;;; FILE I/O
-(defun set-auto-coding (size)
- "Return coding system for a file of which SIZE bytes follow point.
+(defun set-auto-coding (string)
+ "Return coding system for a file which has STRING at the head and tail.
+STRING is a concatination of the first 1K-byte and
+ the last 3K-byte of the file.
-It checks for a -*- coding: tag in the first one or two lines
-following point. If no coding: tag is found, it checks local
-variables spec in the last 3K-byte of SIZE bytes.
+It checks for a -*- coding: tag in the first one or two lines of STRING.
+If there's no coding: tag in the head, it checks local variables spec
+in the tailing 3K-byte oof STRING.
The return value is the specified coding system,
or nil if nothing specified.
The variable `set-auto-coding-function' (which see) is set to this
function by default."
- (let* ((case-fold-search t)
- (head-start (point))
- (head-end (+ head-start (min size 1024)))
- (tail-start (+ head-start (max (- size 3072) 0)))
- (tail-end (+ head-start size))
- coding-system head-found tail-found pos)
- ;; Try a short cut by searching for the string "coding:" at the
- ;; head and tail of SIZE bytes.
- (setq head-found (search-forward "coding:" head-end t))
- (if (and head-found (> head-found tail-start))
- ;; Head and tail are overlapped.
- (setq tail-found head-found)
- (goto-char tail-start)
- (setq tail-found (search-forward "coding:" tail-end t)))
-
- ;; At first check the head.
- (when head-found
- (goto-char head-start)
- (setq pos (re-search-forward "[\n\r]" head-end t))
- (if (and pos
- (= (char-after head-start) ?#)
- (= (char-after (1+ head-start)) ?!))
- ;; If the file begins with "#!" (exec interpreter magic),
- ;; look for coding frobs in the first two lines. You cannot
- ;; necessarily put them in the first line of such a file
- ;; without screwing up the interpreter invocation.
- (setq pos (search-forward "\n" head-end t)))
- (if pos (setq head-end pos))
- (when (< head-found head-end)
- (goto-char head-start)
- (if (re-search-forward
- "-\\*-\\(.*;\\)?[ \t]*coding:[ \t]*\\([^ ;]+\\)" head-end t)
- (progn
- (setq coding-system (intern (match-string 2)))
+ (condition-case nil
+ (let ((case-fold-search t)
+ (len (length string))
+ (limit (string-match "\n" string))
+ (coding-system nil))
+
+ ;; At first check the head.
+ (if limit
+ (when (string-match "^#!" string)
+ ;; If the file begins with "#!" (exec interpreter
+ ;; magic), look for coding frobs in the first two lines.
+ ;; You cannot necessarily put them in the first line of
+ ;; such a file without screwing up the interpreter
+ ;; invocation.
+ (setq limit (string-match "\n" string limit))
+ (or limit
+ (setq limit len)))
+ (setq limit len))
+ (when (and (string-match "-\\*-\\(.*;\\)?[ \t]*coding:[ \t]*\\([^ ;]+\\)" string)
+ (< (match-beginning 2) limit))
+ (setq coding-system
+ (intern (substring string (match-beginning 2) (match-end 2))))
+ (if (not (coding-system-p coding-system))
+ (setq coding-system nil)))
+
+ ;; If no coding system is specified in the head, check the tail.
+ (when (and (not coding-system)
+ (let ((idx (if (> len 3000) (- len 3000) 0))
+ start)
+ (while (setq start (string-match "\n\^L" string idx))
+ (setq idx (+ start 2)))
+ (string-match
+ "^\\(.*\\)[ \t]*Local Variables:[ \t]*\\(.*\\)$"
+ string idx)))
+ ;; The prefix is what comes before "local variables:" in its line.
+ ;; The suffix is what comes after "local variables:" in its line.
+ (let* ((idx (1+ (match-end 0)))
+ (prefix (regexp-quote
+ (substring string
+ (match-beginning 1) (match-end 1))))
+ (suffix (regexp-quote
+ (substring string
+ (match-beginning 2) (match-end 2))))
+ (re-coding (concat "^" prefix
+ "coding[ \t]*:[ \t]*\\([^ \t\n]+\\)[ \t]*"
+ suffix "$"))
+ (re-end (concat "^" prefix "end *:[ \t]*" suffix "$"))
+ (limit (or (string-match re-end string idx) len)))
+ (when (and (setq idx (string-match re-coding string idx))
+ (< idx limit))
+ (setq coding-system
+ (intern (substring string
+ (match-beginning 1) (match-end 1))))
(or (coding-system-p coding-system)
- (setq coding-system nil))))))
-
- ;; If no coding: tag in the head, check the tail.
- (when (and tail-found (not coding-system))
- (goto-char tail-start)
- (search-forward "\n\^L" nil t)
- (if (re-search-forward
- "^\\(.*\\)[ \t]*Local Variables:[ \t]*\\(.*\\)$" tail-end t)
- ;; The prefix is what comes before "local variables:" in its
- ;; line. The suffix is what comes after "local variables:"
- ;; in its line.
- (let* ((prefix (regexp-quote (match-string 1)))
- (suffix (regexp-quote (match-string 2)))
- (re-coding (concat
- "^" prefix
- "coding[ \t]*:[ \t]*\\([^ \t]+\\)[ \t]*"
- suffix "$"))
- (re-end (concat
- "^" prefix "end *:[ \t]*" suffix "$"))
- (pos (point)))
- (re-search-forward re-end tail-end 'move)
- (setq tail-end (point))
- (goto-char pos)
- (if (re-search-forward re-coding tail-end t)
- (progn
- (setq coding-system (intern (match-string 1)))
- (or (coding-system-p coding-system)
- (setq coding-system nil)))))))
- coding-system))
+ (setq coding-system nil)))))
+
+ coding-system)
+ (error nil)))
(setq set-auto-coding-function 'set-auto-coding)
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