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emacs/lisp/international/latexenc.el
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;;; latexenc.el --- guess correct coding system in LaTeX files -*- lexical-binding: t; -*-
;; Copyright (C) 2005-2024 Free Software Foundation, Inc.
;; Author: Arne Jørgensen <arne@arnested.dk>
;; Keywords: mule, coding system, latex
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; This code tries to guess the correct coding system of a LaTeX file.
;; First it searches for a \inputencoding{...} or
;; \usepackage[...]{inputenc} line in the file and looks up the ... in
;; `latex-inputenc-coding-alist' to find the corresponding coding
;; system.
;; If this fails it will search for AUCTeX's TeX-master or tex-mode's
;; tex-main-file variable in the local variables section and visit
;; that file to get the coding system from the master file. This check
;; can be disabled by setting `latexenc-dont-use-TeX-master-flag' to
;; t.
;; If we have still not found a coding system we will try to use the
;; standard tex-mode's `tex-guess-main-file' and get the coding system
;; from the main file. This check can be disabled by setting
;; `latexenc-dont-use-tex-guess-main-file-flag' to t.
;; The functionality is enabled by adding the function
;; `latexenc-find-file-coding-system' to `file-coding-system-alist'
;; like this
;; (add-to-list 'file-coding-system-alist
;; '("\\.\\(tex\\|ltx\\|dtx\\|drv\\)\\'" . latexenc-find-file-coding-system))
;;; Code:
;;;###autoload
(defcustom latex-inputenc-coding-alist
(purecopy
'(("ansinew" . windows-1252) ; MS Windows ANSI encoding, extension of Latin-1
("applemac" . mac-roman)
("ascii" . us-ascii)
("cp1250" . windows-1250) ; MS Windows encoding, codepage 1250
("cp1252" . windows-1252) ; synonym of ansinew
("cp1257" . cp1257)
("cp437de" . cp437) ; IBM code page 437 (German version): 225 is \ss
("cp437" . cp437) ; IBM code page 437: 225 is \beta
("cp850" . cp850) ; IBM code page 850
("cp852" . cp852) ; IBM code page 852
("cp858" . cp858) ; IBM code page 850 but with a euro symbol
("cp865" . cp865) ; IBM code page 865
("latin1" . iso-8859-1)
("latin2" . iso-8859-2)
("latin3" . iso-8859-3)
("latin4" . iso-8859-4)
("latin5" . iso-8859-9)
("latin9" . iso-8859-15)
("latin10" . iso-8859-16)
;; ("macce" . undecided) ; Apple Central European
("next" . next) ; The Next encoding
("utf8" . utf-8)
("utf8x" . utf-8))) ; used by the Unicode LaTeX package
"Mapping from LaTeX encodings in \"inputenc.sty\" to Emacs coding systems.
LaTeX encodings are specified with \"\\usepackage[encoding]{inputenc}\".
Used by the function `latexenc-find-file-coding-system'."
:group 'files
:group 'mule
:type '(alist :key-type (string :tag "LaTeX input encoding")
:value-type (coding-system :tag "Coding system")))
;;;###autoload
(defun latexenc-inputenc-to-coding-system (inputenc)
"Return the corresponding coding-system for the specified input encoding.
Return nil if no matching coding system can be found."
(cdr (assoc inputenc latex-inputenc-coding-alist)))
;;;###autoload
(defun latexenc-coding-system-to-inputenc (cs)
"Return the corresponding input encoding for the specified coding system.
Return nil if no matching input encoding can be found."
(let (result)
(catch 'result
(dolist (elem latex-inputenc-coding-alist result)
(let ((elem-cs (cdr elem)))
(when (and (coding-system-p elem-cs)
(coding-system-p cs)
(eq (coding-system-base cs) (coding-system-base elem-cs)))
(setq result (car elem))
(throw 'result result)))))))
(defvar latexenc-dont-use-TeX-master-flag nil
"Non-nil means don't follow TeX-master to find the coding system.")
(defvar latexenc-dont-use-tex-guess-main-file-flag nil
"Non-nil means don't use tex-guessmain-file to find the coding system.")
(defvar tex-start-of-header)
;;;###autoload
(defun latexenc-find-file-coding-system (arg-list)
"Determine the coding system of a LaTeX file if it uses \"inputenc.sty\".
The mapping from LaTeX's \"inputenc.sty\" encoding names to Emacs
coding system names is determined from `latex-inputenc-coding-alist'."
(if (eq (car arg-list) 'insert-file-contents)
(save-excursion
;; try to find the coding system in this file
(goto-char (point-min))
(if (catch 'cs
(let ((case-fold-search nil))
(while (search-forward "inputenc" nil t)
(goto-char (match-beginning 0))
(beginning-of-line)
(if (or (looking-at "[^%\n]*\\\\usepackage\\[\\([^]]*\\)\\]{\\([^}]*,\\)?inputenc\\(,[^}]*\\)?}")
(looking-at "[^%\n]*\\\\inputencoding{\\([^}]*\\)}"))
(throw 'cs t)
(goto-char (match-end 0))))))
(let* ((match (match-string 1))
(sym (or (latexenc-inputenc-to-coding-system match)
(intern match))))
(cond
((coding-system-p sym) sym)
((and (require 'code-pages nil t) (coding-system-p sym)) sym)
(t 'undecided)))
;; else try to find it in the master/main file
;; Fixme: If the current file is in an archive (e.g. tar,
;; zip), we should find the master file in that archive.
;; But, that is not yet implemented. -- K.Handa
(let ((default-directory (if (stringp (nth 1 arg-list))
(file-name-directory (nth 1 arg-list))
default-directory))
latexenc-main-file)
;; Is there a TeX-master or tex-main-file in the local variables
;; section?
(unless latexenc-dont-use-TeX-master-flag
(goto-char (point-max))
(search-backward "\n\^L" (max (- (point-max) 3000) (point-min))
'move)
(search-forward "Local Variables:" nil t)
(when (re-search-forward
"^%+ *\\(TeX-master\\|tex-main-file\\): *\"\\(.+\\)\""
nil t)
(let ((file (match-string 2)))
(dolist (ext `("" ,(if (boundp 'TeX-default-extension)
(concat "." TeX-default-extension)
"")
".tex" ".ltx" ".dtx" ".drv"))
(if (and (null latexenc-main-file) ;Stop at first.
(file-exists-p (concat file ext)))
(setq latexenc-main-file (concat file ext)))))))
;; try tex-modes tex-guess-main-file
(when (and (not latexenc-dont-use-tex-guess-main-file-flag)
(not latexenc-main-file))
;; Use a separate `when' so the byte-compiler sees the fboundp.
(when (fboundp 'tex-guess-main-file)
(let ((tex-start-of-header "\\\\document\\(style\\|class\\)"))
(setq latexenc-main-file (tex-guess-main-file)))))
;; if we found a master/main file get the coding system from it
(if (and latexenc-main-file
(file-regular-p latexenc-main-file)
(file-readable-p latexenc-main-file))
(let* ((latexenc-dont-use-tex-guess-main-file-flag t)
(latexenc-dont-use-TeX-master-flag t)
(latexenc-main-buffer
(find-file-noselect latexenc-main-file t)))
(coding-system-base ;Disregard the EOL part of the CS.
(with-current-buffer latexenc-main-buffer
(or coding-system-for-write buffer-file-coding-system
'undecided))))
'undecided))))
'undecided))
(provide 'latexenc)
;;; latexenc.el ends here