// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2015 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_META_H
#define EIGEN_CXX11_TENSOR_TENSOR_META_H

namespace Eigen {

template<bool cond> struct Cond {};

template<typename T1, typename T2> EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE
const T1& choose(Cond<true>, const T1& first, const T2&) {
  return first;
}

template<typename T1, typename T2> EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE
const T2& choose(Cond<false>, const T1&, const T2& second) {
  return second;
}


// Default packet types
template <typename Scalar, typename Device>
struct PacketType {
  typedef typename internal::packet_traits<Scalar>::type type;
  static const int size = internal::unpacket_traits<type>::size;
};

// For CUDA packet types when using a GpuDevice
#if defined(EIGEN_USE_GPU) && defined(__CUDACC__)
template <>
struct PacketType<float, GpuDevice> {
  typedef float4 type;
  static const int size = 4;
};
template <>
struct PacketType<double, GpuDevice> {
  typedef double2 type;
  static const int size = 2;
};
#endif


#if defined(EIGEN_HAS_CONSTEXPR)
#define EIGEN_CONSTEXPR constexpr
#else
#define EIGEN_CONSTEXPR
#endif

// Tuple mimics std::pair but works on e.g. nvcc.
template <typename U, typename V> struct Tuple {
 public:
  U first;
  V second;

  typedef U first_type;
  typedef V second_type;

  EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
  Tuple() : first(), second() {}

  EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
  Tuple(const U& f, const V& s) : first(f), second(s) {}

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
  Tuple& operator= (const Tuple& rhs) {
    if (&rhs == this) return *this;
    first = rhs.first;
    second = rhs.second;
    return *this;
  }

  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
  void swap(Tuple& rhs) {
    using numext::swap;
    swap(first, rhs.first);
    swap(second, rhs.second);
  }
};

template <typename U, typename V>
EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
bool operator==(const Tuple<U, V>& x, const Tuple<U, V>& y) {
  return (x.first == y.first && x.second == y.second);
}

template <typename U, typename V>
EIGEN_CONSTEXPR EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
bool operator!=(const Tuple<U, V>& x, const Tuple<U, V>& y) {
  return !(x == y);
}

#undef EIGEN_CONSTEXPR

}  // namespace Eigen

#endif  // EIGEN_CXX11_TENSOR_TENSOR_META_H