438 lines
16 KiB
EmacsLisp
438 lines
16 KiB
EmacsLisp
;;; async.el --- Asynchronous processing in Emacs -*- lexical-binding: t -*-
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;; Copyright (C) 2012-2022 Free Software Foundation, Inc.
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;; Author: John Wiegley <jwiegley@gmail.com>
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;; Maintainer: Thierry Volpiatto <thievol@posteo.net>
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;; Created: 18 Jun 2012
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;; Version: 1.9.6
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;; Package-Requires: ((emacs "24.4"))
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;; Keywords: async
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;; X-URL: https://github.com/jwiegley/emacs-async
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;; This program 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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;; This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Adds the ability to call asynchronous functions and process with ease. See
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;; the documentation for `async-start' and `async-start-process'.
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;;; Code:
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(eval-when-compile (require 'cl-lib))
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(defgroup async nil
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"Simple asynchronous processing in Emacs"
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:group 'lisp)
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(defcustom async-variables-noprops-function #'async--purecopy
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"Default function to remove text properties in variables."
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:type 'function)
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(defvar async-debug nil)
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(defvar async-send-over-pipe t)
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(defvar async-in-child-emacs nil)
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(defvar async-callback nil)
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(defvar async-callback-for-process nil)
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(defvar async-callback-value nil)
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(defvar async-callback-value-set nil)
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(defvar async-current-process nil)
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(defvar async--procvar nil)
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;; For emacs<29 (only exists in emacs-29+).
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(defvar print-symbols-bare)
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(defun async--purecopy (object)
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"Remove text properties in OBJECT.
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Argument OBJECT may be a list or a string, if anything else it
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is returned unmodified."
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(cond ((stringp object)
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(substring-no-properties object))
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((consp object)
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(cl-loop for elm in object
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;; A string.
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if (stringp elm)
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collect (substring-no-properties elm)
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else
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;; Proper lists.
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if (and (consp elm) (null (cdr (last elm))))
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collect (async--purecopy elm)
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else
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;; Dotted lists.
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;; We handle here only dotted list where car and cdr
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;; are atoms i.e. (x . y) and not (x . (x . y)) or
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;; (x . (x y)) which should fit most cases.
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if (and (consp elm) (cdr (last elm)))
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collect (let ((key (car elm))
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(val (cdr elm)))
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(cons (if (stringp key)
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(substring-no-properties key)
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key)
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(if (stringp val)
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(substring-no-properties val)
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val)))
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else
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collect elm))
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(t object)))
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(defun async-inject-variables
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(include-regexp &optional predicate exclude-regexp noprops)
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"Return a `setq' form that replicates part of the calling environment.
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It sets the value for every variable matching INCLUDE-REGEXP and
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also PREDICATE. It will not perform injection for any variable
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matching EXCLUDE-REGEXP (if present) or representing a `syntax-table'
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i.e. ending by \"-syntax-table\".
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When NOPROPS is non nil it tries to strip out text properties of each
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variable's value with `async-variables-noprops-function'.
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It is intended to be used as follows:
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(async-start
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\\=`(lambda ()
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(require \\='smtpmail)
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(with-temp-buffer
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(insert ,(buffer-substring-no-properties (point-min) (point-max)))
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;; Pass in the variable environment for smtpmail
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,(async-inject-variables \"\\\\=`\\(smtpmail\\|\\(user-\\)?mail\\)-\")
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(smtpmail-send-it)))
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\\='ignore)"
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`(setq
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,@(let (bindings)
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(mapatoms
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(lambda (sym)
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(let* ((sname (and (boundp sym) (symbol-name sym)))
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(value (and sname (symbol-value sym))))
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(when (and sname
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(or (null include-regexp)
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(string-match include-regexp sname))
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(or (null exclude-regexp)
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(not (string-match exclude-regexp sname)))
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(not (string-match "-syntax-table\\'" sname)))
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(unless (or (stringp value)
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(memq value '(nil t))
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(numberp value)
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(vectorp value))
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(setq value `(quote ,value)))
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(when noprops
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(setq value (funcall async-variables-noprops-function
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value)))
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(when (or (null predicate)
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(funcall predicate sym))
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(setq bindings (cons value bindings)
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bindings (cons sym bindings)))))))
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bindings)))
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(defalias 'async-inject-environment 'async-inject-variables)
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(defun async-handle-result (func result buf)
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(if (null func)
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(progn
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(set (make-local-variable 'async-callback-value) result)
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(set (make-local-variable 'async-callback-value-set) t))
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(unwind-protect
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(if (and (listp result)
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(eq 'async-signal (nth 0 result)))
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(signal (car (nth 1 result))
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(cdr (nth 1 result)))
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(funcall func result))
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(unless async-debug
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(kill-buffer buf)))))
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(defun async-when-done (proc &optional _change)
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"Process sentinel used to retrieve the value from the child process."
