Lua URI Encode Function

-- Lua uriencode function
-- Can take a table, or a string of comma separated values.
-- Examples:
-- > print(uriencode("this=is,a=/test/,string='quotes'"))
-- a=%2Ftest%2F&string=%27quotes%27&this=is
-- > print(uriencode({this="is", a="/test/", string="'quotes'"}))
-- a=%2Ftest%2F&string=%27quotes%27&this=is
function uriencode(vals)
    function escape (s)
        s = string.gsub(
            s,
            '([\r\n"#%%&+:;<=>?@^`{|}%\\%[%]%(%)$!~,/\'])',
            function (c)
                return '%'..string.format("%02X", string.byte(c));
            end
        );
        s = string.gsub(s, "%s", "+");
        return s;
    end
    function encode (t)
        local s = "";
        for k , v in pairs(t) do
            s = s .. "&" .. escape(k) .. "=" .. escape(v);
        end
        return string.sub(s, 2);
    end
    if type(vals) == 'table' then
        return encode(vals);
    else
        local t = {};
        for k, v in  string.gmatch(vals, ",?([^=]+)=([^,]+)") do
            t[k]=v;
        end
        return encode(t);
    end
end