diff options
Diffstat (limited to 'lisp/international/mule-util.el')
| -rw-r--r-- | lisp/international/mule-util.el | 47 |
1 files changed, 40 insertions, 7 deletions
diff --git a/lisp/international/mule-util.el b/lisp/international/mule-util.el index eae787bbeb9..92c540cea7d 100644 --- a/lisp/international/mule-util.el +++ b/lisp/international/mule-util.el @@ -1,4 +1,4 @@ -;;; mule-util.el --- utility functions for multilingual environment (mule) +;;; mule-util.el --- utility functions for multilingual environment (mule) -*- lexical-binding:t -*- ;; Copyright (C) 1997-1998, 2000-2015 Free Software Foundation, Inc. ;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, @@ -30,8 +30,7 @@ ;;; Code: -;;; String manipulations while paying attention to multibyte -;;; characters. +;;; String manipulations while paying attention to multibyte characters. ;;;###autoload (defsubst string-to-list (string) @@ -49,7 +48,6 @@ (if (integerp obj) (aset string idx obj) (let ((len1 (length obj)) - (len2 (length string)) (i 0)) (while (< i len1) (aset string (+ idx i) (aref obj i)) @@ -90,7 +88,6 @@ defaults to `truncate-string-ellipsis'." (setq ellipsis truncate-string-ellipsis)) (let ((str-len (length str)) (str-width (string-width str)) - (ellipsis-len (if ellipsis (length ellipsis) 0)) (ellipsis-width (if ellipsis (string-width ellipsis) 0)) (idx 0) (column 0) @@ -129,8 +126,8 @@ defaults to `truncate-string-ellipsis'." tail-padding ellipsis)))) -;;; Nested alist handler. Nested alist is alist whose elements are -;;; also nested alist. +;;; Nested alist handler. +;; Nested alist is alist whose elements are also nested alist. ;;;###autoload (defsubst nested-alist-p (obj) @@ -313,6 +310,42 @@ per-character basis, this may not be accurate." (throw 'tag3 charset))) charset-list) nil))))))))) + +;;;###autoload +(defun filepos-to-bufferpos (byte &optional quality coding-system) + "Try to return the buffer position corresponding to a particular file position. +The file position is given as a (0-based) BYTE count. +The function presumes the file is encoded with CODING-SYSTEM, which defaults +to `buffer-file-coding-system'. +QUALITY can be: + `approximate', in which case we may cut some corners to avoid + excessive work. + nil, in which case we may return nil rather than an approximation." + ;; `exact', in which case we may end up re-(en|de)coding a large + ;; part of the file. + (unless coding-system (setq coding-system buffer-file-coding-system)) + (let ((eol (coding-system-eol-type coding-system)) + (type (coding-system-type coding-system)) + (pm (save-restriction (widen) (point-min)))) + (pcase type + (`utf-8 + (when (coding-system-get coding-system :bom) + (setq byte (max 0 (- byte 3)))) + (let (pos lines (eol-offset 0)) + (while + (progn + (setq pos (byte-to-position (+ pm byte (- eol-offset)))) + (setq lines (1- (line-number-at-pos pos))) + (not (= lines eol-offset))) + (setq eol-offset (+ eol-offset lines))) + pos)) + ;; FIXME: What if it's a 2-byte charset? Are there such beasts? + (`charset (+ pm byte)) + (_ + (pcase quality + (`approximate (+ pm (byte-to-position byte))) + ;; (`exact ...) + ))))) (provide 'mule-util) |