lisp/loadhist.el

   1 ;;; loadhist.el --- lisp functions for working with feature groups
   2
   3 ;; Copyright (C) 1995, 1998, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   5
   6 ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
   7 ;; Maintainer: FSF
   8 ;; Keywords: internal
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; These functions exploit the load-history system variable.
  28 ;; Entry points include `unload-feature', `symbol-file', and
  29 ;; `feature-file', documented in the Emacs Lisp manual.
  30
  31 ;;; Code:
  32
  33 (eval-when-compile (require 'cl))
  34
  35 (defun feature-symbols (feature)
  36   "Return the file and list of definitions associated with FEATURE.
  37 The value is actually the element of `load-history'
  38 for the file that did (provide FEATURE)."
  39   (catch 'foundit
  40     (let ((element (cons 'provide feature)))
  41       (dolist (x load-history nil)
  42         (when (member element (cdr x))
  43           (throw 'foundit x))))))
  44
  45 (defun feature-file (feature)
  46   "Return the file name from which a given FEATURE was loaded.
  47 Actually, return the load argument, if any; this is sometimes the name of a
  48 Lisp file without an extension.  If the feature came from an `eval-buffer' on
  49 a buffer with no associated file, or an `eval-region', return nil."
  50   (if (not (featurep feature))
  51       (error "%S is not a currently loaded feature" feature)
  52     (car (feature-symbols feature))))
  53
  54 (defun file-loadhist-lookup (file)
  55   "Return the `load-history' element for FILE.
  56 FILE can be a file name, or a library name.
  57 A library name is equivalent to the file name that `load-library' would load."
  58   ;; First look for FILE as given.
  59   (let ((symbols (assoc file load-history)))
  60     ;; Try converting a library name to an absolute file name.
  61     (and (null symbols)
  62          (let ((absname
  63                 (locate-file file load-path (get-load-suffixes))))
  64            (and absname (not (equal absname file))
  65                 (setq symbols (cdr (assoc absname load-history))))))
  66     symbols))
  67
  68 (defun file-provides (file)
  69   "Return the list of features provided by FILE as it was loaded.
  70 FILE can be a file name, or a library name.
  71 A library name is equivalent to the file name that `load-library' would load."
  72   (let (provides)
  73     (dolist (x (file-loadhist-lookup file) provides)
  74       (when (eq (car-safe x) 'provide)
  75         (push (cdr x) provides)))))
  76
  77 (defun file-requires (file)
  78   "Return the list of features required by FILE as it was loaded.
  79 FILE can be a file name, or a library name.
  80 A library name is equivalent to the file name that `load-library' would load."
  81   (let (requires)
  82     (dolist (x (file-loadhist-lookup file) requires)
  83       (when (eq (car-safe x) 'require)
  84         (push (cdr x) requires)))))
  85
  86 (defsubst file-set-intersect (p q)
  87   "Return the set intersection of two lists."
  88   (let (ret)
  89     (dolist (x p ret)
  90       (when (memq x q) (push x ret)))))
  91
  92 (defun file-dependents (file)
  93   "Return the list of loaded libraries that depend on FILE.
  94 This can include FILE itself.
  95 FILE can be a file name, or a library name.
  96 A library name is equivalent to the file name that `load-library' would load."
  97   (let ((provides (file-provides file))
  98         (dependents nil))
  99     (dolist (x load-history dependents)
 100       (when (file-set-intersect provides (file-requires (car x)))
 101         (push (car x) dependents)))))
 102
 103 (defun read-feature (prompt &optional loaded-p)
 104   "Read feature name from the minibuffer, prompting with string PROMPT.
 105 If optional second arg LOADED-P is non-nil, the feature must be loaded
 106 from a file."
