multishell - Comment and docstring tidying.

[gnu-emacs-elpa] / multishell.el

;;; multishell.el --- facilitate multiple local and remote shell buffers

;; Copyright (C) 1999-2016 Free Software Foundation, Inc. and Ken Manheimer

;; Author: Ken Manheimer <ken.manheimer@gmail.com>
;; Version: 1.0.5
;; Created: 1999 -- first public availability
;; Keywords: processes
;; URL: https://github.com/kenmanheimer/EmacsMultishell
;;
;;; Commentary:
;;
;; Easily use and navigate multiple shell buffers, including remote shells.
;; Fundamentally, multishell is the function `multishell-pop-to-shell' -
;; a la `pop-to-buffer' - plus a keybinding. Together, they enable you to:
;;
;; * Get to the input point from wherever you are in a shell buffer,
;; * ... or to one of your shell buffers if you're not currently in one.
;; * Use universal arguments to launch and choose among alternate shell buffers,
;; * ... and select which is default.
;; * Append a path to a new shell name to launch a shell in that directory,
;; * ... and use a path with Emacs tramp syntax to launch a remote shell.
;;
;;   For example:
;;
;;   * `/ssh:example.net:/` for a shell buffer in / on
;;     example.net; the buffer will be named "*example.net*".
;;
;;   * `#ex/ssh:example.net|sudo:root@example.net:/etc` for a root shell
;;     starting in /etc on example.net named "*#ex*".
;;
;; See the `multishell-pop-to-shell` docstring for details.
;;
;; (NOTE - there's a sporadic problem when opening a shell pointed at a
;; remote homedir, eg `/ssh:example.net:` or `/ssh:example.net:~`. It
;; sometimes fails. Until fixed, you may need to start remote shells with
;; an explicit path, then cd ~. If you set up `multishell`s persistent
;; dir-tracking history, you'll be able to use completion to start that
;; shell in the right place, in your subsequent sessions.)
;;
;; Customize-group `multishell' to select and activate a keybinding and set
;; various behaviors. Customize-group `savehist' to preserve buffer
;; names/paths across emacs sessions.
;;
;; Please use
;; [the multishell repository](https://github.com/kenmanheimer/EmacsMultishell)
;; issue tracker to report problems, suggestions, etc.
;;
;; Change Log:
;;
;; * 2016-01-16 1.0.5 Ken Manheimer:
;;   - History now includes paths, when designated
;;   - Actively track current directory in history entries that have a path.
;;     Custom control: multishell-history-entry-tracks-current-directory
;;   - Offer to remove shell's history entry when buffer is killed.
;;     (Currently the only UI mechanism to remove history entries.)
;;   - Fix - prevent duplicate entries for same name but different paths
;;   - Fix - recognize and respect tramp path syntax to start in home dir
;;     - But tramp bug, remote w/empty path (homedir) often fails, gets wedged.
;;   - Simplify history var name, migrate existing history if any from old name
;; * 2016-01-04 1.0.4 Ken Manheimer - Released to ELPA
;; * 2016-01-02 Ken Manheimer - working on this in public, but not yet released.
;;
;; TODO:
;;
;; * Isolate tramp sporadic failure to connect to remote+homedir (empty path)
;;   syntax
;;   (eg, /ssh:xyz.com|sudo:root@xyz.com: or /ssh:xyz.com|sudo:root@xyz.com:~)
;; * Find suitable, internally consistent ways to sort tidy completions, eg:
;;   - first list completions for active shells, then present but inactive,
;;     then historical
;;   - some way for user to toggle between presenting just buffer names vs
;;     full buffer/path
;;     - without cutting user off from easy editing of path
;; * Find proper method for setting field boundary at beginning of tramp path
;;   in the minibuffer, in order to see whether the field boundary magically
;;   enables tramp completion of the path.
;; * Assess whether option to delete history entry on kill-buffer is
;;   sufficient.

;;; Code:

(require 'comint)
(require 'shell)

(defgroup multishell nil
  "Allout extension that highlights outline structure graphically.

