1;;; loadhist.el --- lisp functions for working with feature groups -*- lexical-binding: t -*- 2 3;; Copyright (C) 1995, 1998, 2000-2021 Free Software Foundation, Inc. 4 5;; Author: Eric S. Raymond <esr@snark.thyrsus.com> 6;; Maintainer: emacs-devel@gnu.org 7;; Keywords: internal 8 9;; This file is part of GNU Emacs. 10 11;; GNU Emacs is free software: you can redistribute it and/or modify 12;; it under the terms of the GNU General Public License as published by 13;; the Free Software Foundation, either version 3 of the License, or 14;; (at your option) any later version. 15 16;; GNU Emacs is distributed in the hope that it will be useful, 17;; but WITHOUT ANY WARRANTY; without even the implied warranty of 18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19;; GNU General Public License for more details. 20 21;; You should have received a copy of the GNU General Public License 22;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. 23 24;;; Commentary: 25 26;; These functions exploit the load-history system variable. 27;; Entry points include `unload-feature', `symbol-file', and 28;; `feature-file', documented in the Emacs Lisp manual. 29 30;;; Code: 31 32(eval-when-compile (require 'cl-lib)) 33 34(defun feature-symbols (feature) 35 "Return the file and list of definitions associated with FEATURE. 36The value is actually the element of `load-history' 37for the file that did (provide FEATURE)." 38 (catch 'foundit 39 (let ((element (cons 'provide feature))) 40 (dolist (x load-history nil) 41 (when (member element (cdr x)) 42 (throw 'foundit x)))))) 43 44(defun feature-file (feature) 45 "Return the file name from which a given FEATURE was loaded. 46Actually, return the load argument, if any; this is sometimes the name of a 47Lisp file without an extension. If the feature came from an `eval-buffer' on 48a buffer with no associated file, or an `eval-region', return nil." 49 (if (not (featurep feature)) 50 (error "%S is not a currently loaded feature" feature) 51 (car (feature-symbols feature)))) 52 53(defun file-loadhist-lookup (file) 54 "Return the `load-history' element for FILE. 55FILE can be a file name, or a library name. 56A library name is equivalent to the file name that `load-library' would load." 57 ;; First look for FILE as given. 58 (let ((symbols (assoc file load-history))) 59 ;; Try converting a library name to an absolute file name. 60 (and (null symbols) 61 (let ((absname 62 (locate-file file load-path (get-load-suffixes)))) 63 (and absname (not (equal absname file)) 64 (setq symbols (cdr (assoc absname load-history)))))) 65 symbols)) 66 67(defun file-provides (file) 68 "Return the list of features provided by FILE as it was loaded. 69FILE can be a file name, or a library name. 70A library name is equivalent to the file name that `load-library' would load." 71 (let (provides) 72 (dolist (x (file-loadhist-lookup file) provides) 73 (when (eq (car-safe x) 'provide) 74 (push (cdr x) provides))))) 75 76(defun file-requires (file) 77 "Return the list of features required by FILE as it was loaded. 78FILE can be a file name, or a library name. 79A library name is equivalent to the file name that `load-library' would load." 80 (let (requires) 81 (dolist (x (file-loadhist-lookup file) requires) 82 (when (eq (car-safe x) 'require) 83 (push (cdr x) requires))))) 84 85(defun file-dependents (file) 86 "Return the list of loaded libraries that depend on FILE. 87This can include FILE itself. 88FILE can be a file name, or a library name. 89A library name is equivalent to the file name that `load-library' would load." 90 (let ((provides (file-provides file)) 91 (dependents nil)) 92 (dolist (x load-history dependents) 93 (when (and (stringp (car x)) 94 (seq-intersection provides (file-requires (car x)) #'eq)) 95 (push (car x) dependents))))) 96 97(defun read-feature (prompt &optional loaded-p) 98 "Read feature name from the minibuffer, prompting with string PROMPT. 