More `unsigned char' -> `re_char' changes.

[bpt/emacs.git] / lisp / comint.el

;;; comint.el --- general command interpreter in a window stuff

;; Copyright (C) 1988, 90, 92, 93, 94, 95, 96, 97, 98, 99, 2000
;;	Free Software Foundation, Inc.

;; Author: Olin Shivers <shivers@cs.cmu.edu> then
;;	Simon Marshall <simon@gnu.org>
;; Maintainer: FSF
;; Keywords: processes

;; 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 2, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; Please send me bug reports, bug fixes, and extensions, so that I can
;; merge them into the master source.
;;     - Olin Shivers (shivers@cs.cmu.edu)
;;     - Simon Marshall (simon@gnu.org)

;; This file defines a general command-interpreter-in-a-buffer package
;; (comint mode). The idea is that you can build specific process-in-a-buffer
;; modes on top of comint mode -- e.g., lisp, shell, scheme, T, soar, ....
;; This way, all these specific packages share a common base functionality,
;; and a common set of bindings, which makes them easier to use (and
;; saves code, implementation time, etc., etc.).

;; Several packages are already defined using comint mode:
;; - shell.el defines a shell-in-a-buffer mode.
;; - cmulisp.el defines a simple lisp-in-a-buffer mode.
;;
;; - The file cmuscheme.el defines a scheme-in-a-buffer mode.
;; - The file tea.el tunes scheme and inferior-scheme modes for T.
;; - The file soar.el tunes lisp and inferior-lisp modes for Soar.
;; - cmutex.el defines tex and latex modes that invoke tex, latex, bibtex,
;;   previewers, and printers from within emacs.
;; - background.el allows csh-like job control inside emacs.
;; It is pretty easy to make new derived modes for other processes.

;; For documentation on the functionality provided by comint mode, and
;; the hooks available for customising it, see the comments below.
;; For further information on the standard derived modes (shell,
;; inferior-lisp, inferior-scheme, ...), see the relevant source files.

;; For hints on converting existing process modes (e.g., tex-mode,
;; background, dbx, gdb, kermit, prolog, telnet) to use comint-mode
;; instead of shell-mode, see the notes at the end of this file.

\f
;; Brief Command Documentation:
;;============================================================================
;; Comint Mode Commands: (common to all derived modes, like shell & cmulisp
;; mode)
;;
;; m-p	   comint-previous-input	   Cycle backwards in input history
;; m-n	   comint-next-input		   Cycle forwards
;; m-r     comint-previous-matching-input  Previous input matching a regexp
;; m-s     comint-next-matching-input      Next input that matches
;; m-c-l   comint-show-output		   Show last batch of process output
;; return  comint-send-input
;; c-d	   comint-delchar-or-maybe-eof     Delete char unless at end of buff
;; c-c c-a comint-bol-or-process-mark      First time, move point to bol;
;;					    second time, move to process-mark.
;; c-c c-u comint-kill-input		    ^u
;; c-c c-w backward-kill-word	    ^w
;; c-c c-c comint-interrupt-subjob	    ^c
;; c-c c-z comint-stop-subjob		    ^z
;; c-c c-\ comint-quit-subjob		    ^\
;; c-c c-o comint-delete-output		    Delete last batch of process output
;; c-c c-r comint-show-output		    Show last batch of process output
;; c-c c-l comint-dynamic-list-input-ring  List input history
;;
;; Not bound by default in comint-mode (some are in shell mode)
;; comint-run				Run a program under comint-mode
;; send-invisible			Read a line w/o echo, and send to proc
;; comint-dynamic-complete-filename	Complete filename at point.
;; comint-dynamic-complete-variable    Complete variable name at point.
;; comint-dynamic-list-filename-completions List completions in help buffer.
;; comint-replace-by-expanded-filename	Expand and complete filename at point;
;;					replace with expanded/completed name.
;; comint-replace-by-expanded-history	Expand history at point;
;;					replace with expanded name.
;; comint-magic-space                  Expand history and add (a) space(s).
;; comint-kill-subjob			No mercy.
;; comint-show-maximum-output          Show as much output as possible.
;; comint-continue-subjob		Send CONT signal to buffer's process
;;					group. Useful if you accidentally
;;					suspend your process (with C-c C-z).
;; comint-get-next-from-history        Fetch successive input history lines
;; comint-accumulate		       Combine lines to send them together
;;					as input.
;; comint-goto-process-mark	       Move point to where process-mark is.
;; comint-set-process-mark	       Set process-mark to point.

;; comint-mode-hook is the comint mode hook. Basically for your keybindings.

;;; Code:

(require 'ring)
\f
;; Buffer Local Variables:
;;============================================================================
;; Comint mode buffer local variables:
;;  comint-prompt-regexp		string	comint-bol uses to match prompt
;;  comint-delimiter-argument-list	list	For delimiters and arguments
;;  comint-last-input-start		marker	Handy if inferior always echoes
;;  comint-last-input-end		marker	For comint-delete-output command
;;  comint-input-ring-size		integer	For the input history
;;  comint-input-ring			ring	mechanism
;;  comint-input-ring-index		number	...
;;  comint-save-input-ring-index	number	...
;;  comint-input-autoexpand		symbol	...
;;  comint-input-ignoredups		boolean	...
;;  comint-dynamic-complete-functions	hook   For the completion mechanism
;;  comint-completion-fignore		list	...
;;  comint-file-name-chars		string	...
;;  comint-file-name-quote-list		list	...
;;  comint-get-old-input		function Hooks for specific
;;  comint-input-filter-functions	hook	process-in-a-buffer
;;  comint-output-filter-functions	hook	function modes.
;;  comint-preoutput-filter-functions   hook
;;  comint-input-filter			function ...
;;  comint-input-sender			function ...
;;  comint-eol-on-send			boolean	...
;;  comint-process-echoes		boolean	...
;;  comint-scroll-to-bottom-on-input	symbol	For scroll behavior
;;  comint-scroll-to-bottom-on-output	symbol	...
;;  comint-scroll-show-maximum-output	boolean	...
;;  comint-accum-marker			maker	  For comint-accumulate
;;  comint-last-output-overlay          overlay
;;
;; Comint mode non-buffer local variables:
;;  comint-completion-addsuffix		boolean/cons	For file name
;;  comint-completion-autolist		boolean		completion behavior
;;  comint-completion-recexact		boolean		...

(defgroup comint nil
  "General command interpreter in a window stuff."
  :group 'processes)

(defgroup comint-completion nil
  "Completion facilities in comint"
  :group 'comint)

(defgroup comint-source nil
  "Source finding facilities in comint"
  :prefix "comint-"
  :group 'comint)

(defvar comint-prompt-regexp "^"
  "Regexp to recognise prompts in the inferior process.
Defaults to \"^\", the null string at BOL.

This variable is only used if the variable
`comint-use-prompt-regexp-instead-of-fields' is non-nil.

Good choices:
  Canonical Lisp: \"^[^> \\n]*>+:? *\" (Lucid, franz, kcl, T, cscheme, oaklisp)
  Lucid Common Lisp: \"^\\\\(>\\\\|\\\\(->\\\\)+\\\\) *\"
  franz: \"^\\\\(->\\\\|<[0-9]*>:\\\\) *\"
  kcl: \"^>+ *\"
  shell: \"^[^#$%>\\n]*[#$%>] *\"
  T: \"^>+ *\"

This is a good thing to set in mode hooks.")

(defvar comint-delimiter-argument-list ()
  "List of characters to recognise as separate arguments in input.
Strings comprising a character in this list will separate the arguments
surrounding them, and also be regarded as arguments in their own right (unlike
whitespace).  See `comint-arguments'.
Defaults to the empty list.

For shells, a good value is (?\\| ?& ?< ?> ?\\( ?\\) ?;).

This is a good thing to set in mode hooks.")

(defcustom comint-input-autoexpand nil
  "*If non-nil, expand input command history references on completion.
This mirrors the optional behavior of tcsh (its autoexpand and histlit).

If the value is `input', then the expansion is seen on input.
If the value is `history', then the expansion is only when inserting
into the buffer's input ring.  See also `comint-magic-space' and
`comint-dynamic-complete'.

This variable is buffer-local."
  :type '(choice (const :tag "off" nil)
		 (const input)
		 (const history)
		 (other :tag "on" t))
  :group 'comint)

(defcustom comint-highlight-input t
  "*If non-nil, highlight input; also allow choosing previous input with a mouse.
The face used is `comint-highlight-input'."
  :type 'boolean
  :group 'comint)

(defface comint-highlight-input '((t (:bold t)))
  "Face to use to highlight input when `comint-highlight-input' is non-nil."
  :group 'comint)

(defcustom comint-highlight-prompt t
  "*If non-nil, highlight program prompts.
The face used is `comint-highlight-prompt'."
  :group 'comint)

(defface comint-highlight-prompt
  '((((background dark)) (:foreground "cyan"))
    (t (:foreground "dark blue")))
  "Face to use to highlight prompt when `comint-highlight-prompt' is non-nil."
  :group 'comint)

(defcustom comint-input-ignoredups nil
  "*If non-nil, don't add input matching the last on the input ring.
This mirrors the optional behavior of bash.

This variable is buffer-local."
  :type 'boolean
  :group 'comint)

(defcustom comint-input-ring-file-name nil
  "*If non-nil, name of the file to read/write input history.
See also `comint-read-input-ring' and `comint-write-input-ring'.

This variable is buffer-local, and is a good thing to set in mode hooks."
  :type '(choice (const :tag "nil" nil)
		 file)
  :group 'comint)

(defcustom comint-scroll-to-bottom-on-input nil
  "*Controls whether input to interpreter causes window to scroll.
If nil, then do not scroll.  If t or `all', scroll all windows showing buffer.
If `this', scroll only the selected window.

The default is nil.

See `comint-preinput-scroll-to-bottom'.  This variable is buffer-local."
  :type '(choice (const :tag "off" nil)
		 (const t)
		 (const all)
		 (const this))
  :group 'comint)

(defcustom comint-scroll-to-bottom-on-output nil
  "*Controls whether interpreter output causes window to scroll.
If nil, then do not scroll.  If t or `all', scroll all windows showing buffer.
If `this', scroll only the selected window.
If `others', scroll only those that are not the selected window.

The default is nil.

See variable `comint-scroll-show-maximum-output' and function
`comint-postoutput-scroll-to-bottom'.  This variable is buffer-local."
  :type '(choice (const :tag "off" nil)
		 (const t)
		 (const all)
		 (const this)
		 (const others))
  :group 'comint)

(defcustom comint-scroll-show-maximum-output nil
  "*Controls how interpreter output causes window to scroll.
If non-nil, then show the maximum output when the window is scrolled.

See variable `comint-scroll-to-bottom-on-output' and function
`comint-postoutput-scroll-to-bottom'.  This variable is buffer-local."
  :type 'boolean
  :group 'comint)

(defcustom comint-buffer-maximum-size 1024
  "*The maximum size in lines for comint buffers.
Comint buffers are truncated from the top to be no greater than this number, if
the function `comint-truncate-buffer' is on `comint-output-filter-functions'."
  :type 'integer
  :group 'comint)

(defvar comint-input-ring-size 32
  "Size of input history ring.")

(defvar comint-input-ring-separator "\n"
  "Separator between commands in the history file.")

(defcustom comint-process-echoes nil
  "*If non-nil, assume that the subprocess echoes any input.
If so, delete one copy of the input so that only one copy eventually
appears in the buffer.

This variable is buffer-local."
  :type 'boolean
  :group 'comint)

;; AIX puts the name of the person being su'd to in front of the prompt.
;; kinit prints a prompt like `Password for devnull@GNU.ORG: '.
;; ksu prints a prompt like `Kerberos password for devnull/root@GNU.ORG: '.
;; ssh-add prints a prompt like `Enter passphrase: '.
;; Some implementations of passwd use "Password (again)" as the 2nd prompt.
(defcustom comint-password-prompt-regexp
  "\\(\\([Oo]ld \\|[Nn]ew \\|Kerberos \\|'s \\|login \\|^\\)\
[Pp]assword\\( (again)\\)?\\|pass phrase\\|Enter passphrase\\)\
\\( for [^@ \t\n]+@[^@ \t\n]+\\)?:\\s *\\'"
  "*Regexp matching prompts for passwords in the inferior process.
This is used by `comint-watch-for-password-prompt'."
  :type 'regexp
  :group 'comint)

;; Here are the per-interpreter hooks.
(defvar comint-get-old-input (function comint-get-old-input-default)
  "Function that returns old text in comint mode.
This function is called when return is typed while the point is in old
text.  It returns the text to be submitted as process input.  The
default is `comint-get-old-input-default', which either grabs the
current input field or grabs the current line and strips off leading
text matching `comint-prompt-regexp', depending on the value of
`comint-use-prompt-regexp-instead-of-fields'.")

(defvar comint-dynamic-complete-functions
  '(comint-replace-by-expanded-history comint-dynamic-complete-filename)
  "List of functions called to perform completion.
Functions should return non-nil if completion was performed.
See also `comint-dynamic-complete'.

This is a good thing to set in mode hooks.")

(defvar comint-input-filter
  (function (lambda (str) (not (string-match "\\`\\s *\\'" str))))
  "Predicate for filtering additions to input history.
Takes one argument, the input.  If non-nil, the input may be saved on the input
history list.  Default is to save anything that isn't all whitespace.")

(defvar comint-input-filter-functions '()
  "Functions to call before input is sent to the process.
These functions get one argument, a string containing the text to send.

This variable is buffer-local.")

(defvar comint-output-filter-functions '(comint-postoutput-scroll-to-bottom)
  "Functions to call after output is inserted into the buffer.
One possible function is `comint-postoutput-scroll-to-bottom'.
These functions get one argument, a string containing the text as originally
inserted.  Note that this might not be the same as the buffer contents between
`comint-last-output-start' and the buffer's `process-mark', if other filter
functions have already modified the buffer.

See also `comint-preoutput-filter-functions'.

This variable is buffer-local.")

(defvar comint-input-sender (function comint-simple-send)
  "Function to actually send to PROCESS the STRING submitted by user.
Usually this is just `comint-simple-send', but if your mode needs to
massage the input string, put a different function here.
`comint-simple-send' just sends the string plus a newline.
This is called from the user command `comint-send-input'.")

(defcustom comint-eol-on-send t
  "*Non-nil means go to the end of the line before sending input.
See `comint-send-input'."
  :type 'boolean
  :group 'comint)

;; Note: If it is decided to purge comint-prompt-regexp from the source
;; entirely, searching for uses of this variable will help to identify
;; places that need attention.
(defcustom comint-use-prompt-regexp-instead-of-fields nil
  "*If non-nil, use `comint-prompt-regexp' to distinguish prompts from user-input.
If nil, then program output and user-input are given different `field'
properties, which emacs commands can use to distinguish them (in
particular, common movement commands such as begining-of-line respect
field boundaries in a natural way)."
  :type 'boolean
  :group 'comint)

(defcustom comint-mode-hook '()
  "Called upon entry into `comint-mode'
This is run before the process is cranked up."
  :type 'hook
  :group 'comint)

(defcustom comint-exec-hook '()
  "Called each time a process is exec'd by `comint-exec'.
This is called after the process is cranked up.  It is useful for things that
must be done each time a process is executed in a comint mode buffer (e.g.,
`(process-kill-without-query)').  In contrast, the `comint-mode-hook' is only
executed once when the buffer is created."
  :type 'hook
  :group 'comint)

(defvar comint-mode-map nil)

(defvar comint-ptyp t
  "Non-nil if communications via pty; false if by pipe.  Buffer local.
This is to work around a bug in Emacs process signaling.")