Customize `allout-widgets-auto-activation' to activate allout-widgets
with allout-mode."
  :group 'shell)

(defcustom multishell-command-key "\M- "
  "The key to use if `multishell-activate-command-key' is true.

You can instead manually bind `multishell-pop-to-shell` using emacs
lisp, eg: (global-set-key \"\\M- \" 'multishell-pop-to-shell)."
  :type 'key-sequence
  :group 'multishell)

(defvar multishell--responsible-for-command-key nil
  "Coordination for multishell key assignment.")
(defun multishell-activate-command-key-setter (symbol setting)
  "Implement `multishell-activate-command-key' choice."
  (set-default 'multishell-activate-command-key setting)
  (when (or setting multishell--responsible-for-command-key)
    (multishell-implement-command-key-choice (not setting))))
(defun multishell-implement-command-key-choice (&optional unbind)
  "If settings dicate, implement binding of multishell command key.

If optional UNBIND is true, globally unbind the key.

* `multishell-activate-command-key' - Set this to get the binding or not.
* `multishell-command-key' - The key to use for the binding, if appropriate."
  (cond (unbind
         (when (and (boundp 'multishell-command-key) multishell-command-key)
           (global-unset-key multishell-command-key)))
        ((not (and (boundp 'multishell-activate-command-key)
                   (boundp 'multishell-command-key)))
         nil)
        ((and multishell-activate-command-key multishell-command-key)
         (setq multishell--responsible-for-command-key t)
         (global-set-key multishell-command-key 'multishell-pop-to-shell))))

(defcustom multishell-activate-command-key nil
  "Set this to impose the `multishell-command-key' binding.

You can instead manually bind `multishell-pop-to-shell` using emacs
lisp, eg: (global-set-key \"\\M- \" 'multishell-pop-to-shell)."
  :type 'boolean
  :set 'multishell-activate-command-key-setter
  :group 'multishell)

;; Assert the customizations whenever the package is loaded:
(with-eval-after-load "multishell"
  (multishell-implement-command-key-choice))

(defcustom multishell-pop-to-frame nil
  "*If non-nil, jump to a frame already showing the shell, if another is.

Otherwise, disregard already-open windows on the shell if they're
in another frame, and open a new window on the shell in the
current frame.

\(Use `pop-up-windows' to change multishell other-buffer vs
current-buffer behavior.)"
  :type 'boolean
  :group 'multishell)

(defcustom multishell-history-entry-tracks-current-directory t
  "Modify shell buffer's multishell entry to track the current directory.

When set, the path part of the name/path entry for each shell
will track the current directory of the shell with emacs. If
`savehist' is active, the directory tracking will extend across
emacs sessions."
 :type 'boolean
 :group 'multishell)

(defvar multishell-history nil
  "Name/path entries, most recent first.")
(when (and (not multishell-history)
           (boundp 'multishell-buffer-name-history)
           multishell-buffer-name-history)
  ;; Migrate few users who had old var to new.
  (setq multishell-history multishell-buffer-name-history)
 )

(defvar multishell-primary-name "*shell*"
  "Shell name to use for un-modified multishell-pop-to-shell buffer target.")

;; Multiple entries happen because completion also adds name to history.
(defun multishell-register-name-to-path (name path)
  "Add or replace entry associating NAME with PATH in `multishell-history'.

If NAME already had a PATH and new PATH is empty, retain old one.

Promote added/changed entry to the front of the list."
  ;; Add or promote to the front, tracking path changes in the process.
  (let* ((entries (multishell-history-entries name))
         (becomes (concat name path))
         oldpath)
    (dolist (entry entries)
      (when (or (not path) (string= path ""))
        ;; Retain explicit established path.
        (setq path (cadr (multishell-split-entry-name-and-tramp entry))
              becomes (concat name path)))
      (setq multishell-history (delete entry multishell-history)))
    (setq multishell-history (push becomes multishell-history))))

(defun multishell-history-entries (name)
  "Return `multishell-history' entry that starts with NAME, or nil if none."
  (let ((match-expr (concat "^" name "\\\(/.*$\\\)?"))
        got)
    (dolist (entry multishell-history)
      (when (and (string-match match-expr entry)
                 (not (member entry got)))
        (setq got (cons entry got))))
    got))

(defun multishell-pop-to-shell (&optional arg)
  "Easily navigate to and within multiple shell buffers, local and remote.