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(when (eq 'exit (process-status proc))
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(with-current-buffer (process-buffer proc)
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(let ((async-current-process proc))
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(if (= 0 (process-exit-status proc))
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(if async-callback-for-process
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(if async-callback
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(prog1
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(funcall async-callback proc)
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(unless async-debug
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(kill-buffer (current-buffer))))
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(set (make-local-variable 'async-callback-value) proc)
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(set (make-local-variable 'async-callback-value-set) t))
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;; Maybe strip out unreadable "#"; They are replaced by
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;; empty string unless they are prefixing a special
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;; object like a marker. See issue #145.
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(goto-char (point-min))
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(save-excursion
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;; Transform markers in list like
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;; (marker (moves after insertion) at 2338 in
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;; test\.org) so that remap text properties function
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;; can parse it to restitute marker.
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(while (re-search-forward "#<\\([^>]*\\)>" nil t)
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(replace-match (concat "(" (match-string 1) ")") t t)))
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(while (re-search-forward "#(" nil t)
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(replace-match "(" t t))
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(goto-char (point-max))
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(backward-sexp)
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(async-handle-result async-callback (read (current-buffer))
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(current-buffer)))
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(set (make-local-variable 'async-callback-value)
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(list 'error
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(format "Async process '%s' failed with exit code %d"
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(process-name proc) (process-exit-status proc))))
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(set (make-local-variable 'async-callback-value-set) t))))))
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(defun async--receive-sexp (&optional stream)
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;; FIXME: Why use `utf-8-auto' instead of `utf-8-unix'? This is
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;; a communication channel over which we have complete control,
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;; so we get to choose exactly which encoding and EOL we use, isn't it?
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(let ((sexp (decode-coding-string (base64-decode-string (read stream))
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'utf-8-auto))
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;; Parent expects UTF-8 encoded text.
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(coding-system-for-write 'utf-8-auto))
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(if async-debug
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(message "Received sexp {{{%s}}}" (pp-to-string sexp)))
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(setq sexp (read sexp))
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(if async-debug
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(message "Read sexp {{{%s}}}" (pp-to-string sexp)))
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(eval sexp t)))
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(defun async--insert-sexp (sexp)
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(let (print-level
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print-length
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(print-escape-nonascii t)
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(print-circle t)
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;; Fix bug#153 in emacs-29 with symbol's positions.
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(print-symbols-bare t))
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(prin1 sexp (current-buffer))
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;; Just in case the string we're sending might contain EOF
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(encode-coding-region (point-min) (point-max) 'utf-8-auto)
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(base64-encode-region (point-min) (point-max) t)
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(goto-char (point-min)) (insert ?\")
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(goto-char (point-max)) (insert ?\" ?\n)))
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(defun async--transmit-sexp (process sexp)
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(with-temp-buffer
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(if async-debug
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(message "Transmitting sexp {{{%s}}}" (pp-to-string sexp)))
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(async--insert-sexp sexp)
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(process-send-region process (point-min) (point-max))))
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(defun async-batch-invoke ()
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"Called from the child Emacs process' command line."
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;; Make sure 'message' and 'prin1' encode stuff in UTF-8, as parent
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;; process expects.
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(let ((coding-system-for-write 'utf-8-auto)
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(args-left command-line-args-left))
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(setq async-in-child-emacs t
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debug-on-error async-debug
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command-line-args-left nil)
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(condition-case-unless-debug err
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(prin1 (funcall
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(async--receive-sexp (unless async-send-over-pipe
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args-left))))
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(error
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(prin1 (list 'async-signal err))))))
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(defun async-ready (future)
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"Query a FUTURE to see if it is ready.
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I.e., if no blocking would result from a call to `async-get' on that FUTURE."
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(and (memq (process-status future) '(exit signal))
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(let ((buf (process-buffer future)))
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(if (buffer-live-p buf)
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(with-current-buffer buf
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async-callback-value-set)
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t))))
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(defun async-wait (future)
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"Wait for FUTURE to become ready."
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(while (not (async-ready future))
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(sleep-for 0.05)))
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(defun async-get (future)
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"Get the value from process FUTURE when it is ready.
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FUTURE is returned by `async-start' or `async-start-process' when
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its FINISH-FUNC is nil."
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(and future (async-wait future))
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(let ((buf (process-buffer future)))
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(when (buffer-live-p buf)
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(with-current-buffer buf
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(async-handle-result
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#'identity async-callback-value (current-buffer))))))
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(defun async-message-p (value)
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"Return non-nil of VALUE is an async.el message packet."
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(and (listp value)
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(plist-get value :async-message)))
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(defun async-send (&rest args)
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"Send the given messages to the asychronous Emacs PROCESS."
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(let ((args (append args '(:async-message t))))
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(if async-in-child-emacs
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(if async-callback
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(funcall async-callback args))
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(async--transmit-sexp (car args) (list 'quote (cdr args))))))
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(defun async-receive ()
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"Send the given messages to the asychronous Emacs PROCESS."
