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- #lang racket
- (provide get-lines
- enumerate
- repeat
- split-list-by
- transpose-list)
- (define (repeat n e)
- (let loop ((i 0) (ret '()))
- (if (>= i n)
- ret
- (loop (+ 1 i) (cons e ret)))))
- (define (trim-lines lines)
- (if (= 0 (string-length (car lines)))
- (trim-lines (cdr lines))
- lines))
- (define (get-lines fp)
- (define lines
- (let loop ((lines '()))
- (define l (read-line fp))
- (if (eof-object? l)
- (reverse lines)
- (loop (cons l lines)))))
- (reverse (trim-lines (reverse (trim-lines lines)))))
- (define (enumerate lst)
- (let loop ((i 1) (ret '()) (remain lst))
- (if (null? remain)
- (reverse ret)
- (loop (+ 1 i) (cons (list (car remain) i) ret) (cdr remain)))))
- (define (split-list-by e lst . eq)
- (define cmp (if (null? eq) equal? eq))
- (let loop ((ret '())
- (cur '())
- (lst lst))
- (if (null? lst)
- (reverse (cons (reverse cur) ret))
- (if (cmp e (car lst))
- (loop (cons (reverse cur) ret) '() (cdr lst))
- (loop ret (cons (car lst) cur) (cdr lst))))))
- (define (transpose-list lines)
- (define width (string-length (car lines)))
- (define new-lines (make-vector width))
- (let loop ((i 0))
- (if (>= i width)
- (vector->list new-lines)
- (let ()
- (define char-list (map (λ (l) (string-ref l i)) lines))
- (vector-set! new-lines i (list->string char-list))
- (loop (+ i 1))))))
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