diff options
Diffstat (limited to 'asl/meta.hpp')
| -rw-r--r-- | asl/meta.hpp | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/asl/meta.hpp b/asl/meta.hpp index 9909be6..a464e36 100644 --- a/asl/meta.hpp +++ b/asl/meta.hpp @@ -117,6 +117,8 @@ template<typename T> struct _is_ref_helper<T&> { static constexpr bool l = true template<typename T> struct _is_ref_helper<T&&> { static constexpr bool l = false; static constexpr bool r = true; }; template<typename T> concept is_ref = _is_ref_helper<T>::l || _is_ref_helper<T>::r; +template<typename T> concept is_rref = _is_ref_helper<T>::r; +template<typename T> concept is_lref = _is_ref_helper<T>::l; template<typename T> struct _is_ptr_helper : false_type {}; template<typename T> struct _is_ptr_helper<T*> : true_type {}; @@ -218,4 +220,29 @@ concept has_niche = constructible_from<T, niche_t> && equality_comparable_with<T template<typename T> concept is_niche = same_as<un_cvref_t<T>, niche_t>; +template<typename T, typename U> +concept _derefs_with_indirection_as = requires(T& t) +{ + *t; + requires convertible_from<U&, decltype(*t)>; +}; + +template<typename T, typename U> +concept _derefs_reference_as = is_ref<T> && convertible_from<U&, T>; + +template<typename T, typename U> +concept _derefs_value_as = !is_ref<T> && convertible_from<U&, T&>; + +template<typename U, _derefs_with_indirection_as<U> T> +constexpr U& deref(T&& t) { return static_cast<U&>(*t); } + +template<typename U, _derefs_reference_as<U> T> +constexpr U& deref(T&& t) { return static_cast<U&>(t); } + +template<typename U, _derefs_value_as<U> T> +constexpr U& deref(T&& t) { return static_cast<U&>(t); } + +template<typename T, typename U> +concept derefs_as = _derefs_with_indirection_as<T, U> || _derefs_reference_as<T, U> || _derefs_value_as<T, U>; + } // namespace asl |