79 lines
2.7 KiB
EmacsLisp
79 lines
2.7 KiB
EmacsLisp
;;; format-spec.el --- functions for formatting arbitrary formatting strings
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;; Copyright (C) 1999-2019 Free Software Foundation, Inc.
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;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
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;; Keywords: tools
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; Code:
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(eval-when-compile (require 'cl))
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(defun format-spec (format specification)
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"Return a string based on FORMAT and SPECIFICATION.
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FORMAT is a string containing `format'-like specs like \"bash %u %k\",
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while SPECIFICATION is an alist mapping from format spec characters
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to values. Any text properties on a %-spec itself are propagated to
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the text that it generates."
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(with-temp-buffer
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(insert format)
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(goto-char (point-min))
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(while (search-forward "%" nil t)
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(cond
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;; Quoted percent sign.
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((eq (char-after) ?%)
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(delete-char 1))
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;; Valid format spec.
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((looking-at "\\([-0-9.]*\\)\\([a-zA-Z]\\)")
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(let* ((num (match-string 1))
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(spec (string-to-char (match-string 2)))
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(val (assq spec specification)))
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(unless val
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(error "Invalid format character: `%%%c'" spec))
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(setq val (cdr val))
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;; Pad result to desired length.
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(let ((text (format (concat "%" num "s") val)))
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;; Insert first, to preserve text properties.
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(insert-and-inherit text)
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;; Delete the specifier body.
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(delete-region (+ (match-beginning 0) (length text))
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(+ (match-end 0) (length text)))
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;; Delete the percent sign.
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(delete-region (1- (match-beginning 0)) (match-beginning 0)))))
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;; Signal an error on bogus format strings.
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(t
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(error "Invalid format string"))))
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(buffer-string)))
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(defun format-spec-make (&rest pairs)
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"Return an alist suitable for use in `format-spec' based on PAIRS.
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PAIRS is a list where every other element is a character and a value,
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starting with a character."
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(let (alist)
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(while pairs
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(unless (cdr pairs)
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(error "Invalid list of pairs"))
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(push (cons (car pairs) (cadr pairs)) alist)
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(setq pairs (cddr pairs)))
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(nreverse alist)))
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(provide 'format-spec)
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;;; format-spec.el ends here
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