 107   (intern
 108    (completing-read prompt
 109                     (cons nil features)
 110                     (and loaded-p
 111                          #'(lambda (f)
 112                              (and f     ; ignore nil
 113                                   (feature-file f))))
 114                     loaded-p)))
 115
 116 (defvaralias 'loadhist-hook-functions 'unload-feature-special-hooks)
 117 (defvar unload-feature-special-hooks
 118   '(after-change-functions after-insert-file-functions
 119     after-make-frame-functions auto-fill-function before-change-functions
 120     blink-paren-function buffer-access-fontify-functions
 121     choose-completion-string-functions command-line-functions
 122     comment-indent-function compilation-finish-functions delete-frame-functions
 123     disabled-command-function find-file-not-found-functions
 124     font-lock-beginning-of-syntax-function font-lock-fontify-buffer-function
 125     font-lock-fontify-region-function font-lock-mark-block-function
 126     font-lock-syntactic-face-function font-lock-unfontify-buffer-function
 127     font-lock-unfontify-region-function kill-buffer-query-functions
 128     kill-emacs-query-functions lisp-indent-function mouse-position-function
 129     redisplay-end-trigger-functions suspend-tty-functions
 130     temp-buffer-show-function window-scroll-functions
 131     window-size-change-functions write-contents-functions write-file-functions
 132     write-region-annotate-functions)
 133   "A list of special hooks from Info node `(elisp)Standard Hooks'.
 134
 135 These are symbols with hooklike values whose names don't end in
 136 `-hook' or `-hooks', from which `unload-feature' should try to remove
 137 pertinent symbols.")
 138
 139 (defvar unload-function-defs-list nil
 140   "List of defintions in the Lisp library being unloaded.
 141
 142 This is meant to be used by `FEATURE-unload-function'; see the
 143 documentation of `unload-feature' for details.")
 144 (define-obsolete-variable-alias 'unload-hook-features-list
 145     'unload-function-defs-list "22.2")
 146
 147 ;;;###autoload
 148 (defun unload-feature (feature &optional force)
 149   "Unload the library that provided FEATURE.
 150 If the feature is required by any other loaded code, and prefix arg FORCE
 151 is nil, raise an error.
 152
 153 Standard unloading activities include restoring old autoloads for
 154 functions defined by the library, undoing any additions that the
 155 library has made to hook variables or to `auto-mode-alist', undoing
 156 ELP profiling of functions in that library, unproviding any features
 157 provided by the library, and canceling timers held in variables
 158 defined by the library.
 159
 160 If a function `FEATURE-unload-function' is defined, this function
 161 calls it with no arguments, before doing anything else.  That function
 162 can do whatever is appropriate to undo the loading of the library.  If
 163 `FEATURE-unload-function' returns non-nil, that suppresses the
 164 standard unloading of the library.  Otherwise the standard unloading
 165 proceeds.
 166
 167 `FEATURE-unload-function' has access to the package's list of
 168 definitions in the variable `unload-function-defs-list' and could
 169 remove symbols from it in the event that the package has done
 170 something strange, such as redefining an Emacs function."
 171   (interactive
 172    (list
 173     (read-feature "Unload feature: " t)
 174     current-prefix-arg))
 175   (unless (featurep feature)
 176     (error "%s is not a currently loaded feature" (symbol-name feature)))
 177   (unless force
 178     (let* ((file (feature-file feature))
 179            (dependents (delete file (copy-sequence (file-dependents file)))))
 180       (when dependents
 181         (error "Loaded libraries %s depend on %s"
 182                (prin1-to-string dependents) file))))
 183   (let* ((unload-function-defs-list (feature-symbols feature))
 184          (file (pop unload-function-defs-list))
 185          ;; If non-nil, this is a symbol for which we should
 186          ;; restore a previous autoload if possible.
 187          restore-autoload
 188          (name (symbol-name feature))
 189          (unload-hook (intern-soft (concat name "-unload-hook")))
 190          (unload-func (intern-soft (concat name "-unload-function"))))
 191     ;; If FEATURE-unload-function is defined and returns non-nil,
 192     ;; don't try to do anything more; otherwise proceed normally.
