/// Copied from libcxx type_traits and simplified

#pragma once

namespace std {

template <class _Tp, _Tp __v>
struct integral_constant {
  static const _Tp value = __v;
  typedef _Tp value_type;
  typedef integral_constant type;
};

typedef integral_constant<bool, true> true_type;
typedef integral_constant<bool, false> false_type;

// is_same, functional
template <class _Tp, class _Up> struct is_same : public false_type {};
template <class _Tp> struct is_same<_Tp, _Tp> : public true_type {};

// is_integral, for some types.
template <class _Tp> struct is_integral
    : public integral_constant<bool, false> {};
template <> struct is_integral<bool>
    : public integral_constant<bool, true> {};
template <> struct is_integral<char>
    : public integral_constant<bool, true> {};
template <> struct is_integral<short>
    : public integral_constant<bool, true> {};
template <> struct is_integral<int>
    : public integral_constant<bool, true> {};
template <> struct is_integral<long>
    : public integral_constant<bool, true> {};
template <> struct is_integral<long long>
    : public integral_constant<bool, true> {};

// enable_if, functional
template <bool _C, typename _Tp> struct enable_if{};
template <typename _Tp> struct enable_if<true, _Tp>{
  using type = _Tp;
};

}