312 lines
16 KiB
Scheme
312 lines
16 KiB
Scheme
;step collector state machine (not yet implemented):
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;
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; datatype held-type = NO-HELD-STEP | SKIPPED-STEP | HELD(args)
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;
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; states: global state of held
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; global: held : held-type
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; edge-names: first, skipped-first, second, skipped-second, double, late-let
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;
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;transitions (& actions):
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;
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; held = NO-HELD-STEP :
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; first(x) : held := HELD(x)
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; skipped-first : held := SKIPPED-STEP
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; second(x) : trigger(NO-HELD-STEP, x), held := NO-HELD-STEP ; this happens when evaluating unannotated code
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; skipped-second : held := NO-HELD-STEP ; I believe this can also arise in unannotated code
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; double(x) : double-trigger(x), held := NO-HELD-STEP
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; late-let(x) : late-let-trigger(x), held := NO-HELD-STEP
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;
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; held = SOME(SKIPPED-STEP) :
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; first(x) : ERROR
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; skipped-first : ERROR
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; second(x) : held := NO-HELD-STEP ; this happens e.g. for evaluation of top-level var bound to a procedure
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; skipped-second : held := NO-HELD-STEP
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; double(x) : ERROR
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; late-let(x) : ERROR
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;
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; held = SOME(HELD(args))
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; first(x) : ERROR
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; skipped-first : ERROR
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; second(x) : trigger(HELD(args),x), held = NO-HELD-STEP
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; skipped-second : held = NO-HELD-STEP
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; double(x) : ERROR
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; late-let(x) : ERROR
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(module model mzscheme
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(require (lib "contract.ss")
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(lib "etc.ss")
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(lib "match.ss")
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(prefix a: "annotate.ss")
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(prefix r: "reconstruct.ss")
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"shared.ss"
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"marks.ss"
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"model-settings.ss"
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"macro-unwind.ss")
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(define program-expander-contract
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((-> void?) ; init
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((or/c eof-object? syntax? (cons/c string? any/c)) (-> void?) . -> . void?) ; iter
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. -> .
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void?))
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(provide/contract [go (program-expander-contract ; program-expander
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(step-result? . -> . void?) ; receive-result
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(or/c render-settings? false/c) ; render-settings
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boolean? ; track-inferred-names?
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string? ; language-level-name
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. -> .
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void?)])
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; go starts a stepper instance
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; see provide stmt for contract
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(define (go program-expander receive-result render-settings track-inferred-names? language-level-name)
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;; finished-exps: (listof (list/c syntax-object? (or/c number? false?)( -> any)))
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;; because of mutation, these cannot be fixed renderings, but must be re-rendered at each step.
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(define finished-exps null)
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(define/contract add-to-finished
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((-> syntax?) (or/c (listof natural-number/c) false/c) (-> any) . -> . void?)
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(lambda (exp-thunk lifting-indices getter)
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(set! finished-exps (append finished-exps (list (list exp-thunk lifting-indices getter))))))
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;; the "held" variables are used to store the "before" step.
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(define held-exp-list no-sexp)
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(define held-step-was-app? #f)
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(define held-finished-list null)
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(define basic-eval (current-eval))
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;; highlight-mutated-expressions :
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;; ((listof (list/c syntax? syntax?)) (listof (list/c syntax? syntax?)) . -> . (list/c (listof syntax?) (listof syntax?)))
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;; highlights changes occurring due to mutation. This function accepts the left-hand-side
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;; expressions and the right-hand-side expressions, and matches them against each other
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;; to see which ones have changed due to mutation, and highlights these.
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;; POSSIBLE RESEARCH POINT: if, say, (list 3 4) is mutated to (list 4 5), should the 4 & 5 be
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;; highlighted individually or should the list as a whole be highlighted. Is either one "wrong?"
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;; equivalences between reduction semantics?
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;;
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;; 2005-11-14: punting. just highlight the whole damn thing if there are any differences.
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;; in fact, just test for eq?-ness.
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#;(define (highlight-mutated-expressions lefts rights)
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(if (or (null? lefts) (null? rights))
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(list lefts rights)
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(let ([left-car (car lefts)]
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[right-car (car rights)])
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(if (eq? (syntax-property left-car 'user-source)
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(syntax-property right-car 'user-source))
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(let ([highlights-added (highlight-mutated-expression left-car right-car)]
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[rest (highlight-mutated-expressions (cdr lefts) (cdr rights))])
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(cons (cons (car highlights-added) (car rest))
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(cons (cadr highlights-added) (cadr rest))))))))
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;; highlight-mutated-expression: syntax? syntax? -> syntax?
