type predicate support (wip)

include/sparrow/mp_utils.hpp

@@ -56,6 +56,59 @@ namespace sparrow::mpl
  template <class T, bool is_const>
  using constify_t = typename constify<T, is_const>::type;
 
+
+
+
+ template< class P >
+ concept ct_type_predicate = requires
+ {
+ { P::value } -> std::same_as<bool>;
+ };
+
+ template< class P, class T >
+ concept callable_type_predicate = std::semiregular<P>
+ and (
+ requires(P predicate)
+ {
+ { predicate(typelist<T>{}) } -> std::same_as<bool>;
+ }
+ or
+ requires(P predicate)
+ {
+ { predicate(std::type_identity_t<T>{}) } -> std::same_as<bool>;
+ }
+ )
+ ;
+
+ template< class P, class T >
+ concept type_predicate = ct_type_predicate<P> or callable_type_predicate<P, T>;
+
+
+ template<class T, template<class> class P>
+ requires ct_type_predicate<P<T>>
+ consteval
+ bool evaluate(P<T>)
+ {
+ return P<T>::value;
+ }
+
+ template<class T, callable_type_predicate<T> P>
+ consteval
+ bool evaluate(P predicate)
+ {
+ if constexpr (requires (P p){ { p(typelist<T>{}) } -> std::same_as<bool>; })
+ {
+ return predicate(typelist<T>{});
+ }
+ else
+ {
+ return predicate(std::type_identity_t<T>{});
+ }
+ }
+
+
+
+
  /// Checks that at least one type in the provided list of is making the provide predicate return `true`.
  /// @returns 'true' if for at least one type T in the type list L,, `Predicate{}(typelist<T>) == true`.
  /// `false` otherwise or if the list is empty.
@@ -64,7 +117,7 @@ namespace sparrow::mpl
  consteval
  bool any_of(L<T...> list, Predicate predicate)
  {
- return (predicate(typelist<T>{}) || ... || false);
+ return (evaluate<T>(predicate) || ... || false);
  }
 
  /// Checks that every type in the provided list of is making the provide predicate return `true`.
@@ -75,7 +128,7 @@ namespace sparrow::mpl
  consteval
  bool all_of(L<T...> list, Predicate predicate)
  {
- return (predicate(typelist<T>{}) && ... && true);
+ return (evaluate<T>(predicate) && ... && true);
  }
 
  /// Compile-time type predicate: `true` if the evaluated type is the same as `T`.
@@ -126,7 +179,7 @@ namespace sparrow::mpl
  }
  };
 
- (check(predicate(typelist<T>{})) || ...);
+ (check(evaluate<T>(predicate)) || ...);
 
  return idx;
  }