-;;;; stream commands
-
-(defstruct (stream-command (:constructor make-stream-command
- (name &optional args))
- (:copier nil))
- (name nil :type symbol)
- (args nil :type list))
-(def!method print-object ((obj stream-command) str)
- (print-unreadable-object (obj str :type t :identity t)
- (prin1 (stream-command-name obj) str)))
-
-;;; Take a stream and wait for text or a command to appear on it. If
-;;; text appears before a command, return NIL, otherwise return a
-;;; command.
-;;;
-;;; We can't simply call the stream's misc method because NIL is an
-;;; ambiguous return value: does it mean text arrived, or does it mean
-;;; the stream's misc method had no :GET-COMMAND implementation? We
-;;; can't return NIL until there is text input. We don't need to loop
-;;; because any stream implementing :GET-COMMAND would wait until it
-;;; had some input. If the LISTEN fails, then we have some stream we
-;;; must wait on.
-(defun get-stream-command (stream)
- (let ((cmdp (funcall (ansi-stream-misc stream) stream :get-command)))
- (cond (cmdp)
- ((listen stream)
- nil)
- (t
- ;; This waits for input and returns NIL when it arrives.
- (unread-char (read-char stream) stream)))))
-\f