;;; **********************************************************************
;;; This code was written as part of the Spice Lisp project at
;;; Carnegie-Mellon University, and has been placed in the public domain.
;;; Spice Lisp is currently incomplete and under active development.
;;; If you want to use this code or any part of Spice Lisp, please contact
;;; Scott Fahlman (FAHLMAN@CMUC).
;;; **********************************************************************
;;;
;;; Spice Lisp Function Stepper
;;; these functions are part of the standard Spice Lisp environment.
;;;
;;; Written by Jim Large
;;;
;;; Maintained by Steven Handerson
;;;
;;; **********************************************************************
(proclaim '(special
*evalhook* ;function which subs for eval
Step-state ;On, off (aborted), or sleeping
step-indentation-level ;# of spaces to indent step output
))
(defvar *step-print-level* 4
"*Print-level* is bound to this when stepper prints forms.")
(defvar *step-print-length* 5
"*Print-length* is bound to this when stepper prints forms.")
(defvar *max-step-indentation* 40
"The maximum number of spaces that step output may be indented.")
(defvar *terminal-line-mode* nil
"When nil, step will not require a terminating end-of-line for commands.")
(defvar step-state nil
"Step's memory. Nil means off, T means on. A list of functions is a
search list. A non-symbol means step is asleep.")
(defvar step-indentation-level 0
"Makes the step facilities prinout nicer.")
(eval-when (compile eval)
(defmacro step-off-p ()
'(null step-state))
(defmacro step-on-p ()
'(eq step-state t))
(defmacro awaken-stepper ()
'(setq step-state t
*evalhook* #'step-command-loop
step-indentation-level 0))
(defmacro abort-stepper ()
'(setq Step-state nil))
(defmacro sleep-stepper (&optional (functions 0))
`(setq step-state ,functions
*evalhook* #'step-command-loop
step-indentation-level 0))
(defmacro step-search-list ()
`(and (listp step-state) step-state))
)
;;; Flushes whitespace.
(eval-when (compile load)
(defmacro step-get-char-CR ()
`(do ((char (read-char *query-io*) (read-char *query-io*)))
((not (member char '(#\return #\tab #\space #\linefeed)))
char))))
#-perq
(defmacro step-get-char () '(step-get-char-CR))
#+perq
(defmacro step-get-char ()
`(cond (*terminal-line-mode* (step-get-char-CR))
(t (finish-output *standard-output*)
(multiple-value-bind (ignore char) (get-event 2)
(declare (ignore ignore))
(terpri *standard-output*)
char))))
(defmacro step-step-form (form environment)
`(let ((results
(multiple-value-list
(apply #'evalhook ,form #'step-command-loop () ,environment))))
(step-print-values results)
(values-list results)))
(defmacro step-eval-form (form environment)
`(let ((results
(multiple-value-list
(apply #'*eval ,form ,environment))))
(step-print-values results)
(values-list results)))
;;; Step-Help
;;;
;;; Usage of return, linefeed differs from that of maclisp.
;;; Step help is called to print a help message on the console.
(defun step-help ()
(princ "
Commands are single characters. If you don't like (linmode nil), then
(setq *terminal-line-mode* t).
N (next) also space evaluate current expression in step mode.
S (skip) CR, tab '' '' '' without stepping.
M (macro) steps a macroexpansion, signaled by a :: prompt.
Q (quit) linefeed finish evaluation, but turn stepper off.
P (print) print current exp
(ignore *step-print-level* & *step-print-length*.)
↑P pretty-print current exp
B (break) enter break loop.
E (eval) evaluate an arbitrary expression,
in the current environment.
? (help) print this text.
R (return) prompt for an arbitrary value to return
as result of current exp.
G throw to top level.
" *standard-output*))
;;; Step-Print
;;; Step-print is called to print a form according to the current indentation
;;; level, and according to *step-print-level* and *step-print-length*.
(defun step-print (form)
(do ((*print-level* *step-print-level*)
(*print-length* *step-print-length*)
(i (min step-indentation-level *max-step-indentation*)
(1- i)))
((zerop i) (prin1 form *standard-output*))
(princ " " *standard-output*)))
;;; Step-print-values is called to print a list of values which were returned
;;; from an evaluation.
(defun step-print-values (value-list)
(fresh-line *standard-output*) ;In case of prints.
