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Update `trace' docs.

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- Move trace implementation to racket/trace.
- Move documentation to new Debugging section in Reference.
- Add example.

original commit: 12f30cf4782d6baa4707f05f95c9e19021685d66
This commit is contained in:
Sam Tobin-Hochstadt 2010-06-27 19:13:33 -04:00
parent fbdc41a561
commit f163787145
1 changed files with 3 additions and 267 deletions
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270
collects/mzlib/trace.rkt
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@ -1,268 +1,4 @@
#lang scheme/base
#lang racket/base
(require scheme/pretty
(for-syntax scheme/base))
(provide trace untrace
current-trace-print-args trace-call
current-trace-notify
current-prefix-out current-prefix-in)
(define max-dash-space-depth 10)
(define number-nesting-depth 6)
(define current-prefix-out (make-parameter "<"))
(define current-prefix-in (make-parameter ">"))
(define (as-spaces s)
(make-string (string-length s) #\space))
(define-struct prefix-entry (for-first for-rest))
(define prefixes (make-hash))
(define (lookup-prefix n label)
(hash-ref prefixes (cons n label) (lambda () #f)))
(define (insert-prefix n label first rest)
(hash-set! prefixes (cons n label) (make-prefix-entry first rest)))
(define (construct-prefixes level label)
(let loop ([n level]
[first (list label)]
[rest '(" ")])
(if (>= n max-dash-space-depth)
(let-values ([(pre-first pre-rest)
(build-prefixes number-nesting-depth label)])
(let ((s (number->string level)))
(values
(string-append pre-first "[" s "] ")
(string-append pre-rest " " (as-spaces s) " "))))
(cond
[(= n 0) (values (apply string-append (reverse first))
(apply string-append (reverse rest)))]
[(= n 1) (loop (- n 1)
(cons '" " first)
(cons '" " rest))]
[else (loop (- n 2)
(cons (format " ~a" label) first)
(cons " " rest))]))))
(define (build-prefixes level label)
(let ([p (lookup-prefix level label)])
(if p
(values (prefix-entry-for-first p)
(prefix-entry-for-rest p))
(let-values (((first rest)
(construct-prefixes level label)))
(insert-prefix level label first rest)
(values first rest)))))
(define current-trace-notify
(make-parameter (lambda (s)
(display s)
(newline))
(lambda (p)
(unless (and (procedure? p)
(procedure-arity-includes? p 1))
(raise-type-error 'current-trace-notify
"procedure (arity 1)"
p))
p)))
(define (as-trace-notify thunk)
(let ([p (open-output-bytes)])
(parameterize ([current-output-port p])
(thunk))
(let ([b (get-output-bytes p #t 0
;; drop newline:
(sub1 (file-position p)))])
((current-trace-notify) (bytes->string/utf-8 b)))))
(define -:trace-print-args
(lambda (name args kws kw-vals level)
(as-trace-notify
(lambda ()
((current-trace-print-args) name args kws kw-vals level)))))
(define current-trace-print-args
(make-parameter
(lambda (name args kws kw-vals level)
(let-values (((first rest)
(build-prefixes level (current-prefix-in))))
(parameterize ((pretty-print-print-line
(lambda (n port offset width)
(display
(if n
(if (zero? n) first
(format "~n~a" rest))
(format "~n"))
port)
(if n
(if (zero? n)
(string-length first)
(string-length rest))
0))))
(pretty-print (append (cons name args)
(apply append (map list kws kw-vals)))))))))
(define -:trace-print-results
(lambda (name results level)
(as-trace-notify
(lambda ()
(trace-print-results name results level)))))
(define trace-print-results
(lambda (name results level)
(let-values (((first rest)
(build-prefixes level (current-prefix-out))))
(parameterize ((pretty-print-print-line
(lambda (n port offset width)
(display
(if n
(if (zero? n) first
(format "~n~a" rest))
(format "~n"))
port)
(if n
(if (zero? n)
(string-length first)
(string-length rest))
0))))
(cond
((null? results)
(pretty-display "*** no values ***"))
((null? (cdr results))
(pretty-print (car results)))
(else
(pretty-print (car results))
(parameterize ((pretty-print-print-line
(lambda (n port offset width)
(display
(if n
(if (zero? n) rest
(format "~n~a" rest))
(format "~n"))
port)
(if n
(string-length rest)
0))))
(for-each pretty-print (cdr results)))))))))
;; A traced-proc struct instance acts like a procedure,
;; but preserves the original, too.
