lisp/dirtrack.el

   1 ;;; dirtrack.el --- Directory Tracking by watching the prompt
   2
   3 ;; Copyright (C) 1996 Free Software Foundation, Inc.
   4
   5 ;; Author: Peter Breton <pbreton@i-kinetics.com>
   6 ;; Created: Sun Nov 17 1996
   7 ;; Keywords: processes
   8 ;; Time-stamp: <97/02/01 20:35:06 peter>
   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 2, or (at your option)
  15 ;; 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; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; Shell directory tracking by watching the prompt.
  30 ;;
  31 ;; This is yet another attempt at a directory-tracking package for
  32 ;; Emacs shell-mode. However, this package makes one strong assumption:
  33 ;; that you can customize your shell's prompt to contain the
  34 ;; current working directory. Most shells do support this, including
  35 ;; almost every type of Bourne and C shell on Unix, the native shells on
  36 ;; Windows95 (COMMAND.COM) and Windows NT (CMD.EXE), and most 3rd party
  37 ;; Windows shells. If you cannot do this, or do not wish to, this package
  38 ;; will be useless to you.
  39 ;;
  40 ;; Installation:
  41 ;;
  42 ;; 1) Set your shell's prompt to contain the current working directory.
  43 ;; You may need to consult your shell's documentation to find out how to
  44 ;; do this.
  45 ;;
  46 ;; Note that directory tracking is done by matching regular expressions,
  47 ;; therefore it is *VERY IMPORTANT* for your prompt to be easily
  48 ;; distinguishable from other output. If your prompt regexp is too general,
  49 ;; you will see error messages from the dirtrack filter as it attempts to cd
  50 ;; to non-existent directories.
  51 ;;
  52 ;; 2) Set the variable 'dirtrack-list' to an appropriate value. This
  53 ;; should be a list of two elements: the first is a regular expression
  54 ;; which matches your prompt up to and including the pathname part.
  55 ;; The second is a number which tells which regular expression group to
  56 ;; match to extract only the pathname. If you use a multi-line prompt,
  57 ;; add 't' as a third element. Note that some of the functions in
  58 ;; 'comint.el' assume a single-line prompt (eg, comint-bol).
  59 ;;
  60 ;; Determining this information may take some experimentation. Setting
  61 ;; the variable 'dirtrack-debug' may help; it causes the directory-tracking
  62 ;; filter to log messages to the buffer 'dirtrack-debug-buffer'.
  63 ;;
  64 ;; 3) Add a hook to shell-mode to enable the directory tracking:
  65 ;;
  66 ;; (add-hook 'shell-mode-hook
  67 ;;   (function (lambda ()
  68 ;;            (setq comint-output-filter-functions
  69 ;;                  (append (list 'dirtrack)
  70 ;;                          comint-output-filter-functions)))))
  71 ;;
  72 ;; You may wish to turn ordinary shell tracking off by calling
  73 ;; 'shell-dirtrack-toggle' or setting 'shell-dirtrackp'.
  74 ;;
  75 ;; Examples:
  76 ;;
  77 ;; 1) On Windows NT, my prompt is set to emacs$S$P$G.
  78 ;; 'dirtrack-list' is set to (list "^emacs \\([a-zA-Z]:.*\\)>" 1)
  79 ;;
  80 ;; 2) On Solaris running bash, my prompt is set like this:
  81 ;;    PS1="\w\012emacs@\h(\!) [\t]% "
  82 ;;    'dirtrack-list' is set to (list "^\\([/~].*\\)\nemacs@[^%]+% *" 1 t)
  83 ;;
  84 ;; I'd appreciate other examples from people who use this package.
  85
  86 ;;; Code:
  87
  88 (eval-when-compile
  89   (require 'comint)
  90   (require 'shell))
  91
  92 (defvar dirtrack-list (list "^emacs \\([a-zA-Z]:.*\\)>" 1)
  93   "*List for directory tracking.
  94 First item is a regexp that describes where to find the path in a prompt.
  95 Second is a number, the regexp group to match. Optional third item is
  96 whether the prompt is multi-line. If nil or omitted, prompt is assumed to
  97 be on a single line.")
  98
  99 (make-variable-buffer-local 'dirtrack-list)
 100
 101 (defvar dirtrack-debug nil
 102   "*If non-nil, the function 'dirtrack' will report debugging info.")
 103
 104 (defvar dirtrack-debug-buffer "*Directory Tracking Log*"
 105   "Buffer to write directory tracking debug information.")
 106
 107 (defvar dirtrackp t
 108   "*If non-nil, directory tracking via 'dirtrack' is enabled.")
 109
 110 (make-variable-buffer-local 'dirtrackp)
 111
 112 (defvar dirtrack-directory-function
 113   (if (memq system-type (list 'ms-dos 'windows-nt))
 114       'dirtrack-windows-directory-function
 115     'dirtrack-default-directory-function)
 116   "*Function to apply to the prompt directory for comparison purposes.")
