lisp/textmodes/text-mode.el

   1 ;;; text-mode.el --- text mode, and its idiosyncratic commands
   2
   3 ;; Copyright (C) 1985, 1992, 1994, 2001-2017 Free Software Foundation,
   4 ;; Inc.
   5
   6 ;; Maintainer: emacs-devel@gnu.org
   7 ;; Keywords: wp
   8 ;; Package: emacs
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This package provides the fundamental text mode documented in the
  28 ;; Emacs user's manual.
  29
  30 ;;; Code:
  31
  32 ;; Normally non-nil defaults for hooks are bad, but since this file is
  33 ;; preloaded it's ok/better, and avoids this showing up in customize-rogue.
  34 (defcustom text-mode-hook '(text-mode-hook-identify)
  35   "Normal hook run when entering Text mode and many related modes."
  36   :type 'hook
  37   :options '(turn-on-auto-fill turn-on-flyspell)
  38   :group 'text)
  39
  40 (defvar text-mode-variant nil
  41   "Non-nil if this buffer's major mode is a variant of Text mode.
  42 Use (derived-mode-p \\='text-mode) instead.")
  43
  44 (defvar text-mode-syntax-table
  45   (let ((st (make-syntax-table)))
  46     (modify-syntax-entry ?\" ".   " st)
  47     (modify-syntax-entry ?\\ ".   " st)
  48     ;; We add `p' so that M-c on 'hello' leads to 'Hello' rather than 'hello'.
  49     (modify-syntax-entry ?' "w p" st)
  50     ;; UAX #29 says HEBREW PUNCTUATION GERESH behaves like a letter
  51     ;; for the purposes of finding word boundaries.
  52     (modify-syntax-entry #x5f3 "w   ") ; GERESH
  53     ;; UAX #29 says HEBREW PUNCTUATION GERSHAYIM should not be a word
  54     ;; boundary when surrounded by letters.  Our infrastructure for
  55     ;; finding a word boundary doesn't support 3-character
  56     ;; definitions, so for now simply make this a word-constituent
  57     ;; character.  This leaves a problem of having GERSHAYIM at the
  58     ;; beginning or end of a word, where it should be a boundary;
  59     ;; FIXME.
  60     (modify-syntax-entry #x5f4 "w   ") ; GERSHAYIM
  61     ;; These all should not be a word boundary when between letters,
  62     ;; according to UAX #29, so they again are prone to the same
  63     ;; problem as GERSHAYIM; FIXME.
  64     (modify-syntax-entry #xb7 "w   ")   ; MIDDLE DOT
  65     (modify-syntax-entry #x2027 "w   ") ; HYPHENATION POINT
  66     (modify-syntax-entry #xff1a "w   ") ; FULLWIDTH COLON
  67     st)
  68   "Syntax table used while in `text-mode'.")
  69
  70 (defvar text-mode-map
  71   (let ((map (make-sparse-keymap)))
  72     (define-key map "\e\t" 'ispell-complete-word)
  73     (define-key map [menu-bar text]
  74       (cons "Text" (make-sparse-keymap "Text")))
  75     (bindings--define-key map [menu-bar text toggle-text-mode-auto-fill]
  76       '(menu-item "Auto Fill" toggle-text-mode-auto-fill
  77                   :button (:toggle . (memq 'turn-on-auto-fill text-mode-hook))
  78                   :help "Automatically fill text while typing in text modes (Auto Fill mode)"))
  79     (bindings--define-key map [menu-bar text paragraph-indent-minor-mode]
  80       '(menu-item "Paragraph Indent" paragraph-indent-minor-mode
  81                   :button (:toggle . (bound-and-true-p paragraph-indent-minor-mode))
  82                   :help "Toggle paragraph indent minor mode"))
  83     (bindings--define-key map [menu-bar text sep] menu-bar-separator)
  84     (bindings--define-key map [menu-bar text center-region]
  85       '(menu-item "Center Region" center-region
  86                   :help "Center the marked region"
  87                   :enable (region-active-p)))
  88     (bindings--define-key map [menu-bar text center-paragraph]
  89       '(menu-item "Center Paragraph" center-paragraph
  90                   :help "Center the current paragraph"))
  91     (bindings--define-key map [menu-bar text center-line]
  92       '(menu-item "Center Line" center-line
  93                   :help "Center the current line"))
  94     map)
  95   "Keymap for `text-mode'.
  96 Many other modes, such as `mail-mode', `outline-mode' and `indented-text-mode',
  97 inherit all the commands defined in this map.")
  98
  99 \f
 100 (define-derived-mode text-mode nil "Text"
 101   "Major mode for editing text written for humans to read.
 102 In this mode, paragraphs are delimited only by blank or white lines.
 103 You can thus get the full benefit of adaptive filling
 104  (see the variable `adaptive-fill-mode').
 105 \\{text-mode-map}
 106 Turning on Text mode runs the normal hook `text-mode-hook'."
 107   (set (make-local-variable 'text-mode-variant) t)
 108   (set (make-local-variable 'require-final-newline)
 109        mode-require-final-newline)
 110   (set (make-local-variable 'indent-line-function) 'indent-relative))
 111
 112 (define-derived-mode paragraph-indent-text-mode text-mode "Parindent"
 113   "Major mode for editing text, with leading spaces starting a paragraph.
 114 In this mode, you do not need blank lines between paragraphs
 115 when the first line of the following paragraph starts with whitespace.
