Function urldecode

dlib/server/server_http.cpp:60–87

        }

        const std::string urldecode (
            const std::string& str
        ) 
        {
            using namespace std;
            string result;
            string::size_type i;
            for (i = 0; i < str.size(); ++i)
            {
                if (str[i] == '+')
                {
                    result += ' ';
                }
                else if (str[i] == '%' && str.size() > i+2)
                {
                    const unsigned char ch1 = from_hex(str[i+1]);
                    const unsigned char ch2 = from_hex(str[i+2]);
                    const unsigned char ch = (ch1 << 4) | ch2;
                    result += ch;
                    i += 2;
                }
                else
                {
                    result += str[i];
                }
            }
            return result;
        }

        void parse_url(
            std::string word,