Use universal arguments to launch and choose between alternate
shell buffers and to select which is default.  Append a path to
a new shell name to launch a shell in that directory, and use
Emacs tramp syntax to launch a remote shell.

Customize-group `multishell' to set up a key binding and tweak behaviors.

==== Basic operation:

 - If the current buffer is shell-mode (or shell-mode derived)
   buffer then focus is moved to the process input point.

   \(You can use a universal argument go to a different shell
   buffer when already in a buffer that has a process - see
   below.)

 - If not in a shell buffer (or with universal argument), go to a
   window that is already showing the (a) shell buffer, if any.

   In this case, the cursor is left in its prior position in the
   shell buffer. Repeating the command will then go to the
   process input point, per the first item in this list.

   We respect `pop-up-windows', so you can adjust it to set the
   other-buffer/same-buffer behavior.

 - Otherwise, start a new shell buffer, using the current
   directory as the working directory.

If a buffer with the resulting name exists and its shell process
was disconnected or otherwise stopped, it's resumed.

===== Universal arg to start and select between named shell buffers:

You can name alternate shell buffers to create or return to using
single or doubled universal arguments:

 - With a single universal argument, prompt for the buffer name
   to use (without the asterisks that shell mode will put around
   the name), defaulting to 'shell'.

   Completion is available.

   This combination makes it easy to start and switch between
   multiple shell buffers.

 - A double universal argument will prompt for the name *and* set
   the default to that name, so the target shell becomes the
   primary.

===== Select starting directory and remote host:

The shell buffer name you give to the prompt for a universal arg
can include an appended path. That will be used for the startup
directory. You can use tramp remote syntax to specify a remote
shell. If there is an element after a final '/', that's used for
the buffer name. Otherwise, the host, domain, or path is used.

For example:

* Use '/ssh:example.net:/home/myaccount' for a shell buffer in
  /home/myaccount on example.net; the buffer will be named
  \"*example.net*\". 
* '\#ex/ssh:example.net|sudo:root@example.net:/etc' for a root
  shell in /etc on example.net named \"*#ex*\".
* '\#in/ssh:corp.com|ssh:internal.corp.com|sudo:root@internal.corp.com:/etc'
  for a root shell name \"*in*\" in /etc on internal.corp.com, via host 
  corp.com.

\(NOTE that there is a problem with specifying a remote homedir using
tramp syntax, eg '/ssh:example.net:'. That sometimes fails on an obscure
bug - particularly for remote with empty path (homedir) syntax. Until fixed,
you may need to start remote shells with an explicit path, then cd ~.)

You can change the startup path for a shell buffer by editing it
at the completion prompt. The new path will be preserved in
history but will not take effect for an already-running shell.

To remove a shell buffer's history entry, kill the buffer and
affirm removal of the entry when prompted.

===== Activate savehist to retain shell buffer names and paths across Emacs sessions:

To have emacs maintain your history of shell buffer names and paths,
customize the savehist group to activate savehist."

