URLEncoder/Decoder for lua

URLEncoder.lua

--[[----------------------------------------------------------------------------

 Copyright 2014 S. Tanaka
 All Rights Reserved.

--------------------------------------------------------------------------------

URLEncoder.lua
Encodes any strings into URL encoded strings with a rule based on rawurlencode in PHP.

------------------------------------------------------------------------------]]
URLEncoder = {
    encode = function(str)
            if (not str) then
                return str
            end

            str = string.gsub (str, "\n", "\r\n")
            str = string.gsub (str, "[^%w.%-_~]",
                function (c) return string.format ("%%%02X", string.byte(c)) end)

            return str
        end,
    decode = function(str)
            str = string.gsub(str, "%%([0-9a-fA-F][0-9a-fA-F])",
                function (c) return string.char(tonumber("0x" .. c)) end)
            str = string.gsub (str, "\n", "\r\n")
            return str
        end,
}

PHPのrawurlencodeと同じ挙動（のつもり）のlua版url encoder/decoder
あんまりググっても見つからなかったので適当に作りました。
間違いがあったら教えて下さい。

使い方

require('URLEncoder')
coded = URLEncoder.encode("エンコードされたい文字列")
print(coded)
raw = URLEncoder.decode(coded)
print(raw)