(if (not (null value-list)) (step-print (car value-list)))
(do ((*print-level* *step-print-level*)
(*print-length* *step-print-length*)
(vlist (cdr value-list) (cdr vlist)))
((null vlist) (terpri *standard-output*))
(princ " " *standard-output*)
(prin1 (car vlist) *standard-output*)))
;;; Step-Command-Loop
;;;
;;; Step-command-loop is a substitute for *eval. It prints the form, and
;;; then enters a command loop. The commands are read as single characters
;;; from the terminal. If the stepper has subsequently been turned off,
;;; do the equivalent of the s command without printing.
(defun step-command-loop (form &rest environment)
(cond
;; If aborted, just eval it.
((step-off-p) (apply #'*eval form environment))
((or (step-on-p)
(And (listp form)
(member (car form) (step-search-list))))
;;Otherwise, bind indent level, print form, and enter command loop.
(let ((step-indentation-level (1+ step-indentation-level)))
(cond ((or (symbolp form)
(constantp form)) ;Could be quoted.
(step-print form)
(princ " = " *standard-output*)
(prog1
(prin1 (apply #'*eval form environment) *standard-output*)
(terpri *standard-output*)))
(t (prog ()
TOP
(step-print form)
NO-PRINT
(if (and (listp form)
(macrop (car form)))
(princ " :: " *standard-output*) ;Notify the user for expansion.
(princ " : " *standard-output*))
NO-PROMPT
(case (step-get-char)
((#\m #\M)
(return (step-step-form form environment)))
((#\n #\N #\space)
(cond ((and (listp form)
(macrop (car form)))
(setq form
(macroexpand form environment))
(go TOP))
(t (return
(step-step-form form environment)))))
((#\s #\S #\return #\tab)
(return (step-eval-form form environment)))
((#\q #\Q #\linefeed) (abort-stepper)
(return (apply #'*eval form
environment)))
((#\p) (prin1 form *standard-output*) (go NO-PRINT))
((#\P) (pprint form *standard-output*) (go NO-PRINT))
((#\b #\B) (break "Step") (terpri *standard-output*))
((#\e #\E) (princ "eval: " *query-io*)
(let ((*evalhook* ()))
(prin1 (apply #'*eval (read *query-io*)
environment)
*standard-output*)
(terpri *standard-output*)))
((#\?) (step-help))
((#\r #\R)
(princ "return: " *standard-output*)
(let* ((*evalhook* ())
(results (multiple-value-list
(apply #'*eval (read) environment))))
(step-print-values results)
(return (values-list results))))
((#\g #\G) (throw 'top-level-catcher ()))
(T (princ "Type ? for help. " *standard-output*)
(clear-input *standard-output*)
(go NO-PROMPT)))
(go TOP))))))
;; Haven't found one yet.
(t (apply #'evalhook form #'step-command-loop () environment))))
;;; Step
;;; Nice to know, but not an error.
(defun step-parse-functions (list)
"Picks out functions from the list, and tells the user about those that
weren't."
(do* ((list list (Cdr list))
(functions ())
(non-functions ()))
((null list)
(if non-functions
(format *error-output* "Non-functions ignored - ~S" non-functions))
functions)
(if (and (symbolp (car list))
(fboundp (Car list)))
(setq functions (cons (car list) functions))
(setq non-functions (cons (car list) non-functions)))))
;;; (Step form) is a special form which "invokes the stepper".
;;; If no form, set up the stepper for being turned on inside a break loop.
;;; If form is T, turn the stepper on,
;;; (), '' '' '' off,
;;; (step &rest functions) looks for any of the functions and steps on them.
;;;
(Defun step fexpr (forms)
"With arg T or (), turns stepper on or off. (Step) at top-level lets
a (step t) in a break loop turn on stepping globally. With a list of
functions, turns on stepping when any are called. Otherwise, the arg
is evaled with stepper bound on."
(cond
((null forms) (sleep-stepper) T)
((equal forms '(nil)) (abort-stepper) nil)
((equal forms '(t)) (awaken-stepper) T)
((symbolp (car forms)) ;Check if function
(let ((functions (step-parse-functions forms)))
(sleep-stepper functions)
functions))
(T (let ((*evalhook* #'step-command-loop)
(step-state t)
(step-indentation-level 0))
(eval (car forms))))))