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;; given two expressions, highlight 'em both if they differ at all.
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;; notes: wanted to use simple "eq?" test... but this will fail when a being-stepped definition (e.g.
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;; in a let) turns into a permanent one. We pay a terrible price for the lifting thing. And, for the fact
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;; that the highlighting follows from the reductions but can't obviously be deduced from them.
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#;(define (highlight-mutated-expression left right)
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(cond
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;; if either one is already highlighted, leave them alone.
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[(or (syntax-property left 'stepper-highlight)
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(syntax-property right 'stepper-highlight))
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(list left right)]
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;; first pass: highlight if not eq?. Should be broken for local-bound things
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;; as they pass into permanence.
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[(eq? left right)
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(list left right)]
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[else (list (syntax-property left 'stepper-highlight)
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(syntax-property right 'stepper-highlight))]))
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;; REDIVIDE MAKES NO SENSE IN THE NEW INTERFACE. THIS WILL BE DELETED AFTER BEING PARTED OUT.
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; redivide takes a list of sexps and divides them into the 'before', 'during', and 'after' lists,
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; where the before and after sets are maximal-length lists where none of the s-expressions contain
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; a highlight-placeholder
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; (->* ((listof syntax)) (list/c syntax syntax syntax))
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#;(define (redivide exprs)
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(letrec ([contains-highlight
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(lambda (expr)
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(or (syntax-property expr 'stepper-highlight)
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(syntax-case expr ()
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[(a . rest) (or (contains-highlight #`a) (contains-highlight #`rest))]
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[else #f])))])
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(let* ([list-length (length exprs)]
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[split-point-a (- list-length (length (or (memf contains-highlight exprs) null)))]
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[split-point-b (length (or (memf contains-highlight (reverse exprs)) null))])
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(if (<= split-point-b split-point-a)
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(error 'redivide-exprs "s-expressions did not contain the highlight-placeholder: ~v" (map syntax-object->hilite-datum exprs))
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(values (sublist 0 split-point-a exprs) ; before
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(sublist split-point-a split-point-b exprs) ; during
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(sublist split-point-b list-length exprs)))))) ; after
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; (redivide `(3 4 (+ (define ,highlight-placeholder) 13) 5 6))
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; (values `(3 4) `((+ (define ,highlight-placeholder) 13)) `(5 6))
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;
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; (redivide `(,highlight-placeholder 5 6))
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; (values `() `(,highlight-placeholder) `(5 6))
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;
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; (redivide `(4 5 ,highlight-placeholder ,highlight-placeholder))
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; (values `(4 5) `(,highlight-placeholder ,highlight-placeholder) `())
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;
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; (printf "will be errors:~n")
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; (equal? (redivide `(1 2 3 4))
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; error-value)
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;
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; (redivide `(1 2 ,highlight-placeholder 3 ,highlight-placeholder 4 5))
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; (values `(1 2) `(,highlight-placeholder 3 ,highlight-placeholder) `(4 5))
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(define (>>> x)
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(fprintf (current-output-port) ">>> ~v\n" x)
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x)
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(define break
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(opt-lambda (mark-set break-kind [returned-value-list #f])
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(let* ([mark-list (and mark-set (extract-mark-list mark-set))])
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(define (reconstruct-all-completed)
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(map (match-lambda
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[`(,source-thunk ,lifting-indices ,getter)
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(match (r:reconstruct-completed (source-thunk) lifting-indices getter render-settings)
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[#(exp #f) (first-of-one (unwind-no-highlight exp))]
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[#(exp #t) exp])])
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finished-exps))
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;; TO BE SCRAPPED
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#;(define (double-redivide finished-exps new-exprs-before new-exprs-after)
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(let*-values ([(before current after) (redivide new-exprs-before)]
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[(before-2 current-2 after-2) (redivide new-exprs-after)])
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(unless (equal? (map syntax-object->hilite-datum before)
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(map syntax-object->hilite-datum before-2))
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(error 'double-redivide "reconstructed before defs are not equal."))
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(unless (equal? (map syntax-object->hilite-datum after)
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(map syntax-object->hilite-datum after-2))
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(error 'double-redivide "reconstructed after defs are not equal."))
