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(define-module (ice-9 debugger utils)
#:use-module (ice-9 debugger state)
#:export (display-position
source-position
write-frame-args-long
write-frame-index-long
write-frame-short/expression
write-frame-short/application
write-frame-long
write-state-long
write-state-short))
;;; Procedures in this module print information about a stack frame.
;;; The available information is as follows.
;;;
;;; * Source code location.
;;;
;;; For an evaluation frame, this is the location recorded at the time
;;; that the expression being evaluated was read, if the 'positions
;;; read option was enabled at that time.
;;;
;;; For an application frame, I'm not yet sure. Some applications
;;; seem to have associated source expressions.
;;;
;;; * Whether frame is still evaluating its arguments.
;;;
;;; Only applies to an application frame. For example, an expression
;;; like `(+ (* 2 3) 4)' goes through the following stages of
;;; evaluation.
;;;
;;; (+ (* 2 3) 4) -- evaluation
;;; [+ ... -- application; the car of the evaluation
;;; has been evaluated and found to be a
;;; procedure; before this procedure can
;;; be applied, its arguments must be evaluated
;;; [+ 6 ... -- same application after evaluating the
;;; first argument
;;; [+ 6 4] -- same application after evaluating all
;;; arguments
;;; 10 -- result
;;;
;;; * Whether frame is real or tail-recursive.
;;;
;;; If a frame is tail-recursive, its containing frame as shown by the
;;; debugger backtrace doesn't really exist as far as the Guile
;;; evaluator is concerned. The effect of this is that when a
;;; tail-recursive frame returns, it looks as though its containing
;;; frame returns at the same time. (And if the containing frame is
;;; also tail-recursive, _its_ containing frame returns at that time
;;; also, and so on ...)
;;;
;;; A `real' frame is one that is not tail-recursive.
(define (write-state-short state)
(let* ((frame (stack-ref (state-stack state) (state-index state)))
(source (frame-source frame))
(position (and source (source-position source))))
(format #t "Frame ~A at " (frame-number frame))
(if position
(display-position position)
(display "unknown source location"))
(newline)
(write-char #\tab)
(write-frame-short frame)
(newline)))
(define (write-state-short* stack index)
(write-frame-index-short stack index)
(write-char #\space)
(write-frame-short (stack-ref stack index))
(newline))
(define (write-frame-index-short stack index)
(let ((s (number->string (frame-number (stack-ref stack index)))))
(display s)
(write-char #\:)
(write-chars #\space (- 4 (string-length s)))))
(define (write-frame-short frame)
(if (frame-procedure? frame)
(write-frame-short/application frame)
(write-frame-short/expression frame)))
(define (write-frame-short/application frame)
(write-char #\[)
(write (let ((procedure (frame-procedure frame)))
(or (and (procedure? procedure)
(procedure-name procedure))
procedure)))
(if (frame-evaluating-args? frame)
(display " ...")
(begin
(for-each (lambda (argument)
(write-char #\space)
(write argument))
(frame-arguments frame))
(write-char #\]))))
;;; Use builtin function instead:
(set! write-frame-short/application
(lambda (frame)
(display-application frame (current-output-port) 12)))
(define (write-frame-short/expression frame)
(write (let* ((source (frame-source frame))
(copy (source-property source 'copy)))
(if (pair? copy)
copy
(unmemoize-expr source)))))
(define (write-state-long state)
(let ((index (state-index state)))
(let ((frame (stack-ref (state-stack state) index)))
(write-frame-index-long frame)
(write-frame-long frame))))
(define (write-frame-index-long frame)
(display "Stack frame: ")
(write (frame-number frame))
(if (frame-real? frame)
(display " (real)"))
(newline))
(define (write-frame-long frame)
(if (frame-procedure? frame)
(write-frame-long/application frame)
(write-frame-long/expression frame)))
(define (write-frame-long/application frame)
(display "This frame is an application.")
(newline)
(if (frame-source frame)
(begin
(display "The corresponding expression is:")
(newline)
(display-source frame)
(newline)))
(display "The procedure being applied is: ")
(write (let ((procedure (frame-procedure frame)))
(or (and (procedure? procedure)
(procedure-name procedure))
procedure)))
(newline)
(display "The procedure's arguments are")
(if (frame-evaluating-args? frame)
(display " being evaluated.")
(begin
(display ": ")
(write (frame-arguments frame))))
(newline))
(define (display-source frame)
(let* ((source (frame-source frame))
(copy (source-property source 'copy)))
(cond ((source-position source)
=> (lambda (p) (display-position p) (display ":\n"))))
(display " ")
(write (or copy (unmemoize-expr source)))))
(define (source-position source)
(let ((fname (source-property source 'filename))
(line (source-property source 'line))
(column (source-property source 'column)))
(and fname
(list fname line column))))
(define (display-position pos)
(format #t "~A:~D:~D" (car pos) (+ 1 (cadr pos)) (+ 1 (caddr pos))))
(define (write-frame-long/expression frame)
(display "This frame is an evaluation.")
(newline)
(display "The expression being evaluated is:")
(newline)
(display-source frame)
(newline))
(define (write-frame-args-long frame)
(if (frame-procedure? frame)
(let ((arguments (frame-arguments frame)))
(let ((n (length arguments)))
(display "This frame has ")
(write n)
(display " argument")
(if (not (= n 1))
(display "s"))
(write-char (if (null? arguments) #\. #\:))
(newline))
(for-each (lambda (argument)
(display " ")
(write argument)
(newline))
arguments))
(begin
(display "This frame is an evaluation frame; it has no arguments.")
(newline))))
(define (write-chars char n)
(do ((i 0 (+ i 1)))
((>= i n))
(write-char char)))
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