;;; dos-w32.el --- Functions shared among MS-DOS and W32 (NT/95) platforms

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

;; Maintainer: Geoff Voelker (voelker@cs.washington.edu)
;; Keywords: internal

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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.

;;; Commentary:

;; Parts of this code are duplicated functions taken from dos-fns.el
;; and winnt.el.

;;; Code:

;; Use ";" instead of ":" as a path separator (from files.el).
(setq path-separator ";")

;; Set the null device (for compile.el).
(setq grep-null-device "NUL")

;; Set the grep regexp to match entries with drive letters.
(setq grep-regexp-alist
  '(("^\\(\\([a-zA-Z]:\\)?[^:( \t\n]+\\)[:( \t]+\\([0-9]+\\)[:) \t]" 1 3)))

;; For distinguishing file types based upon suffixes.
(defvar file-name-buffer-file-type-alist
  '(
    ("[:/].*config.sys$" . nil)		; config.sys text
    ("\\.elc$" . t)			; emacs stuff
    ("\\.\\(obj\\|exe\\|com\\|lib\\|sym\\|sys\\|chk\\|out\\|bin\\|ico\\|pif\\|dos\\|class\\)$" . t)
					; MS-Dos stuff
    ("\\.\\(dll\\|drv\\|cpl\\|scr\\vbx\\|386\\|vxd\\|fon\\|fnt\\|fot\\|ttf\\|grp\\)$" . t)
					; Windows stuff
    ("\\.\\(hlp\\|bmp\\|wav\\|avi\\|mpg\\|jpg\\|tif\\mov\\au\\)" . t)
					; known binary data files
    ("\\.\\(arc\\|zip\\|pak\\|lzh\\|zoo\\)$" . t)
					; Packers
    ("\\.\\(a\\|o\\|tar\\|z\\|gz\\|taz\\|jar\\)$" . t)
					; Unix stuff
    ("\\.tp[ulpw]$" . t)
					; Borland Pascal stuff
    ("[:/]tags$" . t)
					; Emacs TAGS file
    )
  "*Alist for distinguishing text files from binary files.
Each element has the form (REGEXP . TYPE), where REGEXP is matched
against the file name, and TYPE is nil for text, t for binary.")

;; Return the pair matching filename on file-name-buffer-file-type-alist,
;; or nil otherwise.
(defun find-buffer-file-type-match (filename)
  (let ((alist file-name-buffer-file-type-alist)
	(found nil))
    (let ((case-fold-search t))
      (setq filename (file-name-sans-versions filename))
      (while (and (not found) alist)
	(if (string-match (car (car alist)) filename)
	    (setq found (car alist)))
	(setq alist (cdr alist)))
      found)))

;; Don't check for untranslated file systems here.
(defun find-buffer-file-type (filename)
  (let ((match (find-buffer-file-type-match filename))
	(code))
    (if (not match)
	default-buffer-file-type
      (setq code (cdr match))
      (cond ((memq code '(nil t)) code)
	    ((and (symbolp code) (fboundp code))
	     (funcall code filename))))))

(setq-default buffer-file-coding-system 'undecided-dos)

(defun find-buffer-file-type-coding-system (command)
  "Choose a coding system for a file operation.
If COMMAND is `insert-file-contents', the coding system is chosen based
upon the filename, the contents of `untranslated-filesystem-list' and
`file-name-buffer-file-type-alist', and whether the file exists:

  If it matches in `untranslated-filesystem-list':
    If the file exists:					`no-conversion'
    If the file does not exist:				`undecided'
  If it matches in `file-name-buffer-file-type-alist':
    If the match is t (for binary):			`no-conversion'
    If the match is nil (for dos-text):			`undecided-dos'
  Otherwise:
    If the file exists:					`undecided'
    If the file does not exist:				`undecided-dos'

If COMMAND is `write-region', the coding system is chosen based upon
the value of `buffer-file-coding-system' and `buffer-file-type'. If
`buffer-file-coding-system' is non-nil, its value is used.  If it is
nil and `buffer-file-type' is t, the coding system is `no-conversion'.
Otherwise, it is `undecided-dos'.

The two most common situations are when DOS and Unix files are read
and written, and their names do not match in
`untranslated-filesystem-list' and `file-name-buffer-file-type-alist'.
In these cases, the coding system initially will be `undecided'.  As
the file is read in the DOS case, the coding system will be changed to
`undecided-dos' as CR/LFs are detected.  As the file is read in the
Unix case, the coding system will be changed to `undecided-unix' as
LFs are detected.  In both cases, `buffer-file-coding-system' will be
set to the appropriate coding system, and the value of
`buffer-file-coding-system' will be used when writing the file."