 193     (unless (and (fboundp unload-func)
 194                  (funcall unload-func))
 195       ;; Try to avoid losing badly when hooks installed in critical
 196       ;; places go away.  (Some packages install things on
 197       ;; `kill-buffer-hook', `activate-menubar-hook' and the like.)
 198       (if unload-hook
 199           ;; First off, provide a clean way for package FOO to arrange
 200           ;; this by adding hooks on the variable `FOO-unload-hook'.
 201           ;; This is obsolete; FEATURE-unload-function should be used now.
 202           (run-hooks unload-hook)
 203         ;; Otherwise, do our best.  Look through the obarray for symbols
 204         ;; which seem to be hook variables or special hook functions and
 205         ;; remove anything from them which matches the feature-symbols
 206         ;; about to get zapped.  Obviously this won't get anonymous
 207         ;; functions which the package might just have installed, and
 208         ;; there might be other important state, but this tactic
 209         ;; normally works.
 210         (mapatoms
 211          (lambda (x)
 212            (when (and (boundp x)
 213                       (or (and (consp (symbol-value x)) ; Random hooks.
 214                                (string-match "-hooks?\\'" (symbol-name x)))
 215                           (memq x unload-feature-special-hooks)))       ; Known abnormal hooks etc.
 216              (dolist (y unload-function-defs-list)
 217                (when (and (eq (car-safe y) 'defun)
 218                           (not (get (cdr y) 'autoload)))
 219                  (remove-hook x (cdr y)))))))
 220         ;; Remove any feature-symbols from auto-mode-alist as well.
 221         (dolist (y unload-function-defs-list)
 222           (when (and (eq (car-safe y) 'defun)
 223                      (not (get (cdr y) 'autoload)))
 224             (setq auto-mode-alist
 225                   (rassq-delete-all (cdr y) auto-mode-alist)))))
 226       (when (fboundp 'elp-restore-function) ; remove ELP stuff first
 227         (dolist (elt unload-function-defs-list)
 228           (when (symbolp elt)
 229             (elp-restore-function elt))))
 230
 231       (dolist (x unload-function-defs-list)
 232         (if (consp x)
 233             (case (car x)
 234               ;; Remove any feature names that this file provided.
 235               (provide
 236                (setq features (delq (cdr x) features)))
 237               ((defun autoload)
 238                (let ((fun (cdr x)))
 239                  (when (fboundp fun)
 240                    (when (fboundp 'ad-unadvise)
 241                      (ad-unadvise fun))
 242                    (let ((aload (get fun 'autoload)))
 243                      (if (and aload (eq fun restore-autoload))
 244                          (fset fun (cons 'autoload aload))
 245                        (fmakunbound fun))))))
 246               ;; (t . SYMBOL) comes before (defun . SYMBOL)
 247               ;; and says we should restore SYMBOL's autoload
 248               ;; when we undefine it.
 249               ((t) (setq restore-autoload (cdr x)))
 250               ((require defface) nil)
 251               (t (message "Unexpected element %s in load-history" x)))
 252           ;; Kill local values as much as possible.
 253           (dolist (buf (buffer-list))
 254             (with-current-buffer buf
 255               (if (and (boundp x) (timerp (symbol-value x)))
 256                   (cancel-timer (symbol-value x)))
 257               (kill-local-variable x)))
 258           (if (and (boundp x) (timerp (symbol-value x)))
 259               (cancel-timer (symbol-value x)))
 260           ;; Get rid of the default binding if we can.
 261           (unless (local-variable-if-set-p x)
 262             (makunbound x))))
 263       ;; Delete the load-history element for this file.
 264       (setq load-history (delq (assoc file load-history) load-history))))
 265   ;; Don't return load-history, it is not useful.
 266   nil)
 267
 268 (provide 'loadhist)
 269
 270 ;;; loadhist.el ends here