From 0b265f362d7e580ad3f899689092c056b8d85561 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Mon, 23 Sep 2024 14:25:33 +0200
Subject: [PATCH] refactor: `is_derived_from_specialization_of_v` added and
 applied to remove custom traits

---
 src/core/include/mp-units/ext/type_traits.h   |  6 +++++
 .../mp-units/framework/dimension_concepts.h   |  9 +------
 .../mp-units/framework/quantity_point.h       | 24 ++++++++---------
 .../framework/quantity_point_concepts.h       | 26 +++++--------------
 .../mp-units/framework/unit_concepts.h        | 13 +---------
 5 files changed, 26 insertions(+), 52 deletions(-)

diff --git a/src/core/include/mp-units/ext/type_traits.h b/src/core/include/mp-units/ext/type_traits.h
index 2ee78e2a..74a14139 100644
--- a/src/core/include/mp-units/ext/type_traits.h
+++ b/src/core/include/mp-units/ext/type_traits.h
@@ -89,11 +89,17 @@ namespace detail {
 template<template<typename...> typename Type, typename... Params>
 void to_base_specialization_of(const volatile Type<Params...>*);
 
+template<template<auto...> typename Type, auto... Params>
+void to_base_specialization_of_v(const volatile Type<Params...>*);
+
 }  // namespace detail
 
 template<typename T, template<typename...> typename Type>
 constexpr bool is_derived_from_specialization_of = requires(T* t) { detail::to_base_specialization_of<Type>(t); };
 
+template<typename T, template<auto...> typename Type>
+constexpr bool is_derived_from_specialization_of_v = requires(T* t) { detail::to_base_specialization_of_v<Type>(t); };
+
 namespace detail {
 
 template<typename T>
diff --git a/src/core/include/mp-units/framework/dimension_concepts.h b/src/core/include/mp-units/framework/dimension_concepts.h
index 90330eb2..68f6f15d 100644
--- a/src/core/include/mp-units/framework/dimension_concepts.h
+++ b/src/core/include/mp-units/framework/dimension_concepts.h
@@ -49,20 +49,13 @@ struct base_dimension;
 
 namespace detail {
 
-template<symbol_text Symbol>
-void to_base_specialization_of_base_dimension(const volatile base_dimension<Symbol>*);
-
-template<typename T>
-constexpr bool is_derived_from_specialization_of_base_dimension =
-  requires(T* type) { to_base_specialization_of_base_dimension(type); };
-
 /**
  * @brief A concept matching all named base dimensions in the library.
  *
  * Satisfied by all dimension types derived from a specialization of `base_dimension`.
  */
 template<typename T>
-concept BaseDimension = Dimension<T> && is_derived_from_specialization_of_base_dimension<T>;
+concept BaseDimension = Dimension<T> && is_derived_from_specialization_of_v<T, base_dimension>;
 
 template<typename T>
 struct is_dimension_one : std::false_type {};
diff --git a/src/core/include/mp-units/framework/quantity_point.h b/src/core/include/mp-units/framework/quantity_point.h
index 074cd8fa..ba312544 100644
--- a/src/core/include/mp-units/framework/quantity_point.h
+++ b/src/core/include/mp-units/framework/quantity_point.h
@@ -76,13 +76,13 @@ struct point_origin_interface {
 
   template<PointOrigin PO1, detail::SameAbsolutePointOriginAs<PO1{}> PO2>
     requires QuantitySpecOf<std::remove_const_t<decltype(PO1::quantity_spec)>, PO2::quantity_spec> &&
-             (detail::is_derived_from_specialization_of_relative_point_origin<PO1> ||
-              detail::is_derived_from_specialization_of_relative_point_origin<PO2>)
+             (is_derived_from_specialization_of_v<PO1, relative_point_origin> ||
+              is_derived_from_specialization_of_v<PO2, relative_point_origin>)
   [[nodiscard]] friend constexpr Quantity auto operator-(PO1 po1, PO2 po2)
   {
-    if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO1>) {
+    if constexpr (is_derived_from_specialization_of_v<PO1, absolute_point_origin>) {
       return -(po2.quantity_point - po2.quantity_point.absolute_point_origin);
-    } else if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO2>) {
+    } else if constexpr (is_derived_from_specialization_of_v<PO2, absolute_point_origin>) {
       return po1.quantity_point - po1.quantity_point.absolute_point_origin;
     } else {
       return po1.quantity_point - po2.quantity_point;
@@ -92,16 +92,16 @@ struct point_origin_interface {
   template<PointOrigin PO1, PointOrigin PO2>
   [[nodiscard]] friend consteval bool operator==(PO1 po1, PO2 po2)
   {
-    if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO1> &&
-                  detail::is_derived_from_specialization_of_absolute_point_origin<PO2>)
+    if constexpr (is_derived_from_specialization_of_v<PO1, absolute_point_origin> &&
+                  is_derived_from_specialization_of_v<PO2, absolute_point_origin>)
       return is_same_v<PO1, PO2> || (detail::is_zeroth_point_origin(po1) && detail::is_zeroth_point_origin(po2) &&
                                      interconvertible(po1.quantity_spec, po2.quantity_spec));
-    else if constexpr (detail::is_derived_from_specialization_of_relative_point_origin<PO1> &&
-                       detail::is_derived_from_specialization_of_relative_point_origin<PO2>)
+    else if constexpr (is_derived_from_specialization_of_v<PO1, relative_point_origin> &&
+                       is_derived_from_specialization_of_v<PO2, relative_point_origin>)
       return PO1::quantity_point == PO2::quantity_point;
-    else if constexpr (detail::is_derived_from_specialization_of_relative_point_origin<PO1>)
+    else if constexpr (is_derived_from_specialization_of_v<PO1, relative_point_origin>)
       return detail::same_absolute_point_origins(po1, po2) && is_eq_zero(PO1::quantity_point.quantity_from_zero());
-    else if constexpr (detail::is_derived_from_specialization_of_relative_point_origin<PO2>)
+    else if constexpr (is_derived_from_specialization_of_v<PO2, relative_point_origin>)
       return detail::same_absolute_point_origins(po1, po2) && is_eq_zero(PO2::quantity_point.quantity_from_zero());
   }
 };
@@ -154,7 +154,7 @@ namespace detail {
 template<PointOrigin PO>
 [[nodiscard]] consteval PointOrigin auto get_absolute_point_origin(PO po)
 {
-  if constexpr (is_derived_from_specialization_of_absolute_point_origin<PO>)
+  if constexpr (is_derived_from_specialization_of_v<PO, absolute_point_origin>)
     return po;
   else
     return po.quantity_point.absolute_point_origin;
@@ -509,7 +509,7 @@ public:
   {
     if constexpr (point_origin == po)
       return qp.quantity_ref_from(point_origin);
-    else if constexpr (detail::is_derived_from_specialization_of_absolute_point_origin<PO2>) {
+    else if constexpr (is_derived_from_specialization_of_v<PO2, ::mp_units::absolute_point_origin>) {
       if constexpr (point_origin == absolute_point_origin)
         return qp.quantity_ref_from(point_origin);
       else
diff --git a/src/core/include/mp-units/framework/quantity_point_concepts.h b/src/core/include/mp-units/framework/quantity_point_concepts.h
index 89f49dbf..e1c32f7f 100644
--- a/src/core/include/mp-units/framework/quantity_point_concepts.h
+++ b/src/core/include/mp-units/framework/quantity_point_concepts.h
@@ -40,13 +40,6 @@ namespace detail {
 template<typename T>
 constexpr bool is_quantity_point = false;
 
