lisp/loadhist.el

   1 ;;; loadhist.el --- lisp functions for working with feature groups
   2
   3 ;; Copyright (C) 1995 Free Software Foundation, Inc.
   4
   5 ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
   6 ;; Version: 1.0
   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 `feature-file'.
  30
  31 ;;; Code:
  32
  33 (defun symbol-file (sym)
  34   "Return the input source from which SYM was loaded.
  35 This is a file name, or nil if the source was a buffer with no associated file."
  36   (catch 'foundit
  37     (mapcar
  38      (function (lambda (x) (if (memq sym (cdr x)) (throw 'foundit (car x)))))
  39      load-history)
  40     nil))
  41
  42 (defun feature-symbols (feature)
  43   "Return the file and list of symbols associated with a given FEATURE."
  44    (catch 'foundit
  45      (mapcar
  46       (function (lambda (x)
  47                   (if (member (cons 'provide feature) (cdr x))
  48                       (throw 'foundit x))))
  49       load-history)
  50      nil))
  51
  52 (defun feature-file (feature)
  53   "Return the file name from which a given FEATURE was loaded.
  54 Actually, return the load argument, if any; this is sometimes the name of a
  55 Lisp file without an extension.  If the feature came from an eval-buffer on
  56 a buffer with no associated file, or an eval-region, return nil."
  57   (if (not (featurep feature))
  58       (error "%s is not a currently loaded feature" (symbol-name feature))
  59     (car (feature-symbols feature))))
  60
  61 (defun file-provides (file)
  62   "Return the list of features provided by FILE."
  63   (let ((symbols (cdr (assoc file load-history))) (provides nil))
  64     (mapcar
  65      (function (lambda (x)
  66                  (if (and (consp x) (eq (car x) 'provide))
  67                      (setq provides (cons (cdr x) provides)))))
  68      symbols)
  69     provides
  70     ))
  71
  72 (defun file-requires (file)
  73   "Return the list of features required by FILE."
  74   (let ((symbols (cdr (assoc file load-history))) (requires nil))
  75     (mapcar
  76      (function (lambda (x)
  77                  (if (and (consp x) (eq (car x) 'require))
  78                      (setq requires (cons (cdr x) requires)))))
  79      symbols)
  80     requires
  81     ))
  82
  83 (defun file-set-intersect (p q)
  84   ;; Return the set intersection of two lists
  85   (let ((ret nil))
  86     (mapcar
  87      (function (lambda (x) (if (memq x q) (setq ret (cons x ret)))))
  88      p)
  89     ret
  90     ))
  91
  92 (defun file-dependents (file)
  93   "Return the list of loaded libraries that depend on FILE.
  94 This can include FILE itself."
  95   (let ((provides (file-provides file)) (dependents nil))
  96     (mapcar
  97      (function (lambda (x)
  98                  (if (file-set-intersect provides (file-requires (car x)))
  99                      (setq dependents (cons (car x) dependents)))))
 100      load-history)
 101     dependents
 102     ))
 103
 104 ;;;###autoload
 105 (defun unload-feature (feature &optional force)
 106   "Unload the library that provided FEATURE, restoring all its autoloads.
 107 If the feature is required by any other loaded code, and optional FORCE
 108 is nil, raise an error."
 109   (interactive "SFeature: ")
 110   (if (not (featurep feature))
 111       (error "%s is not a currently loaded feature" (symbol-name feature)))
 112   (if (not force)
 113       (let* ((file (feature-file feature))
 114              (dependents (delete file (copy-sequence (file-dependents file)))))
 115         (if dependents
 116             (error "Loaded libraries %s depend on %s"
 117                    (prin1-to-string dependents) file)
 118             )))
 119   (let* ((flist (feature-symbols feature)) (file (car flist)))
 120     (mapcar
 121      (function (lambda (x)
 122                  (cond ((stringp x) nil)
 123                        ((consp x)
 124                         ;; Remove any feature names that this file provided.
 125                         (if (eq (car x) 'provide)
 126                             (setq features (delq (cdr x) features))))
 127                        ((boundp x) (makunbound x))
 128                        ((fboundp x)
 129                         (fmakunbound x)
 130                         (let ((aload (get x 'autoload)))
 131                           (if aload (fset x (cons 'autoload aload))))))))
 132      (cdr flist))
 133     ;; Delete the load-history element for this file.
 134     (let ((elt (assoc file load-history)))
 135       (setq load-history (delq elt load-history)))))
 136
 137 (provide 'loadhist)
 138
 139 ;;; loadhist.el ends here