 117
 118 (defvar dirtrack-canonicalize-function
 119   (if (memq system-type (list 'ms-dos 'windows-nt))
 120       'downcase 'identity)
 121   "*Function to apply to the default directory for comparison purposes.")
 122
 123 (defun dirtrack-default-directory-function (dir)
 124   "Return a canonical directory for comparison purposes.
 125 Such a directory ends with a forward slash."
 126   (let ((directory dir))
 127     (if (not (char-equal ?/ (string-to-char (substring directory -1))))
 128         (concat directory "/")
 129       directory)))
 130
 131 (defun dirtrack-windows-directory-function (dir)
 132   "Return a canonical directory for comparison purposes.
 133 Such a directory is all lowercase, has forward-slashes as delimiters,
 134 and ends with a forward slash."
 135   (let ((directory dir))
 136     (setq directory (downcase (replace-slash directory t)))
 137     (if (not (char-equal ?/ (string-to-char (substring directory -1))))
 138         (concat directory "/")
 139       directory)))
 140
 141 (defconst forward-slash  (regexp-quote "/"))
 142 (defconst backward-slash (regexp-quote "\\"))
 143
 144 (defun replace-slash (string &optional opposite)
 145   "Replace forward slashes with backwards ones.
 146 If additional argument is non-nil, replace backwards slashes with
 147 forward ones."
 148   (let ((orig     (if opposite backward-slash forward-slash))
 149         (replace  (if opposite forward-slash backward-slash))
 150         (newstring string)
 151         )
 152     (while (string-match orig newstring)
 153       (setq newstring (replace-match replace nil t newstring)))
 154   newstring))
 155
 156 ;; Copied from shell.el
 157 (defun dirtrack-toggle ()
 158   "Enable or disable Dirtrack directory tracking in a shell buffer."
 159   (interactive)
 160   (setq dirtrackp (not dirtrackp))
 161   (message "Directory tracking %s" (if dirtrackp "ON" "OFF")))
 162
 163 (defun dirtrack-debug-message (string)
 164   (let ((buf (current-buffer))
 165         (debug-buf (get-buffer-create dirtrack-debug-buffer))
 166         )
 167     (set-buffer debug-buf)
 168     (goto-char (point-max))
 169     (insert (concat string "\n"))
 170     (set-buffer buf)
 171   ))
 172
 173 ;;;###autoload
 174 (defun dirtrack (input)
 175   (if (null dirtrackp)
 176       nil
 177     (let ((prompt-path)
 178           (current-dir default-directory)
 179           (matched)
 180           (dirtrack-regexp    (nth 0 dirtrack-list))
 181           (match-num          (nth 1 dirtrack-list))
 182           (multi-line         (nth 2 dirtrack-list))
 183           )
 184       ;; No output?
 185       (if (eq (point) (point-min))
 186           nil
 187         (save-excursion
 188           (goto-char (point-max))
 189           ;; Look for the prompt
 190           (if multi-line
 191               (setq matched
 192                     (re-search-backward
 193                      dirtrack-regexp
 194                      comint-last-output-start
 195                      t))
 196             (beginning-of-line)
 197             (setq matched (looking-at dirtrack-regexp)))
 198           ;; No match
 199           (if (null matched)
 200               (and dirtrack-debug
 201                    (dirtrack-debug-message
 202                     (format
 203                      "Failed to match regexp: %s"
 204                     dirtrack-regexp)))
 205             (setq prompt-path
 206                   (buffer-substring-no-properties
 207                    (match-beginning match-num) (match-end match-num)))
 208             ;; Empty string
 209             (if (not (> (length prompt-path) 0))
 210                 (and dirtrack-debug
 211                      (dirtrack-debug-message "Match is empty string"))
 212               ;; Transform prompts into canonical forms
 213               (setq prompt-path (funcall dirtrack-directory-function
 214                                          prompt-path))
 215               (setq current-dir (funcall dirtrack-canonicalize-function
 216                                          current-dir))
 217               (and dirtrack-debug
 218                    (dirtrack-debug-message
 219                     (format
 220                      "Prompt is %s\nCurrent directory is %s"
 221                      prompt-path current-dir)))
 222               ;; Compare them
 223               (if (or (string= current-dir prompt-path)
 224                       (string= current-dir
 225                                (abbreviate-file-name prompt-path)))
 226                   (and dirtrack-debug
 227                        (dirtrack-debug-message
 228                         (format "Not changing directory")))
 229                 ;; It's possible that Emacs will think the directory
 230                 ;; won't exist (eg, rlogin buffers)
 231                 (if (file-accessible-directory-p prompt-path)
 232                     ;; Change directory
 233                     (and (shell-process-cd prompt-path)
 234                          dirtrack-debug
 235                          (dirtrack-debug-message
 236                           (format "Changing directory to %s" prompt-path)))
 237                   (error "Directory %s does not exist" prompt-path)))
 238               )))))))
 239
 240 (provide 'dirtrack)
 241
 242 ;;; dirtrack.el ends here