(defvar comint-input-ring nil)
(defvar comint-last-input-start)
(defvar comint-last-input-end)
(defvar comint-last-output-start)
(defvar comint-input-ring-index nil
  "Index of last matched history element.")
(defvar comint-matching-input-from-input-string ""
  "Input previously used to match input history.")
(defvar comint-save-input-ring-index
  "Last input ring index which you copied.
This is to support the command \\[comint-get-next-from-history].")

(defvar comint-accum-marker nil
  "Non-nil if you are accumulating input lines to send as input together.
The command \\[comint-accumulate] sets this.")

(put 'comint-replace-by-expanded-history 'menu-enable 'comint-input-autoexpand)
(put 'comint-input-ring 'permanent-local t)
(put 'comint-input-ring-index 'permanent-local t)
(put 'comint-save-input-ring-index 'permanent-local t)
(put 'comint-input-autoexpand 'permanent-local t)
(put 'comint-input-filter-functions 'permanent-local t)
(put 'comint-output-filter-functions 'permanent-local t)
(put 'comint-preoutput-filter-functions 'permanent-local t)
(put 'comint-scroll-to-bottom-on-input 'permanent-local t)
(put 'comint-scroll-to-bottom-on-output 'permanent-local t)
(put 'comint-scroll-show-maximum-output 'permanent-local t)
(put 'comint-ptyp 'permanent-local t)

(put 'comint-mode 'mode-class 'special)

(define-derived-mode comint-mode fundamental-mode "Comint"
  "Major mode for interacting with an inferior interpreter.
Interpreter name is same as buffer name, sans the asterisks.
Return at end of buffer sends line as input.
Return not at end copies rest of line to end and sends it.
Setting variable `comint-eol-on-send' means jump to the end of the line
before submitting new input.

This mode is customised to create major modes such as Inferior Lisp
mode, Shell mode, etc.  This can be done by setting the hooks
`comint-input-filter-functions', `comint-input-filter', `comint-input-sender'
and `comint-get-old-input' to appropriate functions, and the variable
`comint-prompt-regexp' to the appropriate regular expression.

An input history is maintained of size `comint-input-ring-size', and
can be accessed with the commands \\[comint-next-input], \\[comint-previous-input], and \\[comint-dynamic-list-input-ring].
Input ring history expansion can be achieved with the commands
\\[comint-replace-by-expanded-history] or \\[comint-magic-space].
Input ring expansion is controlled by the variable `comint-input-autoexpand',
and addition is controlled by the variable `comint-input-ignoredups'.

Commands with no default key bindings include `send-invisible',
`comint-dynamic-complete', `comint-dynamic-list-filename-completions', and
`comint-magic-space'.

Input to, and output from, the subprocess can cause the window to scroll to
the end of the buffer.  See variables `comint-output-filter-functions',
`comint-preoutput-filter-functions', `comint-scroll-to-bottom-on-input',
and `comint-scroll-to-bottom-on-output'.

If you accidentally suspend your process, use \\[comint-continue-subjob]
to continue it.

\\{comint-mode-map}

Entry to this mode runs the hooks on `comint-mode-hook'."
  (setq mode-line-process '(":%s"))
  (make-local-variable 'comint-last-input-start)
  (setq comint-last-input-start (make-marker))
  (set-marker comint-last-input-start (point-min))
  (make-local-variable 'comint-last-input-end)
  (setq comint-last-input-end (make-marker))
  (set-marker comint-last-input-end (point-min))
  (make-local-variable 'comint-last-output-start)
  (setq comint-last-output-start (make-marker))
  (make-local-variable 'comint-last-output-overlay)
  (make-local-variable 'comint-last-prompt-overlay)
  (make-local-variable 'comint-prompt-regexp)        ; Don't set; default
  (make-local-variable 'comint-input-ring-size)      ; ...to global val.
  (make-local-variable 'comint-input-ring)
  (make-local-variable 'comint-input-ring-file-name)
  (or (and (boundp 'comint-input-ring) comint-input-ring)
      (setq comint-input-ring (make-ring comint-input-ring-size)))
  (make-local-variable 'comint-input-ring-index)
  (make-local-variable 'comint-save-input-ring-index)
  (or (and (boundp 'comint-input-ring-index) comint-input-ring-index)
      (setq comint-input-ring-index nil))
  (or (and (boundp 'comint-save-input-ring-index) comint-save-input-ring-index)
      (setq comint-save-input-ring-index nil))
  (make-local-variable 'comint-matching-input-from-input-string)
  (make-local-variable 'comint-input-autoexpand)
  (make-local-variable 'comint-input-ignoredups)
  (make-local-variable 'comint-delimiter-argument-list)
  (make-local-hook 'comint-dynamic-complete-functions)
  (make-local-variable 'comint-completion-fignore)
  (make-local-variable 'comint-get-old-input)
  (make-local-hook 'comint-input-filter-functions)
  (make-local-variable 'comint-input-filter)
  (make-local-variable 'comint-input-sender)
  (make-local-variable 'comint-eol-on-send)
  (make-local-variable 'comint-scroll-to-bottom-on-input)
  (make-local-variable 'comint-scroll-to-bottom-on-output)
  (make-local-variable 'comint-scroll-show-maximum-output)
  (make-local-hook 'pre-command-hook)
  (add-hook 'pre-command-hook 'comint-preinput-scroll-to-bottom t t)
  (make-local-hook 'comint-output-filter-functions)
  (make-local-hook 'comint-exec-hook)
  (make-local-variable 'comint-ptyp)
  (make-local-variable 'comint-process-echoes)
  (make-local-variable 'comint-file-name-chars)
  (make-local-variable 'comint-file-name-quote-list)
  (make-local-variable 'comint-accum-marker)
  (setq comint-accum-marker (make-marker))
  (set-marker comint-accum-marker nil))

(if comint-mode-map
    nil
  ;; Keys:
  (setq comint-mode-map (make-sparse-keymap))
  (define-key comint-mode-map "\ep" 'comint-previous-input)
  (define-key comint-mode-map "\en" 'comint-next-input)
  (define-key comint-mode-map [C-up] 'comint-previous-input)
  (define-key comint-mode-map [C-down] 'comint-next-input)
  (define-key comint-mode-map "\er" 'comint-previous-matching-input)
  (define-key comint-mode-map "\es" 'comint-next-matching-input)
  (define-key comint-mode-map [?\C-c ?\M-r] 'comint-previous-matching-input-from-input)
  (define-key comint-mode-map [?\C-c ?\M-s] 'comint-next-matching-input-from-input)
  (define-key comint-mode-map "\e\C-l" 'comint-show-output)
  (define-key comint-mode-map "\C-m" 'comint-send-input)
  (define-key comint-mode-map "\C-d" 'comint-delchar-or-maybe-eof)
  (define-key comint-mode-map "\C-c " 'comint-accumulate)
  (define-key comint-mode-map "\C-c\C-x" 'comint-get-next-from-history)
  (define-key comint-mode-map "\C-c\C-a" 'comint-bol-or-process-mark)
  (define-key comint-mode-map "\C-c\C-u" 'comint-kill-input)
  (define-key comint-mode-map "\C-c\C-w" 'backward-kill-word)
  (define-key comint-mode-map "\C-c\C-c" 'comint-interrupt-subjob)
  (define-key comint-mode-map "\C-c\C-z" 'comint-stop-subjob)
  (define-key comint-mode-map "\C-c\C-\\" 'comint-quit-subjob)
  (define-key comint-mode-map "\C-c\C-m" 'comint-copy-old-input)
  (define-key comint-mode-map "\C-c\C-o" 'comint-delete-output)
  (define-key comint-mode-map "\C-c\C-r" 'comint-show-output)
  (define-key comint-mode-map "\C-c\C-e" 'comint-show-maximum-output)
  (define-key comint-mode-map "\C-c\C-l" 'comint-dynamic-list-input-ring)
  (define-key comint-mode-map "\C-c\C-n" 'comint-next-prompt)
  (define-key comint-mode-map "\C-c\C-p" 'comint-previous-prompt)
  (define-key comint-mode-map "\C-c\C-d" 'comint-send-eof)
  (define-key comint-mode-map "\C-c\C-s" 'comint-write-output)
  ;; Mouse Buttons:
  (define-key comint-mode-map [mouse-2] 'comint-insert-clicked-input)
  ;; Menu bars:
  ;; completion:
  (define-key comint-mode-map [menu-bar completion]
    (cons "Complete" (make-sparse-keymap "Complete")))
  (define-key comint-mode-map [menu-bar completion complete-expand]
    '("Expand File Name" . comint-replace-by-expanded-filename))
  (define-key comint-mode-map [menu-bar completion complete-listing]
    '("File Completion Listing" . comint-dynamic-list-filename-completions))
  (define-key comint-mode-map [menu-bar completion complete-file]
    '("Complete File Name" . comint-dynamic-complete-filename))
  (define-key comint-mode-map [menu-bar completion complete]
    '("Complete Before Point" . comint-dynamic-complete))
  ;; Input history:
  (define-key comint-mode-map [menu-bar inout]
    (cons "In/Out" (make-sparse-keymap "In/Out")))
  (define-key comint-mode-map [menu-bar inout delete-output]
    '("Delete Current Output Group" . comint-delete-output))
  (define-key comint-mode-map [menu-bar inout write-output]
    '("Write Current Output Group to File" . comint-write-output))
  (define-key comint-mode-map [menu-bar inout append-output-to-file]
    '("Append Current Output Group to File" . comint-append-output-to-file))
  (define-key comint-mode-map [menu-bar inout next-prompt]
    '("Forward Output Group" . comint-next-prompt))
  (define-key comint-mode-map [menu-bar inout previous-prompt]
    '("Backward Output Group" . comint-previous-prompt))
  (define-key comint-mode-map [menu-bar inout show-maximum-output]
    '("Show Maximum Output" . comint-show-maximum-output))
  (define-key comint-mode-map [menu-bar inout show-output]
    '("Show Current Output Group" . comint-show-output))
  (define-key comint-mode-map [menu-bar inout kill-input]
    '("Kill Current Input" . comint-kill-input))
  (define-key comint-mode-map [menu-bar inout copy-input]
    '("Copy Old Input" . comint-copy-old-input))
  (define-key comint-mode-map [menu-bar inout forward-matching-history]
    '("Forward Matching Input..." . comint-forward-matching-input))
  (define-key comint-mode-map [menu-bar inout backward-matching-history]
    '("Backward Matching Input..." . comint-backward-matching-input))
  (define-key comint-mode-map [menu-bar inout next-matching-history]
    '("Next Matching Input..." . comint-next-matching-input))
  (define-key comint-mode-map [menu-bar inout previous-matching-history]
    '("Previous Matching Input..." . comint-previous-matching-input))
  (define-key comint-mode-map [menu-bar inout next-matching-history-from-input]
    '("Next Matching Current Input" . comint-next-matching-input-from-input))
  (define-key comint-mode-map [menu-bar inout previous-matching-history-from-input]
    '("Previous Matching Current Input" . comint-previous-matching-input-from-input))
  (define-key comint-mode-map [menu-bar inout next-history]
    '("Next Input" . comint-next-input))
  (define-key comint-mode-map [menu-bar inout previous-history]
    '("Previous Input" . comint-previous-input))
  (define-key comint-mode-map [menu-bar inout list-history]
    '("List Input History" . comint-dynamic-list-input-ring))
  (define-key comint-mode-map [menu-bar inout expand-history]
    '("Expand History Before Point" . comint-replace-by-expanded-history))
  ;; Signals
  (define-key comint-mode-map [menu-bar signals]
    (cons "Signals" (make-sparse-keymap "Signals")))
  (define-key comint-mode-map [menu-bar signals eof]
    '("EOF" . comint-send-eof))
  (define-key comint-mode-map [menu-bar signals kill]
    '("KILL" . comint-kill-subjob))
  (define-key comint-mode-map [menu-bar signals quit]
    '("QUIT" . comint-quit-subjob))
  (define-key comint-mode-map [menu-bar signals cont]
    '("CONT" . comint-continue-subjob))
  (define-key comint-mode-map [menu-bar signals stop]
    '("STOP" . comint-stop-subjob))
  (define-key comint-mode-map [menu-bar signals break]
    '("BREAK" . comint-interrupt-subjob))
  ;; Put them in the menu bar:
  (setq menu-bar-final-items (append '(completion inout signals)
				     menu-bar-final-items))
  )

(defun comint-check-proc (buffer)
  "Return t if there is a living process associated w/buffer BUFFER.
Living means the status is `open', `run', or `stop'.
BUFFER can be either a buffer or the name of one."
  (let ((proc (get-buffer-process buffer)))
    (and proc (memq (process-status proc) '(open run stop)))))

;;;###autoload
(defun make-comint (name program &optional startfile &rest switches)
  "Make a comint process NAME in a buffer, running PROGRAM.
The name of the buffer is made by surrounding NAME with `*'s.
PROGRAM should be either a string denoting an executable program to create
via `start-process', or a cons pair of the form (HOST . SERVICE) denoting a TCP
connection to be opened via `open-network-stream'.  If there is already a
running process in that buffer, it is not restarted.  Optional third arg
STARTFILE is the name of a file to send the contents of to the process.

If PROGRAM is a string, any more args are arguments to PROGRAM."
  (or (fboundp 'start-process)
      (error "Multi-processing is not supported for this system"))
  (let ((buffer (get-buffer-create (concat "*" name "*"))))
    ;; If no process, or nuked process, crank up a new one and put buffer in
    ;; comint mode.  Otherwise, leave buffer and existing process alone.
    (unless (comint-check-proc buffer)
      (with-current-buffer buffer
	(comint-mode)) ; Install local vars, mode, keymap, ...
      (comint-exec buffer name program startfile switches))
    buffer))

;;;###autoload
(defun comint-run (program)
  "Run PROGRAM in a comint buffer and switch to it.
The buffer name is made by surrounding the file name of PROGRAM with `*'s.
The file name is used to make a symbol name, such as `comint-sh-hook', and any
hooks on this symbol are run in the buffer.
See `make-comint' and `comint-exec'."
  (interactive "sRun program: ")
  (let ((name (file-name-nondirectory program)))
    (switch-to-buffer (make-comint name program))
    (run-hooks (intern-soft (concat "comint-" name "-hook")))))

(defun comint-exec (buffer name command startfile switches)
  "Start up a process in buffer BUFFER for comint modes.
Blasts any old process running in the buffer.  Doesn't set the buffer mode.
You can use this to cheaply run a series of processes in the same comint
buffer.  The hook `comint-exec-hook' is run after each exec."
  (save-excursion
    (set-buffer buffer)
    (let ((proc (get-buffer-process buffer)))	; Blast any old process.
      (if proc (delete-process proc)))
    ;; Crank up a new process
    (let ((proc
	   (if (consp command)
	       (open-network-stream name buffer (car command) (cdr command))
	     (comint-exec-1 name buffer command switches))))
      (set-process-filter proc 'comint-output-filter)
      (make-local-variable 'comint-ptyp)
      (setq comint-ptyp process-connection-type) ; T if pty, NIL if pipe.
      ;; Jump to the end, and set the process mark.
      (goto-char (point-max))
      (set-marker (process-mark proc) (point))
      ;; Feed it the startfile.
      (cond (startfile
	     ;;This is guaranteed to wait long enough
	     ;;but has bad results if the comint does not prompt at all
	     ;;	     (while (= size (buffer-size))
	     ;;	       (sleep-for 1))
	     ;;I hope 1 second is enough!
	     (sleep-for 1)
	     (goto-char (point-max))
	     (insert-file-contents startfile)
	     (setq startfile (buffer-substring (point) (point-max)))
	     (delete-region (point) (point-max))
	     (comint-send-string proc startfile)))
    (run-hooks 'comint-exec-hook)
    buffer)))

;; This auxiliary function cranks up the process for comint-exec in
;; the appropriate environment.

