Function: select-safe-coding-system
select-safe-coding-system is a byte-compiled function defined in
mule-cmds.el.gz.
Signature
(select-safe-coding-system FROM TO &optional DEFAULT-CODING-SYSTEM ACCEPT-DEFAULT-P FILE)
Documentation
Ask a user to select a safe coding system from candidates.
The candidates of coding systems which can safely encode a text between FROM and TO are shown in a popup window. Among them, the most proper one is suggested as the default.
The list of buffer-file-coding-system of the current buffer, the
default buffer-file-coding-system, and the most preferred coding
system (if it corresponds to a MIME charset) is treated as the
default coding system list. Among them, the first one that safely
encodes the text is normally selected silently and returned without
any user interaction. See also the command prefer-coding-system.
However, the user is queried if the chosen coding system is
inconsistent with what would be selected by find-auto-coding from
coding cookies &c. if the contents of the region were read from a
file. (That could lead to data corruption in a file subsequently
re-visited and edited.)
Optional 3rd arg DEFAULT-CODING-SYSTEM specifies a coding system or a
list of coding systems to be prepended to the default coding system
list. However, if DEFAULT-CODING-SYSTEM is a list and the first
element is t, the cdr part is used as the default coding system list,
i.e. current buffer-file-coding-system, default buffer-file-coding-system,
and the most preferred coding system are not used.
Optional 4th arg ACCEPT-DEFAULT-P, if non-nil, is a function to determine the acceptability of the silently selected coding system. It is called with that coding system, and should return nil if it should not be silently selected and thus user interaction is required.
Optional 5th arg FILE is the file name to use for this purpose.
That is different from buffer-file-name(var)/buffer-file-name(fun) when handling write-region
(for example).
The variable select-safe-coding-system-accept-default-p, if non-nil,
overrides ACCEPT-DEFAULT-P.
Kludgy feature: if FROM is a string, the string is the target text, and TO is ignored.
Probably introduced at or before Emacs version 20.3.
Aliases
allout-select-safe-coding-system (obsolete since 28.1)
Source Code
;; Defined in /usr/src/emacs/lisp/international/mule-cmds.el.gz
(defun select-safe-coding-system (from to &optional default-coding-system
accept-default-p file)
"Ask a user to select a safe coding system from candidates.
The candidates of coding systems which can safely encode a text
between FROM and TO are shown in a popup window. Among them, the most
proper one is suggested as the default.
The list of `buffer-file-coding-system' of the current buffer, the
default `buffer-file-coding-system', and the most preferred coding
system (if it corresponds to a MIME charset) is treated as the
default coding system list. Among them, the first one that safely
encodes the text is normally selected silently and returned without
any user interaction. See also the command `prefer-coding-system'.
However, the user is queried if the chosen coding system is
inconsistent with what would be selected by `find-auto-coding' from
coding cookies &c. if the contents of the region were read from a
file. (That could lead to data corruption in a file subsequently
re-visited and edited.)
Optional 3rd arg DEFAULT-CODING-SYSTEM specifies a coding system or a
list of coding systems to be prepended to the default coding system
list. However, if DEFAULT-CODING-SYSTEM is a list and the first
element is t, the cdr part is used as the default coding system list,
i.e. current `buffer-file-coding-system', default `buffer-file-coding-system',
and the most preferred coding system are not used.
Optional 4th arg ACCEPT-DEFAULT-P, if non-nil, is a function to
determine the acceptability of the silently selected coding system.
It is called with that coding system, and should return nil if it
should not be silently selected and thus user interaction is required.
Optional 5th arg FILE is the file name to use for this purpose.
That is different from `buffer-file-name' when handling `write-region'
\(for example).
The variable `select-safe-coding-system-accept-default-p', if non-nil,
overrides ACCEPT-DEFAULT-P.
Kludgy feature: if FROM is a string, the string is the target text,
and TO is ignored."
