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Optimise std::remove_cv and use more helper aliases

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Define partial specializations for std::remove_cv so that
std::remove_const and std::remove_volatile don't need to be
instantiated.

	* include/std/type_traits (__remove_cv_t): New alias template.
	(is_void, is_integral, is_floating_point, is_pointer)
	(is_member_object_pointer, is_member_function_pointer, is_null_pointer)
	(is_member_point), __is_signed_integer, __is_unsigned_integer)
	(__make_unsigned_selector, __make_signed_selector, remove_pointer)
	(__decay_selector): Use __remove_cv_t.
	(remove_cv): Add partial specializations for cv-qualified types.
	(__decay_t): New alias template.
	(__decay_and_strip, __common_type_impl, __result_of_impl): Use
	__decay_t.
	(__enable_if_t): Move earlier in the file.
	(_Require): Use __enable_if_t.
	(swap(T&, T&)): Use _Require.
	(swap(T(&)[N])): Use __enable_if_t.

From-SVN: r275562
This commit is contained in:
Jonathan Wakely 2019-09-10 08:35:36 +01:00 committed by Jonathan Wakely
parent 4563bc4dc6
commit 391d5d2e30
2 changed files with 65 additions and 38 deletions
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17
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,20 @@
2019-09-10 Jonathan Wakely <jwakely@redhat.com>
* include/std/type_traits (__remove_cv_t): New alias template.
(is_void, is_integral, is_floating_point, is_pointer)
(is_member_object_pointer, is_member_function_pointer, is_null_pointer)
(is_member_point), __is_signed_integer, __is_unsigned_integer)
(__make_unsigned_selector, __make_signed_selector, remove_pointer)
(__decay_selector): Use __remove_cv_t.
(remove_cv): Add partial specializations for cv-qualified types.
(__decay_t): New alias template.
(__decay_and_strip, __common_type_impl, __result_of_impl): Use
__decay_t.
(__enable_if_t): Move earlier in the file.
(_Require): Use __enable_if_t.
(swap(T&, T&)): Use _Require.
(swap(T(&)[N])): Use __enable_if_t.
2019-09-09 Edward Smith-Rowland <3dw4rd@verizon.net>
Implement C++20 p1424 - 'constexpr' feature macro concerns,

