chibi-scheme/lib/chibi/trace.scm
2021-05-06 10:17:03 +09:00

101 lines
3 KiB
Scheme

;; Table mapping traced procedures to their original untraced values.
(define all-traces
(make-parameter (make-hash-table eq?)))
;; The current number of traced procedure frames on the stack.
(define active-trace-depth
(make-parameter 0))
(define (show-trace cell args)
(let ((out (current-error-port)))
(do ((i 0 (+ i 1)))
((>= i (active-trace-depth)))
(display "| " out))
(display "> " out)
(write/ss (cons (car cell) args) out)
(newline out)))
(define (show-trace-result cell args res)
(let ((out (current-error-port)))
(do ((i 0 (+ i 1)))
((>= i (active-trace-depth)))
(display "| " out))
(write/ss res out)
(newline out)))
(define (make-tracer cell)
(let ((proc (cdr cell)))
(if (macro? proc)
(make-macro
(lambda (expr use-env mac-env)
(show-trace cell (strip-syntactic-closures (cdr expr)))
(active-trace-depth (+ (active-trace-depth) 1))
(let ((res ((macro-procedure proc) expr use-env mac-env)))
(active-trace-depth (- (active-trace-depth) 1))
(show-trace-result cell
(strip-syntactic-closures (cdr expr))
(strip-syntactic-closures res))
res))
(macro-env proc))
(lambda args
(show-trace cell args)
(active-trace-depth (+ (active-trace-depth) 1))
(let ((res (apply proc args)))
(active-trace-depth (- (active-trace-depth) 1))
(show-trace-result cell args res)
res)))))
;;> Write a trace of all calls to the procedure \var{id} to
;;> \scheme{(current-error-port)}.
(define-syntax trace
(syntax-rules ()
((trace id)
(trace-cell (env-cell (interaction-environment) 'id)))))
;;> Remove any active traces on the procedure \var{id}.
(define-syntax untrace
(syntax-rules ()
((untrace id)
(untrace-cell (env-cell (interaction-environment) 'id)))))
(define (warn . args)
(let ((out (current-error-port)))
(display "WARNING: " out)
(for-each (lambda (x) (display x out)) args)
(newline out)))
;;> Trace a specific environment cell.
(define (trace-cell cell)
(let ((tab (all-traces)))
(cond
((not (pair? cell))
(warn "No such binding."))
((hash-table-exists? tab cell)
(warn "Procedure already being traced: " (car cell)))
(else
(hash-table-set! tab cell (cdr cell))
(set-cdr! cell (make-tracer cell))))))
;;> Untrace an environment cell.
(define (untrace-cell cell)
(let ((tab (all-traces)))
(cond
((not (pair? cell))
(warn "No such binding."))
((not (hash-table-exists? tab cell))
(warn "Procedure not being traced: " (car cell)))
(else
(let ((proc (hash-table-ref tab cell)))
(hash-table-delete! tab cell)
(set-cdr! cell proc))))))
;;> Remove all active procedure traces.
(define (untrace-all)
(hash-table-walk (all-traces) (lambda (cell proc) (set-cdr! cell proc)))
(all-traces (make-hash-table eq?)))