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#lang debug racket/base
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(require racket/contract racket/list racket/match txexpr sugar/debug sugar/define sugar/list racket/promise racket/function (only-in racket/control call/prompt)
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"param.rkt" "qexpr.rkt" "atomize.rkt" "quad.rkt" "generic.rkt" "position.rkt")
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(define/contract (distance q [signal #f])
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((quad?) (any/c) . ->* . real?)
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(match-define (list x0 y0) (start-point q))
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(match-define (list x1 y1) (end-point q))
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;; pythagorically
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(sqrt (+ (expt (- x1 x0) 2) (expt (- y1 y0) 2))))
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(define+provide/contract (wrap xs
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[target-size (current-line-width)]
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[debug #f]
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#:break-val [break-val 'break]
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#:mandatory-break-proc [mandatory-break? (const #f)]
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#:optional-break-proc [optional-break? (const #f)]
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#:finish-segment-proc [finish-segment-proc values])
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((any/c) (real? any/c
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#:break-val any/c
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#:mandatory-break-proc procedure?
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#:optional-break-proc procedure?
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#:finish-segment-proc procedure?) . ->* . (listof any/c))
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(define start-signal (gensym))
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(define (finish-segment pieces) (finish-segment-proc (reverse (dropf pieces optional-break?))))
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(define last-optional-break-k #f)
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(call/prompt ;; continuation boundary for last-optional-break-k
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(thunk
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(define (capture-optional-break-k!) (let/cc k (set! last-optional-break-k k) #f))
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(for/fold ([segments null]
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[pieces null]
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[size-so-far start-signal]
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#:result (append* (reverse (cons (finish-segment pieces) segments))))
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([x (in-list xs)])
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(define at-start? (eq? size-so-far start-signal))
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(define underflow? (and (not at-start?) (<= (+ size-so-far (size x 'end)) target-size)))
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(define (add-to-segment) (values segments (cons x pieces) (if at-start?
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(size x 'start)
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(+ size-so-far (size x)))))
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(define (insert-break)
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;; when break is found, q is omitted from accumulation
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;; and any preceding optional breaks are dropped (that would be trailing before the break)
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(values (list* (list break-val) (finish-segment pieces) segments) null start-signal))
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(cond
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[(mandatory-break? x) (when debug (report x 'got-mandatory-break))
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(insert-break)]
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[(optional-break? x)
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(cond
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[at-start? (when debug (report x 'skipping-opt-break-at-beginning)) (values segments null size-so-far)]
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[(and underflow? (capture-optional-break-k!)) (when debug (report x 'resuming-breakpoint))
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(set! last-optional-break-k #f) ;; prevents continuation loop
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(insert-break)]
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[else (when debug (report x 'add-optional-break))
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(add-to-segment)])]
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[(or at-start? underflow?) (when debug (report x 'add-ordinary-char))
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(add-to-segment)]
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[last-optional-break-k (when debug (report x 'invoking-last-breakpoint))
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(last-optional-break-k #t)]
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[else (when debug (report x 'falling-back))
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(match-define-values (vals _ _) (insert-break))
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(values vals (list x) (size x 'start))]))))) ;; fallback if no last-breakpoint-k exists
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(define x (q (hasheq) #\x))
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(define zwx (q (hasheq 'size (delay (values 0 0 0))) #\z))
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(define a (q (hasheq 'size (delay (values 1 1 1))) #\a))
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(define b (q (hasheq 'size (delay (values 1 1 1))) #\b))
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(define c (q (hasheq 'size (delay (values 1 1 1))) #\c))
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(define d (q (hasheq 'size (delay (values 1 1 1))) #\d))
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(define sp (q (hasheq 'size (delay (values 0 1 0))) #\space))
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(define br (q (hasheq 'size (delay (values 0 0 0))) #\newline))
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(define optional-break? (λ (q) (and (quad? q) (memv (car (elems q)) '(#\space)))))
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(define (linewrap xs size [debug #f])
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(wrap xs size debug
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#:break-val 'lb
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#:mandatory-break-proc (λ (q) (and (quad? q) (memv (car (elems q)) '(#\newline))))
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#:optional-break-proc optional-break?
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#|
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#:size-proc (λ (q) (let ([val (hash-ref (attrs q) 'size (λ ()
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(if (memv (car (elems q)) '(#\space))
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(delay (values 0 1 0))
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(delay (values 1 1 1)))))])
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(if (promise? val) (force val) (val))))
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|#
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))
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(module+ test
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(require rackunit)
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(test-case
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"chars"
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(check-equal? (linewrap (list) 1) null)
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(check-equal? (linewrap (list x) 1) (list x))
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#|
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(check-equal? (linewrap (list x x) 1) (list x 'lb x))
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(check-equal? (linewrap (list x x x) 1) (list x 'lb x 'lb x))
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(check-equal? (linewrap (list x x x) 2) (list x x 'lb x))
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(check-equal? (linewrap (list x x x x) 2) (list x x 'lb x x))
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(check-equal? (linewrap (list x x x x x) 3) (list x x x 'lb x x))
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(check-equal? (linewrap (list x x x x x) 1) (list x 'lb x 'lb x 'lb x 'lb x))
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(check-equal? (linewrap (list x x x x x) 10) (list x x x x x))
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|#
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))
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