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(async--receive-sexp))
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;;;###autoload
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(defun async-start-process (name program finish-func &rest program-args)
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"Start the executable PROGRAM asynchronously named NAME. See `async-start'.
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PROGRAM is passed PROGRAM-ARGS, calling FINISH-FUNC with the
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process object when done. If FINISH-FUNC is nil, the future
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object will return the process object when the program is
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finished. Set DEFAULT-DIRECTORY to change PROGRAM's current
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working directory."
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(let* ((buf (generate-new-buffer (concat "*" name "*")))
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(proc (let ((process-connection-type nil))
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(apply #'start-process name buf program program-args))))
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(with-current-buffer buf
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(set (make-local-variable 'async-callback) finish-func)
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(set-process-sentinel proc #'async-when-done)
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(unless (string= name "emacs")
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(set (make-local-variable 'async-callback-for-process) t))
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proc)))
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(defvar async-quiet-switch "-Q"
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"The Emacs parameter to use to call emacs without config.
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Can be one of \"-Q\" or \"-q\".
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Default is \"-Q\" but it is sometimes useful to use \"-q\" to have a
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enhanced config or some more variables loaded.")
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;;;###autoload
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(defun async-start (start-func &optional finish-func)
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"Execute START-FUNC (often a lambda) in a subordinate Emacs process.
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When done, the return value is passed to FINISH-FUNC. Example:
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(async-start
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;; What to do in the child process
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(lambda ()
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(message \"This is a test\")
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(sleep-for 3)
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222)
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;; What to do when it finishes
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(lambda (result)
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(message \"Async process done, result should be 222: %s\"
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result)))
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If FINISH-FUNC is nil or missing, a future is returned that can
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be inspected using `async-get', blocking until the value is
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ready. Example:
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(let ((proc (async-start
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;; What to do in the child process
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(lambda ()
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(message \"This is a test\")
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(sleep-for 3)
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222))))
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(message \"I'm going to do some work here\") ;; ....
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(message \"Waiting on async process, result should be 222: %s\"
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(async-get proc)))
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If you don't want to use a callback, and you don't care about any
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return value from the child process, pass the `ignore' symbol as
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the second argument (if you don't, and never call `async-get', it
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will leave *emacs* process buffers hanging around):
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(async-start
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(lambda ()
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(delete-file \"a remote file on a slow link\" nil))
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\\='ignore)
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Special case:
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If the output of START-FUNC is a string with properties
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e.g. (buffer-string) RESULT will be transformed in a list where the
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car is the string itself (without props) and the cdr the rest of
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properties, this allows using in FINISH-FUNC the string without
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properties and then apply the properties in cdr to this string (if
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needed).
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Properties handling special objects like markers are returned as
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list to allow restoring them later.
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See <https://github.com/jwiegley/emacs-async/issues/145> for more infos.
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Note: Even when FINISH-FUNC is present, a future is still
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returned except that it yields no value (since the value is
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passed to FINISH-FUNC). Call `async-get' on such a future always
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returns nil. It can still be useful, however, as an argument to
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`async-ready' or `async-wait'."
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(let ((sexp start-func)
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;; Subordinate Emacs will send text encoded in UTF-8.
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(coding-system-for-read 'utf-8-auto))
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(setq async--procvar
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(async-start-process
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"emacs" (file-truename
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(expand-file-name invocation-name
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invocation-directory))
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finish-func
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async-quiet-switch "-l"
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;; Using `locate-library' ensure we use the right file
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;; when the .elc have been deleted.
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(locate-library "async")
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"-batch" "-f" "async-batch-invoke"
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(if async-send-over-pipe
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"<none>"
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(with-temp-buffer
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(async--insert-sexp (list 'quote sexp))
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(buffer-string)))))
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(if async-send-over-pipe
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(async--transmit-sexp async--procvar (list 'quote sexp)))
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async--procvar))
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(defmacro async-sandbox(func)
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"Evaluate FUNC in a separate Emacs process, synchronously."
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`(async-get (async-start ,func)))
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(defun async--fold-left (fn forms bindings)
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(let ((res forms))
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(dolist (binding bindings)
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(setq res (funcall fn res
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(if (listp binding)
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binding
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(list binding)))))
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res))
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(defmacro async-let (bindings &rest forms)
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"Implements `let', but each binding is established asynchronously.
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For example:
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(async-let ((x (foo))
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(y (bar)))
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(message \"%s %s\" x y))
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expands to ==>
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(async-start (foo)
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(lambda (x)
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(async-start (bar)
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(lambda (y)
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(message \"%s %s\" x y)))))"
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(declare (indent 1))
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(async--fold-left
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(lambda (acc binding)
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(let ((fun (pcase (cadr binding)
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((and (pred functionp) f) f)
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(f `(lambda () ,f)))))
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`(async-start ,fun
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(lambda (,(car binding))
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,acc))))
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`(progn ,@forms)
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(reverse bindings)))
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(provide 'async)
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;;; async.el ends here
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