On Sun, Mar 2, 2014 at 8:51 PM, Michele La Monaca <
mikele.chic...@lamonaca.net> wrote:
>
> While writing my own version of irregex-replace can be (hopefully) an
> enjoyable
> 6-line coding experience (btw, irregex-apply-match is not documented):
>
Oops, thanks, I'll document it.
(define (my-own-irregex-replace irx s . o)
> (let ((m (irregex-search irx s)))
> (and m (string-append
> (substring s 0 (irregex-match-start-index m 0))
> (apply string-append (reverse (irregex-apply-match m o)))
> (substring s (irregex-match-end-index m 0) (string-length
> s))))))
>
> writing a customized version of irregex-replace/all means writing a real
> non-elementary program.
It's probably not as complicated as you're imagining.
irregex-fold does most of the work:
#;2> (define (my-irregex-replace-all irx str . o)
(irregex-fold
irx
(lambda (i m acc)
(let ((m-start (irregex-match-start-index m 0)))
(cons
(+ 1 (car acc))
(append (irregex-apply-match m o)
(if (>= i m-start)
(cdr acc)
(cons (substring str i m-start) (cdr acc)))))))
'(0)
str
(lambda (i acc)
(let ((end (string-length str)))
(values
(apply
string-append
(reverse (if (>= i end)
(cdr acc)
(cons (substring str i end) (cdr acc)))))
(car acc))))))
#;3> (my-irregex-replace-all '(+ digit) "one 1 two 22 three 333" "?")
"one ? two ? three ?"
3
; 2 values
I'll consider adding this utility, though.
--
Alex
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