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original commit: 0913b67e5f88cfd754cbf7abeb09b0d854fe413f
tokens
Scott Owens 23 years ago
parent b8d4718d9b
commit 6529029f20
1 changed files with 52 additions and 44 deletions
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96
collects/parser-tools/lex.ss
Unescape Escape View File

@ -11,27 +11,35 @@
make-lex-buf
get-position position-offset position-line position-col position?
define-tokens define-empty-tokens)
(define-syntax lexer
(let ((code
`(letrec ((match
(lambda (lb first-pos end-pos longest-match-length longest-match-action length)
(let ((match
(push-back lb (- length longest-match-length))))
(if (not longest-match-action)
(error 'lexer (format "No match found in input starting with: ~a"
(list->string (lex-buffer-from lb)))))
(longest-match-action
(lambda ()
first-pos)
(lambda ()
end-pos)
(lambda ()
(if (char? (car match))
(list->string (reverse match))
(list->string (reverse (cdr match)))))
lb)))))
(lambda (lb first-pos end-pos longest-match-length longest-match-action length)
(let ((match
(push-back lb (- length longest-match-length))))
(if (not longest-match-action)
(raise (make-exn:read
(format "lexer: No match found in input starting with: ~a"
(list->string (lex-buffer-from lb)))
(current-continuation-marks)
(lex-buffer-ip lb)
#f
(position-line first-pos)
(position-col first-pos)
(position-offset first-pos)
(- (position-offset end-pos) (position-offset first-pos)))))
(longest-match-action
(lambda ()
first-pos)
(lambda ()
end-pos)
(lambda ()
(if (char? (car match))
(list->string (reverse match))
(list->string (reverse (cdr match)))))
lb)))))
(lambda (lb)
(unless (lex-buffer? lb)
(raise-type-error
@ -142,7 +150,7 @@
;; c = char | eof
;; lex-buf =
;; (make-lex-buffer input-port (c list) (c list) int int int (int list))
(define-struct lex-buffer (ip from to offset line col line-lengths))
(define-struct lex-buffer (ip from to offset line col line-lengths tab-skips))
;; make-lex-buf: input-port -> lex-buf
(define make-lex-buf
@ -152,7 +160,7 @@
((not (input-port? ip))
(raise-type-error 'make-lex-buf "input-port" 0 ip))
(else
(make-lex-buffer ip null null 1 1 1 null))))
(make-lex-buffer ip null null 1 1 1 null null))))
((ip offsets)
(cond
((not (input-port? ip))
@ -163,13 +171,13 @@
(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 (add1 (caddr offsets)) (add1 (car offsets)) (add1 (cadr offsets)) null))))))
(make-lex-buffer ip null null (add1 (caddr offsets)) (add1 (car offsets)) (add1 (cadr offsets)) null null))))))
;; next-char: lex-buf -> c
;; gets the next character from the buffer
(define (next-char lb)
(let ((get-next
(lambda ()
(lambda ()
(cond
((null? (lex-buffer-from lb))
(read-char (lex-buffer-ip lb)))
@ -190,7 +198,8 @@
(set-lex-buffer-to! lb (cons char-in (lex-buffer-to lb)))
(cond
((eq? #\tab char-in)
(let ((skip-amt 1));(- 8 (modulo (lex-buffer-col lb) 8))))
(let ((skip-amt (- 8 (modulo (lex-buffer-col lb) 8))))
(set-lex-buffer-tab-skips! lb (cons skip-amt (lex-buffer-tab-skips lb)))
(set-lex-buffer-col! lb (+ skip-amt (lex-buffer-col lb)))
(set-lex-buffer-offset! lb (+ skip-amt (lex-buffer-col lb)))))
((eq? #\newline char-in)
@ -225,31 +234,30 @@
(else
(cond
((eq? #\newline (car from))
(set-lex-buffer-line!
lb
(sub1 (lex-buffer-line lb)))
(set-lex-buffer-col!
lb
(car (lex-buffer-line-lengths lb)))
(set-lex-buffer-line-lengths!
lb
(cdr (lex-buffer-line-lengths lb))))
(else
(set-lex-buffer-col!
lb
(sub1 (lex-buffer-col lb)))))
(switch-buffers (cdr from)
(cons (car from) to)
(sub1 num-to-add)))))))
(set-lex-buffer-line! lb (sub1 (lex-buffer-line lb)))
(set-lex-buffer-col! lb (car (lex-buffer-line-lengths lb)))
(set-lex-buffer-line-lengths! lb (cdr (lex-buffer-line-lengths lb))))
((eq? #\tab (car from))
(set-lex-buffer-col! lb (- (lex-buffer-col lb)
(car (lex-buffer-tab-skips lb))))
(set-lex-buffer-offset! lb (- (add1 (lex-buffer-offset lb))
(car (lex-buffer-tab-skips lb))))
(set-lex-buffer-tab-skips! lb (cdr (lex-buffer-tab-skips lb))))
(else
(set-lex-buffer-col! lb (sub1 (lex-buffer-col lb)))))
(switch-buffers (cdr from)
(cons (car from) to)
(sub1 num-to-add)))))))
(let-values (((ret new-from)
(switch-buffers (lex-buffer-to lb)
(lex-buffer-from lb)
i)))
(set-lex-buffer-from! lb new-from)
(set-lex-buffer-to! lb null)
(set-lex-buffer-offset! lb (- (lex-buffer-offset lb) i))
(set-lex-buffer-line-lengths! lb null)
ret)))
(set-lex-buffer-from! lb new-from)
(set-lex-buffer-to! lb null)
(set-lex-buffer-offset! lb (- (lex-buffer-offset lb) i))
(set-lex-buffer-line-lengths! lb null)
(set-lex-buffer-tab-skips! lb null)
ret)))
(define-struct position (offset line col))
(define (get-position lb)

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