This task   (the reverse of   URL encoding   and distinct from   URL parser)   is to provide a function
or mechanism to convert an URL-encoded string into its original unencoded form.



Test cases

   The encoded string   "http%3A%2F%2Ffoo%20bar%2F"   should be reverted to the unencoded form   "http://foo bar/".
   The encoded string   "google.com/search?q=%60Abdu%27l-Bah%C3%A1"   should revert to the unencoded form   "google.com/search?q=`Abdu'l-Bahá".


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-- URL decodes a string
-- @param {string} str
-- @return {string}
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on urldecode (str)
    res = ""
    ba = bytearray()
    len = str.length
    repeat with i = 1 to len
        c = str.char[i]
        if (c = "%") then
            -- fastest hex-to-dec conversion hack based on Lingo's rgb object
            ba.writeInt8(rgb(str.char[i+1..i+2]).blue)
            i = i + 2
        else if (c = "+") then
            ba.writeInt8(32)
        else
            ba.writeInt8(chartonum(c))
        end if
    end repeat
    ba.position = 1
    return ba.readRawString(ba.length)
end