  (let ((op (nth 0 command))
	(target)
	(binary nil) (text nil)
	(undecided nil) (undecided-unix nil))
    (cond ((eq op 'insert-file-contents) 
	   (setq target (nth 1 command))
	   ;; First check for a file name that indicates
	   ;; it is truly binary.
	   (setq binary (find-buffer-file-type target))
	   (cond (binary)
		 ;; Next check for files that MUST use DOS eol conversion.
		 ((find-buffer-file-type-match target)
		  (setq text t))
		 ;; For any other existing file, decide based on contents.
		 ((file-exists-p target)
		  (setq undecided t))
		 ;; Next check for a non-DOS file system.
		 ((untranslated-file-p target)
		  (setq undecided-unix t)))
	   (cond (binary '(no-conversion . no-conversion))
		 (text '(undecided-dos . undecided-dos))
		 (undecided-unix '(undecided-unix . undecided-unix))
		 (undecided '(undecided . undecided))
		 (t '(undecided-dos . undecided-dos))))
	  ((eq op 'write-region)
	   (if buffer-file-coding-system
	       (cons buffer-file-coding-system
		     buffer-file-coding-system)
	     ;; Normally this is used only in a non-file-visiting
	     ;; buffer, because normally buffer-file-coding-system is non-nil
	     ;; in a file-visiting buffer.
	     (if buffer-file-type
		 '(no-conversion . no-conversion)
	       '(undecided-dos . undecided-dos)))))))

(modify-coding-system-alist 'file "" 'find-buffer-file-type-coding-system)

(defun find-file-binary (filename) 
  "Visit file FILENAME and treat it as binary."
  (interactive "FFind file binary: ")
  (let ((file-name-buffer-file-type-alist '(("" . t))))
    (find-file filename)))

(defun find-file-text (filename) 
  "Visit file FILENAME and treat it as a text file."
  (interactive "FFind file text: ")
  (let ((file-name-buffer-file-type-alist '(("" . nil))))
    (find-file filename)))

(defun find-file-not-found-set-buffer-file-coding-system ()
  (save-excursion
    (set-buffer (current-buffer))
    (let* ((dummy-insert-op (list 'insert-file-contents (buffer-file-name)))
	   (coding-system-pair
	    (find-buffer-file-type-coding-system dummy-insert-op)))
      (setq buffer-file-coding-system (car coding-system-pair))
      (setq buffer-file-type (eq buffer-file-coding-system 'no-conversion)))))

;;; To set the default coding system on new files.
(add-hook 'find-file-not-found-hooks 
	  'find-file-not-found-set-buffer-file-coding-system)

;;; To accomodate filesystems that do not require CR/LF translation.
(defvar untranslated-filesystem-list nil
  "List of filesystems that require no CR/LF translation when reading 
and writing files.  Each filesystem in the list is a string naming
the directory prefix corresponding to the filesystem.")

(defun untranslated-canonical-name (filename)
  "Return FILENAME in a canonicalized form for use with the functions
dealing with untranslated filesystems."
  (if (memq system-type '(ms-dos windows-nt))
      ;; The canonical form for DOS/W32 is with A-Z downcased and all
      ;; directory separators changed to directory-sep-char.
      (let ((name nil))
	(setq name (mapconcat 
		    '(lambda (char) 
		       (if (and (<= ?A char) (<= char ?Z))
			   (char-to-string (+ (- char ?A) ?a))
			 (char-to-string char)))
		    filename nil))
	;; Use expand-file-name to canonicalize directory separators, except
	;; with bare drive letters (which would have the cwd appended).
	(if (string-match "^.:$" name)
	    name
	  (expand-file-name name)))
    filename))

(defun untranslated-file-p (filename)
  "Return t if FILENAME is on a filesystem that does not require 
CR/LF translation, and nil otherwise."
  (let ((fs (untranslated-canonical-name filename))
	(ufs-list untranslated-filesystem-list)
	(found nil))
    (while (and (not found) ufs-list)
      (if (string-match (concat "^" (car ufs-list)) fs)
	  (setq found t)
	(setq ufs-list (cdr ufs-list))))
    found))

(defun add-untranslated-filesystem (filesystem)
  "Add FILESYSTEM to the list of filesystems that do not require
CR/LF translation.  FILESYSTEM is a string containing the directory
prefix corresponding to the filesystem.  For example, for a Unix 
filesystem mounted on drive Z:, FILESYSTEM could be \"Z:\"."
  (interactive "fUntranslated file system: ")
  (let ((fs (untranslated-canonical-name filesystem)))
    (if (member fs untranslated-filesystem-list)
	untranslated-filesystem-list
      (setq untranslated-filesystem-list
	    (cons fs untranslated-filesystem-list)))))

(defun remove-untranslated-filesystem (filesystem)
  "Remove FILESYSTEM from the list of filesystems that do not require 
CR/LF translation.  FILESYSTEM is a string containing the directory
prefix corresponding to the filesystem.  For example, for a Unix 
filesystem mounted on drive Z:, FILESYSTEM could be \"Z:\"."
  (interactive "fUntranslated file system: ")
  (setq untranslated-filesystem-list 
	(delete (untranslated-canonical-name filesystem)
		untranslated-filesystem-list)))

;; Process I/O decoding and encoding.

(defun find-binary-process-coding-system (command)
  "Choose a coding system for process I/O.
The coding system for decode is 'no-conversion' if 'binary-process-output'
is non-nil, and 'undecided-dos' otherwise.  Similarly, the coding system 
for encode is 'no-conversion' if 'binary-process-input' is non-nil,
and 'undecided-dos' otherwise."
  (let ((decode 'undecided-dos)
	(encode 'undecided-dos))
    (if binary-process-output
	(setq decode 'no-conversion))
    (if binary-process-input
	(setq encode 'no-conversion))
    (cons decode encode)))

(modify-coding-system-alist 'process "" 'find-binary-process-coding-system)


(provide 'dos-w32)

;;; dos-w32.el ends here