(define-values (struct:traced-proc make-traced-proc traced-proc? traced-proc-ref traced-proc-set!)
(make-struct-type 'traced-proc #f 2 0 #f null (current-inspector) 0))
;; Install traced versions of a given set of procedures. The traced
;; versions are also given, so that they can be constructed to have
;; a nice name.
(define (do-trace ids procs setters traced-procs)
(for-each (lambda (id proc)
(unless (procedure? proc)
(error 'trace
"the value of ~s is not a procedure: ~e" id proc)))
ids procs)
(for-each (lambda (proc setter traced-proc)
(unless (traced-proc? proc)
(setter (make-traced-proc
(let-values ([(a) (procedure-arity proc)]
[(req allowed) (procedure-keywords proc)])
(procedure-reduce-keyword-arity traced-proc
a
req
allowed))
proc))))
procs setters traced-procs))
;; Key used for a continuation mark to indicate
;; the nesting depth:
(define -:trace-level-key (gensym))
(define trace-call
(make-keyword-procedure
(lambda (id f kws vals . args)
(do-traced id args kws vals f))
(lambda (id f . args)
(do-traced id args '() '() f))))
;; Apply a traced procedure to arguments, printing arguments
;; and results. We set and inspect the -:trace-level-key continuation
;; mark a few times to detect tail calls.
(define (do-traced id args kws kw-vals real-value)
(let* ([levels (continuation-mark-set->list
(current-continuation-marks)
-:trace-level-key)]
[level (if (null? levels) 0 (car levels))])
;; Tentatively push the new depth level:
(with-continuation-mark -:trace-level-key (add1 level)
;; Check for tail-call => car of levels replaced,
;; which means that the first two new marks are
;; not consecutive:
(let ([new-levels (continuation-mark-set->list
(current-continuation-marks)
-:trace-level-key)])
(if (and (pair? (cdr new-levels))
(> (car new-levels) (add1 (cadr new-levels))))
;; Tail call: reset level and just call real-value.
;; (This is in tail position to the call to `do-traced'.)
;; We don't print the results, because the original
;; call will.
(begin
(-:trace-print-args id args kws kw-vals (sub1 level))
(with-continuation-mark -:trace-level-key (car levels)
(if (null? kws)
(apply real-value args)
(keyword-apply real-value kws kw-vals args))))
;; Not a tail call; push the old level, again, to ensure
;; that when we push the new level, we have consecutive
;; levels associated with the mark (i.e., set up for
;; tail-call detection the next time around):
(begin
(-:trace-print-args id args kws kw-vals level)
(with-continuation-mark -:trace-level-key level
(call-with-values
(lambda ()
(with-continuation-mark -:trace-level-key (add1 level)
(if (null? kws)
(apply real-value args)
(keyword-apply real-value kws kw-vals args))))
(lambda results
(flush-output)
;; Print the results:
(-:trace-print-results id results level)
;; Return the results:
(apply values results))))))))))
(define-for-syntax (check-ids stx ids)
(for ([id (in-list (syntax->list ids))])
(unless (identifier? id)
(raise-syntax-error #f "not an identifier" stx id)))
#t)
(define-syntax (trace stx)
(syntax-case stx ()
[(_ id ...) (check-ids stx #'(id ...))
(with-syntax ([(tid ...)
(for/list ([id (in-list (syntax->list #'(id ...)))])
(let ([tid (format "traced-~a" (syntax-e id))])
(datum->syntax id (string->symbol tid) #f)))])
#'(do-trace
'(id ...)
(list id ...)
(list (lambda (v) (set! id v)) ...)
(list (let* ([real-value id]
[tid (make-keyword-procedure
(lambda (kws vals . args)
(do-traced 'id args kws vals real-value))
(lambda args
(do-traced 'id args null null real-value)))])
tid)
...)))]))
(define-syntax (untrace stx)
(syntax-case stx ()
[(_ id ...) (check-ids stx #'(id ...))
#'(begin (when (traced-proc? id)
(set! id (traced-proc-ref id 1)))
...)]))
(require racket/trace)
(provide (all-from-out racket/trace))