arg
(not server-process)
(memq (process-status server-process) '(signal exit)))
(server-start nil)
(server-switch-buffer (server-done))))
(defun server-switch-buffer (next-buffer)
"Switch to another buffer, preferably one that has a client.
Arg NEXT-BUFFER is a suggestion; if it is a live buffer, use it."
(if next-buffer
(if (and (bufferp next-buffer)
(buffer-name next-buffer))
(switch-to-buffer next-buffer)
;; If NEXT-BUFFER is a dead buffer,
;; remove the server records for it
;; and try the next surviving server buffer.
(server-switch-buffer
(server-buffer-done next-buffer)))
(if server-clients
(server-switch-buffer (nth 1 (car server-clients)))
(switch-to-buffer (other-buffer)))))
(global-set-key "\C-x#" 'server-edit)