;;; tq.el --- utility to maintain a transaction queue
-;; Copyright (C) 1985, 1986, 1987, 1992 Free Software Foundation, Inc.
+;; Copyright (C) 1985, 1986, 1987, 1992, 2001, 2002, 2003, 2004,
+;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
;; Author: Scott Draves <spot@cs.cmu.edu>
+;; Maintainer: FSF
;; Adapted-By: ESR
;; Keywords: extensions
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; 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.
+;; the Free Software Foundation, either version 3 of the License, 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
;; 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.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
-
-;;; 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.
+;; This file manages receiving a stream asynchronously, parsing it
+;; into transactions, and then calling the associated handler function
+;; upon the completion of each transaction.
+
+;; Our basic structure is the queue/process/buffer triple. Each entry
+;; of the queue part is a list of question, regexp, closure, and
+;; function that is consed to the last element.
+
+;; A transaction queue may be created by calling `tq-create'.
+
+;; A request may be added to the queue by calling `tq-enqueue'. If
+;; the `delay-question' argument is non-nil, we will wait to send the
+;; question to the process until it has finished sending other input.
+;; Otherwise, once a request is enqueued, we send the given question
+;; immediately to the process.
+
+;; We then buffer bytes from the process until we see the regexp that
+;; was provided in the call to `tq-enqueue'. Then we call the
+;; provided function with the closure and the collected bytes. If we
+;; have indicated that the question from the next transaction was not
+;; sent immediately, send it at this point, awaiting the response.
;;; Code:
+;;; Accessors
+
+;; This part looks like (queue . (process . buffer))
+(defun tq-queue (tq) (car tq))
+(defun tq-process (tq) (car (cdr tq)))
+(defun tq-buffer (tq) (cdr (cdr tq)))
+
+;; The structure of `queue' is as follows
+;; ((question regexp closure . fn)
+;; <other queue entries>)
+;; question: string to send to the process
+(defun tq-queue-head-question (tq) (car (car (tq-queue tq))))
+;; regexp: regular expression that matches the end of a response from
+;; the process
+(defun tq-queue-head-regexp (tq) (car (cdr (car (tq-queue tq)))))
+;; closure: additional data to pass to the function
+(defun tq-queue-head-closure (tq) (car (cdr (cdr (car (tq-queue tq))))))
+;; fn: function to call upon receiving a complete response from the
+;; process
+(defun tq-queue-head-fn (tq) (cdr (cdr (cdr (car (tq-queue tq))))))
+
+;; Determine whether queue is empty
+(defun tq-queue-empty (tq) (not (tq-queue tq)))
+
+;;; Core functionality
+
;;;###autoload
(defun tq-create (process)
"Create and return a transaction queue communicating with PROCESS.
(generate-new-buffer
(concat " tq-temp-"
(process-name process)))))))
+ (buffer-disable-undo (tq-buffer tq))
(set-process-filter process
- (`(lambda (proc string)
- (tq-filter '(, tq) string))))
+ `(lambda (proc string)
+ (tq-filter ',tq string)))
tq))
-;;; accessors
-(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)
+(defun tq-queue-add (tq question re closure fn)
(setcar tq (nconc (tq-queue tq)
- (cons (cons re (cons closure fn)) nil)))
+ (cons (cons question (cons re (cons closure fn))) nil)))
'ok)
-(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)))
-
+(defun tq-queue-pop (tq)
+ (setcar tq (cdr (car tq)))
+ (let ((question (tq-queue-head-question tq)))
+ (condition-case nil
+ (process-send-string (tq-process tq) question)
+ (error nil)))
+ (null (car tq)))
-;;; must add to queue before sending!
-(defun tq-enqueue (tq question regexp closure fn)
+(defun tq-enqueue (tq question regexp closure fn &optional delay-question)
"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.
+
+When the corresponding answer comes back, we call FN with two
+arguments: CLOSURE, which may contain additional data that FN
+needs, 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))
+that's how we tell where the answer ends.
+
+If DELAY-QUESTION is non-nil, delay sending this question until
+the process has finished replying to any previous questions.
+This produces more reliable results with some processes."
+ (let ((sendp (or (not delay-question)
+ (not (tq-queue tq)))))
+ (tq-queue-add tq (unless sendp question) regexp closure fn)
+ (when sendp
+ (process-send-string (tq-process tq) question))))
(defun tq-close (tq)
"Shut down transaction queue TQ, terminating the process."
(defun tq-filter (tq string)
"Append STRING to the TQ's buffer; then process the new data."
- (set-buffer (tq-buffer tq))
- (goto-char (point-max))
- (insert string)
- (tq-process-buffer tq))
+ (let ((buffer (tq-buffer tq)))
+ (when (buffer-live-p buffer)
+ (with-current-buffer buffer
+ (goto-char (point-max))
+ (insert string)
+ (tq-process-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 (concat "Spurious communication from process "
- (process-name (tq-process tq))
- ", see buffer " (buffer-name buf) ".")))
- (goto-char (point-min))
- (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-queue-head-closure tq)
- answer)
- (tq-queue-pop tq)
- (tq-process-buffer tq))))))
+ (let ((buffer (tq-buffer tq)))
+ (when (buffer-live-p buffer)
+ (set-buffer buffer)
+ (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))
+ (buffer-name buf)))
+ (goto-char (point-min))
+ (if (re-search-forward (tq-queue-head-regexp tq) nil t)
+ (let ((answer (buffer-substring (point-min) (point))))
+ (delete-region (point-min) (point))
+ (unwind-protect
+ (condition-case nil
+ (funcall (tq-queue-head-fn tq)
+ (tq-queue-head-closure tq)
+ answer)
+ (error nil))
+ (tq-queue-pop tq))
+ (tq-process-buffer tq))))))))
(provide 'tq)
+;; arch-tag: 65dea08c-4edd-4cde-83a5-e8a15b993b79
;;; tq.el ends here