;;; tq.el --- utility to maintain a transaction queue
;; Copyright (C) 1985, 1986, 1987, 1992 Free Software Foundation, Inc.
;; Author: Scott Draves <firstname.lastname@example.org>
;; Adapted-By: ESR
;; Keywords: extensions
;; This file is part of XEmacs.
;; XEmacs 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.
;; XEmacs 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 XEmacs; see the file COPYING. If not, write to the Free
;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
;; 02111-1307, USA.
;;; Synched up with: FSF 21.3.
;;; manages receiving a stream asynchronously,
;;; parsing it into transactions, and then calling
;;; handler functions
;;; Our basic structure is the queue/process/buffer triple. Each entry
;;; of the queue is a regexp/closure/function triple. We buffer
;;; bytes from the process until we see the regexp at the head of the
;;; queue. Then we call the function with the closure and the
;;; collected bytes.
(defun tq-create (process)
"Create and return a transaction queue communicating with PROCESS.
PROCESS should be a subprocess capable of sending and receiving
streams of bytes. It may be a local process, or it may be connected
to a tcp server on another machine."
(let ((tq (cons nil (cons process
(concat " tq-temp-"
`(lambda (proc string)
(tq-filter ',tq string)))
(defun tq-queue (tq) (car tq))
(defun tq-process (tq) (car (cdr tq)))
(defun tq-buffer (tq) (cdr (cdr tq)))
(defun tq-queue-add (tq re closure fn)
(setcar tq (nconc (tq-queue tq)
(cons (cons re (cons closure fn)) nil)))
(defun tq-queue-head-regexp (tq) (car (car (tq-queue tq))))
(defun tq-queue-head-fn (tq) (cdr (cdr (car (tq-queue tq)))))
(defun tq-queue-head-closure (tq) (car (cdr (car (tq-queue tq)))))
(defun tq-queue-empty (tq) (not (tq-queue tq)))
(defun tq-queue-pop (tq) (setcar tq (cdr (car tq))) (null (car tq)))
;;; must add to queue before sending!
(defun tq-enqueue (tq question regexp closure fn)
"Add a transaction to transaction queue TQ.
This sends the string QUESTION to the process that TQ communicates with.
When the corresponding answer comes back, we call FN
with two arguments: CLOSURE, and the answer to the question.
REGEXP is a regular expression to match the entire answer;
that's how we tell where the answer ends."
(tq-queue-add tq regexp closure fn)
(process-send-string (tq-process tq) question))
(defun tq-close (tq)
"Shut down transaction queue TQ, terminating the process."
(delete-process (tq-process tq))
(kill-buffer (tq-buffer tq)))
(defun tq-filter (tq string)
"Append STRING to the TQ's buffer; then process the new data."
(with-current-buffer (tq-buffer tq)
(defun tq-process-buffer (tq)
"Check TQ's buffer for the regexp at the head of the queue."
(set-buffer (tq-buffer tq))
(if (= 0 (buffer-size)) ()
(if (tq-queue-empty tq)
(let ((buf (generate-new-buffer "*spurious*")))
(copy-to-buffer buf (point-min) (point-max))
(delete-region (point-min) (point))
(pop-to-buffer buf nil)
(error "Spurious communication from process %s, see buffer %s"
(process-name (tq-process tq))
(if (re-search-forward (tq-queue-head-regexp tq) nil t)
(let ((answer (buffer-substring (point-min) (point))))
(delete-region (point-min) (point))
(funcall (tq-queue-head-fn tq)
;;; tq.el ends here