lisp/loadhist.el

   1 ;;; loadhist.el --- lisp functions for working with feature groups
   2
   3 ;; Copyright (C) 1995, 1998, 2000 Free Software Foundation, Inc.
   4
   5 ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
   6 ;; Maintainer: FSF
   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 2, or (at your option)
  14 ;; 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; 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.
  25
  26 ;;; Commentary:
  27
  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.
  31
  32 ;;; Code:
  33
  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))
  42
  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))))
  51
  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))
  61
  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))
  71
  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))
  78
  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))
  88
  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)))
  98
  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 the `Standard Hooks' node of the Lisp manual.
 111
 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.")
 115
 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 (fboundp x)       ; Known abnormal hooks etc.
 154                       (memq x loadhist-hook-functions)))
 155              (dolist (y (cdr flist))
 156                (remove-hook x y))))))
 157     (mapc
 158      (lambda (x)
 159        (cond ((stringp x) nil)
 160              ((consp x)
 161               ;; Remove any feature names that this file provided.
 162               (if (eq (car x) 'provide)
 163                   (setq features (delq (cdr x) features))))
 164              (t
 165               (when (boundp x)
 166                 (makunbound x))
 167               (when (fboundp x)
 168                 (fmakunbound x)
 169                 (let ((aload (get x 'autoload)))
 170                   (if aload (fset x (cons 'autoload aload))))))))
 171      (cdr flist))
 172     ;; Delete the load-history element for this file.
 173     (let ((elt (assoc file load-history)))
 174       (setq load-history (delq elt load-history)))))
 175
 176 (provide 'loadhist)
 177
 178 ;;; loadhist.el ends here