99If optional second arg LOADED-P is non-nil, the feature must be loaded 100from a file." 101 (intern (completing-read 102 prompt 103 (mapcar #'symbol-name 104 (if loaded-p 105 (delq nil 106 (mapcar 107 (lambda (x) (and (feature-file x) x)) 108 features)) 109 features))))) 110 111(defvaralias 'loadhist-hook-functions 'unload-feature-special-hooks) 112(defvar unload-feature-special-hooks 113 '(after-change-functions after-insert-file-functions 114 after-make-frame-functions auto-coding-functions 115 auto-fill-function before-change-functions 116 blink-paren-function buffer-access-fontify-functions 117 choose-completion-string-functions 118 comint-output-filter-functions command-line-functions 119 comment-indent-function compilation-finish-functions 120 delete-frame-functions disabled-command-function 121 fill-nobreak-predicate find-directory-functions 122 find-file-not-found-functions 123 font-lock-fontify-buffer-function 124 font-lock-fontify-region-function 125 font-lock-mark-block-function 126 font-lock-syntactic-face-function 127 font-lock-unfontify-buffer-function 128 font-lock-unfontify-region-function 129 kill-buffer-query-functions kill-emacs-query-functions 130 lisp-indent-function mouse-position-function 131 redisplay-end-trigger-functions suspend-tty-functions 132 temp-buffer-show-function window-scroll-functions 133 window-size-change-functions write-contents-functions 134 write-file-functions write-region-annotate-functions) 135 "A list of special hooks from Info node `(elisp)Standard Hooks'. 136 137These are symbols with hooklike values whose names don't end in 138`-hook' or `-hooks', from which `unload-feature' should try to remove 139pertinent symbols.") 140 141(defvar unload-function-defs-list nil 142 "List of definitions in the Lisp library being unloaded. 143 144This is meant to be used by `FEATURE-unload-function'; see the 145documentation of `unload-feature' for details.") 146 147(defun unload--set-major-mode () 148 (save-current-buffer 149 (dolist (buffer (buffer-list)) 150 (set-buffer buffer) 151 (let ((proposed major-mode)) 152 ;; Look for a predecessor mode not defined in the feature we're processing 153 (while (and proposed (rassq proposed unload-function-defs-list)) 154 (setq proposed (get proposed 'derived-mode-parent))) 155 (unless (eq proposed major-mode) 156 ;; Two cases: either proposed is nil, and we want to switch to fundamental 157 ;; mode, or proposed is not nil and not major-mode, and so we use it. 158 (funcall (or proposed 'fundamental-mode))))))) 159 160(cl-defgeneric loadhist-unload-element (x) 161 "Unload an element from the `load-history'." 162 (message "Unexpected element %S in load-history" x)) 163 164;; In `load-history', the definition of a previously autoloaded 165;; function is represented by 2 entries: (t . SYMBOL) comes before 166;; (defun . SYMBOL) and says we should restore SYMBOL's autoload when 167;; we undefine it. 168;; So we use this auxiliary variable to keep track of the last (t . SYMBOL) 169;; that occurred. 170(defvar loadhist--restore-autoload nil 171 "If non-nil, is a symbol for which to try to restore a previous autoload.") 172 173(cl-defmethod loadhist-unload-element ((x (head t))) 174 (setq loadhist--restore-autoload (cdr x))) 175 176(defun loadhist--unload-function (x) 177 (let ((fun (cdr x))) 178 (when (fboundp fun) 179 (when (fboundp 'ad-unadvise) 180 (ad-unadvise fun)) 181 (let ((aload (get fun 'autoload))) 182 (defalias fun 183 (if (and aload (eq fun loadhist--restore-autoload)) 184 (cons 'autoload aload) 185 nil))))) 186 (setq loadhist--restore-autoload nil)) 187 188(cl-defmethod loadhist-unload-element ((x (head defun))) 189 (loadhist--unload-function x)) 190(cl-defmethod loadhist-unload-element ((x (head autoload))) 191 (loadhist--unload-function x)) 192 193(cl-defmethod loadhist-unload-element ((_ (head require))) nil) 194(cl-defmethod loadhist-unload-element ((_ (head defface))) nil) 195 196(cl-defmethod loadhist-unload-element ((x (head provide))) 197 ;; Remove any feature names that this file provided. 198 (setq features (delq (cdr x) features))) 199 200(cl-defmethod loadhist-unload-element ((x symbol)) 201 ;; Kill local values as much as possible. 202 (dolist (buf (buffer-list)) 203 (with-current-buffer buf 204 (if (and (boundp x) (timerp (symbol-value x))) 205 (cancel-timer (symbol-value x))) 206 (kill-local-variable x))) 207 (if (and (boundp x) (timerp (symbol-value x))) 208 (cancel-timer (symbol-value x))) 209 ;; Get rid of the default binding if we can. 210 (unless (local-variable-if-set-p x) 211 (makunbound x))) 212 213(cl-defmethod loadhist-unload-element ((x (head define-type))) 214 (let* ((name (cdr x))) 215 ;; Remove the struct. 216 (setf (cl--find-class name) nil))) 217 218(cl-defmethod loadhist-unload-element ((x (head define-symbol-props))) 219 (pcase-dolist (`(,symbol . ,props) (cdr x)) 220 (dolist (prop props) 221 (put symbol prop nil)))) 222 223;;;###autoload 224(defun unload-feature (feature &optional force) 225 "Unload the library that provided FEATURE. 