lisp/gnus/nnoo.el

   1 ;;; nnoo.el --- OO Gnus Backends
   2
   3 ;; Copyright (C) 1996-2017 Free Software Foundation, Inc.
   4
   5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
   6 ;; Keywords: news
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software: you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation, either version 3 of the License, or
  13 ;; (at your option) any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;;; Code:
  26
  27 (require 'nnheader)
  28 (eval-when-compile (require 'cl))
  29
  30 (defvar nnoo-definition-alist nil)
  31 (defvar nnoo-state-alist nil)
  32 (defvar nnoo-parent-backend nil)
  33
  34 (defmacro defvoo (var init &optional doc &rest map)
  35   "The same as `defvar', only takes list of variables to MAP to."
  36   `(prog1
  37        ,(if doc
  38             `(defvar ,var ,init ,(concat doc "\n\nThis is a Gnus server variable.  See Info node `(gnus)Select Methods'."))
  39           `(defvar ,var ,init))
  40      (nnoo-define ',var ',map)))
  41 (put 'defvoo 'lisp-indent-function 2)
  42 (put 'defvoo 'edebug-form-spec '(var init &optional doc &rest map))
  43
  44 (defmacro deffoo (func args &rest forms)
  45   "The same as `defun', only register FUNC."
  46   `(prog1
  47        (defun ,func ,args ,@forms)
  48      (nnoo-register-function ',func)))
  49 (put 'deffoo 'lisp-indent-function 2)
  50 (put 'deffoo 'edebug-form-spec '(&define name lambda-list def-body))
  51
  52 (defun nnoo-register-function (func)
  53   (let ((funcs (nthcdr 3 (assoc (nnoo-backend func)
  54                                 nnoo-definition-alist))))
  55     (unless funcs
  56       (error "%s belongs to a backend that hasn't been declared" func))
  57     (setcar funcs (cons func (car funcs)))))
  58
  59 (defmacro nnoo-declare (backend &rest parents)
  60   `(eval-and-compile
  61      (if (assq ',backend nnoo-definition-alist)
  62          (setcar (cdr (assq ',backend nnoo-definition-alist))
  63                  (mapcar 'list ',parents))
  64        (push (list ',backend
  65                    (mapcar 'list ',parents)
  66                    nil nil)
  67              nnoo-definition-alist))
  68      (unless (assq ',backend nnoo-state-alist)
  69        (push (list ',backend "*internal-non-initialized-backend*")
  70              nnoo-state-alist))))
  71 (put 'nnoo-declare 'lisp-indent-function 1)
  72
  73 (defun nnoo-parents (backend)
  74   (nth 1 (assoc backend nnoo-definition-alist)))
  75
  76 (defun nnoo-variables (backend)
  77   (nth 2 (assoc backend nnoo-definition-alist)))
  78
  79 (defun nnoo-functions (backend)
  80   (nth 3 (assoc backend nnoo-definition-alist)))
  81
  82 (defmacro nnoo-import (backend &rest imports)
  83   `(nnoo-import-1 ',backend ',imports))
  84 (put 'nnoo-import 'lisp-indent-function 1)
  85
  86 (defun nnoo-import-1 (backend imports)
  87   (let ((call-function
  88          (if (symbolp (car imports)) (pop imports) 'nnoo-parent-function))
  89         imp functions function)
  90     (while (setq imp (pop imports))
  91       (setq functions
  92             (or (cdr imp)
  93                 (nnoo-functions (car imp))))
  94       (while functions
  95         (unless (fboundp
  96                  (setq function
  97                        (nnoo-symbol backend
  98                                     (nnoo-rest-symbol (car functions)))))
  99           (eval `(deffoo ,function (&rest args)
 100                    (,call-function ',backend ',(car functions) args))))
 101         (pop functions)))))
 102
 103 (defun nnoo-parent-function (backend function args)
 104   (let ((pbackend (nnoo-backend function))
 105         (nnoo-parent-backend backend))
 106     (nnoo-change-server pbackend
 107                         (nnoo-current-server backend)
 108                         (cdr (assq pbackend (nnoo-parents backend))))
 109     (prog1
 110         (apply function args)
 111       ;; Copy the changed variables back into the child.
 112       (let ((vars (cdr (assq pbackend (nnoo-parents backend)))))
 113         (while vars
 114           (set (cadar vars) (symbol-value (caar vars)))
 115           (setq vars (cdr vars)))))))
 116
 117 (defun nnoo-execute (backend function &rest args)
 118   "Execute FUNCTION on behalf of BACKEND."