(defun comint-exec-1 (name buffer command switches)
  (let ((process-environment
	 (nconc
	  ;; If using termcap, we specify `emacs' as the terminal type
	  ;; because that lets us specify a width.
	  ;; If using terminfo, we specify `dumb' because that is
	  ;; a defined terminal type.  `emacs' is not a defined terminal type
	  ;; and there is no way for us to define it here.
	  ;; Some programs that use terminfo get very confused
	  ;; if TERM is not a valid terminal type.
	  (if (and (boundp 'system-uses-terminfo) system-uses-terminfo)
	      (list "TERM=dumb" "TERMCAP="
		    (format "COLUMNS=%d" (frame-width)))
	    (list "TERM=emacs"
		  (format "TERMCAP=emacs:co#%d:tc=unknown:" (frame-width))))
	  (if (getenv "EMACS") nil (list "EMACS=t"))
	  process-environment))
	(default-directory
	  (if (file-accessible-directory-p default-directory)
	      default-directory
	    (char-to-string directory-sep-char)))
	proc decoding encoding changed)
    (let ((exec-path (if (file-name-directory command)
			 ;; If the command has slashes, make sure we
			 ;; first look relative to the current directory.
			 (cons default-directory exec-path) exec-path)))
      (setq proc (apply 'start-process name buffer command switches)))
    (let ((coding-systems (process-coding-system proc)))
      (setq decoding (car coding-systems)
	    encoding (cdr coding-systems)))
    ;; If start-process decided to use some coding system for decoding
    ;; data sent from the process and the coding system doesn't
    ;; specify EOL conversion, we had better convert CRLF to LF.
    (if (vectorp (coding-system-eol-type decoding))
	(setq decoding (coding-system-change-eol-conversion decoding 'dos)
	      changed t))
    ;; Even if start-process left the coding system for encoding data
    ;; sent from the process undecided, we had better use the same one
    ;; as what we use for decoding.  But, we should suppress EOL
    ;; conversion.
    (if (and decoding (not encoding))
	(setq encoding (coding-system-change-eol-conversion decoding 'unix)
	      changed t))
    (if changed
	(set-process-coding-system proc decoding encoding))
    proc))


(defun comint-insert-clicked-input (event)
  "In a comint buffer, set the current input to the clicked-on previous input."
  (interactive "e")
  (let ((over (catch 'found
		;; Ignore non-input overlays
		(dolist (ov (overlays-at (posn-point (event-end event))))
		  (when (eq (overlay-get ov 'field) 'input)
		    (throw 'found ov))))))
    ;; do we have input in this area?
    (if over
	(let ((input-str (buffer-substring (overlay-start over)
					   (overlay-end over))))
	  (delete-region
	   ;; Can't use kill-region as it sets this-command
	   (or  (marker-position comint-accum-marker)
		(process-mark (get-buffer-process (current-buffer))))
	   (point))
	  (insert input-str))
      ;; fall back to the user's previous definition if we aren't
      ;; on previous input region.
      (let ((fun (lookup-key global-map (this-command-keys))))
	(if fun (call-interactively fun))))))

\f
;; Input history processing in a buffer
;; ===========================================================================
;; Useful input history functions, courtesy of the Ergo group.

;; Eleven commands:
;; comint-dynamic-list-input-ring	List history in help buffer.
;; comint-previous-input		Previous input...
;; comint-previous-matching-input	...matching a string.
;; comint-previous-matching-input-from-input ... matching the current input.
;; comint-next-input			Next input...
;; comint-next-matching-input		...matching a string.
;; comint-next-matching-input-from-input     ... matching the current input.
;; comint-backward-matching-input      Backwards input...
;; comint-forward-matching-input       ...matching a string.
;; comint-replace-by-expanded-history	Expand history at point;
;;					replace with expanded history.
;; comint-magic-space			Expand history and insert space.
;;
;; Three functions:
;; comint-read-input-ring              Read into comint-input-ring...
;; comint-write-input-ring             Write to comint-input-ring-file-name.
;; comint-replace-by-expanded-history-before-point Workhorse function.

(defun comint-read-input-ring (&optional silent)
  "Sets the buffer's `comint-input-ring' from a history file.
The name of the file is given by the variable `comint-input-ring-file-name'.
The history ring is of size `comint-input-ring-size', regardless of file size.
If `comint-input-ring-file-name' is nil this function does nothing.

If the optional argument SILENT is non-nil, we say nothing about a
failure to read the history file.

This function is useful for major mode commands and mode hooks.

The commands stored in the history file are separated by the
`comint-input-ring-separator'.  The most recent command comes last.

See also `comint-input-ignoredups' and `comint-write-input-ring'."
  (cond ((or (null comint-input-ring-file-name)
	     (equal comint-input-ring-file-name ""))
	 nil)
	((not (file-readable-p comint-input-ring-file-name))
	 (or silent
	     (message "Cannot read history file %s"
		      comint-input-ring-file-name)))
	(t
	 (let* ((history-buf (get-buffer-create " *temp*"))
		(file comint-input-ring-file-name)
		(count 0)
		(size comint-input-ring-size)
		(ring (make-ring size)))
	   (unwind-protect
	       (save-excursion
		 (set-buffer history-buf)
		 (widen)
		 (erase-buffer)
		 (insert-file-contents file)
		 ;; Save restriction in case file is already visited...
		 ;; Watch for those date stamps in history files!
		 (goto-char (point-max))
		 (let (start end history)
		   (while (and (< count comint-input-ring-size)
			       (re-search-backward comint-input-ring-separator nil t)
			       (setq end (match-beginning 0)))
		     (if (re-search-backward comint-input-ring-separator nil t)
			 (setq start (match-end 0))
		       (setq start (point-min)))
		     (setq history (buffer-substring start end))
		     (goto-char start)
		     (if (or (null comint-input-ignoredups)
			     (ring-empty-p ring)
			     (not (string-equal (ring-ref ring 0) history)))
			 (progn
			   (ring-insert-at-beginning ring history)
			   (setq count (1+ count)))))))
	     (kill-buffer history-buf))
	   (setq comint-input-ring ring
		 comint-input-ring-index nil)))))

(defun comint-write-input-ring ()
  "Writes the buffer's `comint-input-ring' to a history file.
The name of the file is given by the variable `comint-input-ring-file-name'.
The original contents of the file are lost if `comint-input-ring' is not empty.
If `comint-input-ring-file-name' is nil this function does nothing.

Useful within process sentinels.

See also `comint-read-input-ring'."
  (cond ((or (null comint-input-ring-file-name)
	     (equal comint-input-ring-file-name "")
	     (null comint-input-ring) (ring-empty-p comint-input-ring))
	 nil)
	((not (file-writable-p comint-input-ring-file-name))
	 (message "Cannot write history file %s" comint-input-ring-file-name))
	(t
	 (let* ((history-buf (get-buffer-create " *Temp Input History*"))
		(ring comint-input-ring)
		(file comint-input-ring-file-name)
		(index (ring-length ring)))
	   ;; Write it all out into a buffer first.  Much faster, but messier,
	   ;; than writing it one line at a time.
	   (save-excursion
	     (set-buffer history-buf)
	     (erase-buffer)
	     (while (> index 0)
	       (setq index (1- index))
	       (insert (ring-ref ring index) comint-input-ring-separator))
	     (write-region (buffer-string) nil file nil 'no-message)
	     (kill-buffer nil))))))


(defun comint-dynamic-list-input-ring ()
  "List in help buffer the buffer's input history."
  (interactive)
  (if (or (not (ring-p comint-input-ring))
	  (ring-empty-p comint-input-ring))
      (message "No history")
    (let ((history nil)
	  (history-buffer " *Input History*")
	  (index (1- (ring-length comint-input-ring)))
	  (conf (current-window-configuration)))
      ;; We have to build up a list ourselves from the ring vector.
      (while (>= index 0)
	(setq history (cons (ring-ref comint-input-ring index) history)
	      index (1- index)))
      ;; Change "completion" to "history reference"
      ;; to make the display accurate.
      (with-output-to-temp-buffer history-buffer
	(display-completion-list history)
	(set-buffer history-buffer)
	(forward-line 3)
	(while (search-backward "completion" nil 'move)
	  (replace-match "history reference")))
      (sit-for 0)
      (message "Hit space to flush")
      (let ((ch (read-event)))
	(if (eq ch ?\ )
	    (set-window-configuration conf)
	  (setq unread-command-events (list ch)))))))


(defun comint-regexp-arg (prompt)
  ;; Return list of regexp and prefix arg using PROMPT.
  (let* (;; Don't clobber this.
	 (last-command last-command)
	 (regexp (read-from-minibuffer prompt nil nil nil
				       'minibuffer-history-search-history)))
    (list (if (string-equal regexp "")
	      (setcar minibuffer-history-search-history
		      (nth 1 minibuffer-history-search-history))
	    regexp)
	  (prefix-numeric-value current-prefix-arg))))

(defun comint-search-arg (arg)
  ;; First make sure there is a ring and that we are after the process mark
  (cond ((not (comint-after-pmark-p))
	 (error "Not at command line"))
	((or (null comint-input-ring)
	     (ring-empty-p comint-input-ring))
	 (error "Empty input ring"))
	((zerop arg)
	 ;; arg of zero resets search from beginning, and uses arg of 1
	 (setq comint-input-ring-index nil)
	 1)
	(t
	 arg)))

(defun comint-search-start (arg)
  ;; Index to start a directional search, starting at comint-input-ring-index
  (if comint-input-ring-index
      ;; If a search is running, offset by 1 in direction of arg
      (mod (+ comint-input-ring-index (if (> arg 0) 1 -1))
	   (ring-length comint-input-ring))
    ;; For a new search, start from beginning or end, as appropriate
    (if (>= arg 0)
	0				       ; First elt for forward search
      (1- (ring-length comint-input-ring)))))  ; Last elt for backward search

(defun comint-previous-input-string (arg)
  "Return the string ARG places along the input ring.
Moves relative to `comint-input-ring-index'."
  (ring-ref comint-input-ring (if comint-input-ring-index
				  (mod (+ arg comint-input-ring-index)
				       (ring-length comint-input-ring))
				arg)))

(defun comint-previous-input (arg)
  "Cycle backwards through input history."
  (interactive "*p")
  (comint-previous-matching-input "." arg))

(defun comint-next-input (arg)
  "Cycle forwards through input history."
  (interactive "*p")
  (comint-previous-input (- arg)))

(defun comint-previous-matching-input-string (regexp arg)
  "Return the string matching REGEXP ARG places along the input ring.
Moves relative to `comint-input-ring-index'."
  (let* ((pos (comint-previous-matching-input-string-position regexp arg)))
    (if pos (ring-ref comint-input-ring pos))))

(defun comint-previous-matching-input-string-position (regexp arg &optional start)
  "Return the index matching REGEXP ARG places along the input ring.
Moves relative to START, or `comint-input-ring-index'."
  (if (or (not (ring-p comint-input-ring))
	  (ring-empty-p comint-input-ring))
      (error "No history"))
  (let* ((len (ring-length comint-input-ring))
	 (motion (if (> arg 0) 1 -1))
	 (n (mod (- (or start (comint-search-start arg)) motion) len))
	 (tried-each-ring-item nil)
	 (prev nil))
    ;; Do the whole search as many times as the argument says.
    (while (and (/= arg 0) (not tried-each-ring-item))
      ;; Step once.
      (setq prev n
	    n (mod (+ n motion) len))
      ;; If we haven't reached a match, step some more.
      (while (and (< n len) (not tried-each-ring-item)
		  (not (string-match regexp (ring-ref comint-input-ring n))))
	(setq n (mod (+ n motion) len)
	      ;; If we have gone all the way around in this search.
	      tried-each-ring-item (= n prev)))
      (setq arg (if (> arg 0) (1- arg) (1+ arg))))
    ;; Now that we know which ring element to use, if we found it, return that.
    (if (string-match regexp (ring-ref comint-input-ring n))
	n)))

(defun comint-previous-matching-input (regexp arg)
  "Search backwards through input history for match for REGEXP.
\(Previous history elements are earlier commands.)
With prefix argument N, search for Nth previous match.
If N is negative, find the next or Nth next match."
  (interactive (comint-regexp-arg "Previous input matching (regexp): "))
  (setq arg (comint-search-arg arg))
  (let ((pos (comint-previous-matching-input-string-position regexp arg)))
    ;; Has a match been found?
    (if (null pos)
	(error "Not found")
      (setq comint-input-ring-index pos)
      (message "History item: %d" (1+ pos))
      (delete-region
       ;; Can't use kill-region as it sets this-command
       (or  (marker-position comint-accum-marker)
	    (process-mark (get-buffer-process (current-buffer))))
       (point))
      (insert (ring-ref comint-input-ring pos)))))

(defun comint-next-matching-input (regexp arg)
  "Search forwards through input history for match for REGEXP.
\(Later history elements are more recent commands.)
With prefix argument N, search for Nth following match.
If N is negative, find the previous or Nth previous match."
  (interactive (comint-regexp-arg "Next input matching (regexp): "))
  (comint-previous-matching-input regexp (- arg)))

(defun comint-previous-matching-input-from-input (arg)
  "Search backwards through input history for match for current input.
\(Previous history elements are earlier commands.)
With prefix argument N, search for Nth previous match.
If N is negative, search forwards for the -Nth following match."
  (interactive "p")
  (if (not (memq last-command '(comint-previous-matching-input-from-input
				comint-next-matching-input-from-input)))
      ;; Starting a new search
      (setq comint-matching-input-from-input-string
	    (buffer-substring
	     (or (marker-position comint-accum-marker)
		 (process-mark (get-buffer-process (current-buffer))))
	     (point))
	    comint-input-ring-index nil))
  (comint-previous-matching-input
   (concat "^" (regexp-quote comint-matching-input-from-input-string))
   arg))

(defun comint-next-matching-input-from-input (arg)
  "Search forwards through input history for match for current input.
\(Following history elements are more recent commands.)
With prefix argument N, search for Nth following match.
If N is negative, search backwards for the -Nth previous match."
  (interactive "p")
  (comint-previous-matching-input-from-input (- arg)))


(defun comint-replace-by-expanded-history (&optional silent start)
  "Expand input command history references before point.
Expansion is dependent on the value of `comint-input-autoexpand'.

This function depends on the buffer's idea of the input history, which may not
match the command interpreter's idea, assuming it has one.

Assumes history syntax is like typical Un*x shells'.  However, since emacs
cannot know the interpreter's idea of input line numbers, assuming it has one,
it cannot expand absolute input line number references.

If the optional argument SILENT is non-nil, never complain
even if history reference seems erroneous.

If the optional argument START is non-nil, that specifies the
start of the text to scan for history references, rather
than the logical beginning of line.

See `comint-magic-space' and `comint-replace-by-expanded-history-before-point'.

Returns t if successful."
  (interactive)
  (if (and comint-input-autoexpand
	   (string-match "!\\|^\\^" (funcall comint-get-old-input))
	   (if comint-use-prompt-regexp-instead-of-fields
	       ;; Use comint-prompt-regexp
	       (save-excursion (beginning-of-line)
			       (looking-at comint-prompt-regexp))
	     ;; Use input fields.  User input that hasn't been entered
	     ;; yet, at the end of the buffer, has a nil `field' property.
	     (null (get-char-property (point) 'field))))
      ;; Looks like there might be history references in the command.
      (let ((previous-modified-tick (buffer-modified-tick)))
	(comint-replace-by-expanded-history-before-point silent start)
	(/= previous-modified-tick (buffer-modified-tick)))))


(defun comint-replace-by-expanded-history-before-point (silent &optional start)
  "Expand directory stack reference before point.
See `comint-replace-by-expanded-history'.  Returns t if successful.

