gistfile1.scm

(define (file-lines file)
  (call-with-input-file file
    (lambda (port)
      (let loop ([line (read-line port)]
                 [l '()])
        (if (eof-object? line) l
            (cons line (loop (read-line port) l)))))))

(define (as-string lines)
  (apply string-append
         (map (lambda (str) (string-append str (string #\newline)))
              lines)))

(define (in-comment? char next-char comment)
  (cond ((eqv? comment 'simple)
         (if (eqv? #\newline char) #f comment))
        ((eqv? comment 'multiline)
         (if (and (eqv? #\* char)
                  (eqv? #\/ next-char)) #f 'multiline))
        ((not comment)
         (cond ((and (eqv? #\/ char)
                     (eqv? #\/ next-char)) 'simple)
               ((and (eqv? #\/ char)
                     (eqv? #\* next-char)) 'multiline)
               (else #f)))))

(define (upcase-comments file)
  (let* ([str (as-string (file-lines file))]
         [max (string-length str)]
         [pick-char (lambda (idx)
                      (if (< idx max)
                          (string-ref str idx) #f))])
    (let loop ([idx 0]
               [comment #f])
      (let ([char (pick-char idx)]
            [next-char (pick-char (+ idx 1))])
        (when char
          (if (in-comment? char next-char comment)
              (display (string-upcase (string char)))
              (display (string char)))
          (loop (+ idx 1) (in-comment? char next-char comment)))))))
  
(define file "/home/daltojr/scheme/compiladores-principios-praticas/test-files/test.c")

(upcase-comments file)