;;; emu.el --- Emulation module for each Emacs variants

;; Copyright (C) 1995,1996,1997,1998 Free Software Foundation, Inc.

;; Author: MORIOKA Tomohiko <morioka@jaist.ac.jp>
;; Keywords: emulation, compatibility, NEmacs, MULE, Emacs/mule, XEmacs

;; This file is part of emu.

;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or (at
;; your option) any later version.

;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Code:

(defmacro defun-maybe (name &rest everything-else)
  (or (and (fboundp name)
	   (not (get name 'defun-maybe))
	   )
      (` (or (fboundp (quote (, name)))
	     (progn
	       (defun (, name) (,@ everything-else))
	       (put (quote (, name)) 'defun-maybe t)
	       ))
	 )))

(defmacro defsubst-maybe (name &rest everything-else)
  (or (and (fboundp name)
	   (not (get name 'defsubst-maybe))
	   )
      (` (or (fboundp (quote (, name)))
	     (progn
	       (defsubst (, name) (,@ everything-else))
	       (put (quote (, name)) 'defsubst-maybe t)
	       ))
	 )))

(defmacro defmacro-maybe (name &rest everything-else)
  (or (and (fboundp name)
	   (not (get name 'defmacro-maybe))
	   )
      (` (or (fboundp (quote (, name)))
	     (progn
	       (defmacro (, name) (,@ everything-else))
	       (put (quote (, name)) 'defmacro-maybe t)
	       ))
	 )))

(put 'defun-maybe 'lisp-indent-function 'defun)
(put 'defsubst-maybe 'lisp-indent-function 'defun)
(put 'defmacro-maybe 'lisp-indent-function 'defun)

(defmacro defconst-maybe (name &rest everything-else)
  (or (and (boundp name)
	   (not (get name 'defconst-maybe))
	   )
      (` (or (boundp (quote (, name)))
	     (progn
	       (defconst (, name) (,@ everything-else))
	       (put (quote (, name)) 'defconst-maybe t)
	       ))
	 )))


(defconst-maybe emacs-major-version (string-to-int emacs-version))
(defconst-maybe emacs-minor-version
  (string-to-int
   (substring emacs-version
	      (string-match (format "%d\\." emacs-major-version)
			    emacs-version))))

(defvar running-emacs-18 (<= emacs-major-version 18))
(defvar running-xemacs (string-match "XEmacs" emacs-version))

(defvar running-mule-merged-emacs (and (not (boundp 'MULE))
				       (not running-xemacs) (featurep 'mule)))
(defvar running-xemacs-with-mule (and running-xemacs (featurep 'mule)))

(defvar running-emacs-19 (and (not running-xemacs) (= emacs-major-version 19)))
(defvar running-emacs-19_29-or-later
  (or (and running-emacs-19 (>= emacs-minor-version 29))
      (and (not running-xemacs)(>= emacs-major-version 20))))

(defvar running-xemacs-19 (and running-xemacs
			       (= emacs-major-version 19)))
(defvar running-xemacs-20-or-later (and running-xemacs
					(>= emacs-major-version 20)))
(defvar running-xemacs-19_14-or-later
  (or (and running-xemacs-19 (>= emacs-minor-version 14))
      running-xemacs-20-or-later))

(cond (running-xemacs
       ;; for XEmacs
       (require 'emu-xemacs)
       (if (featurep 'mule)
	   ;; for XEmacs with MULE
	   (require 'emu-x20)
	 ;; for XEmacs without MULE
	 (require 'emu-latin1)
	 ))
      (running-mule-merged-emacs
       ;; for Emacs 20.1 and 20.2
       (require 'emu-e20)
       )
      ((boundp 'MULE)
       ;; for MULE 1.* and 2.*
       (require 'emu-mule)
       )
      ((boundp 'NEMACS)
       ;; for NEmacs and NEpoch
       (require 'emu-nemacs)
       )
      (t
       ;; for Emacs 19
       (require 'emu-e19)
       (require 'emu-latin1)
       ))


;;; @ MIME charset
;;;

(defun charsets-to-mime-charset (charsets)
  "Return MIME charset from list of charset CHARSETS.
This function refers variable `charsets-mime-charset-alist'
and `default-mime-charset'."
  (if charsets
      (or (catch 'tag
	    (let ((rest charsets-mime-charset-alist)
		  cell)
	      (while (setq cell (car rest))
		(if (catch 'not-subset
		      (let ((set1 charsets)
			    (set2 (car cell))
			    obj)
			(while set1
			  (setq obj (car set1))
			  (or (memq obj set2)
			      (throw 'not-subset nil))
			  (setq set1 (cdr set1)))
			t))
		    (throw 'tag (cdr cell)))
		(setq rest (cdr rest)))))
	  default-mime-charset)))


;;; @ Emacs 19 emulation
;;;

(defun-maybe minibuffer-prompt-width ()
  "Return the display width of the minibuffer prompt."
  (save-excursion
    (set-buffer (window-buffer (minibuffer-window)))
    (current-column)))


;;; @ Emacs 19.29 emulation
;;;

(defvar path-separator ":"
  "Character used to separate concatenated paths.")