If the optional argument START is non-nil, that specifies the
start of the text to scan for history references, rather
than the logical beginning of line."
  (save-excursion
    (let ((toend (- (line-end-position) (point)))
	  (start (comint-line-beginning-position)))
      (while (progn
	       (skip-chars-forward "^!^" (- (line-end-position) toend))
	       (< (point) (- (line-end-position) toend)))
	;; This seems a bit complex.  We look for references such as !!, !-num,
	;; !foo, !?foo, !{bar}, !?{bar}, ^oh, ^my^, ^god^it, ^never^ends^.
	;; If that wasn't enough, the plings can be suffixed with argument
	;; range specifiers.
	;; Argument ranges are complex too, so we hive off the input line,
	;; referenced with plings, with the range string to `comint-args'.
	(setq comint-input-ring-index nil)
	(cond ((or (= (preceding-char) ?\\)
		   (comint-within-quotes start (point)))
	       ;; The history is quoted, or we're in quotes.
	       (goto-char (1+ (point))))
	      ((looking-at "![0-9]+\\($\\|[^-]\\)")
	       ;; We cannot know the interpreter's idea of input line numbers.
	       (goto-char (match-end 0))
	       (message "Absolute reference cannot be expanded"))
	      ((looking-at "!-\\([0-9]+\\)\\(:?[0-9^$*-]+\\)?")
	       ;; Just a number of args from `number' lines backward.
	       (let ((number (1- (string-to-number
				  (buffer-substring (match-beginning 1)
						    (match-end 1))))))
		 (if (<= number (ring-length comint-input-ring))
		     (progn
		       (replace-match
			(comint-args (comint-previous-input-string number)
				     (match-beginning 2) (match-end 2))
			t t)
		       (setq comint-input-ring-index number)
		       (message "History item: %d" (1+ number)))
		   (goto-char (match-end 0))
		   (message "Relative reference exceeds input history size"))))
	      ((or (looking-at "!!?:?\\([0-9^$*-]+\\)") (looking-at "!!"))
	       ;; Just a number of args from the previous input line.
	       (replace-match
		(comint-args (comint-previous-input-string 0)
			     (match-beginning 1) (match-end 1))
		t t)
	       (message "History item: previous"))
	      ((looking-at
		"!\\??\\({\\(.+\\)}\\|\\(\\sw+\\)\\)\\(:?[0-9^$*-]+\\)?")
	       ;; Most recent input starting with or containing (possibly
	       ;; protected) string, maybe just a number of args.  Phew.
	       (let* ((mb1 (match-beginning 1)) (me1 (match-end 1))
		      (mb2 (match-beginning 2)) (me2 (match-end 2))
		      (exp (buffer-substring (or mb2 mb1) (or me2 me1)))
		      (pref (if (save-match-data (looking-at "!\\?")) "" "^"))
		      (pos (save-match-data
			     (comint-previous-matching-input-string-position
			      (concat pref (regexp-quote exp)) 1))))
		 (if (null pos)
		     (progn
		       (goto-char (match-end 0))
		       (or silent
			   (progn (message "Not found")
				  (ding))))
		   (setq comint-input-ring-index pos)
		   (replace-match
		    (comint-args (ring-ref comint-input-ring pos)
				 (match-beginning 4) (match-end 4))
		    t t)
		   (message "History item: %d" (1+ pos)))))
	      ((looking-at "\\^\\([^^]+\\)\\^?\\([^^]*\\)\\^?")
	       ;; Quick substitution on the previous input line.
	       (let ((old (buffer-substring (match-beginning 1) (match-end 1)))
		     (new (buffer-substring (match-beginning 2) (match-end 2)))
		     (pos nil))
		 (replace-match (comint-previous-input-string 0) t t)
		 (setq pos (point))
		 (goto-char (match-beginning 0))
		 (if (not (search-forward old pos t))
		     (or silent
			 (error "Not found"))
		   (replace-match new t t)
		   (message "History item: substituted"))))
	      (t
	       (forward-char 1)))))))


(defun comint-magic-space (arg)
  "Expand input history references before point and insert ARG spaces.
A useful command to bind to SPC.  See `comint-replace-by-expanded-history'."
  (interactive "p")
  (comint-replace-by-expanded-history)
  (self-insert-command arg))
\f
(defun comint-within-quotes (beg end)
  "Return t if the number of quotes between BEG and END is odd.
Quotes are single and double."
  (let ((countsq (comint-how-many-region "\\(^\\|[^\\\\]\\)\'" beg end))
	(countdq (comint-how-many-region "\\(^\\|[^\\\\]\\)\"" beg end)))
    (or (= (mod countsq 2) 1) (= (mod countdq 2) 1))))

(defun comint-how-many-region (regexp beg end)
  "Return number of matches for REGEXP from BEG to END."
  (let ((count 0))
    (save-excursion
      (save-match-data
	(goto-char beg)
	(while (re-search-forward regexp end t)
	  (setq count (1+ count)))))
    count))

(defun comint-args (string begin end)
  ;; From STRING, return the args depending on the range specified in the text
  ;; from BEGIN to END.  If BEGIN is nil, assume all args.  Ignore leading `:'.
  ;; Range can be x-y, x-, -y, where x/y can be [0-9], *, ^, $.
  (save-match-data
    (if (null begin)
	(comint-arguments string 0 nil)
      (let* ((range (buffer-substring
		     (if (eq (char-after begin) ?:) (1+ begin) begin) end))
	     (nth (cond ((string-match "^[*^]" range) 1)
			((string-match "^-" range) 0)
			((string-equal range "$") nil)
			(t (string-to-number range))))
	     (mth (cond ((string-match "[-*$]$" range) nil)
			((string-match "-" range)
			 (string-to-number (substring range (match-end 0))))
			(t nth))))
	(comint-arguments string nth mth)))))

;; Return a list of arguments from ARG.  Break it up at the
;; delimiters in comint-delimiter-argument-list.  Returned list is backwards.
(defun comint-delim-arg (arg)
  (if (null comint-delimiter-argument-list)
      (list arg)
    (let ((args nil)
	  (pos 0)
	  (len (length arg)))
      (while (< pos len)
	(let ((char (aref arg pos))
	      (start pos))
	  (if (memq char comint-delimiter-argument-list)
	      (while (and (< pos len) (eq (aref arg pos) char))
		(setq pos (1+ pos)))
	    (while (and (< pos len)
			(not (memq (aref arg pos)
				   comint-delimiter-argument-list)))
	      (setq pos (1+ pos))))
	  (setq args (cons (substring arg start pos) args))))
      args)))

(defun comint-arguments (string nth mth)
  "Return from STRING the NTH to MTH arguments.
NTH and/or MTH can be nil, which means the last argument.
Returned arguments are separated by single spaces.
We assume whitespace separates arguments, except within quotes
and except for a space or tab that immediately follows a backslash.
Also, a run of one or more of a single character
in `comint-delimiter-argument-list' is a separate argument.
Argument 0 is the command name."
  ;; The first line handles ordinary characters and backslash-sequences
  ;; (except with w32 msdos-like shells, where backslashes are valid).
  ;; The second matches "-quoted strings.
  ;; The third matches '-quoted strings.
  ;; The fourth matches `-quoted strings.
  ;; This seems to fit the syntax of BASH 2.0.
  (let* ((first (if (and (eq system-type 'windows-nt)
			 (w32-shell-dos-semantics))
		    "[^ \n\t\"'`]+\\|"
		  "[^ \n\t\"'`\\]+\\|\\\\[\"'`\\ \t]+\\|"))
	 (argpart (concat first
			  "\\(\"\\([^\"\\]\\|\\\\.\\)*\"\\|\
'[^']*'\\|\
`[^`]*`\\)"))
	 (args ()) (pos 0)
	 (count 0)
	 beg str value quotes)
    ;; Build a list of all the args until we have as many as we want.
    (while (and (or (null mth) (<= count mth))
		(string-match argpart string pos))
      (if (and beg (= pos (match-beginning 0)))
	  ;; It's contiguous, part of the same arg.
	  (setq pos (match-end 0)
		quotes (or quotes (match-beginning 1)))
	;; It's a new separate arg.
	(if beg
	    ;; Put the previous arg, if there was one, onto ARGS.
	    (setq str (substring string beg pos)
		  args (if quotes (cons str args)
			 (nconc (comint-delim-arg str) args))
		  count (1+ count)))
	(setq quotes (match-beginning 1))
	(setq beg (match-beginning 0))
	(setq pos (match-end 0))))
    (if beg
	(setq str (substring string beg pos)
	      args (if quotes (cons str args)
		     (nconc (comint-delim-arg str) args))
	      count (1+ count)))
    (let ((n (or nth (1- count)))
	  (m (if mth (1- (- count mth)) 0)))
      (mapconcat
       (function (lambda (a) a)) (nthcdr n (nreverse (nthcdr m args))) " "))))
\f
;;
;; Input processing stuff
;;

(defun comint-send-input ()
  "Send input to process.
After the process output mark, sends all text from the process mark to
point as input to the process.  Before the process output mark, calls value
of variable `comint-get-old-input' to retrieve old input, copies it to the
process mark, and sends it.  If variable `comint-process-echoes' is nil,
a terminal newline is also inserted into the buffer and sent to the process
\(if it is non-nil, all text from the process mark to point is deleted,
since it is assumed the remote process will re-echo it).

Any history reference may be expanded depending on the value of the variable
`comint-input-autoexpand'.  The list of function names contained in the value
of `comint-input-filter-functions' is called on the input before sending it.
The input is entered into the input history ring, if the value of variable
`comint-input-filter' returns non-nil when called on the input.

If variable `comint-eol-on-send' is non-nil, then point is moved to the
end of line before sending the input.

The values of `comint-get-old-input', `comint-input-filter-functions', and
`comint-input-filter' are chosen according to the command interpreter running
in the buffer.  E.g.,

If the interpreter is the csh,
    comint-get-old-input is the default: either return the current
	field, or take the current line and discard any
	initial string matching regexp `comint-prompt-regexp', depending
	on the value of `comint-use-prompt-regexp-instead-of-fields'.
    comint-input-filter-functions monitors input for \"cd\", \"pushd\", and
	\"popd\" commands. When it sees one, it cd's the buffer.
    comint-input-filter is the default: returns t if the input isn't all white
	space.

If the comint is Lucid Common Lisp,
    comint-get-old-input snarfs the sexp ending at point.
    comint-input-filter-functions does nothing.
    comint-input-filter returns nil if the input matches input-filter-regexp,
	which matches (1) all whitespace (2) :a, :c, etc.

Similarly for Soar, Scheme, etc."
  (interactive)
  ;; Note that the input string does not include its terminal newline.
  (let ((proc (get-buffer-process (current-buffer))))
    (if (not proc) (error "Current buffer has no process")
	(let* ((pmark (process-mark proc))
	       (intxt (if (>= (point) (marker-position pmark))
			  (progn (if comint-eol-on-send (end-of-line))
				 (buffer-substring pmark (point)))
			(let ((copy (funcall comint-get-old-input)))
			  (goto-char pmark)
			  (insert copy)
			  copy)))
	       (input (if (not (eq comint-input-autoexpand 'input))
			  ;; Just whatever's already there
			  intxt
			;; Expand and leave it visible in buffer
			(comint-replace-by-expanded-history t pmark)
			(buffer-substring pmark (point))))
	       (history (if (not (eq comint-input-autoexpand 'history))
			    input
			  ;; This is messy 'cos ultimately the original
			  ;; functions used do insertion, rather than return
			  ;; strings.  We have to expand, then insert back.
			  (comint-replace-by-expanded-history t pmark)
			  (let ((copy (buffer-substring pmark (point)))
				(start (point)))
			    (insert input)
			    (delete-region pmark start)
			    copy))))

	  (if comint-process-echoes
	      (delete-region pmark (point))
	    (insert ?\n))

	  (if (and (funcall comint-input-filter history)
		   (or (null comint-input-ignoredups)
		       (not (ring-p comint-input-ring))
		       (ring-empty-p comint-input-ring)
		       (not (string-equal (ring-ref comint-input-ring 0)
					  history))))
	      (ring-insert comint-input-ring history))

	  (run-hook-with-args 'comint-input-filter-functions
			      (concat input "\n"))

	  (let ((beg (marker-position pmark))
		(end (1- (point))))
	    (when (not (> beg end))	; handle a special case
	      ;; Make an overlay for the input field
	      (let ((over (make-overlay beg end nil nil t)))
		(unless comint-use-prompt-regexp-instead-of-fields
		  ;; Give old user input a field property of `input', to
		  ;; distinguish it from both process output and unsent
		  ;; input.  The terminating newline is put into a special
		  ;; `boundary' field to make cursor movement between input
		  ;; and output fields smoother.
		  (overlay-put over 'field 'input))
		(when comint-highlight-input
		  (overlay-put over 'face 'comint-highlight-input)
		  (overlay-put over 'mouse-face 'highlight)
		  (overlay-put over 'evaporate t))))
	    (unless comint-use-prompt-regexp-instead-of-fields
	      ;; Make an overlay for the terminating newline
	      (let ((over (make-overlay end (1+ end) nil t nil)))
		(overlay-put over 'field 'boundary)
		(overlay-put over 'evaporate t))))

	  (comint-snapshot-last-prompt)

	  (setq comint-save-input-ring-index comint-input-ring-index)
	  (setq comint-input-ring-index nil)
	  ;; Update the markers before we send the input
	  ;; in case we get output amidst sending the input.
	  (set-marker comint-last-input-start pmark)
	  (set-marker comint-last-input-end (point))
	  (set-marker (process-mark proc) (point))
	  ;; clear the "accumulation" marker
	  (set-marker comint-accum-marker nil)
	  (funcall comint-input-sender proc input)
	  ;; This used to call comint-output-filter-functions,
	  ;; but that scrolled the buffer in undesirable ways.
	  (run-hook-with-args 'comint-output-filter-functions "")))))

(defvar comint-preoutput-filter-functions nil
  "List of functions to call before inserting Comint output into the buffer.
Each function gets one argument, a string containing the text received
from the subprocess.  It should return the string to insert, perhaps
the same string that was received, or perhaps a modified or transformed
string.

The functions on the list are called sequentially, and each one is
given the string returned by the previous one.  The string returned by
the last function is the text that is actually inserted in the
redirection buffer.

This variable is permanent-local.")

