implement std::type_traits (C++11 and C++14)

#include <string>

namespace op {

// ------------------------------------

template<typename T>
struct remove_const {
    typedef T type;
};

template<typename T>
struct remove_const<T const> {
    typedef T type;
};

template<typename T>
using remove_const_t = typename remove_const<T>::type;

// ------------------------------------

template<typename T>
struct remove_reference {
    typedef T type;
};

template<typename T>
struct remove_reference<T&> {
    typedef T type;
};

template<typename T>
struct remove_reference < T&& > {
    typedef T type;
};

template<typename T>
using remove_reference_t = typename remove_reference<T>::type;

// ------------------------------------

}

int main()
{
    using T1 = op::remove_const<const std::string>::type;   // C++11
    T1 str1 = "Das";
    str1 += " ist ein Test!";

    using T2 = op::remove_reference<T1&>::type;             // C++11
    T2 str2 = "No more ref now";

    using T3 = op::remove_const_t<const std::string>;       // C++14
    T3 str3 = "A string";

    op::remove_reference_t<T3&> str4 = "some string";       // C++14

    return 0;
}