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2 parital specializations of a derived_dimension split to different types

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Mateusz Pusz committed 2019-12-14 11:44:56 +01:00
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commit b1b63e1b3a
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+152 -166
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src/include/units/derived_dimension.h
+62 -66
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@@ -31,41 +31,6 @@
namespace units {
/**
* @brief A derived dimension
*
* There are 2 partial specializations of this primary class template. One of them is used by the library engine
* and another one is the interface for the user to define a derived dimension.
*/
template<typename...>
struct derived_dimension;
/**
* @brief Dimensionless quantity
*/
template<>
struct derived_dimension<> : downcast_base<derived_dimension<>> {};
/**
* @brief A dimension of a derived quantity
*
* Expression of the dependence of a quantity on the base quantities (and their base dimensions) of a system of
* quantities as a product of powers of factors corresponding to the base quantities, omitting any numerical factors.
* A power of a factor is the factor raised to an exponent.
*
* A derived dimension can be formed from multiple exponents (i.e. velocity is represented as "exp<L, 1>, exp<T, -1>").
* It is also possible to form a derived dimension with only one exponent (i.e. frequency is represented as just
* "exp<T, -1>").
*
* @note This partial class template specialization is used by the library engine and should not be directly instantiated
* by the user (see the other partial specialization).
*
* @tparam E a first exponent of a derived dimension
* @tparam ERest zero or more following exponents of a derived dimension
*/
template<Exponent E, Exponent... ERest>
struct derived_dimension<E, ERest...> : downcast_base<derived_dimension<E, ERest...>> {}; // TODO rename to 'dimension'?
/**
* @brief A power of factor corresponding to the dimension of a quantity
*
@@ -119,6 +84,31 @@ struct exp_multiply_impl {
template<Exponent E, int Num, int Den>
using exp_multiply = detail::exp_multiply_impl<E, Num, Den>::type;
template<Exponent... Es>
struct exp_list {};
/**
* @brief A dimension of a derived quantity
*
* Expression of the dependence of a quantity on the base quantities (and their base dimensions) of a system of
* quantities as a product of powers of factors corresponding to the base quantities, omitting any numerical factors.
* A power of a factor is the factor raised to an exponent.
*
* A derived dimension can be formed from multiple exponents (i.e. velocity is represented as "exp<L, 1>, exp<T, -1>").
* It is also possible to form a derived dimension with only one exponent (i.e. frequency is represented as just
* "exp<T, -1>").
*
* @note This class template is used by the library engine and should not be directly instantiated by the user.
*
* @tparam E a first exponent of a derived dimension
* @tparam ERest zero or more following exponents of a derived dimension
*/
template<Exponent E, Exponent... ERest>
requires (BaseDimension<typename E::dimension> && ... && BaseDimension<typename ERest::dimension>)
struct derived_dimension_base : downcast_base<derived_dimension_base<E, ERest...>> {
using exponents = exp_list<E, ERest...>;
};
// make_dimension
namespace detail {
@@ -130,32 +120,32 @@ namespace detail {
*
* @tparam D derived dimension to consolidate
*/
template<DerivedDimension D>
template<typename ExpList>
struct dim_consolidate;
template<>
struct dim_consolidate<derived_dimension<>> {
using type = derived_dimension<>;
struct dim_consolidate<exp_list<>> {
using type = exp_list<>;
};
template<typename E>
struct dim_consolidate<derived_dimension<E>> {
using type = derived_dimension<E>;
struct dim_consolidate<exp_list<E>> {
using type = exp_list<E>;
};
template<typename E1, typename... ERest>
struct dim_consolidate<derived_dimension<E1, ERest...>> {
using type = type_list_push_front<typename dim_consolidate<derived_dimension<ERest...>>::type, E1>;
struct dim_consolidate<exp_list<E1, ERest...>> {
using type = type_list_push_front<typename dim_consolidate<exp_list<ERest...>>::type, E1>;
};
template<BaseDimension Dim, int Num1, int Den1, int Num2, int Den2, typename... ERest>
struct dim_consolidate<derived_dimension<exp<Dim, Num1, Den1>, exp<Dim, Num2, Den2>, ERest...>> {
struct dim_consolidate<exp_list<exp<Dim, Num1, Den1>, exp<Dim, Num2, Den2>, ERest...>> {
// TODO: provide custom implementation for ratio_add
using r1 = std::ratio<Num1, Den1>;
using r2 = std::ratio<Num2, Den2>;
using r = std::ratio_add<r1, r2>;
using type = conditional<r::num == 0, typename dim_consolidate<derived_dimension<ERest...>>::type,
typename dim_consolidate<derived_dimension<exp<Dim, r::num, r::den>, ERest...>>::type>;
using type = conditional<r::num == 0, typename dim_consolidate<exp_list<ERest...>>::type,
typename dim_consolidate<exp_list<exp<Dim, r::num, r::den>, ERest...>>::type>;
};
/**
@@ -168,7 +158,7 @@ struct extract;
template<>
struct extract<> {
using type = derived_dimension<>;
using type = exp_list<>;
};
template<BaseDimension Dim, int Num, int Den, Exponent... ERest>
@@ -182,12 +172,21 @@ struct extract<exp<Dim, Num, Den>, ERest...> {
};
template<Exponent... Es, int Num, int Den, Exponent... ERest>
struct extract<exp<derived_dimension<Es...>, Num, Den>, ERest...> {
struct extract<exp<derived_dimension_base<Es...>, Num, Den>, ERest...> {
using type = type_list_push_front<typename extract<ERest...>::type, exp_multiply<Es, Num, Den>...>;
};
template<typename T>
struct to_derived_dimension_base;
template<Exponent... Es>
struct to_derived_dimension_base<exp_list<Es...>> {
using type = derived_dimension_base<Es...>;
};
/**
* @brief Converts user provided derived dimension specification into a valid units::derived_dimension definition
* @brief Converts user provided derived dimension specification into a valid units::derived_dimension_base definition
*
* User provided definition of a derived dimension may contain the same base dimension repeated more than once on the
* list possibly hidden in other derived units provided by the user. The process here should:
@@ -197,7 +196,7 @@ struct extract<exp<derived_dimension<Es...>, Num, Den>, ERest...> {
* this base dimension.