;; When non-nil, this is the last overlay used for output.
;; It is kept around so that we can extend it instead of creating
;; multiple contiguous overlays for multiple contiguous output chunks.
(defvar comint-last-output-overlay nil)

;; When non-nil, this is an overlay over the last recognized prompt in
;; the buffer; it is used when highlighting the prompt.
(defvar comint-last-prompt-overlay nil)

;; `snapshot' any current comint-last-prompt-overlay, freezing it in place.
;; Any further output will then create a new comint-last-prompt-overlay.
(defun comint-snapshot-last-prompt ()
  (when comint-last-prompt-overlay
    (overlay-put comint-last-prompt-overlay 'evaporate t)
    (setq comint-last-prompt-overlay nil)))

;; The purpose of using this filter for comint processes
;; is to keep comint-last-input-end from moving forward
;; when output is inserted.
(defun comint-output-filter (process string)
  (let ((oprocbuf (process-buffer process)))
    ;; First check for killed buffer or no input.
    (when (and string oprocbuf (buffer-name oprocbuf))
      (with-current-buffer oprocbuf
	;; Run preoutput filters
	(let ((functions comint-preoutput-filter-functions))
	  (while (and functions string)
	    (setq string (funcall (car functions) string))
	    (setq functions (cdr functions))))

	;; Insert STRING
	(let ((buffer-read-only nil)
	      ;; Avoid the overhead of save-excursion, since we just
	      ;; fiddle with the point
	      (saved-point (point-marker)))

	  ;; The point should float after any insertion we do
	  (set-marker-insertion-type saved-point t)

	  ;; We temporarly remove any buffer narrowing, in case the
	  ;; process mark is outside of the restriction
	  (save-restriction
	    (widen)

	    (goto-char (process-mark process))
	    (set-marker comint-last-output-start (point))

	    ;; insert-before-markers is a bad thing. XXX
	    ;;
	    ;; It is used here to force window-point markers (used to
	    ;; store the value of point in non-selected windows) to
	    ;; advance, but it also screws up any other markers that we
	    ;; don't _want_ to advance, such as the start-marker of some
	    ;; of the overlays we create.
	    ;;
	    ;; We work around the problem with the overlays by
	    ;; explicitly adjusting them after we do the insertion, but
	    ;; in the future this problem should be solved correctly, by
	    ;; using `insert', and making the insertion-type of
	    ;; window-point markers settable (via a buffer-local
	    ;; variable).  In comint buffers, this variable would be set
	    ;; to `t', to cause point in non-select windows to advance.
	    (insert-before-markers string)
	    ;; Fixup markers and overlays that got screwed up because we
	    ;; used `insert-before-markers'.
	    (let ((old-point (- (point) (length string))))
	      ;; comint-last-output-start
	      (set-marker comint-last-output-start old-point)
	      ;; comint-last-input-end
	      (when (and comint-last-input-end
			 (equal (marker-position comint-last-input-end)
				(point)))
		(set-marker comint-last-input-end old-point))
	      ;; No overlays we create are set to advance upon insertion
	      ;; (at the start/end), so we assume that any overlay which
	      ;; is at the current point was incorrectly advanced by
	      ;; insert-before-markers.  First fixup overlays that might
	      ;; start at point:
	      (dolist (over (overlays-at (point)))
		(when (= (overlay-start over) (point))
		  (let ((end (overlay-end over)))
		    (move-overlay over
				  old-point
				  (if (= end (point)) old-point end)))))
	      ;; Then do overlays that might end at point:
	      (dolist (over (overlays-at (1- (point))))
		(when (= (overlay-end over) (point))
		  (move-overlay over
				(min (overlay-start over) old-point)
				old-point))))

	    ;; Advance process-mark
	    (set-marker (process-mark process) (point))

	    (unless comint-use-prompt-regexp-instead-of-fields
	      ;; We check to see if the last overlay used for output is
	      ;; adjacent to the new input, and if so, just extend it.
	      (if (and comint-last-output-overlay
		       (equal (overlay-end comint-last-output-overlay)
			      (marker-position comint-last-output-start)))
		  ;; Extend comint-last-output-overlay to include the
		  ;; most recent output
		  (move-overlay comint-last-output-overlay
				(overlay-start comint-last-output-overlay)
				(point))
		;; Create a new overlay
		(let ((over (make-overlay comint-last-output-start (point))))
		  (overlay-put over 'field 'output)
		  (overlay-put over 'inhibit-line-move-field-capture t)
		  (overlay-put over 'evaporate t)
		  (setq comint-last-output-overlay over))))

	    (when comint-highlight-prompt
	      ;; Highlight the prompt, where we define `prompt' to mean
	      ;; the most recent output that doesn't end with a newline.
	      (unless (and (bolp) (null comint-last-prompt-overlay))
		;; Need to create or move the prompt overlay (in the case
		;; where there is no prompt ((bolp) == t), we still do
		;; this if there's already an existing overlay).
		(let ((prompt-start (save-excursion (forward-line 0) (point))))
		  (if comint-last-prompt-overlay
		      ;; Just move an existing overlay
		      (move-overlay comint-last-prompt-overlay
				    prompt-start (point))
		    ;; Need to create the overlay
		    (setq comint-last-prompt-overlay
			  (make-overlay prompt-start (point)))
		    (overlay-put comint-last-prompt-overlay
				 'face 'comint-highlight-prompt)))))

	    (goto-char saved-point)

	    (run-hook-with-args 'comint-output-filter-functions string)))))))

(defun comint-preinput-scroll-to-bottom ()
  "Go to the end of buffer in all windows showing it.
Movement occurs if point in the selected window is not after the process mark,
and `this-command' is an insertion command.  Insertion commands recognised
are `self-insert-command', `comint-magic-space', `yank', and `hilit-yank'.
Depends on the value of `comint-scroll-to-bottom-on-input'.

This function should be a pre-command hook."
  (if (and comint-scroll-to-bottom-on-input
	   (memq this-command '(self-insert-command comint-magic-space yank
				hilit-yank)))
      (let* ((selected (selected-window))
	     (current (current-buffer))
	     (process (get-buffer-process current))
	     (scroll comint-scroll-to-bottom-on-input))
	(if (and process (< (point) (process-mark process)))
	    (if (eq scroll 'this)
		(goto-char (point-max))
	      (walk-windows
	       (function (lambda (window)
		 (if (and (eq (window-buffer window) current)
			  (or (eq scroll t) (eq scroll 'all)))
		     (progn
		       (select-window window)
		       (goto-char (point-max))
		       (select-window selected)))))
	       nil t))))))

(defun comint-postoutput-scroll-to-bottom (string)
  "Go to the end of buffer in all windows showing it.
Does not scroll if the current line is the last line in the buffer.
Depends on the value of `comint-scroll-to-bottom-on-output' and
`comint-scroll-show-maximum-output'.

This function should be in the list `comint-output-filter-functions'."
  (let* ((selected (selected-window))
	 (current (current-buffer))
	 (process (get-buffer-process current))
	 (scroll comint-scroll-to-bottom-on-output))
    (unwind-protect
	(if process
	    (walk-windows
	     (function (lambda (window)
	       (if (eq (window-buffer window) current)
		   (progn
		     (select-window window)
		     (if (and (< (point) (process-mark process))
			      (or (eq scroll t) (eq scroll 'all)
				  ;; Maybe user wants point to jump to end.
				  (and (eq scroll 'this) (eq selected window))
				  (and (eq scroll 'others) (not (eq selected window)))
				  ;; If point was at the end, keep it at end.
				  (and (marker-position comint-last-output-start)
				       (>= (point) comint-last-output-start))))
			 (goto-char (process-mark process)))
		     ;; Optionally scroll so that the text
		     ;; ends at the bottom of the window.
		     (if (and comint-scroll-show-maximum-output
			      (>= (point) (process-mark process)))
			 (save-excursion
			   (goto-char (point-max))
			   (recenter -1)))
		     (select-window selected)))))
	     nil t))
      (set-buffer current))))

(defun comint-truncate-buffer (&optional string)
  "Truncate the buffer to `comint-buffer-maximum-size'.
This function could be on `comint-output-filter-functions' or bound to a key."
  (interactive)
  (save-excursion
    (goto-char (process-mark (get-buffer-process (current-buffer))))
    (forward-line (- comint-buffer-maximum-size))
    (beginning-of-line)
    (delete-region (point-min) (point))))

(defun comint-strip-ctrl-m (&optional string)
  "Strip trailing `^M' characters from the current output group.
This function could be on `comint-output-filter-functions' or bound to a key."
  (interactive)
  (let ((pmark (process-mark (get-buffer-process (current-buffer)))))
    (save-excursion
      (condition-case nil
	  (goto-char
	   (if (interactive-p) comint-last-input-end comint-last-output-start))
	(error nil))
      (while (re-search-forward "\r+$" pmark t)
	(replace-match "" t t)))))
(defalias 'shell-strip-ctrl-m 'comint-strip-ctrl-m)

(defun comint-show-maximum-output ()
  "Put the end of the buffer at the bottom of the window."
  (interactive)
  (goto-char (point-max))
  (recenter -1))

(defun comint-get-old-input-default ()
  "Default for `comint-get-old-input'.
Returns either the current field, or the current line with any initial
text matching `comint-prompt-regexp' stripped off, depending on the
value of `comint-use-prompt-regexp-instead-of-fields'."
  (if comint-use-prompt-regexp-instead-of-fields
      (save-excursion
	(beginning-of-line)
	(comint-skip-prompt)
	(let ((beg (point)))
	  (end-of-line)
	  (buffer-substring beg (point))))
    ;; Return the contents of the field at the current point.
    (field-string)))


(defun comint-copy-old-input ()
  "Insert after prompt old input at point as new input to be edited.
Calls `comint-get-old-input' to get old input."
  (interactive)
  (let ((input (funcall comint-get-old-input))
	(process (get-buffer-process (current-buffer))))
    (if (not process)
	(error "Current buffer has no process")
      (goto-char (process-mark process))
      (insert input))))

(defun comint-skip-prompt ()
  "Skip past the text matching regexp `comint-prompt-regexp'.
If this takes us past the end of the current line, don't skip at all."
  (let ((eol (save-excursion (end-of-line) (point))))
    (if (and (looking-at comint-prompt-regexp)
	     (<= (match-end 0) eol))
	(goto-char (match-end 0)))))

(defun comint-after-pmark-p ()
  "Return t if point is after the process output marker."
  (let ((pmark (process-mark (get-buffer-process (current-buffer)))))
    (<= (marker-position pmark) (point))))

(defun comint-simple-send (proc string)
  "Default function for sending to PROC input STRING.
This just sends STRING plus a newline. To override this,
set the hook `comint-input-sender'."
  (comint-send-string proc string)
  (comint-send-string proc "\n"))

(defun comint-line-beginning-position ()
  "Returns the buffer position of the beginning of the line, after any prompt.
If `comint-use-prompt-regexp-instead-of-fields' is non-nil, then the
prompt skip is done by skipping text matching the regular expression
`comint-prompt-regexp', a buffer local variable."
  (if comint-use-prompt-regexp-instead-of-fields
      ;; Use comint-prompt-regexp
      (save-excursion
	(beginning-of-line)
	(comint-skip-prompt)
	(point))
    ;; Use input fields.  Note that, unlike the behavior of
    ;; `line-beginning-position' inside a field, this function will
    ;; return the position of the end of a prompt, even if the point is
    ;; already inside the prompt.  In order to do this, it assumes that
    ;; if there are two fields on a line, then the first one is the
    ;; prompt, and the second one is an input field, and is front-sticky
    ;; (as input fields should be).
    (constrain-to-field (line-beginning-position) (line-end-position))))

(defun comint-bol (&optional arg)
  "Goes to the beginning of line, then skips past the prompt, if any.
If prefix argument is given (\\[universal-argument]) the prompt is not skipped.
If `comint-use-prompt-regexp-instead-of-fields' is non-nil, then the
prompt skip is done by skipping text matching the regular expression
`comint-prompt-regexp', a buffer local variable."
  (interactive "P")
  (if arg
      ;; Unlike `beginning-of-line', forward-line ignores field boundaries
      (forward-line 0)
    (goto-char (comint-line-beginning-position))))

;; These three functions are for entering text you don't want echoed or
;; saved -- typically passwords to ftp, telnet, or somesuch.
;; Just enter m-x send-invisible and type in your line, or add
;; `comint-watch-for-password-prompt' to `comint-output-filter-functions'.

(defun comint-read-noecho (prompt &optional stars)
  "Read a single line of text from user without echoing, and return it.
Prompt with argument PROMPT, a string.  Optional argument STARS causes
input to be echoed with '*' characters on the prompt line.  Input ends with
RET, LFD, or ESC.  DEL or C-h rubs out.  C-u kills line.  C-g aborts (if
`inhibit-quit' is set because e.g. this function was called from a process
filter and C-g is pressed, this function returns nil rather than a string).

Note that the keystrokes comprising the text can still be recovered
\(temporarily) with \\[view-lossage].  Some people find this worrysome.
Once the caller uses the password, it can erase the password
by doing (fillarray STRING 0)."
  (let ((ans "")
	(newans nil)
	(c 0)
	(echo-keystrokes 0)
	(cursor-in-echo-area t)
	(message-log-max nil)
	(done nil))
    (while (not done)
      (if stars
	  (message "%s%s" prompt (make-string (length ans) ?*))
	(message "%s" prompt))
      ;; Use this instead of `read-char' to avoid "Non-character input-event".
      (setq c (read-char-exclusive))
      (cond ((= c ?\C-g)
	     ;; This function may get called from a process filter, where
	     ;; inhibit-quit is set.  In later versions of emacs read-char
	     ;; may clear quit-flag itself and return C-g.  That would make
	     ;; it impossible to quit this loop in a simple way, so
	     ;; re-enable it here (for backward-compatibility the check for
	     ;; quit-flag below would still be necessary, so this seems
	     ;; like the simplest way to do things).
	     (setq quit-flag t
		   done t))
	    ((or (= c ?\r) (= c ?\n) (= c ?\e))
	     (setq done t))
	    ((= c ?\C-u)
	     (fillarray ans 0)
	     (setq ans ""))
	    ((and (/= c ?\b) (/= c ?\177))
	     (setq newans (concat ans (char-to-string c)))
	     (fillarray ans 0)
	     (setq ans newans))
	    ((> (length ans) 0)
	     (aset ans (1- (length ans)) 0)
	     (setq ans (substring ans 0 -1)))))
    (if quit-flag
	;; Emulate a true quit, except that we have to return a value.
	(prog1
	    (setq quit-flag nil)
	  (message "Quit")
	  (beep t))
      (message "")
      ans)))

(defun send-invisible (str)
  "Read a string without echoing.
Then send it to the process running in the current buffer.
The string is sent using `comint-input-sender'.
Security bug: your string can still be temporarily recovered with
\\[view-lossage]."
  (interactive "P")			; Defeat snooping via C-x ESC ESC
  (let ((proc (get-buffer-process (current-buffer))))
    (cond ((not proc)
	   (error "Current buffer has no process"))
	  ((stringp str)
	   (comint-snapshot-last-prompt)
	   (funcall comint-input-sender proc str))
	  (t
	   (let ((str (comint-read-noecho "Non-echoed text: " t)))
	     (if (stringp str)
		 (send-invisible str)
	       (message "Warning: text will be echoed")))))))

(defun comint-watch-for-password-prompt (string)
  "Prompt in the minibuffer for password and send without echoing.
This function uses `send-invisible' to read and send a password to the buffer's
process if STRING contains a password prompt defined by
`comint-password-prompt-regexp'.

This function could be in the list `comint-output-filter-functions'."
  (when (string-match comint-password-prompt-regexp string)
    (let ((pw (comint-read-noecho string t)))
      (send-invisible pw))))
\f
;; Low-level process communication

(defun comint-send-string (process string)
  "Like `process-send-string', but also does extra bookkeeping for comint mode."
  (with-current-buffer (process-buffer process)
    (comint-snapshot-last-prompt))
  (process-send-string process string))

(defun comint-send-region (process start end)
  "Like `process-send-region', but also does extra bookkeeping for comint mode."
  (with-current-buffer (process-buffer process)
    (comint-snapshot-last-prompt))
  (process-send-region process start end))
\f
;; Random input hackage

(defun comint-delete-output ()
  "Delete all output from interpreter since last input.
Does not delete the prompt."
  (interactive)
  (let ((proc (get-buffer-process (current-buffer)))
	(replacement nil))
    (save-excursion
      (let ((pmark (progn (goto-char (process-mark proc))
			  (forward-line 0)
			  (point-marker))))
	(delete-region comint-last-input-end pmark)
	(goto-char (process-mark proc))
	(setq replacement (concat "*** output flushed ***\n"
				  (buffer-substring pmark (point))))
	(delete-region pmark (point))))
    ;; Output message and put back prompt
    (comint-output-filter proc replacement)))
(defalias 'comint-kill-output 'comint-delete-output)
(make-obsolete 'comint-kill-output 'comint-delete-output "21.1")

(defun comint-write-output (filename &optional append mustbenew)
  "Write output from interpreter since last input to FILENAME.
Any prompt at the end of the output is not written.

If the optional argument APPEND (the prefix argument when interactive)
is non-nil, the output is appended to the file instead.

