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 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, or (at your option)
  15 ;; 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; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; These functions exploit the load-history system variable.
  30 ;; Entry points include `unload-feature', `symbol-file', and
  31 ;; `feature-file', documented in the Emacs Lisp manual.
  32
  33 ;;; Code:
  34
  35 (eval-when-compile (require 'cl))
  36
  37 (defun feature-symbols (feature)
  38   "Return the file and list of definitions associated with FEATURE.
  39 The value is actually the element of `load-history'
  40 for the file that did (provide FEATURE)."
  41   (catch 'foundit
  42     (let ((element (cons 'provide feature)))
  43       (dolist (x load-history nil)
  44         (when (member element (cdr x))
  45           (throw 'foundit x))))))
  46
  47 (defun feature-file (feature)
  48   "Return the file name from which a given FEATURE was loaded.
  49 Actually, return the load argument, if any; this is sometimes the name of a
  50 Lisp file without an extension.  If the feature came from an `eval-buffer' on
  51 a buffer with no associated file, or an `eval-region', return nil."
  52   (if (not (featurep feature))
  53       (error "%S is not a currently loaded feature" feature)
  54     (car (feature-symbols feature))))
  55
  56 (defun file-loadhist-lookup (file)
  57   "Return the `load-history' element for FILE.
  58 FILE can be a file name, or a library name.
  59 A library name is equivalent to the file name that `load-library' would load."
  60   ;; First look for FILE as given.
  61   (let ((symbols (assoc file load-history)))
  62     ;; Try converting a library name to an absolute file name.
  63     (and (null symbols)
  64          (let ((absname
  65                 (locate-file file load-path (get-load-suffixes))))
  66            (and absname (not (equal absname file))
  67                 (setq symbols (cdr (assoc absname load-history))))))
  68     symbols))
  69
  70 (defun file-provides (file)
  71   "Return the list of features provided by FILE as it was loaded.
  72 FILE can be a file name, or a library name.
  73 A library name is equivalent to the file name that `load-library' would load."
  74   (let (provides)
  75     (dolist (x (file-loadhist-lookup file) provides)
  76       (when (eq (car-safe x) 'provide)
  77         (push x provides)))))
  78
  79 (defun file-requires (file)
  80   "Return the list of features required by FILE as it was loaded.
  81 FILE can be a file name, or a library name.
  82 A library name is equivalent to the file name that `load-library' would load."
  83   (let (requires)
  84     (dolist (x (file-loadhist-lookup file) requires)
  85       (when (eq (car-safe x) 'require)
  86         (push x requires)))))
  87
  88 (defsubst file-set-intersect (p q)
  89   "Return the set intersection of two lists."
  90   (let (ret)
  91     (dolist (x p ret)
  92       (when (memq x q) (push x ret)))))
  93
  94 (defun file-dependents (file)
  95   "Return the list of loaded libraries that depend on FILE.
  96 This can include FILE itself.
  97 FILE can be a file name, or a library name.
  98 A library name is equivalent to the file name that `load-library' would load."
  99   (let ((provides (file-provides file))
 100         (dependents nil))
 101     (dolist (x load-history dependents)
 102       (when (file-set-intersect provides (file-requires (car x)))
 103         (push (car x) dependents)))))
 104
 105 (defun read-feature (prompt &optional loaded-p)
 106   "Read feature name from the minibuffer, prompting with string PROMPT.
 107 If optional second arg LOADED-P is non-nil, the feature must be loaded
 108 from a file."
 109   (intern
 110    (completing-read prompt
 111                     (cons nil features)
 112                     (and loaded-p
 113                          #'(lambda (f)
 114                              (and f     ; ignore nil
 115                                   (feature-file f))))
 116                     loaded-p)))
 117
 118 (defvaralias 'loadhist-hook-functions 'unload-feature-special-hooks)
 119 (defvar unload-feature-special-hooks
 120   '(after-change-functions after-insert-file-functions
 121     after-make-frame-functions auto-fill-function before-change-functions
 122     blink-paren-function buffer-access-fontify-functions command-line-functions
 123     comment-indent-function compilation-finish-functions delete-frame-functions
 124     disabled-command-function find-file-not-found-functions
 125     font-lock-beginning-of-syntax-function font-lock-fontify-buffer-function
 126     font-lock-fontify-region-function font-lock-mark-block-function
 127     font-lock-syntactic-face-function font-lock-unfontify-buffer-function
 128     font-lock-unfontify-region-function kill-buffer-query-functions
 129     kill-emacs-query-functions lisp-indent-function mouse-position-function
 130     redisplay-end-trigger-functions suspend-tty-functions
 131     temp-buffer-show-function window-scroll-functions
 132     window-size-change-functions write-contents-functions write-file-functions
 133     write-region-annotate-functions)
 134   "A list of special hooks from Info node `(elisp)Standard Hooks'.
 135
 136 These are symbols with hooklike values whose names don't end in
 137 `-hook' or `-hooks', from which `unload-feature' should try to remove
 138 pertinent symbols.")
 139
 140 (defvar unload-function-defs-list nil
 141   "List of defintions in the Lisp library being unloaded.
 142
 143 This is meant to be used by `FEATURE-unload-function'; see the
 144 documentation of `unload-feature' for details.")
 145 (define-obsolete-variable-alias 'unload-hook-features-list
 146     'unload-function-defs-list "22.2")
 147
 148 ;;;###autoload
 149 (defun unload-feature (feature &optional force)
 150   "Unload the library that provided FEATURE.
 151 If the feature is required by any other loaded code, and prefix arg FORCE
 152 is nil, raise an error.