(defun-maybe buffer-substring-no-properties (start end)
  "Return the characters of part of the buffer, without the text properties.
The two arguments START and END are character positions;
they can be in either order. [Emacs 19.29 emulating function]"
  (let ((string (buffer-substring start end)))
    (set-text-properties 0 (length string) nil string)
    string))

(defun-maybe match-string (num &optional string)
  "Return string of text matched by last search.
NUM specifies which parenthesized expression in the last regexp.
 Value is nil if NUMth pair didn't match, or there were less than NUM pairs.
Zero means the entire text matched by the whole regexp or whole string.
STRING should be given if the last search was by `string-match' on STRING.
\[Emacs 19.29 emulating function]"
  (if (match-beginning num)
      (if string
	  (substring string (match-beginning num) (match-end num))
	(buffer-substring (match-beginning num) (match-end num)))))

(or running-emacs-19_29-or-later
    running-xemacs
    ;; for Emacs 19.28 or earlier
    (fboundp 'si:read-string)
    (progn
      (fset 'si:read-string (symbol-function 'read-string))
      
      (defun read-string (prompt &optional initial-input history)
	"Read a string from the minibuffer, prompting with string PROMPT.
If non-nil, second arg INITIAL-INPUT is a string to insert before reading.
The third arg HISTORY, is dummy for compatibility. [emu.el]
See `read-from-minibuffer' for details of HISTORY argument."
	(si:read-string prompt initial-input))
      ))


;;; @ Emacs 19.30 emulation
;;;

;; This function was imported Emacs 19.30.
(defun-maybe add-to-list (list-var element)
  "Add to the value of LIST-VAR the element ELEMENT if it isn't there yet.
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.
\[Emacs 19.30 emulating function]"
  (or (member element (symbol-value list-var))
      (set list-var (cons element (symbol-value list-var)))))

(cond ((fboundp 'insert-file-contents-literally)
       )
      ((boundp 'file-name-handler-alist)
       (defun insert-file-contents-literally
	 (filename &optional visit beg end replace)
	 "Like `insert-file-contents', q.v., but only reads in the file.
A buffer may be modified in several ways after reading into the buffer due
to advanced Emacs features, such as file-name-handlers, format decoding,
find-file-hooks, etc.
  This function ensures that none of these modifications will take place.
\[Emacs 19.30 emulating function]"
	 (let (file-name-handler-alist)
	   (insert-file-contents filename visit beg end replace)))
       )
      (t
       (defalias 'insert-file-contents-literally 'insert-file-contents)
       ))


;;; @ Emacs 19.31 emulation
;;;

(defun-maybe buffer-live-p (object)
  "Return non-nil if OBJECT is a buffer which has not been killed.
Value is nil if OBJECT is not a buffer or if it has been killed.
\[Emacs 19.31 emulating function]"
  (and object
       (get-buffer object)
       (buffer-name (get-buffer object))))

;; This macro was imported Emacs 19.33.
(defmacro-maybe save-selected-window (&rest body)
  "Execute BODY, then select the window that was selected before BODY.
\[Emacs 19.31 emulating function]"
  (list 'let
	'((save-selected-window-window (selected-window)))
	(list 'unwind-protect
	      (cons 'progn body)
	      (list 'select-window 'save-selected-window-window))))


;;; @ Emacs 20.1 emulation
;;;

;; This macro was imported Emacs 20.2.
(defmacro-maybe when (cond &rest body)
  "(when COND BODY...): if COND yields non-nil, do BODY, else return nil."
  (list 'if cond (cons 'progn body)))

(defmacro-maybe save-current-buffer (&rest body)
  "Save the current buffer; execute BODY; restore the current buffer.
Executes BODY just like `progn'."
  (` (let ((orig-buffer (current-buffer)))
       (unwind-protect
	   (progn (,@ body))
	 (set-buffer orig-buffer)))))

;; This macro was imported Emacs 20.2.
(defmacro-maybe with-current-buffer (buffer &rest body)
  "Execute the forms in BODY with BUFFER as the current buffer.
The value returned is the value of the last form in BODY.
See also `with-temp-buffer'."
  (` (save-current-buffer
       (set-buffer (, buffer))
       (,@ body))))