If the optional argument MUSTBENEW is non-nil, check for an existing
file with the same name.  If MUSTBENEW is `excl', that means to get an
error if the file already exists; never overwrite.  If MUSTBENEW is
neither nil nor `excl', that means ask for confirmation before
overwriting, but do go ahead and overwrite the file if the user
confirms.  When interactive, MUSTBENEW is nil when appending, and t
otherwise."
  (interactive
   (list (read-file-name
	  (if current-prefix-arg
	      "Append output to file: "
	    "Write output to file: "))
	 current-prefix-arg
	 (not current-prefix-arg)))
  (save-excursion
    (goto-char (process-mark (get-buffer-process (current-buffer))))
    (forward-line 0)
    (write-region comint-last-input-end (point) filename
		  append nil nil mustbenew)))

(defun comint-show-output ()
  "Display start of this batch of interpreter output at top of window.
Sets mark to the value of point when this command is run."
  (interactive)
  (push-mark)
  (let ((pos (or (marker-position comint-last-input-end) (point-max))))
    (cond (comint-use-prompt-regexp-instead-of-fields
	   (goto-char pos)
	   (beginning-of-line 0)
	   (set-window-start (selected-window) (point))
	   (comint-skip-prompt))
	  (t
	   (goto-char (field-beginning pos))
	   (set-window-start (selected-window) (point))))))


(defun comint-interrupt-subjob ()
  "Interrupt the current subjob.
This command also kills the pending input
between the process-mark and point."
  (interactive)
  (comint-kill-input)
  (interrupt-process nil comint-ptyp))

(defun comint-kill-subjob ()
  "Send kill signal to the current subjob.
This command also kills the pending input
between the process-mark and point."
  (interactive)
  (comint-kill-input)
  (kill-process nil comint-ptyp))

(defun comint-quit-subjob ()
  "Send quit signal to the current subjob.
This command also kills the pending input
between the process-mark and point."
  (interactive)
  (comint-kill-input)
  (quit-process nil comint-ptyp))

(defun comint-stop-subjob ()
  "Stop the current subjob.
This command also kills the pending input
between the process-mark and point.

WARNING: if there is no current subjob, you can end up suspending
the top-level process running in the buffer. If you accidentally do
this, use \\[comint-continue-subjob] to resume the process. (This
is not a problem with most shells, since they ignore this signal.)"
  (interactive)
  (comint-kill-input)
  (stop-process nil comint-ptyp))

(defun comint-continue-subjob ()
  "Send CONT signal to process buffer's process group.
Useful if you accidentally suspend the top-level process."
  (interactive)
  (continue-process nil comint-ptyp))

(defun comint-kill-input ()
  "Kill all text from last stuff output by interpreter to point."
  (interactive)
  (let ((pmark (process-mark (get-buffer-process (current-buffer)))))
    (if (> (point) (marker-position pmark))
	(kill-region pmark (point)))))

(defun comint-delchar-or-maybe-eof (arg)
  "Delete ARG characters forward or send an EOF to subprocess.
Sends an EOF only if point is at the end of the buffer and there is no input."
  (interactive "p")
  (let ((proc (get-buffer-process (current-buffer))))
    (if (and (eobp) proc (= (point) (marker-position (process-mark proc))))
	(comint-send-eof)
      (delete-char arg))))

(defun comint-send-eof ()
  "Send an EOF to the current buffer's process."
  (interactive)
  (comint-snapshot-last-prompt)
  (process-send-eof))


(defun comint-backward-matching-input (regexp arg)
  "Search backward through buffer for input fields that match REGEXP.
If `comint-use-prompt-regexp-instead-of-fields' is non-nil, then input
fields are identified by lines that match `comint-prompt-regexp'.

With prefix argument N, search for Nth previous match.
If N is negative, find the next or Nth next match."
  (interactive (comint-regexp-arg "Backward input matching (regexp): "))
  (if comint-use-prompt-regexp-instead-of-fields
      ;; Use comint-prompt-regexp
      (let* ((re (concat comint-prompt-regexp ".*" regexp))
	     (pos (save-excursion (end-of-line (if (> arg 0) 0 1))
				  (if (re-search-backward re nil t arg)
				      (point)))))
	(if (null pos)
	    (progn (message "Not found")
		   (ding))
	  (goto-char pos)
	  (comint-bol nil)))
    ;; Use input fields
    (let* ((dir (if (< arg 0) -1 1))
	   (pos
	    (save-excursion
	      (while (/= arg 0)
		(unless (re-search-backward regexp nil t dir)
		  (error "Not found"))
		(when (eq (get-char-property (point) 'field) 'input)
		  (setq arg (- arg dir))))
	      (field-beginning))))
      (goto-char pos))))


(defun comint-forward-matching-input (regexp arg)
  "Search forward through buffer for input fields that match REGEXP.
If `comint-use-prompt-regexp-instead-of-fields' is non-nil, then input
fields are identified by lines that match `comint-prompt-regexp'.

With prefix argument N, search for Nth following match.
If N is negative, find the previous or Nth previous match."
  (interactive (comint-regexp-arg "Forward input matching (regexp): "))
  (comint-backward-matching-input regexp (- arg)))


(defun comint-next-prompt (n)
  "Move to end of Nth next prompt in the buffer.
If `comint-use-prompt-regexp-instead-of-fields' is nil, then this means
the beginning of the Nth next `input' field, otherwise, it means the Nth
occurance of text matching `comint-prompt-regexp'."
  (interactive "p")
  (if comint-use-prompt-regexp-instead-of-fields
      ;; Use comint-prompt-regexp
      (let ((paragraph-start comint-prompt-regexp))
	(end-of-line (if (> n 0) 1 0))
	(forward-paragraph n)
	(comint-skip-prompt))
    ;; Use input fields
    (let ((pos (point))
	  (input-pos nil))
      (while (/= n 0)
	(setq pos
	      (if (> n 0)
		  (next-single-char-property-change pos 'field)
		(previous-single-char-property-change pos 'field)))
	(cond ((null pos)
	       ;; Ran off the end of the buffer.
	       (setq n 0))
	      ((eq (get-char-property pos 'field) 'input)
	       (setq n (if (< n 0) (1+ n) (1- n)))
	       (setq input-pos pos))))
      (when input-pos
	(goto-char input-pos)))))


(defun comint-previous-prompt (n)
  "Move to end of Nth previous prompt in the buffer.
If `comint-use-prompt-regexp-instead-of-fields' is nil, then this means
the beginning of the Nth previous `input' field, otherwise, it means the Nth
occurance of text matching `comint-prompt-regexp'."
  (interactive "p")
  (comint-next-prompt (- n)))
\f
;; Support for source-file processing commands.
;;============================================================================
;; Many command-interpreters (e.g., Lisp, Scheme, Soar) have
;; commands that process files of source text (e.g. loading or compiling
;; files). So the corresponding process-in-a-buffer modes have commands
;; for doing this (e.g., lisp-load-file). The functions below are useful
;; for defining these commands.
;;
;; Alas, these guys don't do exactly the right thing for Lisp, Scheme
;; and Soar, in that they don't know anything about file extensions.
;; So the compile/load interface gets the wrong default occasionally.
;; The load-file/compile-file default mechanism could be smarter -- it
;; doesn't know about the relationship between filename extensions and
;; whether the file is source or executable. If you compile foo.lisp
;; with compile-file, then the next load-file should use foo.bin for
;; the default, not foo.lisp. This is tricky to do right, particularly
;; because the extension for executable files varies so much (.o, .bin,
;; .lbin, .mo, .vo, .ao, ...).


;; COMINT-SOURCE-DEFAULT -- determines defaults for source-file processing
;; commands.
;;
;; COMINT-CHECK-SOURCE -- if FNAME is in a modified buffer, asks you if you
;; want to save the buffer before issuing any process requests to the command
;; interpreter.
;;
;; COMINT-GET-SOURCE -- used by the source-file processing commands to prompt
;; for the file to process.

;; (COMINT-SOURCE-DEFAULT previous-dir/file source-modes)
;;============================================================================
;; This function computes the defaults for the load-file and compile-file
;; commands for tea, soar, cmulisp, and cmuscheme modes.
;;
;; - PREVIOUS-DIR/FILE is a pair (directory . filename) from the last
;; source-file processing command. NIL if there hasn't been one yet.
;; - SOURCE-MODES is a list used to determine what buffers contain source
;; files: if the major mode of the buffer is in SOURCE-MODES, it's source.
;; Typically, (lisp-mode) or (scheme-mode).
;;
;; If the command is given while the cursor is inside a string, *and*
;; the string is an existing filename, *and* the filename is not a directory,
;; then the string is taken as default. This allows you to just position
;; your cursor over a string that's a filename and have it taken as default.
;;
;; If the command is given in a file buffer whose major mode is in
;; SOURCE-MODES, then the the filename is the default file, and the
;; file's directory is the default directory.
;;
;; If the buffer isn't a source file buffer (e.g., it's the process buffer),
;; then the default directory & file are what was used in the last source-file
;; processing command (i.e., PREVIOUS-DIR/FILE).  If this is the first time
;; the command has been run (PREVIOUS-DIR/FILE is nil), the default directory
;; is the cwd, with no default file. (\"no default file\" = nil)
;;
;; SOURCE-REGEXP is typically going to be something like (tea-mode)
;; for T programs, (lisp-mode) for Lisp programs, (soar-mode lisp-mode)
;; for Soar programs, etc.
;;
;; The function returns a pair: (default-directory . default-file).

(defun comint-source-default (previous-dir/file source-modes)
  (cond ((and buffer-file-name (memq major-mode source-modes))
	 (cons (file-name-directory    buffer-file-name)
	       (file-name-nondirectory buffer-file-name)))
	(previous-dir/file)
	(t
	 (cons default-directory nil))))


;; (COMINT-CHECK-SOURCE fname)
;;============================================================================
;; Prior to loading or compiling (or otherwise processing) a file (in the CMU
;; process-in-a-buffer modes), this function can be called on the filename.
;; If the file is loaded into a buffer, and the buffer is modified, the user
;; is queried to see if he wants to save the buffer before proceeding with
;; the load or compile.

(defun comint-check-source (fname)
  (let ((buff (get-file-buffer fname)))
    (if (and buff
	     (buffer-modified-p buff)
	     (y-or-n-p (format "Save buffer %s first? " (buffer-name buff))))
	;; save BUFF.
	(let ((old-buffer (current-buffer)))
	  (set-buffer buff)
	  (save-buffer)
	  (set-buffer old-buffer)))))


;; (COMINT-GET-SOURCE prompt prev-dir/file source-modes mustmatch-p)
;;============================================================================
;; COMINT-GET-SOURCE is used to prompt for filenames in command-interpreter
;; commands that process source files (like loading or compiling a file).
;; It prompts for the filename, provides a default, if there is one,
;; and returns the result filename.
;;
;; See COMINT-SOURCE-DEFAULT for more on determining defaults.
;;
;; PROMPT is the prompt string. PREV-DIR/FILE is the (directory . file) pair
;; from the last source processing command.  SOURCE-MODES is a list of major
;; modes used to determine what file buffers contain source files.  (These
;; two arguments are used for determining defaults). If MUSTMATCH-P is true,
;; then the filename reader will only accept a file that exists.
;;
;; A typical use:
;; (interactive (comint-get-source "Compile file: " prev-lisp-dir/file
;;                                 '(lisp-mode) t))

;; This is pretty stupid about strings. It decides we're in a string
;; if there's a quote on both sides of point on the current line.
(defun comint-extract-string ()
  "Return string around POINT that starts the current line, or nil."
  (save-excursion
    (let* ((point (point))
	   (bol (progn (beginning-of-line) (point)))
	   (eol (progn (end-of-line) (point)))
	   (start (progn (goto-char point)
			 (and (search-backward "\"" bol t)
			      (1+ (point)))))
	   (end (progn (goto-char point)
		       (and (search-forward "\"" eol t)
			    (1- (point))))))
      (and start end
	   (buffer-substring start end)))))

(defun comint-get-source (prompt prev-dir/file source-modes mustmatch-p)
  (let* ((def (comint-source-default prev-dir/file source-modes))
	 (stringfile (comint-extract-string))
	 (sfile-p (and stringfile
		       (condition-case ()
			   (file-exists-p stringfile)
			 (error nil))
		       (not (file-directory-p stringfile))))
	 (defdir  (if sfile-p (file-name-directory stringfile)
		      (car def)))
	 (deffile (if sfile-p (file-name-nondirectory stringfile)
		      (cdr def)))
	 (ans (read-file-name (if deffile (format "%s(default %s) "
						  prompt    deffile)
				  prompt)
			      defdir
			      (concat defdir deffile)
			      mustmatch-p)))
    (list (expand-file-name (substitute-in-file-name ans)))))

;; I am somewhat divided on this string-default feature. It seems
;; to violate the principle-of-least-astonishment, in that it makes
;; the default harder to predict, so you actually have to look and see
;; what the default really is before choosing it. This can trip you up.
;; On the other hand, it can be useful, I guess. I would appreciate feedback
;; on this.
;;     -Olin

\f
;; Simple process query facility.
;; ===========================================================================
;; This function is for commands that want to send a query to the process
;; and show the response to the user. For example, a command to get the
;; arglist for a Common Lisp function might send a "(arglist 'foo)" query
;; to an inferior Common Lisp process.
;;
;; This simple facility just sends strings to the inferior process and pops
;; up a window for the process buffer so you can see what the process
;; responds with.  We don't do anything fancy like try to intercept what the
;; process responds with and put it in a pop-up window or on the message
;; line. We just display the buffer. Low tech. Simple. Works good.

;; Send to the inferior process PROC the string STR. Pop-up but do not select
;; a window for the inferior process so that its response can be seen.
(defun comint-proc-query (proc str)
  (let* ((proc-buf (process-buffer proc))
	 (proc-mark (process-mark proc)))
    (display-buffer proc-buf)
    (set-buffer proc-buf) ; but it's not the selected *window*
    (let ((proc-win (get-buffer-window proc-buf))
	  (proc-pt (marker-position proc-mark)))
      (comint-send-string proc str) ; send the query
      (accept-process-output proc)  ; wait for some output
      ;; Try to position the proc window so you can see the answer.
      ;; This is bogus code. If you delete the (sit-for 0), it breaks.
      ;; I don't know why. Wizards invited to improve it.
      (unless (pos-visible-in-window-p proc-pt proc-win)
	(let ((opoint (window-point proc-win)))
	  (set-window-point proc-win proc-mark)
	  (sit-for 0)
	  (if (not (pos-visible-in-window-p opoint proc-win))
	      (push-mark opoint)
	    (set-window-point proc-win opoint)))))))

\f
;; Filename/command/history completion in a buffer
;; ===========================================================================
;; Useful completion functions, courtesy of the Ergo group.

;; Six commands:
;; comint-dynamic-complete		Complete or expand command, filename,
;;                                     history at point.
;; comint-dynamic-complete-filename	Complete filename at point.
;; comint-dynamic-list-filename-completions List completions in help buffer.
;; comint-replace-by-expanded-filename	Expand and complete filename at point;
;;					replace with expanded/completed name.
;; comint-dynamic-simple-complete	Complete stub given candidates.

;; These are not installed in the comint-mode keymap. But they are
;; available for people who want them. Shell-mode installs them:
;; (define-key shell-mode-map "\t" 'comint-dynamic-complete)
;; (define-key shell-mode-map "\M-?"
;;             'comint-dynamic-list-filename-completions)))
;;
;; Commands like this are fine things to put in load hooks if you
;; want them present in specific modes.

