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[emacs.git] / lisp / loadhist.el
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1 ;;; loadhist.el --- lisp functions for working with feature groups
3 ;; Copyright (C) 1995, 1998, 2000 Free Software Foundation, Inc.
5 ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
6 ;; Maintainer: FSF
7 ;; Keywords: internal
9 ;; This file is part of GNU Emacs.
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 2, or (at your option)
14 ;; any later version.
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.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
26 ;;; Commentary:
28 ;; These functions exploit the load-history system variable.
29 ;; Entry points include `unload-feature', `symbol-file', and
30 ;; `feature-file', documented in the Emacs Lisp manual.
32 ;;; Code:
34 (defun feature-symbols (feature)
35 "Return the file and list of symbols associated with a given FEATURE."
36 (catch 'foundit
37 (mapc (lambda (x)
38 (if (member (cons 'provide feature) (cdr x))
39 (throw 'foundit x)))
40 load-history)
41 nil))
43 (defun feature-file (feature)
44 "Return the file name from which a given FEATURE was loaded.
45 Actually, return the load argument, if any; this is sometimes the name of a
46 Lisp file without an extension. If the feature came from an `eval-buffer' on
47 a buffer with no associated file, or an `eval-region', return nil."
48 (if (not (featurep feature))
49 (error "%S is not a currently loaded feature" feature)
50 (car (feature-symbols feature))))
52 (defun file-provides (file)
53 "Return the list of features provided by FILE."
54 (let ((symbols (cdr (assoc file load-history)))
55 provides)
56 (mapc (lambda (x)
57 (if (and (consp x) (eq (car x) 'provide))
58 (setq provides (cons (cdr x) provides))))
59 symbols)
60 provides))
62 (defun file-requires (file)
63 "Return the list of features required by FILE."
64 (let ((symbols (cdr (assoc file load-history)))
65 requires)
66 (mapc (lambda (x)
67 (if (and (consp x) (eq (car x) 'require))
68 (setq requires (cons (cdr x) requires))))
69 symbols)
70 requires))
72 (defsubst file-set-intersect (p q)
73 "Return the set intersection of two lists."
74 (let ((ret nil))
75 (dolist (x p ret)
76 (if (memq x q) (setq ret (cons x ret))))
77 ret))
79 (defun file-dependents (file)
80 "Return the list of loaded libraries that depend on FILE.
81 This can include FILE itself."
82 (let ((provides (file-provides file))
83 (dependents nil))
84 (dolist (x load-history dependents)
85 (if (file-set-intersect provides (file-requires (car x)))
86 (setq dependents (cons (car x) dependents))))
87 dependents))
89 (defun read-feature (prompt)
90 "Read a feature name \(string\) from the minibuffer.
91 Prompt with PROMPT and completing from `features', and
92 return the feature \(symbol\)."
93 (intern (completing-read prompt
94 (mapcar (lambda (feature)
95 (list (symbol-name feature)))
96 features)
97 nil t)))
99 (defvar loadhist-hook-functions
100 '(after-change-functions
101 after-insert-file-functions auto-fill-function
102 before-change-functions blink-paren-function
103 buffer-access-fontify-functions command-line-functions
104 comment-indent-function kill-buffer-query-functions
105 kill-emacs-query-functions lisp-indent-function
106 mouse-position-function
107 redisplay-end-trigger-functions temp-buffer-show-function
108 window-scroll-functions window-size-change-functions
109 write-region-annotate-functions)
110 "A list of special hooks from Info node `(elisp)Standard Hooks'.
112 These are symbols with hook-type values whose names don't end in
113 `-hook' or `-hooks', from which `unload-feature' tries to remove
114 pertinent symbols.")
116 ;;;###autoload
117 (defun unload-feature (feature &optional force)
118 "Unload the library that provided FEATURE, restoring all its autoloads.
119 If the feature is required by any other loaded code, and prefix arg FORCE
120 is nil, raise an error."
121 (interactive (list (read-feature "Feature: ") current-prefix-arg))
122 (if (not (featurep feature))
123 (error "%s is not a currently loaded feature" (symbol-name feature)))
124 (if (not force)
125 (let* ((file (feature-file feature))
126 (dependents (delete file (copy-sequence (file-dependents file)))))
127 (if dependents
128 (error "Loaded libraries %s depend on %s"
129 (prin1-to-string dependents) file))))
130 (let* ((flist (feature-symbols feature))
131 (file (car flist))
132 (unload-hook (intern-soft (concat (symbol-name feature)
133 "-unload-hook"))))
134 ;; Try to avoid losing badly when hooks installed in critical
135 ;; places go away. (Some packages install things on
136 ;; `kill-buffer-hook', `activate-menubar-hook' and the like.)
137 ;; First off, provide a clean way for package `foo' to arrange
138 ;; this by defining `foo-unload-hook'.
139 (if unload-hook
140 (run-hooks unload-hook)
141 ;; Otherwise, do our best. Look through the obarray for symbols
142 ;; which seem to be hook variables or special hook functions and
143 ;; remove anything from them which matches the feature-symbols
144 ;; about to get zapped. Obviously this won't get anonymous
145 ;; functions which the package might just have installed, and
146 ;; there might be other important state, but this tactic
147 ;; normally works.
148 (mapatoms
149 (lambda (x)
150 (if (or (and (boundp x) ; Random hooks.
151 (consp (symbol-value x))
152 (string-match "-hooks?\\'" (symbol-name x)))
153 (and (boundp x) ; Known abnormal hooks etc.
154 (memq x loadhist-hook-functions)))
155 (dolist (y (cdr flist))
156 (remove-hook x y))))))
157 (if (fboundp 'elp-restore-function) ; remove ELP stuff first
158 (dolist (elt (cdr flist))
159 (if (symbolp elt)
160 (elp-restore-function elt))))
161 (mapc
162 (lambda (x)
163 (cond ((stringp x) nil)
164 ((consp x)
165 ;; Remove any feature names that this file provided.
166 (if (eq (car x) 'provide)
167 (setq features (delq (cdr x) features))))
169 (when (boundp x)
170 (makunbound x))
171 (when (fboundp x)
172 (if (fboundp 'ad-unadvise)
173 (ad-unadvise x))
174 (fmakunbound x)
175 (let ((aload (get x 'autoload)))
176 (if aload (fset x (cons 'autoload aload))))))))
177 (cdr flist))
178 ;; Delete the load-history element for this file.
179 (let ((elt (assoc file load-history)))
180 (setq load-history (delq elt load-history)))))
182 (provide 'loadhist)
184 ;;; loadhist.el ends here