 119   (let ((pbackend (nnoo-backend function))
 120         (nnoo-parent-backend backend))
 121     (nnoo-change-server pbackend
 122                         (nnoo-current-server backend)
 123                         (cdr (assq pbackend (nnoo-parents backend))))
 124     (prog1
 125         (apply function args)
 126       ;; Copy the changed variables back into the child.
 127       (let ((vars (cdr (assq pbackend (nnoo-parents backend)))))
 128         (while vars
 129           (set (cadar vars) (symbol-value (caar vars)))
 130           (setq vars (cdr vars)))))))
 131
 132 (defmacro nnoo-map-functions (backend &rest maps)
 133   `(nnoo-map-functions-1 ',backend ',maps))
 134 (put 'nnoo-map-functions 'lisp-indent-function 1)
 135
 136 (defun nnoo-map-functions-1 (backend maps)
 137   (let (m margs i)
 138     (while (setq m (pop maps))
 139       (setq i 0
 140             margs nil)
 141       (while (< i (length (cdr m)))
 142         (if (numberp (nth i (cdr m)))
 143             (push `(nth ,i args) margs)
 144           (push (nth i (cdr m)) margs))
 145         (incf i))
 146       (eval `(deffoo ,(nnoo-symbol backend (nnoo-rest-symbol (car m)))
 147                  (&rest args)
 148                (nnoo-parent-function ',backend ',(car m)
 149                                      ,(cons 'list (nreverse margs))))))))
 150
 151 (defun nnoo-backend (symbol)
 152   (string-match "^[^-]+-" (symbol-name symbol))
 153   (intern (substring (symbol-name symbol) 0 (1- (match-end 0)))))
 154
 155 (defun nnoo-rest-symbol (symbol)
 156   (string-match "^[^-]+-" (symbol-name symbol))
 157   (intern (substring (symbol-name symbol) (match-end 0))))
 158
 159 (defun nnoo-symbol (backend symbol)
 160   (intern (format "%s-%s" backend symbol)))
 161
 162 (defun nnoo-define (var map)
 163   (let* ((backend (nnoo-backend var))
 164          (def (assq backend nnoo-definition-alist))
 165          (parents (nth 1 def)))
 166     (unless def
 167       (error "%s belongs to a backend that hasn't been declared" var))
 168     (setcar (nthcdr 2 def)
 169             (delq (assq var (nth 2 def)) (nth 2 def)))
 170     (setcar (nthcdr 2 def)
 171             (cons (cons var (symbol-value var))
 172                   (nth 2 def)))
 173     (while map
 174       (nconc (assq (nnoo-backend (car map)) parents)
 175              (list (list (pop map) var))))))
 176
 177 (defun nnoo-change-server (backend server defs)
 178   (let* ((bstate (cdr (assq backend nnoo-state-alist)))
 179          (current (car bstate))
 180          (parents (nnoo-parents backend))
 181          (server (if nnoo-parent-backend
 182                      (format "%s+%s" nnoo-parent-backend server)
 183                    server))
 184          (bvariables (nnoo-variables backend))
 185          state def)
 186     ;; If we don't have a current state, we push an empty state
 187     ;; onto the alist.
 188     (unless bstate
 189       (push (setq bstate (list backend nil))
 190             nnoo-state-alist)
 191       (pop bstate))
 192     (if (equal server current)
 193         t
 194       (nnoo-push-server backend current)
 195       (setq state (or (cdr (assoc server (cddr bstate)))
 196                       (nnoo-variables backend)))
 197       (while state
 198         (set (caar state) (cdar state))
 199         (pop state))
 200       (setcar bstate server)
 201       (unless (cdr (assoc server (cddr bstate)))
 202         (while (setq def (pop defs))
 203           (unless (assq (car def) bvariables)
 204             (nconc bvariables
 205                    (list (cons (car def) (and (boundp (car def))
 206                                               (symbol-value (car def)))))))
 207           (if (equal server "*internal-non-initialized-backend*")
 208               (set (car def) (symbol-value (cadr def)))
 209             (set (car def) (cadr def)))))
 210       (while parents
 211         (nnoo-change-server
 212          (caar parents) (format "%s+%s" backend server)
 213          (mapcar (lambda (def) (list (car def) (symbol-value (cadr def))))
 214                  (cdar parents)))
 215         (pop parents))))
 216   t)
 217
 218 (defun nnoo-push-server (backend current)
 219   (let ((bstate (assq backend nnoo-state-alist))
 220         (defs (nnoo-variables backend)))
 221     ;; Remove the old definition.
