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        • *url-encode-array*
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• Url-encoding

Url-encode-string-aux

Efficiently way to URL encode a string, in reverse order, without exploding it.

Signature

(url-encode-string-aux x n xl acc) → *

Arguments

x — Guard (stringp x).

n — Guard (natp n).

xl — Guard (eql xl (length x)).

This has such a nice logical definition that we just leave it enabled.

Definitions and Theorems

Function: url-encode-string-aux

(defun
 url-encode-string-aux (x n xl acc)
 (declare (xargs :guard (and (stringp x)
                             (natp n)
                             (eql xl (length x)))))
 (declare (xargs :guard (<= n xl)))
 (let ((acl2::__function__ 'url-encode-string-aux))
      (declare (ignorable acl2::__function__))
      (mbe :logic (url-encode-chars-aux (nthcdr n (explode x))
                                        acc)
           :exec (b* (((when (mbe :logic (zp (- (nfix xl) (nfix n)))
                                  :exec (eql n xl)))
                       acc)
                      (char (char x n))
                      (encoding (fast-url-encode-char char))
                      (acc (revappend encoding acc)))
                     (url-encode-string-aux x (+ 1 (lnfix n))
                                            xl acc)))))