86
libstdc++-v3/include/std/type_traits
View File

@ -226,6 +226,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename>
struct remove_cv;
// __remove_cv_t (std::remove_cv_t for C++11).
template<typename _Tp>
using __remove_cv_t = typename remove_cv<_Tp>::type;
template<typename>
struct is_const;
@ -242,7 +246,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_void
template<typename _Tp>
struct is_void
: public __is_void_helper<typename remove_cv<_Tp>::type>::type
: public __is_void_helper<__remove_cv_t<_Tp>>::type
{ };
template<typename>
@ -359,7 +363,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_integral
template<typename _Tp>
struct is_integral
: public __is_integral_helper<typename remove_cv<_Tp>::type>::type
: public __is_integral_helper<__remove_cv_t<_Tp>>::type
{ };
template<typename>
@ -387,7 +391,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_floating_point
template<typename _Tp>
struct is_floating_point
: public __is_floating_point_helper<typename remove_cv<_Tp>::type>::type
: public __is_floating_point_helper<__remove_cv_t<_Tp>>::type
{ };
/// is_array
@ -414,7 +418,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_pointer
template<typename _Tp>
struct is_pointer
: public __is_pointer_helper<typename remove_cv<_Tp>::type>::type
: public __is_pointer_helper<__remove_cv_t<_Tp>>::type
{ };
/// is_lvalue_reference
@ -446,8 +450,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_member_object_pointer
template<typename _Tp>
struct is_member_object_pointer
: public __is_member_object_pointer_helper<
typename remove_cv<_Tp>::type>::type
: public __is_member_object_pointer_helper<__remove_cv_t<_Tp>>::type
{ };
template<typename>
@ -461,8 +464,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_member_function_pointer
template<typename _Tp>
struct is_member_function_pointer
: public __is_member_function_pointer_helper<
typename remove_cv<_Tp>::type>::type
: public __is_member_function_pointer_helper<__remove_cv_t<_Tp>>::type
{ };
/// is_enum
@ -509,7 +511,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_null_pointer (LWG 2247).
template<typename _Tp>
struct is_null_pointer
: public __is_null_pointer_helper<typename remove_cv<_Tp>::type>::type
: public __is_null_pointer_helper<__remove_cv_t<_Tp>>::type
{ };
/// __is_nullptr_t (deprecated extension).
@ -573,7 +575,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// is_member_pointer
template<typename _Tp>
struct is_member_pointer
: public __is_member_pointer_helper<typename remove_cv<_Tp>::type>::type
: public __is_member_pointer_helper<__remove_cv_t<_Tp>>::type
{ };
template<typename, typename>
@ -584,7 +586,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Check if a type is one of the signed integer types.
template<typename _Tp>
using __is_signed_integer = __is_one_of<typename remove_cv<_Tp>::type,
using __is_signed_integer = __is_one_of<__remove_cv_t<_Tp>,
signed char, signed short, signed int, signed long,
signed long long
#if defined(__GLIBCXX_TYPE_INT_N_0)
@ -603,7 +605,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Check if a type is one of the unsigned integer types.
template<typename _Tp>
using __is_unsigned_integer = __is_one_of<typename remove_cv<_Tp>::type,
using __is_unsigned_integer = __is_one_of<__remove_cv_t<_Tp>,
unsigned char, unsigned short, unsigned int, unsigned long,
unsigned long long
#if defined(__GLIBCXX_TYPE_INT_N_0)
@ -1507,10 +1509,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// remove_cv
template<typename _Tp>
struct remove_cv
{
typedef typename
remove_const<typename remove_volatile<_Tp>::type>::type type;
};
{ using type = _Tp; };
template<typename _Tp>
struct remove_cv<const _Tp>
{ using type = _Tp; };
template<typename _Tp>
struct remove_cv<volatile _Tp>
{ using type = _Tp; };
template<typename _Tp>
struct remove_cv<const volatile _Tp>
{ using type = _Tp; };
/// add_const
template<typename _Tp>
@ -1709,7 +1720,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class __make_unsigned_selector<_Tp, true, false>
{
using __unsigned_type
= typename __make_unsigned<typename remove_cv<_Tp>::type>::__type;
= typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
public:
using __type
@ -1863,7 +1874,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class __make_signed_selector<_Tp, true, false>
{
using __signed_type
= typename __make_signed<typename remove_cv<_Tp>::type>::__type;
= typename __make_signed<__remove_cv_t<_Tp>>::__type;
public:
using __type
@ -1989,7 +2000,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// remove_pointer
template<typename _Tp>
struct remove_pointer
: public __remove_pointer_helper<_Tp, typename remove_cv<_Tp>::type>
: public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
{ };
/// add_pointer
@ -2105,7 +2116,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// NB: DR 705.
template<typename _Up>
struct __decay_selector<_Up, false, false>
{ typedef typename remove_cv<_Up>::type __type; };
{ typedef __remove_cv_t<_Up> __type; };
template<typename _Up>
struct __decay_selector<_Up, true, false>
@ -2125,6 +2136,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef typename __decay_selector<__remove_type>::__type type;
};
// __decay_t (std::decay_t for C++11).
template<typename _Tp>
using __decay_t = typename decay<_Tp>::type;
template<typename _Tp>
class reference_wrapper;
@ -2142,11 +2157,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
};
template<typename _Tp>
struct __decay_and_strip
{
typedef typename __strip_reference_wrapper<
typename decay<_Tp>::type>::__type __type;
};
using __decay_and_strip = __strip_reference_wrapper<__decay_t<_Tp>>;
// Primary template.
@ -2160,8 +2171,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct enable_if<true, _Tp>
{ typedef _Tp type; };
// __enable_if_t (std::enable_if_t for C++11)
template<bool _Cond, typename _Tp = void>
using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
template<typename... _Cond>
using _Require = typename enable_if<__and_<_Cond...>::value>::type;
using _Require = __enable_if_t<__and_<_Cond...>::value>;
// Primary template.
/// Define a member typedef @c type to one of two argument types.
@ -2208,8 +2223,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// If sizeof...(T) is two, ...
template<typename _Tp1, typename _Tp2,
typename _Dp1 = typename decay<_Tp1>::type,
typename _Dp2 = typename decay<_Tp2>::type>
typename _Dp1 = __decay_t<_Tp1>, typename _Dp2 = __decay_t<_Tp2>>
struct __common_type_impl
{
// If is_same_v<T1, D1> is false or is_same_v<T2, D2> is false,
@ -2444,13 +2458,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _MemPtr, typename _Arg>
struct __result_of_impl<true, false, _MemPtr, _Arg>
: public __result_of_memobj<typename decay<_MemPtr>::type,
: public __result_of_memobj<__decay_t<_MemPtr>,
typename __inv_unwrap<_Arg>::type>
{ };
template<typename _MemPtr, typename _Arg, typename... _Args>
struct __result_of_impl<false, true, _MemPtr, _Arg, _Args...>
: public __result_of_memfun<typename decay<_MemPtr>::type,
: public __result_of_memfun<__decay_t<_MemPtr>,
typename __inv_unwrap<_Arg>::type, _Args...>
{ };
@ -2526,10 +2540,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
using result_of_t = typename result_of<_Tp>::type;
#endif // C++14
// __enable_if_t (std::enable_if_t for C++11)
template<bool _Cond, typename _Tp = void>
using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
#if __cplusplus >= 201703L || !defined(__STRICT_ANSI__) // c++17 or gnu++11
#define __cpp_lib_void_t 201411
/// A metafunction that always yields void, used for detecting valid types.
@ -2607,9 +2617,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
_GLIBCXX20_CONSTEXPR
inline
typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
is_move_constructible<_Tp>,
is_move_assignable<_Tp>>::value>::type
_Require<__not_<__is_tuple_like<_Tp>>,
is_move_constructible<_Tp>,
is_move_assignable<_Tp>>
swap(_Tp&, _Tp&)
noexcept(__and_<is_nothrow_move_constructible<_Tp>,
is_nothrow_move_assignable<_Tp>>::value);
@ -2617,7 +2627,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, size_t _Nm>
_GLIBCXX20_CONSTEXPR
inline
typename enable_if<__is_swappable<_Tp>::value>::type
__enable_if_t<__is_swappable<_Tp>::value>
swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
noexcept(__is_nothrow_swappable<_Tp>::value);