226If the feature is required by any other loaded code, and prefix arg FORCE 227is nil, raise an error. 228 229Standard unloading activities include restoring old autoloads for 230functions defined by the library, removing such functions from 231hooks and `auto-mode-alist', undoing their ELP profiling, 232unproviding any features provided by the library, and canceling 233timers held in variables defined by the library. 234 235If a function `FEATURE-unload-function' is defined, this function 236calls it with no arguments, before doing anything else. That function 237can do whatever is appropriate to undo the loading of the library. If 238`FEATURE-unload-function' returns non-nil, that suppresses the 239standard unloading of the library. Otherwise the standard unloading 240proceeds. 241 242`FEATURE-unload-function' has access to the package's list of 243definitions in the variable `unload-function-defs-list' and could 244remove symbols from it in the event that the package has done 245something strange, such as redefining an Emacs function." 246 (interactive 247 (list 248 (read-feature "Unload feature: " t) 249 current-prefix-arg)) 250 (unless (featurep feature) 251 (error "%s is not a currently loaded feature" (symbol-name feature))) 252 (unless force 253 (let* ((file (feature-file feature)) 254 (dependents (delete file (copy-sequence (file-dependents file))))) 255 (when dependents 256 (error "Loaded libraries %s depend on %s" 257 (prin1-to-string dependents) file)))) 258 (let* ((unload-function-defs-list (feature-symbols feature)) 259 (file (pop unload-function-defs-list)) 260 (name (symbol-name feature)) 261 (unload-hook (intern-soft (concat name "-unload-hook"))) 262 (unload-func (intern-soft (concat name "-unload-function")))) 263 ;; If FEATURE-unload-function is defined and returns non-nil, 264 ;; don't try to do anything more; otherwise proceed normally. 265 (unless (and (fboundp unload-func) 266 (funcall unload-func)) 267 ;; Try to avoid losing badly when hooks installed in critical 268 ;; places go away. (Some packages install things on 269 ;; `kill-buffer-hook', `activate-menubar-hook' and the like.) 270 (if unload-hook 271 ;; First off, provide a clean way for package FOO to arrange 272 ;; this by adding hooks on the variable `FOO-unload-hook'. 273 ;; This is obsolete; FEATURE-unload-function should be used now. 274 (run-hooks unload-hook) 275 ;; Otherwise, do our best. Look through the obarray for symbols 276 ;; which seem to be hook variables or special hook functions and 277 ;; remove anything from them which matches the feature-symbols 278 ;; about to get zapped. Obviously this won't get anonymous 279 ;; functions which the package might just have installed, and 280 ;; there might be other important state, but this tactic 281 ;; normally works. 282 (let ((removables (cl-loop for def in unload-function-defs-list 283 when (and (eq (car-safe def) 'defun) 284 (not (get (cdr def) 'autoload))) 285 collect (cdr def)))) 286 (mapatoms 287 (lambda (x) 288 (when (and (boundp x) 289 (or (and (consp (symbol-value x)) ; Random hooks. 290 (string-match "-hooks?\\'" (symbol-name x))) 291 ;; Known abnormal hooks etc. 292 (memq x unload-feature-special-hooks))) 293 (dolist (func removables) 294 (remove-hook x func))))) 295 (save-current-buffer 296 (dolist (buffer (buffer-list)) 297 (pcase-dolist (`(,sym . ,val) (buffer-local-variables buffer)) 298 (when (or (and (consp val) 299 (string-match "-hooks?\\'" (symbol-name sym))) 300 (memq sym unload-feature-special-hooks)) 301 (set-buffer buffer) 302 (dolist (func removables) 303 (remove-hook sym func t)))))) 304 ;; Remove any feature-symbols from auto-mode-alist as well. 305 (dolist (func removables) 306 (setq auto-mode-alist 307 (rassq-delete-all func auto-mode-alist))))) 308 309 ;; Change major mode in all buffers using one defined in the feature being unloaded. 310 (unload--set-major-mode) 311 312 (mapc #'loadhist-unload-element unload-function-defs-list) 313 ;; Delete the load-history element for this file. 314 (setq load-history (delq (assoc file load-history) load-history)))) 315 ;; Don't return load-history, it is not useful. 316 nil) 317 318;; Obsolete. 319 320(defsubst file-set-intersect (p q) 321 "Return the set intersection of two lists." 322 (declare (obsolete seq-intersection "28.1")) 323 (nreverse (seq-intersection p q #'eq))) 324 325(provide 'loadhist) 326 327;;; loadhist.el ends here 328