  (interactive "P")

  (let* ((from-buffer (current-buffer))
         (from-buffer-is-shell (derived-mode-p 'shell-mode))
         (doublearg (equal arg '(16)))
         (target-name-and-path
          (multishell-derive-target-name-and-path
           (if arg
               (multishell-read-bare-shell-buffer-name
                (format "Shell buffer name [%s]%s "
                        (substring-no-properties
                         multishell-primary-name
                         1 (- (length multishell-primary-name) 1))
                        (if doublearg " <==" ":"))
                multishell-primary-name)
             multishell-primary-name)))
         (use-default-dir (cadr target-name-and-path))
         (target-shell-buffer-name (car target-name-and-path))
         (curr-buff-proc (get-buffer-process from-buffer))
         (target-buffer (if from-buffer-is-shell
                            from-buffer
                          (let ((got (get-buffer target-shell-buffer-name)))
                            (if (buffer-live-p got)
                                got
                              (kill-buffer got)
                              (get-buffer target-shell-buffer-name)))))
         inwin
         already-there)

    (when doublearg
      (setq multishell-primary-name target-shell-buffer-name))

    ;; Situate:

    (cond 

     ((and (or curr-buff-proc from-buffer-is-shell)
           (not arg)
           (eq from-buffer target-buffer)
           (not (eq target-shell-buffer-name (buffer-name from-buffer))))
      ;; In a shell buffer, but not named - stay in buffer, but go to end.
      (setq already-there t))

     ((string= (buffer-name) target-shell-buffer-name)
      ;; Already in the specified shell buffer:
      (setq already-there t))

     ((or (not target-buffer)
          (not (setq inwin
                     (multishell-get-visible-window-for-buffer target-buffer))))
      ;; No preexisting shell buffer, or not in a visible window:
      (pop-to-buffer target-shell-buffer-name pop-up-windows))

       ;; Buffer exists and already has a window - jump to it:
     (t (if (and multishell-pop-to-frame
                 inwin
                 (not (equal (window-frame (selected-window))
                             (window-frame inwin))))
            (select-frame-set-input-focus (window-frame inwin)))
        (if (not (string= (buffer-name (current-buffer))
                          target-shell-buffer-name))
            (pop-to-buffer target-shell-buffer-name t))))

    ;; We're in the buffer. Activate:

    (if (not (comint-check-proc (current-buffer)))
        (multishell-start-shell-in-buffer (buffer-name (current-buffer))
                                          use-default-dir))

    ;; If the destination buffer has a stopped process, resume it:
    (let ((process (get-buffer-process (current-buffer))))
      (if (and process (equal 'stop (process-status process)))
          (continue-process process)))
    (multishell-register-name-to-path (multishell-unbracket-asterisks
                                       target-shell-buffer-name)
                                      use-default-dir)
    (when (or already-there
             (equal (current-buffer) from-buffer))
      (goto-char (point-max))
      (and (get-buffer-process from-buffer)
           (goto-char (process-mark (get-buffer-process from-buffer)))))))

(defun multishell-kill-buffer-query-function ()
  "Offer to remove multishell-history entry for buffer."
  ;; Removal choice is crucial, so users can, eg, kill and a runaway shell
  ;; and keep the history entry to easily restart it.
  ;;
  ;; We use kill-buffer-query-functions instead of kill-buffer-hook because:
  ;;
  ;; 1. It enables the user to remove the history without killing the buffer,
  ;;    by cancelling the kill-buffer process after affirming history removal.
  ;; 2. kill-buffer-hooks often fails to run when killing shell buffers!
  ;;    I've failed to resolve that, and like the first reason well enough.

  ;; (Use condition-case to avoid inadvertant disruption of kill-buffer
  ;; activity.  kill-buffer happens behind the scenes a whole lot.)
  (condition-case anyerr
      (let ((entries (and (derived-mode-p 'shell-mode)
                          (multishell-history-entries
                           (multishell-unbracket-asterisks (buffer-name))))))
        (dolist (entry entries)
          (when (and entry
                     (y-or-n-p (format "Remove multishell history entry `%s'? "
                                       entry)))
            (setq multishell-history
                  (delete entry multishell-history)))))
    (error nil))
  t)
(add-hook 'kill-buffer-query-functions 'multishell-kill-buffer-query-function)

(defun multishell-get-visible-window-for-buffer (buffer)
  "Return visible window containing buffer."
  (catch 'got-a-vis
    (walk-windows
     (function (lambda (win)
                 (if (and (eq (window-buffer win) buffer)
                          (equal (frame-parameter
                                  (selected-frame) 'display)
                                 (frame-parameter
                                  (window-frame win) 'display)))
                     (throw 'got-a-vis win))))
     nil 'visible)
    nil))

(defun multishell-read-bare-shell-buffer-name (prompt default)
  "PROMPT for shell buffer name, sans asterisks.