(defcustom comint-completion-autolist nil
  "*If non-nil, automatically list possibilities on partial completion.
This mirrors the optional behavior of tcsh."
  :type 'boolean
  :group 'comint-completion)

(defcustom comint-completion-addsuffix t
  "*If non-nil, add a `/' to completed directories, ` ' to file names.
If a cons pair, it should be of the form (DIRSUFFIX . FILESUFFIX) where
DIRSUFFIX and FILESUFFIX are strings added on unambiguous or exact completion.
This mirrors the optional behavior of tcsh."
  :type 'boolean
  :group 'comint-completion)

(defcustom comint-completion-recexact nil
  "*If non-nil, use shortest completion if characters cannot be added.
This mirrors the optional behavior of tcsh.

A non-nil value is useful if `comint-completion-autolist' is non-nil too."
  :type 'boolean
  :group 'comint-completion)

(defcustom comint-completion-fignore nil
  "*List of suffixes to be disregarded during file completion.
This mirrors the optional behavior of bash and tcsh.

Note that this applies to `comint-dynamic-complete-filename' only."
  :type '(repeat (string :tag "Suffix"))
  :group 'comint-completion)

(defvar comint-file-name-prefix ""
  "Prefix prepended to absolute file names taken from process input.
This is used by comint's and shell's completion functions, and by shell's
directory tracking functions.")

(defvar comint-file-name-chars
  (if (memq system-type '(ms-dos windows-nt))
      "~/A-Za-z0-9_^$!#%&{}@`'.,:()-"
    "~/A-Za-z0-9+@:_.$#%,={}-")
  "String of characters valid in a file name.
Note that all non-ASCII characters are considered valid in a file name
regardless of what this variable says.

This is a good thing to set in mode hooks.")

(defvar comint-file-name-quote-list nil
  "List of characters to quote with `\\' when in a file name.

This is a good thing to set in mode hooks.")


(defun comint-directory (directory)
  ;; Return expanded DIRECTORY, with `comint-file-name-prefix' if absolute.
  (expand-file-name (if (file-name-absolute-p directory)
			(concat comint-file-name-prefix directory)
		      directory)))


(defun comint-word (word-chars)
  "Return the word of WORD-CHARS at point, or nil if non is found.
Word constituents are considered to be those in WORD-CHARS, which is like the
inside of a \"[...]\" (see `skip-chars-forward'),
plus all non-ASCII characters."
  (save-excursion
    (let ((non-word-chars (concat "[^\\\\" word-chars "]")) (here (point)))
      (while (and (re-search-backward non-word-chars nil 'move)
		  ;;(memq (char-after (point)) shell-file-name-quote-list)
		  (or (>= (following-char) 128)
		      (eq (preceding-char) ?\\)))
	(backward-char 1))
      ;; Don't go forward over a word-char (this can happen if we're at bob).
      (when (or (not (bobp)) (looking-at non-word-chars))
	(forward-char 1))
      ;; Set match-data to match the entire string.
      (when (< (point) here)
	(set-match-data (list (point) here))
	(match-string 0)))))

(defun comint-substitute-in-file-name (filename)
  "Return FILENAME with environment variables substituted.
Supports additional environment variable syntax of the command
interpreter (e.g., the percent notation of cmd.exe on NT)."
  (let ((name (substitute-in-file-name filename)))
    (if (memq system-type '(ms-dos windows-nt))
	(let (env-var-name
	      env-var-val)
	  (save-match-data
	    (while (string-match "%\\([^\\\\/]*\\)%" name)
	      (setq env-var-name
		    (substring name (match-beginning 1) (match-end 1)))
	      (setq env-var-val (if (getenv env-var-name)
				    (getenv env-var-name)
				  ""))
	      (setq name (replace-match env-var-val t t name))))))
    name))

(defun comint-match-partial-filename ()
  "Return the filename at point, or nil if non is found.
Environment variables are substituted.  See `comint-word'."
  (let ((filename (comint-word comint-file-name-chars)))
    (and filename (comint-substitute-in-file-name
		   (comint-unquote-filename filename)))))


(defun comint-quote-filename (filename)
  "Return FILENAME with magic characters quoted.
Magic characters are those in `comint-file-name-quote-list'."
  (if (null comint-file-name-quote-list)
      filename
    (let ((regexp
	   (format "\\(^\\|[^\\]\\)\\([%s]\\)"
	    (mapconcat 'char-to-string comint-file-name-quote-list ""))))
      (save-match-data
	(while (string-match regexp filename)
	  (setq filename (replace-match "\\1\\\\\\2" nil nil filename)))
	filename))))

(defun comint-unquote-filename (filename)
  "Return FILENAME with quoted characters unquoted."
  (if (null comint-file-name-quote-list)
      filename
    (save-match-data
      (let ((i 0))
	(while (string-match "\\\\\\(.\\)" filename i)
	  (setq filename (replace-match "\\1" nil nil filename))
	  (setq i (+ 1 (match-beginning 0)))))
      filename)))


(defun comint-dynamic-complete ()
  "Dynamically perform completion at point.
Calls the functions in `comint-dynamic-complete-functions' to perform
completion until a function returns non-nil, at which point completion is
assumed to have occurred."
  (interactive)
  (run-hook-with-args-until-success 'comint-dynamic-complete-functions))


(defun comint-dynamic-complete-filename ()
  "Dynamically complete the filename at point.
Completes if after a filename.  See `comint-match-partial-filename' and
`comint-dynamic-complete-as-filename'.
This function is similar to `comint-replace-by-expanded-filename', except that
it won't change parts of the filename already entered in the buffer; it just
adds completion characters to the end of the filename.  A completions listing
may be shown in a help buffer if completion is ambiguous.

Completion is dependent on the value of `comint-completion-addsuffix',
`comint-completion-recexact' and `comint-completion-fignore', and the timing of
completions listing is dependent on the value of `comint-completion-autolist'.

Returns t if successful."
  (interactive)
  (when (comint-match-partial-filename)
    (unless (window-minibuffer-p (selected-window))
      (message "Completing file name..."))
    (comint-dynamic-complete-as-filename)))

(defun comint-dynamic-complete-as-filename ()
  "Dynamically complete at point as a filename.
See `comint-dynamic-complete-filename'.  Returns t if successful."
  (let* ((completion-ignore-case (memq system-type '(ms-dos windows-nt)))
	 (completion-ignored-extensions comint-completion-fignore)
	 ;; If we bind this, it breaks remote directory tracking in rlogin.el.
	 ;; I think it was originally bound to solve file completion problems,
	 ;; but subsequent changes may have made this unnecessary.  sm.
	 ;;(file-name-handler-alist nil)
	 (minibuffer-p (window-minibuffer-p (selected-window)))
	 (success t)
	 (dirsuffix (cond ((not comint-completion-addsuffix)
			   "")
			  ((not (consp comint-completion-addsuffix))
			   (char-to-string directory-sep-char))
			  (t
			   (car comint-completion-addsuffix))))
	 (filesuffix (cond ((not comint-completion-addsuffix)
			    "")
			   ((not (consp comint-completion-addsuffix))
			    " ")
			   (t
			    (cdr comint-completion-addsuffix))))
	 (filename (or (comint-match-partial-filename) ""))
	 (pathdir (file-name-directory filename))
	 (pathnondir (file-name-nondirectory filename))
	 (directory (if pathdir (comint-directory pathdir) default-directory))
	 (completion (file-name-completion pathnondir directory)))
    (cond ((null completion)
	   (message "No completions of %s" filename)
	   (setq success nil))
	  ((eq completion t)            ; Means already completed "file".
	   (insert filesuffix)
	   (unless minibuffer-p
	     (message "Sole completion")))
	  ((string-equal completion "") ; Means completion on "directory/".
	   (comint-dynamic-list-filename-completions))
	  (t                            ; Completion string returned.
	   (let ((file (concat (file-name-as-directory directory) completion)))
	     (insert (comint-quote-filename
		      (substring (directory-file-name completion)
				 (length pathnondir))))
	     (cond ((symbolp (file-name-completion completion directory))
		    ;; We inserted a unique completion.
		    (insert (if (file-directory-p file) dirsuffix filesuffix))
		    (unless minibuffer-p
		      (message "Completed")))
		   ((and comint-completion-recexact comint-completion-addsuffix
			 (string-equal pathnondir completion)
			 (file-exists-p file))
		    ;; It's not unique, but user wants shortest match.
		    (insert (if (file-directory-p file) dirsuffix filesuffix))
		    (unless minibuffer-p
		      (message "Completed shortest")))
		   ((or comint-completion-autolist
			(string-equal pathnondir completion))
		    ;; It's not unique, list possible completions.
		    (comint-dynamic-list-filename-completions))
		   (t
		    (unless minibuffer-p
		      (message "Partially completed")))))))
    success))


(defun comint-replace-by-expanded-filename ()
  "Dynamically expand and complete the filename at point.
Replace the filename with an expanded, canonicalised and completed replacement.
\"Expanded\" means environment variables (e.g., $HOME) and `~'s are replaced
with the corresponding directories.  \"Canonicalised\" means `..'  and `.' are
removed, and the filename is made absolute instead of relative.  For expansion
see `expand-file-name' and `substitute-in-file-name'.  For completion see
`comint-dynamic-complete-filename'."
  (interactive)
  (replace-match (expand-file-name (comint-match-partial-filename)) t t)
  (comint-dynamic-complete-filename))


(defun comint-dynamic-simple-complete (stub candidates)
  "Dynamically complete STUB from CANDIDATES list.
This function inserts completion characters at point by completing STUB from
the strings in CANDIDATES.  A completions listing may be shown in a help buffer
if completion is ambiguous.

Returns nil if no completion was inserted.
Returns `sole' if completed with the only completion match.
Returns `shortest' if completed with the shortest of the completion matches.
Returns `partial' if completed as far as possible with the completion matches.
Returns `listed' if a completion listing was shown.

See also `comint-dynamic-complete-filename'."
  (let* ((completion-ignore-case (memq system-type '(ms-dos windows-nt)))
	 (suffix (cond ((not comint-completion-addsuffix) "")
		       ((not (consp comint-completion-addsuffix)) " ")
		       (t (cdr comint-completion-addsuffix))))
	 (candidates (mapcar (function (lambda (x) (list x))) candidates))
	 (completions (all-completions stub candidates)))
    (cond ((null completions)
	   (message "No completions of %s" stub)
	   nil)
	  ((= 1 (length completions))	; Gotcha!
	   (let ((completion (car completions)))
	     (if (string-equal completion stub)
		 (message "Sole completion")
	       (insert (substring completion (length stub)))
	       (message "Completed"))
	     (insert suffix)
	     'sole))
	  (t				; There's no unique completion.
	   (let ((completion (try-completion stub candidates)))
	     ;; Insert the longest substring.
	     (insert (substring completion (length stub)))
	     (cond ((and comint-completion-recexact comint-completion-addsuffix
			 (string-equal stub completion)
			 (member completion completions))
		    ;; It's not unique, but user wants shortest match.
		    (insert suffix)
		    (message "Completed shortest")
		    'shortest)
		   ((or comint-completion-autolist
			(string-equal stub completion))
		    ;; It's not unique, list possible completions.
		    (comint-dynamic-list-completions completions)
		    'listed)
		   (t
		    (message "Partially completed")
		    'partial)))))))


(defun comint-dynamic-list-filename-completions ()
  "List in help buffer possible completions of the filename at point."
  (interactive)
  (let* ((completion-ignore-case (memq system-type '(ms-dos windows-nt)))
	 ;; If we bind this, it breaks remote directory tracking in rlogin.el.
	 ;; I think it was originally bound to solve file completion problems,
	 ;; but subsequent changes may have made this unnecessary.  sm.
	 ;;(file-name-handler-alist nil)
	 (filename (or (comint-match-partial-filename) ""))
	 (pathdir (file-name-directory filename))
	 (pathnondir (file-name-nondirectory filename))
	 (directory (if pathdir (comint-directory pathdir) default-directory))
	 (completions (file-name-all-completions pathnondir directory)))
    (if (not completions)
	(message "No completions of %s" filename)
      (comint-dynamic-list-completions
       (mapcar 'comint-quote-filename completions)))))


(defun comint-dynamic-list-completions (completions)
  "List in help buffer sorted COMPLETIONS.
Typing SPC flushes the help buffer."
  (let ((conf (current-window-configuration)))
    (with-output-to-temp-buffer "*Completions*"
      (display-completion-list (sort completions 'string-lessp)))
    (message "Hit space to flush")
    (let (key first)
      (if (save-excursion
	    (set-buffer (get-buffer "*Completions*"))
	    (setq key (read-key-sequence nil)
		  first (aref key 0))
	    (and (consp first) (consp (event-start first))
		 (eq (window-buffer (posn-window (event-start first)))
		     (get-buffer "*Completions*"))
		 (eq (key-binding key) 'mouse-choose-completion)))
	  ;; If the user does mouse-choose-completion with the mouse,
	  ;; execute the command, then delete the completion window.
	  (progn
	    (mouse-choose-completion first)
	    (set-window-configuration conf))
	(if (eq first ?\ )
	    (set-window-configuration conf)
	  (setq unread-command-events (listify-key-sequence key)))))))
\f
(defun comint-get-next-from-history ()
  "After fetching a line from input history, this fetches the following line.
In other words, this recalls the input line after the line you recalled last.
You can use this to repeat a sequence of input lines."
  (interactive)
  (if comint-save-input-ring-index
      (progn
	(setq comint-input-ring-index (1+ comint-save-input-ring-index))
	(comint-next-input 1))
    (message "No previous history command")))

(defun comint-accumulate ()
  "Accumulate a line to send as input along with more lines.
This inserts a newline so that you can enter more text
to be sent along with this line.  Use \\[comint-send-input]
to send all the accumulated input, at once.
The entire accumulated text becomes one item in the input history
when you send it."
  (interactive)
  (insert "\n")
  (set-marker comint-accum-marker (point))
  (if comint-input-ring-index
      (setq comint-save-input-ring-index
	    (- comint-input-ring-index 1))))

(defun comint-goto-process-mark ()
  "Move point to the process mark.
The process mark separates output, and input already sent,
from input that has not yet been sent."
  (interactive)
  (let ((proc (or (get-buffer-process (current-buffer))
		  (error "Current buffer has no process"))))
    (goto-char (process-mark proc))
    (message "Point is now at the process mark")))

(defun comint-bol-or-process-mark ()
  "Move point to beginning of line (after prompt) or to the process mark.
The first time you use this command, it moves to the beginning of the line
\(but after the prompt, if any).  If you repeat it again immediately,
it moves point to the process mark.

