- (- nil)
- (+ nil) (++ nil) (+++ nil)
- (/// nil) (// nil) (/ nil)
- (eof-marker (cons :eof nil)))
- (loop
- (/show0 "at head of outer LOOP in TOPLEVEL-REPL")
- ;; There should only be one TOPLEVEL restart, and it's here, so
- ;; restarting at TOPLEVEL always bounces you all the way out here.
- (with-simple-restart (toplevel
- "Restart at toplevel READ/EVAL/PRINT loop.")
- ;; We add a new ABORT restart for every debugger level, so
- ;; restarting at ABORT in a nested debugger gets you out to the
- ;; innermost enclosing debugger, and only when you're in the
- ;; outermost, unnested debugger level does restarting at ABORT
- ;; get you out to here.
- (with-simple-restart (abort
- "Reduce debugger level (leaving debugger).")
- (catch 'top-level-catcher
- (sb!unix:unix-sigsetmask 0) ; FIXME: What is this for?
- (/show0 "about to enter inner LOOP in TOPLEVEL-REPL")
- (loop ; FIXME: Do we need this inner LOOP?
- ;; FIXME: It seems bad to have GC behavior depend on scrubbing
- ;; the control stack before each interactive command. Isn't
- ;; there some way we can convince the GC to just ignore
- ;; dead areas of the control stack, so that we don't need to
- ;; rely on this half-measure?
- (scrub-control-stack)
- (unless noprint
- (fresh-line)
- (princ (if (functionp *prompt*)
- (funcall *prompt*)
- *prompt*))
- (flush-standard-output-streams))
- (let ((form (read *standard-input* nil eof-marker)))
- (if (eq form eof-marker)
- (quit)
- (let ((results
- (multiple-value-list (interactive-eval form))))
- (unless noprint
- (dolist (result results)
- (fresh-line)
- (prin1 result)))))))))))))
+ (- nil)
+ (+ nil) (++ nil) (+++ nil)
+ (/// nil) (// nil) (/ nil))
+ (/show0 "about to funcall *REPL-FUN-GENERATOR*")
+ (let ((repl-fun (funcall *repl-fun-generator*)))
+ ;; Each REPL in a multithreaded world should have bindings of
+ ;; most CL specials (most critically *PACKAGE*).
+ (with-rebound-io-syntax
+ (handler-bind ((step-condition 'invoke-stepper))
+ (loop
+ (/show0 "about to set up restarts in TOPLEVEL-REPL")
+ ;; CLHS recommends that there should always be an
+ ;; ABORT restart; we have this one here, and one per
+ ;; debugger level.
+ (with-simple-restart
+ (abort "~@<Exit debugger, returning to top level.~@:>")
+ (catch 'toplevel-catcher
+ #!-win32 (sb!unix::reset-signal-mask)
+ ;; In the event of a control-stack-exhausted-error, we
+ ;; should have unwound enough stack by the time we get
+ ;; here that this is now possible.
+ #!-win32
+ (sb!kernel::protect-control-stack-guard-page 1)
+ (funcall repl-fun noprint)
+ (critically-unreachable "after REPL")))))))))
+
+;;; Our default REPL prompt is the minimal traditional one.
+(defun repl-prompt-fun (stream)
+ (fresh-line stream)
+ (write-string "* " stream)) ; arbitrary but customary REPL prompt
+
+;;; Our default form reader does relatively little magic, but does
+;;; handle the Unix-style EOF-is-end-of-process convention.
+(defun repl-read-form-fun (in out)
+ (declare (type stream in out) (ignore out))
+ (let* ((eof-marker (cons nil nil))
+ (form (read in nil eof-marker)))
+ (if (eq form eof-marker)
+ (quit)
+ form)))
+
+(defun repl-fun (noprint)
+ (/show0 "entering REPL")
+ (loop
+ (unwind-protect
+ (progn
+ ;; (See comment preceding the definition of SCRUB-CONTROL-STACK.)
+ (scrub-control-stack)
+ (sb!thread::get-foreground)
+ (unless noprint
+ (flush-standard-output-streams)
+ (funcall *repl-prompt-fun* *standard-output*)
+ ;; (Should *REPL-PROMPT-FUN* be responsible for doing its own
+ ;; FORCE-OUTPUT? I can't imagine a valid reason for it not to
+ ;; be done here, so leaving it up to *REPL-PROMPT-FUN* seems
+ ;; odd. But maybe there *is* a valid reason in some
+ ;; circumstances? perhaps some deadlock issue when being driven
+ ;; by another process or something...)
+ (force-output *standard-output*))
+ (let* ((form (funcall *repl-read-form-fun*
+ *standard-input*
+ *standard-output*))
+ (results (multiple-value-list (interactive-eval form))))
+ (unless noprint
+ (dolist (result results)
+ (fresh-line)
+ (prin1 result)))))
+ ;; If we started stepping in the debugger we want to stop now.
+ (disable-stepping))))