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original commit: 631f97d1b63162787ab940fddbef588e44b184b2
tokens
Scott Owens 23 years ago
parent 7074f0dd48
commit a5cce475d1

@ -144,32 +144,66 @@
(define-struct lex-buffer (ip from to offset line col line-lengths))
;; make-lex-buf: input-port -> lex-buf
(define (make-lex-buf ip)
(make-lex-buffer ip null null 1 1 1 null))
(define make-lex-buf
(case-lambda
((ip)
(cond
((not (input-port? ip))
(raise-type-error 'make-lex-buf "input-port" 0 ip))
(else
(make-lex-buffer ip null null 0 0 0 null))))
((ip offsets)
(cond
((not (input-port? ip))
(raise-type-error 'make-lex-buf "input-port" 0 ip offsets))
((or (not (= 3 (length offsets)))
(not (andmap integer? offsets))
(not (andmap exact? offsets))
(not (andmap (lambda (x) (>= x 0)) offsets)))
(raise-type-error 'make-lex-buf "list of 3 non-negative exact integers" 1 ip offsets))
(else
(make-lex-buffer ip null null (caddr offsets) (car offsets) (cadr offsets) null))))))
;; next-char: lex-buf -> c
;; gets the next character from the buffer
(define (next-char lb)
(let ((char-in
(let ((get-next
(lambda ()
(cond
((null? (lex-buffer-from lb))
(read-char (lex-buffer-ip lb)))
(else (begin0
(else
(begin0
(car (lex-buffer-from lb))
(set-lex-buffer-from! lb (cdr (lex-buffer-from lb))))))))
(set-lex-buffer-from! lb (cdr (lex-buffer-from lb)))))))))
(let ((char-in
(let ((real-char (get-next)))
(if (char=? #\return real-char)
(let ((second-char (get-next)))
(if (not (char=? second-char #\newline))
(set-lex-buffer-from!
lb
(cons second-char (lex-buffer-from lb))))
#\newline)
real-char))))
(set-lex-buffer-to! lb (cons char-in (lex-buffer-to lb)))
(cond
((eq? #\newline char-in)
((char=? #\tab char-in)
(let ((skip-amt (- 8 (modulo (lex-buffer-col lb) 8))))
(set-lex-buffer-col! lb (+ skip-amt (lex-buffer-col lb)))
(set-lex-buffer-offset! lb (+ skip-amt (lex-buffer-col lb)))))
((char=? #\newline char-in)
(set-lex-buffer-line-lengths!
lb
(cons (lex-buffer-col lb)
(lex-buffer-line-lengths lb)))
(set-lex-buffer-line! lb (add1 (lex-buffer-line lb)))
(set-lex-buffer-col! lb 1))
(set-lex-buffer-col! lb 0)
(set-lex-buffer-offset! lb (add1 (lex-buffer-offset lb))))
(else
(set-lex-buffer-col! lb (add1 (lex-buffer-col lb)))))
(set-lex-buffer-offset! lb (add1 (lex-buffer-offset lb)))
char-in))
(set-lex-buffer-col! lb (add1 (lex-buffer-col lb)))
(set-lex-buffer-offset! lb (add1 (lex-buffer-offset lb)))))
char-in)))
;; push-back: lex-buf * int -> c list
;; pushes the last read i characters back to be read again
@ -189,7 +223,7 @@
((= 0 num-to-add) (values from to))
(else
(cond
((eq? #\newline (car from))
((char=? #\newline (car from))
(set-lex-buffer-line!
lb
(sub1 (lex-buffer-line lb)))

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