lisp/erc/erc-ring.el

   1 ;; erc-ring.el -- Command history handling for erc using ring.el
   2
   3 ;; Copyright (C) 2001-2004, 2006-2018 Free Software Foundation, Inc.
   4
   5 ;; Author: Alex Schroeder <alex@gnu.org>
   6 ;; Maintainer: emacs-devel@gnu.org
   7 ;; Keywords: comm
   8 ;; URL: http://www.emacswiki.org/cgi-bin/wiki.pl?ErcHistory
   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 <https://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file implements an input ring -- a history of the stuff you
  28 ;; wrote.  To activate:
  29 ;;
  30 ;; (require 'erc-auto) or (require 'erc-ring)
  31 ;; (erc-ring-mode 1)
  32 ;;
  33 ;; Use M-n and M-p to navigate the ring
  34
  35 ;;; Code:
  36
  37 (require 'erc)
  38 (require 'comint)
  39 (require 'ring)
  40
  41 (defgroup erc-ring nil
  42   "An input ring for ERC."
  43   :group 'erc)
  44
  45 ;;;###autoload(autoload 'erc-ring-mode "erc-ring" nil t)
  46 (define-erc-module ring nil
  47   "Stores input in a ring so that previous commands and messages can
  48 be recalled using M-p and M-n."
  49   ((add-hook 'erc-send-pre-hook 'erc-add-to-input-ring)
  50    (define-key erc-mode-map "\M-p" 'erc-previous-command)
  51    (define-key erc-mode-map "\M-n" 'erc-next-command))
  52   ((remove-hook 'erc-send-pre-hook 'erc-add-to-input-ring)
  53    (define-key erc-mode-map "\M-p" 'undefined)
  54    (define-key erc-mode-map "\M-n" 'undefined)))
  55
  56 (defvar erc-input-ring nil "Input ring for erc.")
  57 (make-variable-buffer-local 'erc-input-ring)
  58
  59 (defvar erc-input-ring-index nil
  60   "Position in the input ring for erc.
  61 If nil, the input line is blank and the user is conceptually after
  62 the most recently added item in the ring. If an integer, the input
  63 line is non-blank and displays the item from the ring indexed by this
  64 variable.")
  65 (make-variable-buffer-local 'erc-input-ring-index)
  66
  67 (defun erc-input-ring-setup ()
  68   "Do the setup required so that we can use comint style input rings.
  69 Call this function when setting up the mode."
  70   (unless (ring-p erc-input-ring)
  71     (setq erc-input-ring (make-ring comint-input-ring-size)))
  72   (setq erc-input-ring-index nil))
  73
  74 (defun erc-add-to-input-ring (s)
  75   "Add string S to the input ring and reset history position."
  76   (unless erc-input-ring (erc-input-ring-setup))
  77   (ring-insert erc-input-ring s)
  78   (setq erc-input-ring-index nil))
  79
  80 (defun erc-clear-input-ring ()
  81   "Remove all entries from the input ring, then call garbage-collect.
  82 You might use this for security purposes if you have typed a command
  83 containing a password."
  84   (interactive)
  85   (setq erc-input-ring (make-ring comint-input-ring-size)
  86         erc-input-ring-index nil)
  87   (garbage-collect)
  88   (message "ERC input ring cleared."))
  89
  90 (defun erc-previous-command ()
  91   "Replace current command with the previous one from the history."
  92   (interactive)
  93   (unless erc-input-ring (erc-input-ring-setup))
  94   ;; if the ring isn't empty
  95   (when (> (ring-length erc-input-ring) 0)
  96     (if (and erc-input-ring-index
  97              (= (ring-length erc-input-ring) (1+ erc-input-ring-index)))
  98         (progn
  99           (erc-replace-current-command "")
 100           (setq erc-input-ring-index nil))
 101
 102       ;; If we are not viewing old input and there's text in the input
 103       ;; area, push it on the history ring before moving back through
 104       ;; the input history, so it will be there when we return to the
 105       ;; front.
 106       (if (null erc-input-ring-index)
 107           (when (> (point-max) erc-input-marker)
 108             (erc-add-to-input-ring (buffer-substring erc-input-marker
 109                                                      (point-max)))
 110             (setq erc-input-ring-index 0)))
 111
 112       (setq erc-input-ring-index (if erc-input-ring-index
 113                                      (ring-plus1 erc-input-ring-index
 114                                                  (ring-length erc-input-ring))
 115                                    0))
 116       (erc-replace-current-command (ring-ref erc-input-ring
 117                                              erc-input-ring-index)))))
 118
 119 (defun erc-next-command ()
 120   "Replace current command with the next one from the history."
 121   (interactive)
 122   (unless erc-input-ring (erc-input-ring-setup))
 123   ;; if the ring isn't empty
 124   (when (> (ring-length erc-input-ring) 0)
 125     (if (and erc-input-ring-index
 126              (= 0 erc-input-ring-index))
 127         (progn
 128           (erc-replace-current-command "")
 129           (setq erc-input-ring-index nil))
 130       (setq erc-input-ring-index (ring-minus1 (or erc-input-ring-index 0)
 131                                               (ring-length erc-input-ring)))
 132       (erc-replace-current-command (ring-ref erc-input-ring
 133       erc-input-ring-index)))))
 134
 135
 136 (defun erc-replace-current-command (s)
 137   "Replace current command with string S."
 138   ;; delete line
 139   (let ((inhibit-read-only t))
 140     (delete-region
 141      (progn (goto-char erc-insert-marker) (erc-bol))
 142      (goto-char (point-max)))
 143     (insert s)))
 144
 145 (provide 'erc-ring)
 146
 147 ;;; erc-ring.el ends here
 148 ;; Local Variables:
 149 ;; generated-autoload-file: "erc-loaddefs.el"
 150 ;; indent-tabs-mode: nil
 151 ;; End: