scheme-libraries/retropikzel/url-encoding.scm

60 lines
1.9 KiB
Scheme

(define encode-replacements
(list (list " " "%20")
(list " " "+")
(list "!" "%21")
(list "#" "%23")
(list "$" "%24")
(list "%" "%25")
(list "&" "%26")
(list "'" "%27")
(list "(" "%28")
(list ")" "%29")
(list "*" "%2A")
(list "+" "%2B")
(list "," "%2C")
(list "/" "%2F")
(list ":" "%3A")
(list ";" "%3B")
(list "=" "%3D")
(list "?" "%3F")
(list "@" "%40")
(list "[" "%5B")
(list "]" "%5D")
(list "<" "%3C")
(list ">" "%3E")
(list "\\" "%5C")
(list "\"" "%22")
(list "\n" "%0A")
(list "\r" "%0D")))
(define decode-replacements (map reverse encode-replacements))
(define (get-replacement key mode)
(let ((r (if (string=? mode "encode")
(assoc key encode-replacements)
(assoc key decode-replacements))))
(if r (car (cdr r)) key)))
(define (endecode mode s)
(if (not s)
""
(letrec ((s-length (string-length s))
(looper
(lambda (i result)
(if (< i s-length)
(let ((key-length (if (and (string=? mode "decode")
(string=? (string-copy s i (+ i 1)) "%")
(> s-length (+ i 2)))
3
1)))
(looper (+ i key-length)
(string-append result
(get-replacement
(string-copy s i (+ i key-length))
mode))))
result))))
(looper 0 ""))))
(define (url-encode str) (cond ((string? str) (endecode "encode" str)) (else str)))
(define (url-decode str) (cond ((string? str) (endecode "decode" str)) (else str)))