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

Url-encode-char

URL encode a single character. (slow, logically nice version).

Signature

(url-encode-char x) → encoding

Arguments

x — Guard (characterp x).

Returns

encoding — Encoded version of X, in proper order.
    Type (character-listp encoding).

See fast-url-encode-char for an faster, array-lookup alternative.

Definitions and Theorems

Function: url-encode-char

(defun url-encode-char (x)
  (declare (xargs :guard (characterp x)))
  (let ((acl2::__function__ 'url-encode-char))
    (declare (ignorable acl2::__function__))
    (b* ((x (char-fix x))
         ((when (or (and (char<= #\A x) (char<= x #\Z))
                    (and (char<= #\a x) (char<= x #\z))
                    (and (char<= #\0 x) (char<= x #\9))
                    (member x '(#\- #\_ #\. #\~))))
          (list x))
         (hex-code (nat-to-hex-chars (char-code x)))
         (hex-code (if (eql (len hex-code) 1)
                       (cons #\0 hex-code)
                     hex-code)))
      (cons #\% hex-code))))

Theorem: character-listp-of-url-encode-char

(defthm character-listp-of-url-encode-char
  (b* ((encoding (url-encode-char x)))
    (character-listp encoding))
  :rule-classes :rewrite)

Theorem: url-encode-char-of-char-fix-x

(defthm url-encode-char-of-char-fix-x
  (equal (url-encode-char (char-fix x))
         (url-encode-char x)))

Theorem: url-encode-char-chareqv-congruence-on-x

(defthm url-encode-char-chareqv-congruence-on-x
  (implies (chareqv x x-equiv)
           (equal (url-encode-char x)
                  (url-encode-char x-equiv)))
  :rule-classes :congruence)