Return the supplied name bracketed with the asterisks, or specified DEFAULT
on empty input."
  (let* ((candidates
          (append
           ;; Plain shell buffer names appended with names from name/path hist:
           (remq nil
                 (mapcar (lambda (buffer)
                           (let* ((name (multishell-unbracket-asterisks
                                         (buffer-name buffer))))
                             (and (buffer-live-p buffer)
                                  (with-current-buffer buffer
                                    ;; Shell mode buffers.
                                    (derived-mode-p 'shell-mode))
                                  (not (multishell-history-entries name))
                                  name)))
                         (buffer-list)))
           multishell-history))
         (got (completing-read prompt
                               ;; COLLECTION:
                               (reverse candidates)
                               ;; PREDICATE:
                               nil
                               ;; REQUIRE-MATCH:
                               'confirm
                               ;; INITIAL-INPUT
                               nil
                               ;; HIST:
                               'multishell-history)))
    (if (not (string= got ""))
        (multishell-bracket-asterisks got)
      default)))

(defun multishell-derive-target-name-and-path (path-ish)
  "Give tramp-style PATH-ISH, determine target name and default directory.

The name is the part of the string before the initial '/' slash,
if any. Otherwise, it's either the host-name, domain-name, final
directory name, or local host name. The path is everything
besides the string before the initial '/' slash.

Return them as a list (name dir), with dir nil if none given."
  (let (name (path "") dir)
    (cond ((string= path-ish "") (setq dir multishell-primary-name))
          ((string-match "^\\*\\([^/]*\\)\\(/.*\\)\\*" path-ish)
           ;; We have a path, use it
           (let ((overt-name (match-string 1 path-ish)))
             (setq path (match-string 2 path-ish))
             (if (string= overt-name "") (setq overt-name nil))
             (if (string= path "") (setq path nil))
             (setq name
                   (multishell-bracket-asterisks
                    (or overt-name
                        (if (file-remote-p path)
                            (let ((vec (tramp-dissect-file-name path)))
                              (or (tramp-file-name-host vec)
                                  (tramp-file-name-domain vec)
                                  (tramp-file-name-localname vec)
                                  system-name))
                          (multishell-unbracket-asterisks
                           multishell-primary-name)))))))
          (t (setq name (multishell-bracket-asterisks path-ish))))
    (list name path)))

(defun multishell-bracket-asterisks (name)
  "Return a copy of name, ensuring it has an asterisk at the beginning and end."
  (if (not (string= (substring name 0 1) "*"))
      (setq name (concat "*" name)))
  (if (not (string= (substring name -1) "*"))
      (setq name (concat name "*")))
  name)
(defun multishell-unbracket-asterisks (name)
  "Return a copy of name, removing asterisks, if any, at beginning and end."
  (if (string= (substring name 0 1) "*")
      (setq name (substring name 1)))
  (if (string= (substring name -1) "*")
      (setq name (substring name 0 -1)))
  name)

(defun multishell-start-shell-in-buffer (buffer-name path)
  "Ensure a shell is started, with name NAME and PATH."
  ;; We work around shell-mode's bracketing of the buffer name, and do
  ;; some tramp-mode hygiene for remote connections.