(setq default-coding-system (ensure-list default-coding-system))
(let ((no-other-defaults nil)
auto-cs)
(unless (or (stringp from) find-file-literally)
;; Find an auto-coding that is specified for the current
;; buffer and file from the region FROM and TO.
(save-excursion
(save-restriction
(widen)
(goto-char from)
(setq auto-cs (find-auto-coding (or file buffer-file-name "")
(- to from)))
(if auto-cs
(if (coding-system-p (car auto-cs))
(setq auto-cs (car auto-cs))
(display-warning
'mule
(format-message "\
Invalid coding system `%s' is specified
for the current buffer/file by the %s.
It is highly recommended to fix it before writing to a file."
(car auto-cs)
(if (eq (cdr auto-cs) :coding) ":coding tag"
(format-message "variable `%s'" (cdr auto-cs))))
:warning)
(or (yes-or-no-p "Really proceed with writing? ")
(error "Save aborted"))
(setq auto-cs nil))))))
(if (eq (car default-coding-system) t)
(setq no-other-defaults t
default-coding-system (cdr default-coding-system)))
;; Change elements of the list to (coding . base-coding).
(setq default-coding-system
(mapcar (lambda (x) (cons x (coding-system-base x)))
default-coding-system))
(if (and auto-cs (not no-other-defaults))
;; If the file has a coding cookie, use it regardless of any
;; other setting.
(let ((base (coding-system-base auto-cs)))
(unless (memq base '(nil undecided))
;; For encoding, no-conversion-multibyte is the same as
;; no-conversion.
(if (eq base 'no-conversion-multibyte)
(setq auto-cs 'no-conversion
base 'no-conversion))
(setq default-coding-system (list (cons auto-cs base)))
(setq no-other-defaults t))))
(unless no-other-defaults
;; If buffer-file-coding-system is not nil nor undecided, append it
;; to the defaults.
(if buffer-file-coding-system
(let ((base (coding-system-base buffer-file-coding-system)))
(or (eq base 'undecided)
(rassq base default-coding-system)
(setq default-coding-system
(append default-coding-system
(list (cons buffer-file-coding-system base)))))))
(unless (and buffer-file-coding-system-explicit
(cdr buffer-file-coding-system-explicit))
;; If default buffer-file-coding-system is not nil nor undecided,
;; append it to the defaults.
(when (default-value 'buffer-file-coding-system)
(let ((base (coding-system-base
(default-value 'buffer-file-coding-system))))
(or (eq base 'undecided)
(rassq base default-coding-system)
(setq default-coding-system
(append default-coding-system
(list (cons (default-value
'buffer-file-coding-system)
base)))))))
;; If the most preferred coding system has the property mime-charset,
;; append it to the defaults.
(let ((preferred (coding-system-priority-list t))
base)
(and (coding-system-p preferred)
(setq base (coding-system-base preferred))
(coding-system-get preferred :mime-charset)
(not (rassq base default-coding-system))
(setq default-coding-system
(append default-coding-system
(list (cons preferred base))))))))
(if select-safe-coding-system-accept-default-p
(setq accept-default-p select-safe-coding-system-accept-default-p))
;; Decide the eol-type from the top of the default codings,
;; current buffer-file-coding-system, or default buffer-file-coding-system.
(if default-coding-system
(let ((default-eol-type (coding-system-eol-type
(caar default-coding-system))))
(if (and (vectorp default-eol-type) buffer-file-coding-system)
(setq default-eol-type (coding-system-eol-type
buffer-file-coding-system)))
(if (and (vectorp default-eol-type)
(default-value 'buffer-file-coding-system))
(setq default-eol-type
(coding-system-eol-type
(default-value 'buffer-file-coding-system))))
(if (and default-eol-type (not (vectorp default-eol-type)))
(dolist (elt default-coding-system)
(setcar elt (coding-system-change-eol-conversion
(car elt) default-eol-type))))))
(let ((codings (find-coding-systems-region from to))
(coding-system nil)
(tick (if (not (stringp from)) (buffer-chars-modified-tick)))
safe rejected unsafe)
(if (eq (car codings) 'undecided)
;; Any coding system is ok.
