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172 lines
6.1 KiB
EmacsLisp
172 lines
6.1 KiB
EmacsLisp
;;; tq.el --- utility to maintain a transaction queue
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;; Copyright (C) 1985, 1986, 1987, 1992, 2001, 2002, 2003, 2004,
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;; 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
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;; Author: Scott Draves <spot@cs.cmu.edu>
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;; Maintainer: FSF
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;; Adapted-By: ESR
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;; Keywords: extensions
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This file manages receiving a stream asynchronously, parsing it
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;; into transactions, and then calling the associated handler function
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;; upon the completion of each transaction.
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;; Our basic structure is the queue/process/buffer triple. Each entry
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;; of the queue part is a list of question, regexp, closure, and
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;; function that is consed to the last element.
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;; A transaction queue may be created by calling `tq-create'.
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;; A request may be added to the queue by calling `tq-enqueue'. If
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;; the `delay-question' argument is non-nil, we will wait to send the
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;; question to the process until it has finished sending other input.
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;; Otherwise, once a request is enqueued, we send the given question
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;; immediately to the process.
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;; We then buffer bytes from the process until we see the regexp that
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;; was provided in the call to `tq-enqueue'. Then we call the
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;; provided function with the closure and the collected bytes. If we
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;; have indicated that the question from the next transaction was not
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;; sent immediately, send it at this point, awaiting the response.
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;;; Code:
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;;; Accessors
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;; This part looks like (queue . (process . buffer))
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(defun tq-queue (tq) (car tq))
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(defun tq-process (tq) (car (cdr tq)))
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(defun tq-buffer (tq) (cdr (cdr tq)))
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;; The structure of `queue' is as follows
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;; ((question regexp closure . fn)
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;; <other queue entries>)
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;; question: string to send to the process
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(defun tq-queue-head-question (tq) (car (car (tq-queue tq))))
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;; regexp: regular expression that matches the end of a response from
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;; the process
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(defun tq-queue-head-regexp (tq) (car (cdr (car (tq-queue tq)))))
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;; closure: additional data to pass to the function
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(defun tq-queue-head-closure (tq) (car (cdr (cdr (car (tq-queue tq))))))
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;; fn: function to call upon receiving a complete response from the
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;; process
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(defun tq-queue-head-fn (tq) (cdr (cdr (cdr (car (tq-queue tq))))))
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;; Determine whether queue is empty
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(defun tq-queue-empty (tq) (not (tq-queue tq)))
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;;; Core functionality
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;;;###autoload
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(defun tq-create (process)
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"Create and return a transaction queue communicating with PROCESS.
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PROCESS should be a subprocess capable of sending and receiving
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streams of bytes. It may be a local process, or it may be connected
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to a tcp server on another machine."
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(let ((tq (cons nil (cons process
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(generate-new-buffer
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(concat " tq-temp-"
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(process-name process)))))))
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(buffer-disable-undo (tq-buffer tq))
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(set-process-filter process
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`(lambda (proc string)
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(tq-filter ',tq string)))
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tq))
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(defun tq-queue-add (tq question re closure fn)
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(setcar tq (nconc (tq-queue tq)
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(cons (cons question (cons re (cons closure fn))) nil)))
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'ok)
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(defun tq-queue-pop (tq)
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(setcar tq (cdr (car tq)))
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(let ((question (tq-queue-head-question tq)))
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(condition-case nil
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(process-send-string (tq-process tq) question)
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(error nil)))
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(null (car tq)))
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(defun tq-enqueue (tq question regexp closure fn &optional delay-question)
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"Add a transaction to transaction queue TQ.
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This sends the string QUESTION to the process that TQ communicates with.
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When the corresponding answer comes back, we call FN with two
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arguments: CLOSURE, which may contain additional data that FN
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needs, and the answer to the question.
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REGEXP is a regular expression to match the entire answer;
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that's how we tell where the answer ends.
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If DELAY-QUESTION is non-nil, delay sending this question until
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the process has finished replying to any previous questions.
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This produces more reliable results with some processes."
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(let ((sendp (or (not delay-question)
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(not (tq-queue tq)))))
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(tq-queue-add tq (unless sendp question) regexp closure fn)
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(when sendp
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(process-send-string (tq-process tq) question))))
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(defun tq-close (tq)
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"Shut down transaction queue TQ, terminating the process."
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(delete-process (tq-process tq))
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(kill-buffer (tq-buffer tq)))
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(defun tq-filter (tq string)
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"Append STRING to the TQ's buffer; then process the new data."
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(let ((buffer (tq-buffer tq)))
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(when (buffer-live-p buffer)
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(with-current-buffer buffer
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(goto-char (point-max))
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(insert string)
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(tq-process-buffer tq)))))
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(defun tq-process-buffer (tq)
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"Check TQ's buffer for the regexp at the head of the queue."
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(let ((buffer (tq-buffer tq)))
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(when (buffer-live-p buffer)
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(set-buffer buffer)
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(if (= 0 (buffer-size)) ()
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(if (tq-queue-empty tq)
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(let ((buf (generate-new-buffer "*spurious*")))
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(copy-to-buffer buf (point-min) (point-max))
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(delete-region (point-min) (point))
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(pop-to-buffer buf nil)
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(error "Spurious communication from process %s, see buffer %s"
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(process-name (tq-process tq))
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(buffer-name buf)))
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(goto-char (point-min))
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(if (re-search-forward (tq-queue-head-regexp tq) nil t)
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(let ((answer (buffer-substring (point-min) (point))))
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(delete-region (point-min) (point))
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(unwind-protect
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(condition-case nil
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(funcall (tq-queue-head-fn tq)
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(tq-queue-head-closure tq)
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answer)
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(error nil))
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(tq-queue-pop tq))
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(tq-process-buffer tq))))))))
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(provide 'tq)
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;; arch-tag: 65dea08c-4edd-4cde-83a5-e8a15b993b79
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;;; tq.el ends here
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