  (let* ((buffer buffer-name)
         (prog (or explicit-shell-file-name
                   (getenv "ESHELL")
                   (getenv "SHELL")
                   "/bin/sh"))
         (name (file-name-nondirectory prog))
         (startfile (concat "~/.emacs_" name))
         (xargs-name (intern-soft (concat "explicit-" name "-args")))
         is-remote)
    (set-buffer buffer-name)
    (if (and path (not (string= path "")))
        (setq default-directory path))
    (setq is-remote (file-remote-p default-directory))
    (when (and is-remote
               (derived-mode-p 'shell-mode)
               (not (comint-check-proc (current-buffer))))
      ;; We're returning to an already established but disconnected remote
      ;; shell, tidy it:
      (tramp-cleanup-connection
       (tramp-dissect-file-name default-directory 'noexpand)
       'keep-debug 'keep-password))
    ;; (cd default-directory) will connect if remote:
    (when is-remote
      (message "Connecting to %s" default-directory))
    (condition-case err
        (cd default-directory)
      (error
       ;; Aargh. Need to isolate this tramp bug.
       (when (and (stringp (cadr err))
                  (string-equal (cadr err)
                                "Selecting deleted buffer"))
         (signal (car err)
                 (list
                  (format "%s, %s (\"%s\")"
                          "Tramp shell can fail on empty (homedir) path"
                          "please try again with an explicit path"
                          (cadr err)))))))
    (setq buffer (set-buffer (apply 'make-comint
                                    (multishell-unbracket-asterisks buffer-name)
                                    prog
                                    (if (file-exists-p startfile)
                                        startfile)
                                    (if (and xargs-name
                                             (boundp xargs-name))
                                        (symbol-value xargs-name)
                                      '("-i")))))
    (shell-mode)))

(defun multishell-track-dirchange (name newpath)
  "Change multishell history entry to track current directory."
  (let* ((entries (multishell-history-entries name)))
    (dolist (entry entries)
      (let* ((name-path (multishell-split-entry-name-and-tramp entry))
             (name (car name-path))
             (path (cadr name-path)))
        (when path
          (let* ((is-remote (file-remote-p path))
                 (vec (and is-remote (tramp-dissect-file-name path nil)))
                 (localname (if is-remote
                                (tramp-file-name-localname vec)
                              path))
                 (newlocalname
                  (replace-regexp-in-string (if (string= localname "")
                                                "$"
                                              (regexp-quote localname))
                                            ;; REP
                                            newpath
                                            ;; STRING
                                            localname
                                            ;; FIXEDCASE
                                            t
                                            ;; LITERAL
                                            t
                                            ))
                 (newpath (if is-remote
                              (tramp-make-tramp-file-name (aref vec 0)
                                                          (aref vec 1)
                                                          (aref vec 2)
                                                          newlocalname
                                                          (aref vec 4))
                            newlocalname))
                 (newentry (concat name newpath))
                 (membership (member entry multishell-history)))
            (when membership
              (setcar membership newentry))))))))
(defvar multishell-was-default-directory ()
  "Provide for tracking directory changes.")
(make-variable-buffer-local 'multishell-was-default-directory)
(defun multishell-post-command-business ()
  "Do multishell bookkeeping."
  ;; Update multishell-history with dir changes.
  (condition-case err
      (when (and multishell-history-entry-tracks-current-directory
                 (derived-mode-p 'shell-mode))
        (let ((curdir (if (file-remote-p default-directory)
                          (tramp-file-name-localname
                           (tramp-dissect-file-name default-directory))
                        default-directory)))
          (when (and multishell-was-default-directory
                     (not (string= curdir multishell-was-default-directory)))
            (multishell-track-dirchange (multishell-unbracket-asterisks
                                         (buffer-name))
                                        curdir))
          (setq multishell-was-default-directory curdir)))
    ;; To avoid disruption as a pervasive hook function, swallow all errors:
    (error nil)))
(add-hook 'post-command-hook 'multishell-post-command-business)

(defun multishell-split-entry-name-and-tramp (entry)
  "Given multishell name/path ENTRY, return the separated name and path pair.

Returns nil for empty parts, rather than the empty string."
  (string-match "^\\([^/]*\\)\\(/?.*\\)?" entry)
  (let ((name (match-string 1 entry))
        (path (match-string 2 entry)))
    (and (string= name "") (setq name nil))
    (and (string= path "") (setq path nil))
    (list name path)))

(provide 'multishell)

;;; multishell.el ends here