(defvar display-subprocess-window nil
"If non-nil, the subprocess window is displayed whenever input is received.")
(defvar command-prefix-string "$ "
"String to insert to distinguish commands entered by user.")
(defvar subprocess-running nil)
(defvar subprocess-buf nil)
(defvar command-mode-map
(let ((map (make-sparse-keymap)))
(define-key map "\C-m" 'command-send-input)
(define-key map "\C-u" 'command-kill-line)
map))
(defun subprocess-input (name str)
"Handle input from a subprocess. Called by Emacs."
(if display-subprocess-window
(display-buffer subprocess-buf))
(with-current-buffer subprocess-buf
(goto-char (point-max))
(insert str ?\n)))
(defun subprocess-exit (name)
"Called by Emacs upon subprocess exit."
(setq subprocess-running nil))
(defun start-subprocess ()
"Spawn an asynchronous subprocess with output redirected to
the buffer *COMMAND*. Within this buffer, use C-m to send
the last line to the subprocess or to bring another line to
the end."
(if subprocess-running
(return t))
(setq subprocess-buf (get-buffer-create "*COMMAND*"))
(with-current-buffer subprocess-buf
(use-local-map command-mode-map))
(setq subprocess-running (spawn-subprocess 1 'subprocess-input
'subprocess-exit))
(and subprocess-running
(send-command-to-subprocess 1 "ON SEVERE_ERROR THEN CONTINUE")))
(defun subprocess-command-to-buffer (command buffer)
"Execute COMMAND and redirect output into BUFFER."
(let (cmd args)
(setq cmd (substring command 0 (string-match " " command)))
(setq args (substring command (string-match " " command)))
(call-process cmd nil buffer nil "*dcl*" args)))
(defun subprocess-command ()
"Start asynchronous subprocess if not running and switch to its window."
(interactive)
(if (not subprocess-running)
(start-subprocess))
(and subprocess-running
(progn (pop-to-buffer subprocess-buf) (goto-char (point-max)))))
(defun command-send-input ()
"If at last line of buffer, send the current line to
the spawned subprocess. Otherwise bring back current
line to the last line for resubmission."
(interactive)
(beginning-of-line)
(let ((current-line (buffer-substring (point) (line-end-position))))
(if (eobp)
(progn
(if (not subprocess-running)
(start-subprocess))
(if subprocess-running
(progn
(beginning-of-line)
(send-command-to-subprocess 1 current-line)
(if command-prefix-string
(progn (beginning-of-line) (insert command-prefix-string)))
(next-line 1))))
(goto-char (point-max))
(backward-char)
(next-line 1)
(insert
(if (compare-strings command-prefix-string nil nil
current-line 0 (length command-prefix-string))
(substring current-line (length command-prefix-string))
current-line)))))
(defun command-kill-line ()
"Kill the current line. Used in command mode."
(interactive)
(beginning-of-line)
(kill-line))
(define-key esc-map "$" 'subprocess-command)