+;; Actually, `butlast' and `nbutlast' are defined in lisp/cl.el.
+(defun-maybe butlast (x &optional n)
+ "Returns a copy of LIST with the last N elements removed."
+ (if (and n (<= n 0)) x
+ (nbutlast (copy-sequence x) n)))
+
+(defun-maybe nbutlast (x &optional n)
+ "Modifies LIST to remove the last N elements."
+ (let ((m (length x)))
+ (or n (setq n 1))
+ (and (< n m)
+ (progn
+ (if (> n 0) (setcdr (nthcdr (- (1- m) n) x) nil))
+ x))))
+
+;; Emacs 20.3 and later: (assoc-default KEY ALIST &optional TEST DEFAULT)
+(defun-maybe assoc-default (key alist &optional test default)
+ "Find object KEY in a pseudo-alist ALIST.
+ALIST is a list of conses or objects. Each element (or the element's car,
+if it is a cons) is compared with KEY by evaluating (TEST (car elt) KEY).
+If that is non-nil, the element matches;
+then `assoc-default' returns the element's cdr, if it is a cons,
+or DEFAULT if the element is not a cons.
+
+If no element matches, the value is nil.
+If TEST is omitted or nil, `equal' is used."
+ (let (found (tail alist) value)
+ (while (and tail (not found))
+ (let ((elt (car tail)))
+ (when (funcall (or test 'equal) (if (consp elt) (car elt) elt) key)
+ (setq found t value (if (consp elt) (cdr elt) default))))
+ (setq tail (cdr tail)))
+ value))
+
+;; The following two function use `compare-strings', which we don't
+;; support yet.
+;; (defun assoc-ignore-case (key alist))
+;; (defun assoc-ignore-representation (key alist))
+
+;; Emacs 19.29/XEmacs 19.14(?) and later: (rassoc KEY LIST)
+;; Actually, `rassoc' is defined in src/fns.c.
+(defun-maybe rassoc (key list)
+ "Return non-nil if KEY is `equal' to the cdr of an element of LIST.
+The value is actually the element of LIST whose cdr equals KEY.
+Elements of LIST that are not conses are ignored."
+ (catch 'found
+ (while list
+ (cond ((not (consp (car list))))
+ ((equal (cdr (car list)) key)
+ (throw 'found (car list))))
+ (setq list (cdr list)))))
+
+;;; Define `functionp' here because "localhook" uses it.
+
+;; Emacs 20.1/XEmacs 20.3 (but first appeared in Epoch?): (functionp OBJECT)
+(defun-maybe functionp (object)
+ "Non-nil if OBJECT is a type of object that can be called as a function."
+ (or (subrp object) (byte-code-function-p object)
+ (eq (car-safe object) 'lambda)
+ (and (symbolp object) (fboundp object))))
+
+;;; @@ Hook manipulation functions.
+
+;; "localhook" package is written for Emacs 19.28 and earlier.
+;; `run-hooks' was a lisp function in Emacs 19.29 and earlier.
+;; So, in Emacs 19.29, `run-hooks' and others will be overrided.
+;; But, who cares it?
+(static-unless (subrp (symbol-function 'run-hooks))
+ (require 'localhook))
+
+;; Emacs 19.29/XEmacs 19.14(?) and later: (add-to-list LIST-VAR ELEMENT)
+(defun-maybe add-to-list (list-var element)
+ "Add to the value of LIST-VAR the element ELEMENT if it isn't there yet.
+The test for presence of ELEMENT is done with `equal'.
+If you want to use `add-to-list' on a variable that is not defined
+until a certain package is loaded, you should put the call to `add-to-list'
+into a hook function that will be run only after loading the package.
+`eval-after-load' provides one way to do this. In some cases
+other hooks, such as major mode hooks, can do the job."
+ (or (member element (symbol-value list-var))
+ (set list-var (cons element (symbol-value list-var)))))
+
+;; (eval-after-load FILE FORM)
+;; Emacs 19.28 and earlier do not evaluate FORM if FILE is already loaded.
+;; XEmacs 20.2 and earlier have `after-load-alist', but refuse to support
+;; `eval-after-load'. (see comments in XEmacs/lisp/subr.el.)
+(static-cond
+ ((featurep 'xemacs)
+ ;; for XEmacs 20.2 and earlier.
+ (defun-maybe eval-after-load (file form)
+ "Arrange that, if FILE is ever loaded, FORM will be run at that time.
+This makes or adds to an entry on `after-load-alist'.
+If FILE is already loaded, evaluate FORM right now.
+It does nothing if FORM is already on the list for FILE.
+FILE should be the name of a library, with no directory name."
+ ;; Make sure there is an element for FILE.
+ (or (assoc file after-load-alist)
+ (setq after-load-alist (cons (list file) after-load-alist)))
+ ;; Add FORM to the element if it isn't there.
+ (let ((elt (assoc file after-load-alist)))
+ (or (member form (cdr elt))
+ (progn
+ (nconc elt (list form))
+ ;; If the file has been loaded already, run FORM right away.
+ (and (assoc file load-history)
+ (eval form)))))
+ form))
+ ((>= emacs-major-version 20))
+ ((and (= emacs-major-version 19)
+ (< emacs-minor-version 29))
+ ;; for Emacs 19.28 and earlier.
+ (defun eval-after-load (file form)
+ "Arrange that, if FILE is ever loaded, FORM will be run at that time.
+This makes or adds to an entry on `after-load-alist'.
+If FILE is already loaded, evaluate FORM right now.
+It does nothing if FORM is already on the list for FILE.
+FILE should be the name of a library, with no directory name."
+ ;; Make sure there is an element for FILE.
+ (or (assoc file after-load-alist)
+ (setq after-load-alist (cons (list file) after-load-alist)))
+ ;; Add FORM to the element if it isn't there.
+ (let ((elt (assoc file after-load-alist)))
+ (or (member form (cdr elt))
+ (progn
+ (nconc elt (list form))
+ ;; If the file has been loaded already, run FORM right away.
+ (and (assoc file load-history)
+ (eval form)))))
+ form))
+ (t
+ ;; should emulate for v18?
+ ))
+
+(defun-maybe eval-next-after-load (file)
+ "Read the following input sexp, and run it whenever FILE is loaded.
+This makes or adds to an entry on `after-load-alist'.
+FILE should be the name of a library, with no directory name."
+ (eval-after-load file (read)))
+
+;;; @@ Input and display facilities.
+
+;; XXX: (defun read-passwd (prompt &optional confirm default))
+
+;;; @@ Miscellanea.
+
+;; Avoid compiler warnings about this variable,
+;; which has a special meaning on certain system types.
+(defvar-maybe buffer-file-type nil
+ "Non-nil if the visited file is a binary file.
+This variable is meaningful on MS-DOG and Windows NT.
+On those systems, it is automatically local in every buffer.
+On other systems, this variable is normally always nil.")
+
+;; Emacs 20.1/XEmacs 20.3(?) and later: (save-current-buffer &rest BODY)
+;;
+;; v20 defines `save-current-buffer' as a C primitive (in src/editfns.c)
+;; and introduces a new bytecode Bsave_current_buffer(_1), replacing an
+;; obsolete bytecode Bread_char. To make things worse, Emacs 20.1 and
+;; 20.2 have a bug that it will restore the current buffer without
+;; confirming that it is alive.
+;;
+;; This is a source of incompatibility of .elc between v18/v19 and v20.
+;; (XEmacs compiler takes care of it if compatibility mode is enabled.)