--- /dev/null
+;;; format-spec.el --- functions for formatting arbitrary formatting strings
+
+;; Copyright (C) 1999-2016 Free Software Foundation, Inc.
+
+;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
+;; Keywords: tools
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; Code:
+
+(eval-when-compile (require 'cl))
+
+(defun format-spec (format specification)
+ "Return a string based on FORMAT and SPECIFICATION.
+FORMAT is a string containing `format'-like specs like \"bash %u %k\",
+while SPECIFICATION is an alist mapping from format spec characters
+to values. Any text properties on a %-spec itself are propagated to
+the text that it generates."
+ (with-temp-buffer
+ (insert format)
+ (goto-char (point-min))
+ (while (search-forward "%" nil t)
+ (cond
+ ;; Quoted percent sign.
+ ((eq (char-after) ?%)
+ (delete-char 1))
+ ;; Valid format spec.
+ ((looking-at "\\([-0-9.]*\\)\\([a-zA-Z]\\)")
+ (let* ((num (match-string 1))
+ (spec (if (featurep 'xemacs)
+ (char-to-int (string-to-char (match-string 2)))
+ (string-to-char (match-string 2))))
+ (val (assq spec specification)))
+ (unless val
+ (error "Invalid format character: `%%%c'" spec))
+ (setq val (cdr val))
+ ;; Pad result to desired length.
+ (let ((text (format (concat "%" num "s") val)))
+ ;; Insert first, to preserve text properties.
+ (insert-and-inherit text)
+ ;; Delete the specifier body.
+ (delete-region (+ (match-beginning 0) (length text))
+ (+ (match-end 0) (length text)))
+ ;; Delete the percent sign.
+ (delete-region (1- (match-beginning 0)) (match-beginning 0)))))
+ ;; Signal an error on bogus format strings.
+ (t
+ (error "Invalid format string"))))
+ (buffer-string)))
+
+(defun format-spec-make (&rest pairs)
+ "Return an alist suitable for use in `format-spec' based on PAIRS.
+PAIRS is a list where every other element is a character and a value,
+starting with a character."
+ (let (alist)
+ (while pairs
+ (unless (cdr pairs)
+ (error "Invalid list of pairs"))
+ (push (cons (if (featurep 'xemacs)
+ (if (characterp (car pairs))
+ (char-to-int (car pairs))
+ (car pairs))
+ (car pairs))
+ (cadr pairs))
+ alist)
+ (setq pairs (cddr pairs)))
+ (nreverse alist)))
+
+(provide 'format-spec)
+
+;;; format-spec.el ends here