 153
 154 Standard unloading activities include restoring old autoloads for
 155 functions defined by the library, undoing any additions that the
 156 library has made to hook variables or to `auto-mode-alist', undoing
 157 ELP profiling of functions in that library, unproviding any features
 158 provided by the library, and canceling timers held in variables
 159 defined by the library.
 160
 161 If a function `FEATURE-unload-function' is defined, this function
 162 calls it with no arguments, before doing anything else.  That function
 163 can do whatever is appropriate to undo the loading of the library.  If
 164 `FEATURE-unload-function' returns non-nil, that suppresses the
 165 standard unloading of the library.  Otherwise the standard unloading
 166 proceeds.
 167
 168 `FEATURE-unload-function' has access to the package's list of
 169 definitions in the variable `unload-function-defs-list' and could
 170 remove symbols from it in the event that the package has done
 171 something strange, such as redefining an Emacs function."
 172   (interactive
 173    (list
 174     (read-feature "Unload feature: " t)
 175     current-prefix-arg))
 176   (unless (featurep feature)
 177     (error "%s is not a currently loaded feature" (symbol-name feature)))
 178   (unless force
 179     (let* ((file (feature-file feature))
 180            (dependents (delete file (copy-sequence (file-dependents file)))))
 181       (when dependents
 182         (error "Loaded libraries %s depend on %s"
 183                (prin1-to-string dependents) file))))
 184   (let* ((unload-function-defs-list (feature-symbols feature))
 185          (file (pop unload-function-defs-list))
 186          ;; If non-nil, this is a symbol for which we should
 187          ;; restore a previous autoload if possible.
 188          restore-autoload
 189          (name (symbol-name feature))
 190          (unload-hook (intern-soft (concat name "-unload-hook")))
 191          (unload-func (intern-soft (concat name "-unload-function"))))
 192     ;; If FEATURE-unload-function is defined and returns non-nil,
 193     ;; don't try to do anything more; otherwise proceed normally.
 194     (unless (and (bound-and-true-p unload-func)
 195                  (funcall unload-func))
 196       ;; Try to avoid losing badly when hooks installed in critical
 197       ;; places go away.  (Some packages install things on
 198       ;; `kill-buffer-hook', `activate-menubar-hook' and the like.)
 199       (if unload-hook
 200           ;; First off, provide a clean way for package FOO to arrange
 201           ;; this by adding hooks on the variable `FOO-unload-hook'.
 202           ;; This is obsolete; FEATURE-unload-function should be used now.
 203           (run-hooks unload-hook)
 204         ;; Otherwise, do our best.  Look through the obarray for symbols
 205         ;; which seem to be hook variables or special hook functions and
 206         ;; remove anything from them which matches the feature-symbols
 207         ;; about to get zapped.  Obviously this won't get anonymous
 208         ;; functions which the package might just have installed, and
 209         ;; there might be other important state, but this tactic
 210         ;; normally works.
 211         (mapatoms
 212          (lambda (x)
 213            (when (and (boundp x)
 214                       (or (and (consp (symbol-value x)) ; Random hooks.
 215                                (string-match "-hooks?\\'" (symbol-name x)))
 216                           (memq x unload-feature-special-hooks)))       ; Known abnormal hooks etc.
 217              (dolist (y unload-function-defs-list)
 218                (when (and (eq (car-safe y) 'defun)
 219                           (not (get (cdr y) 'autoload)))
 220                  (remove-hook x (cdr y)))))))
 221         ;; Remove any feature-symbols from auto-mode-alist as well.
 222         (dolist (y unload-function-defs-list)
 223           (when (and (eq (car-safe y) 'defun)
 224                      (not (get (cdr y) 'autoload)))
 225             (setq auto-mode-alist
 226                   (rassq-delete-all (cdr y) auto-mode-alist)))))
 227       (when (fboundp 'elp-restore-function) ; remove ELP stuff first
 228         (dolist (elt unload-function-defs-list)
 229           (when (symbolp elt)
 230             (elp-restore-function elt))))
 231
 232       (dolist (x unload-function-defs-list)
 233         (if (consp x)
 234             (case (car x)
 235               ;; Remove any feature names that this file provided.
 236               (provide
 237                (setq features (delq (cdr x) features)))
 238               ((defun autoload)
 239                (let ((fun (cdr x)))
 240                  (when (fboundp fun)
 241                    (when (fboundp 'ad-unadvise)
 242                      (ad-unadvise fun))
 243                    (let ((aload (get fun 'autoload)))
 244                      (if (and aload (eq fun restore-autoload))
 245                          (fset fun (cons 'autoload aload))
 246                        (fmakunbound fun))))))
 247               ;; (t . SYMBOL) comes before (defun . SYMBOL)
 248               ;; and says we should restore SYMBOL's autoload
 249               ;; when we undefine it.
 250               ((t) (setq restore-autoload (cdr x)))
 251               ((require defface) nil)
 252               (t (message "Unexpected element %s in load-history" x)))
 253           ;; Kill local values as much as possible.
 254           (dolist (buf (buffer-list))
 255             (with-current-buffer buf
 256               (if (and (boundp x) (timerp (symbol-value x)))
 257                   (cancel-timer (symbol-value x)))
 258               (kill-local-variable x)))
 259           (if (and (boundp x) (timerp (symbol-value x)))
 260               (cancel-timer (symbol-value x)))
 261           ;; Get rid of the default binding if we can.
 262           (unless (local-variable-if-set-p x)
 263             (makunbound x))))
 264       ;; Delete the load-history element for this file.
 265       (setq load-history (delq (assoc file load-history) load-history))))
 266   ;; Don't return load-history, it is not useful.
 267   nil)
 268
 269 (provide 'loadhist)
 270
 271 ;; arch-tag: 70bb846a-c413-4f01-bf88-78dba4ac0798
 272 ;;; loadhist.el ends here