41 lines
1.3 KiB
Scheme
41 lines
1.3 KiB
Scheme
; returns a list of numbers parsed from the first line of the file,
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; separated by commas
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(define (read-comma-separated-numbers file)
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(let loop [(draws '()) (n 0)]
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(let [(c (get-char file))]
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(cond
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[(char=? c #\,) (loop (cons n draws) 0)]
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[(char-whitespace? c) (reverse (cons n draws))]
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[else (loop draws (+ (* n 10) (string->number (string c))))]))))
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; returns numbers 0 to 9 from ascii character
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(define (char->number c)
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(- (char->integer c) 48)) ; 48 is ASCII's number zero
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(define-record-type matrix (fields width height data))
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(define (matrix-get matrix x y)
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(if (or (< x 0)
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(< y 0)
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(>= x (matrix-width matrix))
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(>= y (matrix-height matrix)))
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9
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(vector-ref (vector-ref (matrix-data matrix) y) x)))
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(define (matrix-from-data data)
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(make-matrix
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(vector-length (vector-ref data 0))
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(vector-length data)
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data))
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; parse 0-9 numerical data from file and return a matrix
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(define (load-matrix file)
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(let y-loop [(heightmap '())]
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(let x-loop [(line '())]
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(let [(c (get-char file))]
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(cond
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[(eof-object? c)
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(matrix-from-data (reverse-list->vector heightmap))]
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[(char-whitespace? c)
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(y-loop (cons (reverse-list->vector line) heightmap))]
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[(char-numeric? c)
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(x-loop (cons (char->number c) line))])))))
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