[PATCH] Optimise std::remove_cv and use more helper aliases
Jonathan Wakely
jwakely@redhat.com
Tue Sep 10 07:18:00 GMT 2019
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.
Tested x86_64-linux, committed to trunk.
-------------- next part --------------
commit 547d1d1bf1f7a3c0e93d978df605e660b15f7c56
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Sep 9 13:13:08 2019 +0100
Optimise std::remove_cv and use more helper aliases
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.
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 443208813b1..d2f53591e5a 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -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);
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