EmulateCXX11Meta.h

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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 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_EMULATE_CXX11_META_H
#define EIGEN_EMULATE_CXX11_META_H



namespace Eigen {

namespace internal {

struct empty_list { static const std::size_t count = 0; };

template<typename T, typename Tail=empty_list> struct type_list {
  typedef T HeadType;
  typedef Tail TailType;
  static const T head;
  static const Tail tail;
  static const std::size_t count = 1 + Tail::count;
};

struct null_type { };

template<typename T1 = null_type, typename T2 = null_type, typename T3 = null_type,
         typename T4 = null_type, typename T5 = null_type, typename T6 = null_type,
         typename T7 = null_type, typename T8 = null_type>
struct make_type_list {
  typedef typename make_type_list<T2, T3, T4, T5, T6, T7, T8>::type tailresult;

  typedef type_list<T1, tailresult> type;
};

template<> struct make_type_list<> {
  typedef empty_list type;
};


template <std::size_t index, class TList> struct get_type;

template <class Head, class Tail>
struct get_type<0, type_list<Head, Tail> >
{
  typedef Head type;
};

template <std::size_t i, class Head, class Tail>
struct get_type<i, type_list<Head, Tail> >
{
  typedef typename get_type<i-1, Tail>::type type;
};


/* numeric list */
template <typename T, T n>
struct type2val {
  typedef T type;
  static const T value = n;
};


template<typename T, size_t n, T V> struct gen_numeric_list_repeated;

template<typename T, T V> struct gen_numeric_list_repeated<T, 1, V> {
  typedef typename make_type_list<type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 2, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 3, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 4, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V>, type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 5, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V>, type2val<T, V>, type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 6, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V>,
                                  type2val<T, V>, type2val<T, V>, type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 7, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V>,
                                  type2val<T, V>, type2val<T, V>, type2val<T, V>,
                                  type2val<T, V> >::type type;
};

template<typename T, T V> struct gen_numeric_list_repeated<T, 8, V> {
  typedef typename make_type_list<type2val<T, V>, type2val<T, V>, type2val<T, V>,
                                  type2val<T, V>, type2val<T, V>, type2val<T, V>,
                                  type2val<T, V>, type2val<T, V> >::type type;
};


template <std::size_t index, class NList> struct get;

template <std::size_t i>
struct get<i, empty_list>
{
  get() { eigen_assert(false && "index overflow"); }
  typedef void type;
  static const char value = '\0';
};

template <std::size_t i, class Head>
struct get<i, type_list<Head, empty_list> >
{
  get() { eigen_assert(false && "index overflow"); }
  typedef void type;
  static const char value = '\0';
};

template <class Head>
struct get<0, type_list<Head, empty_list> >
{
  typedef typename Head::type type;
  static const type value = Head::value;
};

template <class Head, class Tail>
struct get<0, type_list<Head, Tail> >
{
  typedef typename Head::type type;
  static const type value = Head::value;
};

template <std::size_t i, class Head, class Tail>
struct get<i, type_list<Head, Tail> >
{
  typedef typename Tail::HeadType::type type;
  static const type value = get<i-1, Tail>::value;
};


template <class NList> struct arg_prod {
  static const typename NList::HeadType::type value = get<0, NList>::value * arg_prod<typename NList::TailType>::value;
};
template <> struct arg_prod<empty_list> {
  static const int value = 1;
};


template<int n, typename t>
array<t, n> repeat(t v) {
  array<t, n> array;
  array.fill(v);
  return array;
}

template<std::size_t I, class Head, class Tail>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE typename Head::type array_get(type_list<Head, Tail>&) {
  return get<I, type_list<Head, Tail> >::value;
}
template<std::size_t I, class Head, class Tail>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE typename Head::type array_get(const type_list<Head, Tail>&) {
  return get<I, type_list<Head, Tail> >::value;
}

template <class NList>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE typename NList::HeadType::type array_prod(const NList&) {
  return arg_prod<NList>::value;
}

template<typename t, std::size_t n>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE t array_prod(const array<t, n>& a) {
  t prod = 1;
  for (size_t i = 0; i < n; ++i) { prod *= a[i]; }
  return prod;
}
template<typename t>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE t array_prod(const array<t, 0>& /*a*/) {
  return 0;
}

template<typename t>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE t array_prod(const std::vector<t>& a) {
  eigen_assert(a.size() > 0);
  t prod = 1;
  for (size_t i = 0; i < a.size(); ++i) { prod *= a[i]; }
  return prod;
}


template<std::size_t I, class T>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T& array_get(std::vector<T>& a) {
  return a[I];
}
template<std::size_t I, class T>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const T& array_get(const std::vector<T>& a) {
  return a[I];
}

struct sum_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a + b; }
};
struct product_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a * b; }
};

struct logical_and_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a && b; }
};
struct logical_or_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a || b; }
};

struct equal_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a == b; }
};
struct not_equal_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a != b; }
};
struct lesser_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a < b; }
};
struct lesser_equal_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a <= b; }
};

struct greater_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a > b; }
};
struct greater_equal_op {
  template<typename A, typename B> static inline bool run(A a, B b) { return a >= b; }
};

struct not_op {
  template<typename A> static inline bool run(A a) { return !a; }
};
struct negation_op {
  template<typename A> static inline bool run(A a) { return -a; }
};
struct greater_equal_zero_op {
  template<typename A> static inline bool run(A a) { return a >= 0; }
};


template<typename Reducer, typename Op, typename A, std::size_t N>
struct ArrayApplyAndReduce {
  static inline bool run(const array<A, N>& a) {
    EIGEN_STATIC_ASSERT(N >= 2, YOU_MADE_A_PROGRAMMING_MISTAKE);
    bool result = Reducer::run(Op::run(a[0]), Op::run(a[1]));
    for (size_t i = 2; i < N; ++i) {
      result = Reducer::run(result, Op::run(a[i]));
    }
    return result;
  }
};

template<typename Reducer, typename Op, typename A>
struct ArrayApplyAndReduce<Reducer, Op, A, 1>  {
  static inline bool run(const array<A, 1>& a) {
    return Op::run(a[0]);
  }
};

template<typename Reducer, typename Op, typename A, std::size_t N>
inline bool array_apply_and_reduce(const array<A, N>& a) {
  return ArrayApplyAndReduce<Reducer, Op, A, N>::run(a);
}

template<typename Reducer, typename Op, typename A, typename B, std::size_t N>
struct ArrayZipAndReduce {
  static inline bool run(const array<A, N>& a, const array<B, N>& b) {
    EIGEN_STATIC_ASSERT(N >= 2, YOU_MADE_A_PROGRAMMING_MISTAKE);
    bool result = Reducer::run(Op::run(a[0], b[0]), Op::run(a[1], b[1]));
    for (size_t i = 2; i < N; ++i) {
      result = Reducer::run(result, Op::run(a[i], b[i]));
    }
    return result;
  }
};

template<typename Reducer, typename Op, typename A, typename B>
struct ArrayZipAndReduce<Reducer, Op, A, B, 1> {
  static inline bool run(const array<A, 1>& a, const array<B, 1>& b) {
    return Op::run(a[0], b[0]);
  }
};

template<typename Reducer, typename Op, typename A, typename B, std::size_t N>
inline bool array_zip_and_reduce(const array<A, N>& a, const array<B, N>& b) {
  return ArrayZipAndReduce<Reducer, Op, A, B, N>::run(a, b);
}

}  // end namespace internal

}  // end namespace Eigen



#endif  // EIGEN_EMULATE_CXX11_META_H