*/
template<Exponent... Es>
using make_dimension = dim_consolidate<type_list_sort<typename extract<Es...>::type, exp_less>>::type;
using make_dimension = to_derived_dimension_base<typename dim_consolidate<type_list_sort<typename extract<Es...>::type, exp_less>>::type>::type;
template<Exponent E>
requires (E::den == 1 || E::den == 2) // TODO provide support for any den
@@ -209,31 +208,31 @@ struct exp_ratio {
using type = conditional<E::den == 2, ratio_sqrt<pow>, pow>;
};
template<DerivedDimension D>
template<typename ExpList>
struct base_units_ratio_impl;
template<typename E, typename... Es>
struct base_units_ratio_impl<derived_dimension<E, Es...>> {
using type = ratio_multiply<typename exp_ratio<E>::type, typename base_units_ratio_impl<derived_dimension<Es...>>::type>;
struct base_units_ratio_impl<exp_list<E, Es...>> {
using type = ratio_multiply<typename exp_ratio<E>::type, typename base_units_ratio_impl<exp_list<Es...>>::type>;
};
template<typename E>
struct base_units_ratio_impl<derived_dimension<E>> {
struct base_units_ratio_impl<exp_list<E>> {
using type = exp_ratio<E>::type;
};
/**
* @brief Calculates the common ratio of all the references of base units in the derived dimension
*/
template<DerivedDimension D>
using base_units_ratio = base_units_ratio_impl<D>::type;
template<typename D>
using base_units_ratio = base_units_ratio_impl<typename D::exponents>::type;
} // namespace detail
/**
* @brief The list of exponents of dimensions (both base and derived) provided by the user
*
* This is the primary interface to create derived dimensions. Exponents list can contain powers of factors of both
* This is the user's interface to create derived dimensions. Exponents list can contain powers of factors of both
* base and derived dimensions. This is called a "recipe" of the dimension and among others is used to print
* unnamed coherent units of this dimension.
*
@@ -241,21 +240,18 @@ using base_units_ratio = base_units_ratio_impl<D>::type;
* of powers of base units with no other proportionality factor than one.
*
* The implementation is responsible for unpacking all of the dimensions into a list containing only base dimensions
* and their factors and putting them to the other (private) units::derived_dimension class template partial
* specialization.
*
* @note User should always use only this partial specialization to create derived dimensions.
* and their factors and putting them to derived_dimension_base class template.
*
* @tparam Child inherited class type used by the downcasting facility (CRTP Idiom)
* @tparam E The list of exponents of ingredient dimensions
* @tparam ERest The list of exponents of ingredient dimensions
* @tparam U a coherent unit of a derived dimension
* @tparam E the list of exponents of ingredient dimensions
* @tparam ERest the list of exponents of ingredient dimensions
*/
template<typename Child, Unit U, Exponent E, Exponent... ERest>
requires (!Exponent<Child>)
struct derived_dimension<Child, U, E, ERest...> : downcast_child<Child, typename detail::make_dimension<E, ERest...>> {
using recipe = derived_dimension<E, ERest...>;
struct derived_dimension : downcast_child<Child, typename detail::make_dimension<E, ERest...>> {
using recipe = exp_list<E, ERest...>;
using coherent_unit = U;
using base_units_ratio = detail::base_units_ratio<typename downcast_child<Child, typename detail::make_dimension<E, ERest...>>::downcast_base_type>;
using base_units_ratio = detail::base_units_ratio<derived_dimension>;
};
} // namespace units