mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-15 09:47:20 +00:00
6bfd7cd07a
An earlier version of this function returned the value, ref http://lists.gnu.org/archive/html/emacs-devel/2011-05/msg00708.html but now it returns the function (see commentary).
101 lines
3.5 KiB
EmacsLisp
101 lines
3.5 KiB
EmacsLisp
;;; url-future.el --- general futures facility for url.el
|
|
|
|
;; Copyright (C) 2011-2013 Free Software Foundation, Inc.
|
|
|
|
;; Author: Teodor Zlatanov <tzz@lifelogs.com>
|
|
;; Keywords: data
|
|
|
|
;; 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 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
|
|
;; 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. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
;;; Commentary:
|
|
|
|
;; Make a url-future (basically a defstruct):
|
|
;; (make-url-future :value (lambda () (calculation goes here))
|
|
;; :callback (lambda (future) (use future on success))
|
|
;; :errorback (lambda (future &rest error) (error handler)))
|
|
|
|
;; Then either call it with `url-future-call' or cancel it with
|
|
;; `url-future-cancel'. Generally the functions will return the
|
|
;; future itself, not the value it holds. Also the functions will
|
|
;; throw a url-future-already-done error if you try to call or cancel
|
|
;; a future more than once.
|
|
|
|
;; So, to get the value:
|
|
;; (when (url-future-completed-p future) (url-future-value future))
|
|
|
|
;; See `url-future-tests' and the code below for further details.
|
|
|
|
;;; Code:
|
|
|
|
(eval-when-compile (require 'cl-lib))
|
|
|
|
(cl-defstruct url-future callback errorback status value)
|
|
|
|
(defmacro url-future-done-p (url-future)
|
|
`(url-future-status ,url-future))
|
|
|
|
(defmacro url-future-completed-p (url-future)
|
|
`(eq (url-future-status ,url-future) t))
|
|
|
|
(defmacro url-future-errored-p (url-future)
|
|
`(eq (url-future-status ,url-future) 'error))
|
|
|
|
(defmacro url-future-cancelled-p (url-future)
|
|
`(eq (url-future-status ,url-future) 'cancel))
|
|
|
|
(defun url-future-finish (url-future &optional status)
|
|
(if (url-future-done-p url-future)
|
|
(signal 'error 'url-future-already-done)
|
|
(setf (url-future-status url-future) (or status t))
|
|
;; the status must be such that the future was completed
|
|
;; to run the callback
|
|
(when (url-future-completed-p url-future)
|
|
(funcall (or (url-future-callback url-future) 'ignore)
|
|
url-future))
|
|
url-future))
|
|
|
|
(defun url-future-errored (url-future errorcons)
|
|
(if (url-future-done-p url-future)
|
|
(signal 'error 'url-future-already-done)
|
|
(setf (url-future-status url-future) 'error)
|
|
(setf (url-future-value url-future) errorcons)
|
|
(funcall (or (url-future-errorback url-future) 'ignore)
|
|
url-future errorcons)))
|
|
|
|
(defun url-future-call (url-future)
|
|
(if (url-future-done-p url-future)
|
|
(signal 'error 'url-future-already-done)
|
|
(let ((ff (url-future-value url-future)))
|
|
(when (functionp ff)
|
|
(condition-case catcher
|
|
(setf (url-future-value url-future)
|
|
(funcall ff))
|
|
(error (url-future-errored url-future catcher)))
|
|
;; Unused return value.
|
|
;;; (url-future-value url-future)
|
|
))
|
|
(if (url-future-errored-p url-future)
|
|
url-future
|
|
(url-future-finish url-future))))
|
|
|
|
(defun url-future-cancel (url-future)
|
|
(if (url-future-done-p url-future)
|
|
(signal 'error 'url-future-already-done)
|
|
(url-future-finish url-future 'cancel)))
|
|
|
|
(provide 'url-future)
|
|
;;; url-future.el ends here
|