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(values (append finished-exps before) current current-2 after)))
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#;(printf "break called with break-kind: ~a ..." break-kind)
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(if (r:skip-step? break-kind mark-list render-settings)
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(begin
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#;(printf " but it was skipped!\n")
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(when (or (eq? break-kind 'normal-break)
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(eq? break-kind 'nomal-break/values)) ;; not sure about this...
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(set! held-exp-list skipped-step)))
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(begin
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#;(printf "and it wasn't skipped.\n")
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(case break-kind
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[(normal-break normal-break/values)
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(begin
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(when (and (eq? break-kind 'normal-break) returned-value-list)
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(error 'break "broken invariant: normal-break can't have returned values"))
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(set! held-finished-list (reconstruct-all-completed))
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(set! held-exp-list (unwind (r:reconstruct-left-side mark-list returned-value-list render-settings) #f))
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(set! held-step-was-app? (r:step-was-app? mark-list)))]
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[(result-exp-break result-value-break)
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(if (eq? held-exp-list skipped-step)
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; don't render if before step was a skipped-step
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(set! held-exp-list no-sexp)
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(let* ([new-finished-list (reconstruct-all-completed)]
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[reconstructed (unwind (r:reconstruct-right-side mark-list returned-value-list render-settings) #f)]
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[result
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(if (eq? held-exp-list no-sexp)
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;; in this case, there was no "before" step, due to
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;; unannotated code. In this case, we make the
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;; optimistic guess that none of the finished expressions
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;; were mutated. It would be somewhat painful to do a better
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;; job, and the stepper makes no guarantees in this case.
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(make-before-after-result
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(list #`(... ...))
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(append new-finished-list reconstructed)
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'normal)
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(let*-values
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([(step-kind) (if (and held-step-was-app?
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(eq? break-kind 'result-exp-break))
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'user-application
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'normal)]
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[(left-exps right-exps)
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;; write this later:
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#;(identify-changed (append held-finished-list held-exps) (append new-finished-list reconstructed))
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(values (append held-finished-list held-exp-list)
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(append new-finished-list reconstructed))])
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(make-before-after-result left-exps right-exps step-kind)))])
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(set! held-exp-list no-sexp)
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(receive-result result)))]
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[(double-break)
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;; a double-break occurs at the beginning of a let's evaluation.
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(when (not (eq? held-exp-list no-sexp))
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(error 'break-reconstruction
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"held-exp-list not empty when a double-break occurred"))
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(let* ([new-finished-list (reconstruct-all-completed)]
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[reconstruct-result (r:reconstruct-double-break mark-list render-settings)]
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[left-side (unwind (car reconstruct-result) #f)]
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[right-side (unwind (cadr reconstruct-result) #t)])
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;; add highlighting code as for other cases...
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(receive-result (make-before-after-result (append new-finished-list left-side)
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(append new-finished-list right-side)
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'normal)))]
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[(expr-finished-break)
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(unless (not mark-list)
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(error 'break "expected no mark-list with expr-finished-break"))
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;; in an expr-finished-break, the returned-vals hold (listof (list/c source lifting-index getter))
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;; this will now include define-struct breaks, for which the source is the source and the getter
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;; causes an error.
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(for-each (lambda (source/index/getter)
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(apply add-to-finished source/index/getter))
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returned-value-list)]
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[else (error 'break "unknown label on break")]))))))
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(define (step-through-expression expanded expand-next-expression)
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(let* ([annotated (a:annotate expanded break track-inferred-names? language-level-name)])
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(eval-syntax annotated)
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(expand-next-expression)))
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(define (err-display-handler message exn)
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(if (not (eq? held-exp-list no-sexp))
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(begin
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(receive-result (make-before-error-result (append held-finished-list held-exp-list)
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message))
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(set! held-exp-list no-sexp))
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(receive-result (make-error-result message))))
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(program-expander
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(lambda ()
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; swap these to allow errors to escape (e.g., when debugging)
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(error-display-handler err-display-handler)
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#;(void)
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)
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(lambda (expanded continue-thunk) ; iter
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(if (eof-object? expanded)
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(begin
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(receive-result (make-finished-stepping)))
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(step-through-expression expanded continue-thunk)))))
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(define (first-of-one x)
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(unless (and (pair? x) (null? (cdr x)))
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(error 'first-of-one "expected a list of length one in: ~v" x))
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(car x)))
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