The process mark separates the process output, along with input already sent,
from input that has not yet been sent.  Ordinarily, the process mark
is at the beginning of the current input line; but if you have
used \\[comint-accumulate] to send multiple lines at once,
the process mark is at the beginning of the accumulated input."
  (interactive)
  (if (not (eq last-command 'comint-bol-or-process-mark))
      (comint-bol nil)
    (comint-goto-process-mark)))

(defun comint-set-process-mark ()
  "Set the process mark at point."
  (interactive)
  (let ((proc (or (get-buffer-process (current-buffer))
		  (error "Current buffer has no process"))))
    (set-marker (process-mark proc) (point))
    (message "Process mark set")))

\f
;; Author:  Peter Breton <pbreton@ne.mediaone.net>

;; This little add-on for comint is intended to make it easy to get
;; output from currently active comint buffers into another buffer,
;; or buffers, and then go back to using the comint shell.
;;
;; My particular use is SQL interpreters; I want to be able to execute a
;; query using the process associated with a comint-buffer, and save that
;; somewhere else. Because the process might have state (for example, it
;; could be in an uncommitted transaction), just running starting a new
;; process and having it execute the query and then finish, would not
;; work. I'm sure there are other uses as well, although in many cases
;; starting a new process is the simpler, and thus preferable, approach.
;;
;; The basic implementation is as follows: comint-redirect changes the
;; preoutput filter functions (comint-preoutput-filter-functions) to use
;; its own filter. The filter puts the output into the designated buffer,
;; or buffers, until it sees a regexp that tells it to stop (by default,
;; this is the prompt for the interpreter, comint-prompt-regexp). When it
;; sees the stop regexp, it restores the old filter functions, and runs
;; comint-redirect-hook.
;;
;; Each comint buffer may only use one redirection at a time, but any number
;; of different comint buffers may be simultaneously redirected.
;;
;; NOTE: It is EXTREMELY important that `comint-prompt-regexp' be set to the
;; correct prompt for your interpreter, or that you supply a regexp that says
;; when the redirection is finished. Otherwise, redirection will continue
;; indefinitely. The code now does a sanity check to ensure that it can find
;; a prompt in the comint buffer; however, it is still important to ensure that
;; this prompt is set correctly.
;;
;; XXX: This doesn't work so well unless comint-prompt-regexp is set;
;; perhaps it should prompt for a terminating string (with an
;; appropriate magic default by examining what we think is the prompt)?
;;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Variables
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defcustom comint-redirect-verbose nil
  "*If non-nil, print messages each time the redirection filter is invoked.
Also print a message when redirection is completed."
  :group 'comint
  :type 'boolean)

;; Directly analagous to comint-preoutput-filter-functions
(defvar comint-redirect-filter-functions nil
  "List of functions to call before inserting redirected process output.
Each function gets one argument, a string containing the text received
from the subprocess.  It should return the string to insert, perhaps
the same string that was received, or perhaps a modified or transformed
string.

The functions on the list are called sequentially, and each one is given
the string returned by the previous one.  The string returned by the
last function is the text that is actually inserted in the redirection buffer.")

(make-variable-buffer-local 'comint-redirect-filter-functions)

;; Internal variables

(defvar comint-redirect-output-buffer nil
  "The buffer or list of buffers to put output into.")

(defvar comint-redirect-finished-regexp nil
  "Regular expression that determines when to stop redirection in Comint.
When the redirection filter function is given output that matches this regexp,
the output is inserted as usual, and redirection is completed.")

(defvar comint-redirect-insert-matching-regexp nil
  "If non-nil, the text that ends a redirection is included in it.
More precisely, the text that matches `comint-redirect-finished-regexp'
and therefore terminates an output redirection is inserted in the
redirection target buffer, along with the preceding output.")

(defvar comint-redirect-echo-input nil
  "Non-nil means echo input in the process buffer even during redirection.")

(defvar comint-redirect-completed nil
  "Non-nil if redirection has completed in the current buffer.")

(defvar comint-redirect-original-mode-line-process nil
  "Original mode line for redirected process.")

(defvar comint-redirect-perform-sanity-check t
  "If non-nil, check that redirection is likely to complete successfully.
More precisely, before starting a redirection, verify that the
regular expression `comint-redirect-finished-regexp' that controls
when to terminate it actually matches some text already in the process
buffer.  The idea is that this regular expression should match a prompt
string, and that there ought to be at least one copy of your prompt string
in the process buffer already.")

(defvar comint-redirect-original-filter-function nil
  "The process filter that was in place when redirection is started.
When redirection is completed, the process filter is restored to
this value.")

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Functions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun comint-redirect-setup (output-buffer
			      comint-buffer
			      finished-regexp
			      &optional echo-input)
  "Set up for output redirection.
This function sets local variables that are used by `comint-redirect-filter'
to perform redirection.

Output from COMINT-BUFFER is redirected to OUTPUT-BUFFER, until something
in the output matches FINISHED-REGEXP.

If optional argument ECHO-INPUT is non-nil, output is echoed to the
original comint buffer.

This function is called by `comint-redirect-send-command-to-process',
and does not normally need to be invoked by the end user or programmer."
  (with-current-buffer comint-buffer

    (make-local-variable 'comint-redirect-original-mode-line-process)
    (setq comint-redirect-original-mode-line-process mode-line-process)

    (make-local-variable 'comint-redirect-output-buffer)
    (setq comint-redirect-output-buffer output-buffer)

    (make-local-variable 'comint-redirect-finished-regexp)
    (setq comint-redirect-finished-regexp finished-regexp)

    (make-local-variable 'comint-redirect-echo-input)
    (setq comint-redirect-echo-input echo-input)

    (make-local-variable 'comint-redirect-completed)
    (setq comint-redirect-completed nil)

    (setq mode-line-process
	  (if mode-line-process
	      (list (concat (elt mode-line-process 0) " Redirection"))
	    (list ":%s Redirection")))))

(defun comint-redirect-cleanup ()
  "End a Comint redirection.  See `comint-redirect-send-command'."
  (interactive)
  ;; Restore the process filter
  (set-process-filter (get-buffer-process (current-buffer))
		      comint-redirect-original-filter-function)
  ;; Restore the mode line
  (setq mode-line-process comint-redirect-original-mode-line-process)
  ;; Set the completed flag
  (setq comint-redirect-completed t))

;; Because the cleanup happens as a callback, it's not easy to guarantee
;; that it really occurs.
(defalias 'comint-redirect-remove-redirection 'comint-redirect-cleanup)

(defun comint-redirect-filter (process input-string)
  "Filter function which redirects output from PROCESS to a buffer or buffers.
The variable `comint-redirect-output-buffer' says which buffer(s) to
place output in.

INPUT-STRING is the input from the comint process.

This function runs as a process filter, and does not need to be invoked by the
end user."
  (and process
       (with-current-buffer (process-buffer process)
	 (comint-redirect-preoutput-filter input-string)
	 ;; If we have to echo output, give it to the original filter function
	 (and comint-redirect-echo-input
	      comint-redirect-original-filter-function
	      (funcall comint-redirect-original-filter-function
		       process input-string)))))


(defun comint-redirect-preoutput-filter (input-string)
  "Comint filter function which redirects comint output to a buffer or buffers.
The variable `comint-redirect-output-buffer' says which buffer(s) to
place output in.

INPUT-STRING is the input from the comint process.

This function does not need to be invoked by the end user."
  (let ((output-buffer-list
	 (if (listp comint-redirect-output-buffer)
	    comint-redirect-output-buffer
	   (list comint-redirect-output-buffer)))
	(filtered-input-string input-string))

    ;; If there are any filter functions, give them a chance to modify the string
    (let ((functions comint-redirect-filter-functions))
      (while (and functions filtered-input-string)
	(setq filtered-input-string
	      (funcall (car functions) filtered-input-string))
	(setq functions (cdr functions))))

    ;; Clobber `comint-redirect-finished-regexp'
    (or comint-redirect-insert-matching-regexp
	(and (string-match comint-redirect-finished-regexp filtered-input-string)
	     (setq filtered-input-string
		   (replace-match "" nil nil filtered-input-string))))

    ;; Send output to all registered buffers
    (save-excursion
      (mapcar
       (function (lambda(buf)
		   ;; Set this buffer to the output buffer
		   (set-buffer (get-buffer-create buf))
		   ;; Go to the end of the buffer
		   (goto-char (point-max))
		   ;; Insert the output
		   (insert filtered-input-string)))
       output-buffer-list))

    ;; Message
    (and comint-redirect-verbose
	 (message "Redirected output to buffer(s) %s"
		  (mapconcat 'identity output-buffer-list " ")))

    ;; If we see the prompt, tidy up
    ;; We'll look for the prompt in the original string, so nobody can
    ;; clobber it
    (and (string-match comint-redirect-finished-regexp input-string)
	 (progn
	   (and comint-redirect-verbose
		(message "Redirection completed"))
	   (comint-redirect-cleanup)
	   (run-hooks 'comint-redirect-hook)))
    ;; Echo input?
    (if comint-redirect-echo-input
	filtered-input-string
      "")))

;;;###autoload
(defun comint-redirect-send-command (command output-buffer echo &optional no-display)
  "Send COMMAND to process in current buffer, with output to OUTPUT-BUFFER.
With prefix arg, echo output in process buffer.

If NO-DISPLAY is non-nil, do not show the output buffer."
  (interactive "sCommand: \nBOutput Buffer: \nP")
  (let ((process (get-buffer-process (current-buffer))))
    (if process
	(comint-redirect-send-command-to-process
	 command output-buffer (current-buffer) echo no-display)
      (error "No process for current buffer"))))

;;;###autoload
(defun comint-redirect-send-command-to-process
  (command output-buffer process echo &optional no-display)
  "Send COMMAND to PROCESS, with output to OUTPUT-BUFFER.
With prefix arg, echo output in process buffer.

If NO-DISPLAY is non-nil, do not show the output buffer."
  (interactive "sCommand: \nBOutput Buffer: \nbProcess Buffer: \nP")
  (let* (;; The process buffer
	 (process-buffer (if (processp process)
			     (process-buffer process)
			   process))
	 (proc (get-buffer-process process-buffer)))
    ;; Change to the process buffer
    (set-buffer process-buffer)

    ;; Make sure there's a prompt in the current process buffer
    (and comint-redirect-perform-sanity-check
	 (save-excursion
	   (goto-char (point-max))
	   (or (re-search-backward comint-prompt-regexp nil t)
	       (error "No prompt found or `comint-prompt-regexp' not set properly"))))

    ;;;;;;;;;;;;;;;;;;;;;
    ;; Set up for redirection
    ;;;;;;;;;;;;;;;;;;;;;
    (comint-redirect-setup
     ;; Output Buffer
     output-buffer
     ;; Comint Buffer
     (current-buffer)
     ;; Finished Regexp
     comint-prompt-regexp
     ;; Echo input
     echo)

    ;;;;;;;;;;;;;;;;;;;;;
    ;; Set the filter
    ;;;;;;;;;;;;;;;;;;;;;
    ;; Save the old filter
    (setq comint-redirect-original-filter-function
	  (process-filter proc))
    (set-process-filter proc 'comint-redirect-filter)

    ;;;;;;;;;;;;;;;;;;;;;
    ;; Send the command
    ;;;;;;;;;;;;;;;;;;;;;
    (process-send-string
     (current-buffer)
     (concat command "\n"))

    ;;;;;;;;;;;;;;;;;;;;;
    ;; Show the output
    ;;;;;;;;;;;;;;;;;;;;;
    (or no-display
	 (display-buffer
	  (get-buffer-create
	   (if (listp output-buffer)
	       (car output-buffer)
	     output-buffer))))))

;;;###autoload
(defun comint-redirect-results-list (command regexp regexp-group)
  "Send COMMAND to current process.
Return a list of expressions in the output which match REGEXP.
REGEXP-GROUP is the regular expression group in REGEXP to use."
  (comint-redirect-results-list-from-process
   (get-buffer-process (current-buffer))
   command regexp regexp-group))

;;;###autoload
(defun comint-redirect-results-list-from-process (process command regexp regexp-group)
  "Send COMMAND to PROCESS.
Return a list of expressions in the output which match REGEXP.
REGEXP-GROUP is the regular expression group in REGEXP to use."
  (let ((output-buffer " *Comint Redirect Work Buffer*")
	results)
    (save-excursion
      (set-buffer (get-buffer-create output-buffer))
      (erase-buffer)
      (comint-redirect-send-command-to-process command
					       output-buffer process nil t)
      ;; Wait for the process to complete
      (set-buffer (process-buffer process))
      (while (null comint-redirect-completed)
	(accept-process-output nil 1))
      ;; Collect the output
      (set-buffer output-buffer)
      (goto-char (point-min))
      ;; Skip past the command, if it was echoed
      (and (looking-at command)
	   (forward-line))
      (while (re-search-forward regexp nil t)
	(setq results
	      (cons (buffer-substring-no-properties
		     (match-beginning regexp-group)
		     (match-end regexp-group))
		    results)))
      results)))

(mapc (lambda (x)
	(add-to-list 'debug-ignored-errors x))
      '("^Not at command line$"
	"^Empty input ring$"
	"^No history$"
	"^Not found$"			; Too common?
	"^Current buffer has no process$"))
\f
;; Converting process modes to use comint mode
;; ===========================================================================
;; The code in the Emacs 19 distribution has all been modified to use comint
;; where needed.  However, there are `third-party' packages out there that
;; still use the old shell mode.  Here's a guide to conversion.
;;
;; Renaming variables
;; Most of the work is renaming variables and functions. These are the common
;; ones:
;; Local variables:
;;	last-input-start	comint-last-input-start
;;	last-input-end		comint-last-input-end
;;	shell-prompt-pattern	comint-prompt-regexp
;;     shell-set-directory-error-hook <no equivalent>
;; Miscellaneous:
;;	shell-set-directory	<unnecessary>
;;	shell-mode-map		comint-mode-map
;; Commands:
;;	shell-send-input	comint-send-input
;;	shell-send-eof		comint-delchar-or-maybe-eof
;;	kill-shell-input	comint-kill-input
;;	interrupt-shell-subjob	comint-interrupt-subjob
;;	stop-shell-subjob	comint-stop-subjob
;;	quit-shell-subjob	comint-quit-subjob
;;	kill-shell-subjob	comint-kill-subjob
;;	kill-output-from-shell	comint-delete-output
;;	show-output-from-shell	comint-show-output
;;	copy-last-shell-input	Use comint-previous-input/comint-next-input
;;
;; SHELL-SET-DIRECTORY is gone, its functionality taken over by
;; SHELL-DIRECTORY-TRACKER, the shell mode's comint-input-filter-functions.
;; Comint mode does not provide functionality equivalent to
;; shell-set-directory-error-hook; it is gone.
;;
;; comint-last-input-start is provided for modes which want to munge
;; the buffer after input is sent, perhaps because the inferior
;; insists on echoing the input.  The LAST-INPUT-START variable in
;; the old shell package was used to implement a history mechanism,
;; but you should think twice before using comint-last-input-start
;; for this; the input history ring often does the job better.
;;
;; If you are implementing some process-in-a-buffer mode, called foo-mode, do
;; *not* create the comint-mode local variables in your foo-mode function.
;; This is not modular.  Instead, call comint-mode, and let *it* create the
;; necessary comint-specific local variables. Then create the
;; foo-mode-specific local variables in foo-mode.  Set the buffer's keymap to
;; be foo-mode-map, and its mode to be foo-mode.  Set the comint-mode hooks
;; (comint-{prompt-regexp, input-filter, input-filter-functions,
;; get-old-input) that need to be different from the defaults.  Call
;; foo-mode-hook, and you're done. Don't run the comint-mode hook yourself;
;; comint-mode will take care of it. The following example, from shell.el,
;; is typical:
;;
;; (defvar shell-mode-map '())
;; (cond ((not shell-mode-map)
;;        (setq shell-mode-map (copy-keymap comint-mode-map))
;;        (define-key shell-mode-map "\C-c\C-f" 'shell-forward-command)
;;        (define-key shell-mode-map "\C-c\C-b" 'shell-backward-command)
;;        (define-key shell-mode-map "\t" 'comint-dynamic-complete)
;;        (define-key shell-mode-map "\M-?"
;;          'comint-dynamic-list-filename-completions)))
;;
;; (defun shell-mode ()
;;   (interactive)
;;   (comint-mode)
;;   (setq comint-prompt-regexp shell-prompt-pattern)
;;   (setq major-mode 'shell-mode)
;;   (setq mode-name "Shell")
;;   (use-local-map shell-mode-map)
;;   (make-local-variable 'shell-directory-stack)
;;   (setq shell-directory-stack nil)
;;   (add-hook 'comint-input-filter-functions 'shell-directory-tracker)
;;   (run-hooks 'shell-mode-hook))
;;
;;
;; Completion for comint-mode users
;;
;; For modes that use comint-mode, comint-dynamic-complete-functions is the
;; hook to add completion functions to.  Functions on this list should return
;; non-nil if completion occurs (i.e., further completion should not occur).
;; You could use comint-dynamic-simple-complete to do the bulk of the
;; completion job.
\f
(provide 'comint)

;; comint.el ends here