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|
;;; -*-Scheme-*-
;;;
;;; A simple debugger (improvements by Thomas M. Breuel <tmb@ai.mit.edu>).
(define (backtrace . args)
(if (> (length args) 1)
(error 'backtrace "too many arguments"))
(if (not (null? args))
(if (not (eq? (type (car args)) 'control-point))
(error 'backtrace "argument must be a control point")))
(let ((trace (apply backtrace-list args)))
(if (null? args)
(set! trace (cdddr trace)))
(show-backtrace trace 0 999999)))
(define (show-backtrace trace start-frame end-frame)
(define (rjust n x)
(let* ((y (string-append (make-string n #\space) x))
(l (string-length y)))
(substring y (- l n) l)))
(let ((maxlen 28))
(let loop ((frames (list-tail trace start-frame)) (num start-frame))
(if (or (null? frames) (>= num end-frame)) #v
(let ((frame (car frames)))
(let* ((func
(format #f "~s" (vector-ref frame 0)))
(indent
(- maxlen (+ 5 (string-length func)))))
(display (rjust 4 (number->string num)))
(display " ")
(display func)
(if (negative? indent)
(begin
(newline)
(set! indent maxlen)))
(do ((i indent (1- i)))
((> 0 i))
(display " ")))
(fluid-let
((print-depth 2)
(print-length 3))
(display (vector-ref frame 1)))
(newline))
(loop (cdr frames) (1+ num))))))
(define (show-environment env)
(fluid-let
((print-length 2)
(print-depth 2))
(do ((f (environment->list env) (cdr f)))
((null? f))
(do ((b (car f) (cdr b)))
((null? b))
(format #t "~s\t~s~%" (caar b) (cdar b)))
(print '-------)))
#v)
(define inspect)
(let ((frame)
(trace)
(help-text
'("q -- quit inspector"
"f -- print current frame"
"u -- go up one frame"
"d -- go down one frame"
"^ -- go to top frame"
"$ -- go to bottom frame"
"g <n> -- goto to n-th frame"
"e -- eval expressions in environment"
"p -- pretty-print procedure"
"v -- show environment"
"<n> -- pretty-print n-th argument"
"b -- show backtrace starting at current frame"
"t -- show top of bracktrace starting at current frame"
"z -- show and move top of backtrace starting at current frame"
"o -- obarray information")))
(define (inspect-command-loop)
(let ((input) (done #f))
(display "inspect> ")
(set! input (read))
(case input
(q
(set! done #t))
(?
(for-each
(lambda (msg)
(display msg)
(newline))
help-text))
(f
(print-frame))
(^
(set! frame 0)
(print-frame))
($
(set! frame (1- (length trace)))
(print-frame))
(u
(if (zero? frame)
(format #t "Already on top frame.~%")
(set! frame (1- frame))
(print-frame)))
(d
(if (= frame (1- (length trace)))
(format #t "Already on bottom frame.~%")
(set! frame (1+ frame))
(print-frame)))
(g
(set! input (read))
(if (integer? input)
(set! frame
(cond ((negative? input) 0)
((>= input (length trace)) (1- (length trace)))
(else input)))
(format #t "Frame number must be an integer.~%")))
(v
(show-environment (vector-ref (list-ref trace frame) 2)))
(e
(format #t "Type ^D to return to Inspector.~%")
(let loop ()
(display "eval> ")
(set! input (read))
(if (not (eof-object? input))
(begin
(write (eval input
(vector-ref (list-ref trace frame) 2)))
(newline)
(loop))))
(newline))
(p
(pp (vector-ref (list-ref trace frame) 0))
(newline))
(z
(show-backtrace trace frame (+ frame 10))
(set! frame (+ frame 9))
(if (>= frame (length trace)) (set! frame (1- (length trace)))))
(t
(show-backtrace trace frame (+ frame 10)))
(b
(show-backtrace trace frame 999999))
(o
(let ((l (map length (oblist))))
(let ((n 0))
(for-each (lambda (x) (set! n (+ x n))) l)
(format #t "~s symbols " n)
(format #t "(maximum bucket: ~s).~%" (apply max l)))))
(else
(cond
((integer? input)
(let ((args (vector-ref (list-ref trace frame) 1)))
(if (or (< input 1) (> input (length args)))
(format #t "No such argument.~%")
(pp (list-ref args (1- input)))
(newline))))
((eof-object? input)
(set! done #t))
(else
(format #t "Invalid command. Type ? for help.~%")))))
(if (not done)
(inspect-command-loop))))
(define (print-frame)
(format #t "~%Frame ~s of ~s:~%~%" frame (1- (length trace)))
(let* ((f (list-ref trace frame)) (args (vector-ref f 1)))
(format #t "Procedure: ~s~%" (vector-ref f 0))
(format #t "Environment: ~s~%" (vector-ref f 2))
(if (null? args)
(format #t "No arguments.~%")
(fluid-let
((print-depth 2)
(print-length 3))
(do ((i 1 (1+ i)) (args args (cdr args))) ((null? args))
(format #t "Argument ~s: ~s~%" i (car args))))))
(newline))
(define (find-frame proc)
(let loop ((l trace) (i 0))
(cond ((null? l) -1)
((eq? (vector-ref (car l) 0) proc) i)
(else (loop (cdr l) (1+ i))))))
(set! inspect
(lambda ()
(set! trace (backtrace-list))
(set! trace (cddr trace))
(do ((t trace (cdr t)) (f 1 (1+ f))) ((null? t))
(if (not (null? (vector-ref (car t) 1)))
(let ((last (last-pair (vector-ref (car t) 1))))
(if (not (null? (cdr last)))
(begin
(format #t
"[inspector: fixing improper arglist in frame ~s]~%" f)
(set-cdr! last (cons (cdr last) '())))))))
(set! frame (find-frame error-handler))
(if (negative? frame)
(set! frame 0))
(format #t "Inspector (type ? for help):~%")
(let loop ()
(if (call-with-current-continuation
(lambda (control-point)
(push-frame control-point)
(inspect-command-loop)
#f))
(begin
(pop-frame)
(loop))))
(newline)
(pop-frame)
(let ((next-frame (car rep-frames)))
(next-frame #t)))))
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