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[meta] Add add_const, add_pointer, add_lvalue_reference, add_rvalue_reference

This commit is contained in:
Behdad Esfahbod 2019-05-10 19:29:32 -07:00
parent 2fb3a8327a
commit 9574de7a3e
1 changed files with 11 additions and 0 deletions
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11
src/hb-meta.hh
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@ -102,17 +102,28 @@ template <typename T> static inline T hb_declval ();
template <typename T> struct hb_match_const { typedef T type; static constexpr bool value = false; };
template <typename T> struct hb_match_const<const T> { typedef T type; static constexpr bool value = true; };
template <typename T> using hb_remove_const = typename hb_match_const<T>::type;
template <typename T> using hb_add_const = const T;
#define hb_is_const(T) hb_match_const<T>::value
template <typename T> struct hb_match_reference { typedef T type; static constexpr bool value = false; };
template <typename T> struct hb_match_reference<T &> { typedef T type; static constexpr bool value = true; };
template <typename T> struct hb_match_reference<T &&> { typedef T type; static constexpr bool value = true; };
template <typename T> using hb_remove_reference = typename hb_match_reference<T>::type;
template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<1>) -> hb_type_identity<T&>;
template <typename T> auto _hb_try_add_lvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
template <typename T> using hb_add_lvalue_reference = decltype (_hb_try_add_lvalue_reference<T> (hb_prioritize));
template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<1>) -> hb_type_identity<T&&>;
template <typename T> auto _hb_try_add_rvalue_reference (hb_priority<0>) -> hb_type_identity<T>;
template <typename T> using hb_add_rvalue_reference = decltype (_hb_try_add_rvalue_reference<T> (hb_prioritize));
#define hb_is_reference(T) hb_match_reference<T>::value
template <typename T> struct hb_match_pointer { typedef T type; static constexpr bool value = false; };
template <typename T> struct hb_match_pointer<T *> { typedef T type; static constexpr bool value = true; };
template <typename T> using hb_remove_pointer = typename hb_match_pointer<T>::type;
template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<hb_remove_reference<T>*>;
template <typename T> auto _hb_try_add_pointer (hb_priority<1>) -> hb_type_identity<T>;
template <typename T> using hb_add_pointer = decltype (_hb_try_add_pointer<T> (hb_prioritize));
#define hb_is_pointer(T) hb_match_pointer<T>::value
/* TODO Add feature-parity to std::decay. */
template <typename T> using hb_decay = hb_remove_const<hb_remove_reference<T>>;