;; This macro was imported Emacs 20.2.
(defmacro-maybe with-temp-buffer (&rest forms)
  "Create a temporary buffer, and evaluate FORMS there like `progn'.
See also `with-temp-file' and `with-output-to-string'."
  (let ((temp-buffer (make-symbol "temp-buffer")))
    (` (let (((, temp-buffer)
	      (get-buffer-create (generate-new-buffer-name " *temp*"))))
	 (unwind-protect
	     (with-current-buffer (, temp-buffer)
	       (,@ forms))
	   (and (buffer-name (, temp-buffer))
		(kill-buffer (, temp-buffer))))))))

;; This function was imported Emacs 20.3.
(defun-maybe last (x &optional n)
  "Return the last link of the list X.  Its car is the last element.
If X is nil, return nil.
If N is non-nil, return the Nth-to-last link of X.
If N is bigger than the length of X, return X."
  (if n
      (let ((m 0) (p x))
	(while (consp p)
	  (setq m (1+ m) p (cdr p)))
	(if (<= n 0) p
	  (if (< n m) (nthcdr (- m n) x) x)))
    (while (cdr x)
      (setq x (cdr x)))
    x))

;; This function was imported Emacs 20.3. (cl function)
(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)))
  
;; This function was imported Emacs 20.3. (cl function)
(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))))

;; This function was imported from XEmacs 21.
(defun-maybe split-string (string &optional pattern)
  "Return a list of substrings of STRING which are separated by PATTERN.
If PATTERN is omitted, it defaults to \"[ \\f\\t\\n\\r\\v]+\"."
  (or pattern
      (setq pattern "[ \f\t\n\r\v]+"))
  ;; The FSF version of this function takes care not to cons in case
  ;; of infloop.  Maybe we should synch?
  (let (parts (start 0))
    (while (string-match pattern string start)
      (setq parts (cons (substring string start (match-beginning 0)) parts)
	    start (match-end 0)))
    (nreverse (cons (substring string start) parts))))


;;; @ Emacs 20.3 emulation
;;;

(defmacro-maybe string-as-unibyte (string)
  "Return a unibyte string with the same individual bytes as STRING.
If STRING is unibyte, the result is STRING itself.
\[Emacs 20.3 emulating macro]"
  string)

(defmacro-maybe string-as-multibyte (string)
  "Return a multibyte string with the same individual bytes as STRING.
If STRING is multibyte, the result is STRING itself.
\[Emacs 20.3 emulating macro]"
  string)


;;; @ XEmacs emulation
;;;

(defun-maybe functionp (obj)
  "Returns t if OBJ is a function, nil otherwise.
\[XEmacs emulating function]"
  (or (subrp obj)
      (byte-code-function-p obj)
      (and (symbolp obj)(fboundp obj))
      (and (consp obj)(eq (car obj) 'lambda))
      ))

(defun-maybe point-at-eol (&optional arg buffer)
  "Return the character position of the last character on the current line.
With argument N not nil or 1, move forward N - 1 lines first.
If scan reaches end of buffer, return that position.
This function does not move point. [XEmacs emulating function]"
  (save-excursion
    (if buffer
	(set-buffer buffer)
      )
    (if arg
	(forward-line (1- arg))
      )
    (end-of-line)
    (point)))


;;; @ for XEmacs 20
;;;

(or (fboundp 'char-int)
    (fset 'char-int (symbol-function 'identity))
    )
(or (fboundp 'int-char)
    (fset 'int-char (symbol-function 'identity))
    )
(or (fboundp 'char-or-char-int-p)
    (fset 'char-or-char-int-p (symbol-function 'integerp))
    )


;;; @ for text/richtext and text/enriched
;;;

(cond ((fboundp 'richtext-decode)
       ;; have richtext.el
       )
      ((or running-emacs-19_29-or-later running-xemacs-19_14-or-later)
       ;; have enriched.el
       (autoload 'richtext-decode "richtext")
       (or (assq 'text/richtext format-alist)
	   (setq format-alist
		 (cons
		  (cons 'text/richtext
			'("Extended MIME text/richtext format."
			  "Content-[Tt]ype:[ \t]*text/richtext"
			  richtext-decode richtext-encode t enriched-mode))
		  format-alist)))
       )
      (t
       ;; don't have enriched.el
       (autoload 'richtext-decode "tinyrich")
       (autoload 'enriched-decode "tinyrich")
       ))


;;; @ end
;;;

(provide 'emu)

;;; emu.el ends here