diff options
Diffstat (limited to 'main.rkt')
| -rw-r--r-- | main.rkt | 55 |
1 files changed, 28 insertions, 27 deletions
@@ -1,8 +1,11 @@ #lang racket/base +(require pict) (require racket/gui/base) (require racket/format) +(require racket/function) +(require racket/match) (require racket/contract) -(require pict) +(require tojoqk/amb) (define CELL-SIZE 30) (define ARROW-LENGTH 40) @@ -69,49 +72,47 @@ (cc-superimpose (cellophane (filled-rectangle CELL-SIZE CELL-SIZE) 0) (text (~a x)))) - (define (cdr* lst) (if (null? lst) '() (cdr lst))) -(define (pict-sexp/helper sexp height-list fail) +(define (%pict-sexp sexp height-list) (when (and (pair? height-list) (<= 0 (car height-list))) - (fail)) + (amb)) (cond [(pair? sexp) - (let*-values ([(cell) (pict-cons-cell sexp)] - [(cell-1 height-list) + (let*-values ([(p) (pict-cons-cell sexp)] + [(p-1 height-list) (cond [(need-arrow? (cdr sexp)) (let-values ([(pict-cdr cdr-height-list) - (pict-sexp/helper (cdr sexp) - (cdr* height-list) - fail)]) - (values (arrow-from-cdr cell pict-cdr) + (%pict-sexp (cdr sexp) (cdr* height-list))]) + (values (arrow-from-cdr p pict-cdr) (cons 0 cdr-height-list)))] - [else (values cell (cons 0 (cdr* height-list)))])] - [(cell-2 height-list) + [else (values p (cons 0 (cdr* height-list)))])] + [(p-2 height-list) (cond [(need-arrow? (car sexp)) - (let retry ([len 1] [height-list (map sub1 height-list)]) - (let/cc escape - (let/cc fail - (let-values ([(pict-car height-list) - (pict-sexp/helper (car sexp) - height-list - fail)]) - (escape (arrow-from-car len cell pict-car) - (map (λ (x) (+ x len)) height-list)))) - (retry (add1 len) (map sub1 height-list))))] - [else (values cell height-list)])]) - (values (lt-superimpose cell-1 cell-2) height-list))] + (match-let ([(cons len height-list) + (let retry ([len 0] + [height-list height-list]) + (amb (cons len height-list) + (retry (add1 len) (map sub1 height-list))))]) + (let-values ([(pict-car height-list) + (%pict-sexp (car sexp) height-list)]) + (values (arrow-from-car len p pict-car) + (map (λ (x) (+ x len)) height-list))))] + [else (values p height-list)])]) + (values (lt-superimpose p-1 p-2) height-list))] [else (values (pict-atom sexp) (cons 0 (cdr* height-list)))])) (define (pict-sexp sexp) - (define-values (result height-list) - (pict-sexp/helper sexp '() (λ () (error "pict-sexp: implementation error")))) - result) + (call-with-amb + (thunk + (define-values (result height-list) + (%pict-sexp sexp '())) + result))) (provide/contract [pict-sexp (any/c . -> . pict?)]) |