-template<auto Q>
-void to_base_specialization_of_absolute_point_origin(const volatile absolute_point_origin<Q>*);
-
-template<typename T>
-constexpr bool is_derived_from_specialization_of_absolute_point_origin =
-  requires(T* type) { to_base_specialization_of_absolute_point_origin(type); };
-
 }  // namespace detail
 
 /**
@@ -62,13 +55,6 @@ struct relative_point_origin;
 
 namespace detail {
 
-template<auto QP>
-void to_base_specialization_of_relative_point_origin(const volatile relative_point_origin<QP>*);
-
-template<typename T>
-constexpr bool is_derived_from_specialization_of_relative_point_origin =
-  requires(T* type) { to_base_specialization_of_relative_point_origin(type); };
-
 struct point_origin_interface;
 
 }  // namespace detail
@@ -109,15 +95,15 @@ constexpr bool is_quantity_point<T> = true;
 template<PointOrigin PO1, PointOrigin PO2>
 [[nodiscard]] consteval bool same_absolute_point_origins(PO1 po1, PO2 po2)
 {
-  if constexpr (is_derived_from_specialization_of_absolute_point_origin<PO1> &&
-                is_derived_from_specialization_of_absolute_point_origin<PO2>)
+  if constexpr (is_derived_from_specialization_of_v<PO1, absolute_point_origin> &&
+                is_derived_from_specialization_of_v<PO2, absolute_point_origin>)
     return po1 == po2;
-  else if constexpr (is_derived_from_specialization_of_relative_point_origin<PO1> &&
-                     is_derived_from_specialization_of_relative_point_origin<PO2>)
+  else if constexpr (is_derived_from_specialization_of_v<PO1, relative_point_origin> &&
+                     is_derived_from_specialization_of_v<PO2, relative_point_origin>)
     return po1.absolute_point_origin == po2.absolute_point_origin;
-  else if constexpr (is_derived_from_specialization_of_relative_point_origin<PO1>)
+  else if constexpr (is_derived_from_specialization_of_v<PO1, relative_point_origin>)
     return po1.absolute_point_origin == po2;
-  else if constexpr (is_derived_from_specialization_of_relative_point_origin<PO2>)
+  else if constexpr (is_derived_from_specialization_of_v<PO2, relative_point_origin>)
     return po1 == po2.absolute_point_origin;
   else
     return false;
diff --git a/src/core/include/mp-units/framework/unit_concepts.h b/src/core/include/mp-units/framework/unit_concepts.h
index 92a2199b..f752a22e 100644
--- a/src/core/include/mp-units/framework/unit_concepts.h
+++ b/src/core/include/mp-units/framework/unit_concepts.h
@@ -53,22 +53,11 @@ struct named_unit;
 
 MP_UNITS_EXPORT struct one;
 
-namespace detail {
-
-template<symbol_text Symbol, auto... Args>
-void to_base_specialization_of_named_unit(const volatile named_unit<Symbol, Args...>*);
-
-template<typename T>
-constexpr bool is_derived_from_specialization_of_named_unit =
-  requires(T* t) { to_base_specialization_of_named_unit(t); };
-
-}  // namespace detail
-
 /**
  * @brief A concept to be used to define prefixes for a unit
  */
 MP_UNITS_EXPORT template<typename T>
-concept PrefixableUnit = Unit<T> && detail::is_derived_from_specialization_of_named_unit<T>;
+concept PrefixableUnit = Unit<T> && is_derived_from_specialization_of_v<T, named_unit>;
 
 namespace detail {