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Supporting =, >= and ** repetition patterns.

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This commit is contained in:
Alex Shinn 2013-10-20 18:27:10 +09:00
parent 8f9ba977c3
commit ce3b1fcecf
1 changed files with 38 additions and 0 deletions
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38
lib/chibi/regexp.scm
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@ -546,6 +546,31 @@
(else (error "invalid sre char-set" sre)))))
(else (error "invalid sre char-set" sre)))))
(define (strip-submatches sre)
(if (pair? sre)
(case (car sre)
(($ submatch) (strip-submatches (cons ': (cdr sre))))
((=> submatch-named) (strip-submatches (cons ': (cddr sre))))
(else (cons (strip-submatches (car sre))
(strip-submatches (cdr sre)))))
sre))
(define (sre-expand-reps from to sre)
(let ((sre0 (strip-submatches sre)))
(let lp ((i 0) (res '(:)))
(if (= i from)
(cond
((not to)
(reverse (cons `(* ,sre) res)))
((= from to)
(reverse (cons sre (cdr res))))
(else
(let lp ((i (+ i 1)) (res res))
(if (>= i to)
(reverse (cons `(? ,sre) res))
(lp (+ i 1) (cons `(? ,sre0) res))))))
(lp (+ i 1) (cons sre0 res))))))
;;> Compile an \var{sre} into a regexp.
(define (regexp sre . o)
@ -632,6 +657,19 @@
(n1 (->rx (cons 'seq (cdr sre)) flags n2)))
(state-next2-set! n2 n1)
n1))
((=)
;; Exact repetition.
(->rx (sre-expand-reps (cadr sre) (cadr sre) (cons 'seq (cddr sre)))
flags next))
((>=)
;; n-or-more repetition.
(->rx (sre-expand-reps (cadr sre) #f (cons 'seq (cddr sre)))
flags next))
((**)
;; n-to-m repetition.
(->rx (sre-expand-reps (cadr sre) (car (cddr sre))
(cons 'seq (cdr (cddr sre))))
flags next))
((=> submatch-named)
;; Named submatches just record the name for the current
;; match and rewrite as a non-named submatch.