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; Scheme 9 from Empty Space, Function Library
; By Nils M Holm, 2009-2010
; Placed in the Public Domain
;
; (string-parse string1 string2) ==> list
;
; Split a string into substrings. STRING1 is a set of separators.
; Return a list containing all coherent sequences of non-separating
; characters contained in the given string.
;
; Example: (string-parse " ?" " to be or not to be? ")
; ==> ("to" "be" "or" "not" "to" "be")
(define (string-parse c* s)
(let ((c* (string->list c*)))
(letrec
((skip-separators
(lambda (i k)
(cond ((= i k)
i)
((memv (string-ref s i) c*)
(skip-separators (+ i 1) k))
(else
i))))
(parse
(lambda (i k tmp res)
(cond ((= i k)
(if (string=? "" tmp)
res
(cons tmp res)))
((memv (string-ref s i) c*)
(parse (skip-separators i k)
k
""
(cons tmp res)))
(else
(parse (+ 1 i)
k
(string-append
tmp
(string (string-ref s i)))
res))))))
(let ((k (string-length s)))
(reverse! (parse (skip-separators 0 k) k "" '()))))))
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