promote_scalar.hpp

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#ifndef STAN_MATH_PRIM_FUN_PROMOTE_SCALAR_HPP
#define STAN_MATH_PRIM_FUN_PROMOTE_SCALAR_HPP
 
#include <stan/math/prim/fun/Eigen.hpp>
#include <stan/math/prim/meta.hpp>
#include <vector>
#include <tuple>
#include <type_traits>
 
namespace stan {
namespace math {
 
template <typename PromotionScalar, typename UnPromotedType,
          require_constructible_t<PromotionScalar, UnPromotedType>* = nullptr,
          require_not_same_t<PromotionScalar, UnPromotedType>* = nullptr,
          require_all_not_tuple_t<PromotionScalar, UnPromotedType>* = nullptr>
inline constexpr auto promote_scalar(UnPromotedType&& x) {
  return PromotionScalar(std::forward<UnPromotedType>(x));
}
 
template <
    typename PromotionScalar, typename UnPromotedType,
    require_same_t<PromotionScalar, scalar_type_t<UnPromotedType>>* = nullptr>
inline constexpr auto promote_scalar(UnPromotedType&& x) noexcept {
  return std::forward<UnPromotedType>(x);
}
 
template <typename PromotionScalar, typename UnPromotedType,
          require_eigen_t<UnPromotedType>* = nullptr,
          require_not_same_t<PromotionScalar,
                             value_type_t<UnPromotedType>>* = nullptr>
inline auto promote_scalar(UnPromotedType&& x) {
  return x.template cast<PromotionScalar>();
}
 
// Forward decl for iterating over tuples used in std::vector<tuple>
template <typename PromotionScalars, typename UnPromotedTypes,
          require_all_tuple_t<PromotionScalars, UnPromotedTypes>* = nullptr,
          require_not_same_t<PromotionScalars, UnPromotedTypes>* = nullptr>
inline constexpr promote_scalar_t<PromotionScalars, UnPromotedTypes>
promote_scalar(UnPromotedTypes&& x);
 
template <typename PromotionScalar, typename UnPromotedType,
          require_std_vector_t<UnPromotedType>* = nullptr,
          require_not_same_t<PromotionScalar,
                             scalar_type_t<UnPromotedType>>* = nullptr>
inline auto promote_scalar(UnPromotedType&& x) {
  const auto x_size = x.size();
  promote_scalar_t<PromotionScalar, UnPromotedType> ret(x_size);
  for (size_t i = 0; i < x_size; ++i) {
    ret[i] = promote_scalar<PromotionScalar>(x[i]);
  }
  return ret;
}
 
template <typename PromotionScalars, typename UnPromotedTypes,
          require_all_tuple_t<PromotionScalars, UnPromotedTypes>*,
          require_not_same_t<PromotionScalars, UnPromotedTypes>*>
inline constexpr promote_scalar_t<PromotionScalars, UnPromotedTypes>
promote_scalar(UnPromotedTypes&& x) {
  return index_apply<std::tuple_size<std::decay_t<UnPromotedTypes>>::value>(
      [&x](auto... Is) {
        return std::make_tuple(
            promote_scalar<std::decay_t<decltype(std::get<Is>(
                std::declval<PromotionScalars>()))>>(std::get<Is>(x))...);
      });
}
 
}  // namespace math
}  // namespace stan
 
#endif