 222     (setcdr (cdr bstate) (delq (assoc current (cddr bstate)) (cddr bstate)))
 223     ;; If this is the first time we push the server (i. e., this is
 224     ;; the nil server), then we update the default values of
 225     ;; all the variables to reflect the current values.
 226     (when (equal current "*internal-non-initialized-backend*")
 227       (let ((defaults (nnoo-variables backend))
 228             def)
 229         (while (setq def (pop defaults))
 230           (setcdr def (symbol-value (car def))))))
 231     (let (state)
 232       (while defs
 233         (push (cons (caar defs) (symbol-value (caar defs)))
 234               state)
 235         (pop defs))
 236       (nconc bstate (list (cons current state))))))
 237
 238 (defsubst nnoo-current-server-p (backend server)
 239   (equal (nnoo-current-server backend)
 240          (if nnoo-parent-backend
 241              (format "%s+%s" nnoo-parent-backend server)
 242            server)))
 243
 244 (defun nnoo-current-server (backend)
 245   (nth 1 (assq backend nnoo-state-alist)))
 246
 247 (defun nnoo-close-server (backend &optional server)
 248   (unless server
 249     (setq server (nnoo-current-server backend)))
 250   (when server
 251     (let* ((bstate (cdr (assq backend nnoo-state-alist)))
 252            (defs (assoc server (cdr bstate))))
 253       (when bstate
 254         (setcar bstate nil)
 255         (setcdr bstate (delq defs (cdr bstate)))
 256         (pop defs)
 257         (while defs
 258           (set (car (pop defs)) nil)))))
 259   t)
 260
 261 (defun nnoo-close (backend)
 262   (setq nnoo-state-alist
 263         (delq (assq backend nnoo-state-alist)
 264               nnoo-state-alist))
 265   t)
 266
 267 (defun nnoo-status-message (backend server)
 268   (nnheader-get-report backend))
 269
 270 (defun nnoo-server-opened (backend server)
 271   (and (nnoo-current-server-p backend server)
 272        nntp-server-buffer
 273        (buffer-name nntp-server-buffer)))
 274
 275 (defmacro nnoo-define-basics (backend)
 276   "Define `close-server', `server-opened' and `status-message'."
 277   `(eval-and-compile
 278      (nnoo-define-basics-1 ',backend)))
 279
 280 (defun nnoo-define-basics-1 (backend)
 281   (let ((functions '(close-server server-opened status-message)))
 282     (while functions
 283       (eval `(deffoo ,(nnoo-symbol backend (car functions))
 284                  (&optional server)
 285                (,(nnoo-symbol 'nnoo (pop functions)) ',backend server)))))
 286   (eval `(deffoo ,(nnoo-symbol backend 'open-server)
 287              (server &optional defs)
 288            (nnoo-change-server ',backend server defs))))
 289
 290 (defmacro nnoo-define-skeleton (backend)
 291   "Define all required backend functions for BACKEND.
 292 All functions will return nil and report an error."
 293   `(eval-and-compile
 294      (nnoo-define-skeleton-1 ',backend)))
 295
 296 (defun nnoo-define-skeleton-1 (backend)
 297   (let ((functions '(retrieve-headers
 298                      request-close request-article
 299                      request-group close-group
 300                      request-list request-post request-list-newsgroups))
 301         function fun)
 302     (while (setq function (pop functions))
 303       (when (not (fboundp (setq fun (nnoo-symbol backend function))))
 304         (eval `(deffoo ,fun
 305                    (&rest args)
 306                  (nnheader-report ',backend ,(format "%s-%s not implemented"
 307                                                      backend function))))))))
 308
 309 (defun nnoo-set (server &rest args)
 310   (let ((parents (nnoo-parents (car server)))
 311         (nnoo-parent-backend (car server)))
 312     (while parents
 313       (nnoo-change-server (caar parents)
 314                           (cadr server)
 315                           (cdar parents))
 316       (pop parents)))
 317   (nnoo-change-server (car server)
 318                       (cadr server) (cddr server))
 319   (while args
 320     (set (pop args) (pop args))))
 321
 322 (provide 'nnoo)
 323
 324 ;;; nnoo.el ends here