 116 `paragraph-indent-minor-mode' provides a similar facility as a minor mode.
 117 Special commands:
 118 \\{text-mode-map}
 119 Turning on Paragraph-Indent Text mode runs the normal hooks
 120 `text-mode-hook' and `paragraph-indent-text-mode-hook'."
 121   :abbrev-table nil :syntax-table nil
 122   (paragraph-indent-minor-mode))
 123
 124 (define-minor-mode paragraph-indent-minor-mode
 125   "Minor mode for editing text, with leading spaces starting a paragraph.
 126 In this mode, you do not need blank lines between paragraphs when the
 127 first line of the following paragraph starts with whitespace, as with
 128 `paragraph-indent-text-mode'.
 129 Turning on Paragraph-Indent minor mode runs the normal hook
 130 `paragraph-indent-text-mode-hook'."
 131   :initial-value nil
 132   ;; Change the definition of a paragraph start.
 133   (let ((ps-re "[ \t\n\f]\\|"))
 134     (if (eq t (compare-strings ps-re nil nil
 135                                paragraph-start nil (length ps-re)))
 136         (if (not paragraph-indent-minor-mode)
 137             (set (make-local-variable 'paragraph-start)
 138                  (substring paragraph-start (length ps-re))))
 139       (if paragraph-indent-minor-mode
 140           (set (make-local-variable 'paragraph-start)
 141                (concat ps-re paragraph-start)))))
 142   ;; Change the indentation function.
 143   (if paragraph-indent-minor-mode
 144       (add-function :override (local 'indent-line-function)
 145                     #'indent-to-left-margin)
 146     (remove-function (local 'indent-line-function)
 147                      #'indent-to-left-margin)))
 148
 149 (defalias 'indented-text-mode 'text-mode)
 150
 151 ;; This can be made a no-op once all modes that use text-mode-hook
 152 ;; are "derived" from text-mode.  (As of 2015/04, and probably well before,
 153 ;; the only one I can find that doesn't so derive is rmail-edit-mode.)
 154 (defun text-mode-hook-identify ()
 155   "Mark that this mode has run `text-mode-hook'.
 156 This is how `toggle-text-mode-auto-fill' knows which buffers to operate on."
 157   (set (make-local-variable 'text-mode-variant) t))
 158
 159 (defun toggle-text-mode-auto-fill ()
 160   "Toggle whether to use Auto Fill in Text mode and related modes.
 161 This command affects all buffers that use modes related to Text mode,
 162 both existing buffers and buffers that you subsequently create."
 163   (interactive)
 164   (let ((enable-mode (not (memq 'turn-on-auto-fill text-mode-hook))))
 165     (if enable-mode
 166         (add-hook 'text-mode-hook 'turn-on-auto-fill)
 167       (remove-hook 'text-mode-hook 'turn-on-auto-fill))
 168     (dolist (buffer (buffer-list))
 169       (with-current-buffer buffer
 170         (if (or (derived-mode-p 'text-mode) text-mode-variant)
 171             (auto-fill-mode (if enable-mode 1 0)))))
 172     (message "Auto Fill %s in Text modes"
 173              (if enable-mode "enabled" "disabled"))))
 174 \f
 175
 176 (define-key facemenu-keymap "\eS" 'center-paragraph)
 177
 178 (defun center-paragraph ()
 179   "Center each nonblank line in the paragraph at or after point.
 180 See `center-line' for more info."
 181   (interactive)
 182   (save-excursion
 183     (forward-paragraph)
 184     (or (bolp) (newline 1))
 185     (let ((end (point)))
 186       (backward-paragraph)
 187       (center-region (point) end))))
 188
 189 (defun center-region (from to)
 190   "Center each nonblank line starting in the region.
 191 See `center-line' for more info."
 192   (interactive "r")
 193   (if (> from to)
 194       (let ((tem to))
 195         (setq to from from tem)))
 196   (save-excursion
 197     (save-restriction
 198       (narrow-to-region from to)
 199       (goto-char from)
 200       (while (not (eobp))
 201         (or (save-excursion (skip-chars-forward " \t") (eolp))
 202             (center-line))
 203         (forward-line 1)))))
 204
 205 (define-key facemenu-keymap "\es" 'center-line)
 206
 207 (defun center-line (&optional nlines)
 208   "Center the line point is on, within the width specified by `fill-column'.
 209 This means adjusting the indentation so that it equals
 210 the distance between the end of the text and `fill-column'.
 211 The argument NLINES says how many lines to center."
 212   (interactive "P")
 213   (if nlines (setq nlines (prefix-numeric-value nlines)))
 214   (while (not (eq nlines 0))
 215     (save-excursion
 216       (let ((lm (current-left-margin))
 217             line-length)
 218         (beginning-of-line)
 219         (delete-horizontal-space)
 220         (end-of-line)
 221         (delete-horizontal-space)
 222         (setq line-length (current-column))
 223         (if (> (- fill-column lm line-length) 0)
 224             (indent-line-to
 225              (+ lm (/ (- fill-column lm line-length) 2))))))
 226     (cond ((null nlines)
 227            (setq nlines 0))
 228           ((> nlines 0)
 229            (setq nlines (1- nlines))
 230            (forward-line 1))
 231           ((< nlines 0)
 232            (setq nlines (1+ nlines))
 233            (forward-line -1)))))
 234
 235 (provide 'text-mode)
 236
 237 ;;; text-mode.el ends here