(setq coding-system (caar default-coding-system))
;; Reverse the list so that elements are accumulated in safe,
;; rejected, and unsafe in the correct order.
(setq default-coding-system (nreverse default-coding-system))
;; Classify the defaults into safe, rejected, and unsafe.
(dolist (elt default-coding-system)
(if (memq (cdr elt) codings)
;; This is safe. Is it acceptable?
(if (and (functionp accept-default-p)
(not (funcall accept-default-p (cdr elt))))
;; No, not acceptable.
(push (car elt) rejected)
;; Yes, acceptable.
(push (car elt) safe))
;; This is not safe.
(push (car elt) unsafe)))
;; If there are safe ones, the first one is what we want.
(if safe
(setq coding-system (car safe))))
;; If all the defaults failed, ask a user.
(when (not coding-system)
;; If UTF-8 is in CODINGS, but is not its first member, make
;; it the first one, so it is offered as the default.
(and (memq 'utf-8 codings) (not (eq 'utf-8 (car codings)))
(setq codings (append '(utf-8) (delq 'utf-8 codings))))
(setq coding-system (select-safe-coding-system-interactively
from to codings unsafe rejected (car codings))))
;; Check we're not inconsistent with what `coding:' spec &c would
;; give when file is re-read.
;; But don't do this if we explicitly ignored the cookie
;; by using `find-file-literally'.
(when (and auto-cs
(not (and
coding-system
(memq (coding-system-type coding-system) '(0 5)))))
;; Merge coding-system and auto-cs as far as possible.
(if (not coding-system)
(setq coding-system auto-cs)
(if (not auto-cs)
(setq auto-cs coding-system)
(let ((eol-type-1 (coding-system-eol-type coding-system))
(eol-type-2 (coding-system-eol-type auto-cs)))
(if (eq (coding-system-base coding-system) 'undecided)
(setq coding-system (coding-system-change-text-conversion
coding-system auto-cs))
(if (eq (coding-system-base auto-cs) 'undecided)
(setq auto-cs (coding-system-change-text-conversion
auto-cs coding-system))))
(if (vectorp eol-type-1)
(or (vectorp eol-type-2)
(setq coding-system (coding-system-change-eol-conversion
coding-system eol-type-2)))
(if (vectorp eol-type-2)
(setq auto-cs (coding-system-change-eol-conversion
auto-cs eol-type-1)))))))
(if (and auto-cs
;; Don't barf if writing a compressed file, say.
;; This check perhaps isn't ideal, but is probably
;; the best thing to do.
(not (auto-coding-alist-lookup (or file buffer-file-name "")))
(not (coding-system-equal coding-system auto-cs))
;; coding-system-equal barfs on 'charset'.
(or (equal (coding-system-type auto-cs) 'charset)
(equal (coding-system-type coding-system) 'charset)
(not (coding-system-equal (coding-system-type auto-cs)
(coding-system-type
coding-system)))))
(unless (yes-or-no-p
(format "Selected encoding %s disagrees with \
%s specified by file contents. Really save (else edit coding cookies \
and try again)? " coding-system auto-cs))
(error "Save aborted"))))
(when (and tick (/= tick (buffer-chars-modified-tick)))
(error "Canceled because the buffer was modified"))
(if (and (eq (coding-system-type coding-system) 'undecided)
(coding-system-get coding-system :prefer-utf-8)
(or (multibyte-string-p from)
(and (number-or-marker-p from)
(< (- to from)
(- (position-bytes to) (position-bytes from))))))
(setq coding-system
(coding-system-change-text-conversion coding-system 'utf-8)))
coding-system)))