[libc++] [P0879] constexpr std::sort
This completes libc++'s implementation of
P0879 "Constexpr for swap and swap related functions."
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0879r0.html
For the feature-macro adjustment, see
https://cplusplus.github.io/LWG/issue3256
Differential Revision: https://reviews.llvm.org/D93661
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index d8fbac7..7220585 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -351,11 +351,11 @@
is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
template <class RandomAccessIterator>
- void
+ constexpr void // constexpr in C++20
sort(RandomAccessIterator first, RandomAccessIterator last);
template <class RandomAccessIterator, class Compare>
- void
+ constexpr void // constexpr in C++20
sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
template <class RandomAccessIterator>
@@ -4047,7 +4047,6 @@
void
__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
{
- // _Compare is known to be a reference type
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
@@ -4236,47 +4235,13 @@
}
}
-// This forwarder keeps the top call and the recursive calls using the same instantiation, forcing a reference _Compare
-template <class _RandomAccessIterator, class _Compare>
+template <class _Compare, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
void
-sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+__sort(_Tp** __first, _Tp** __last, __less<_Tp*>&)
{
- typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
- _VSTD::__sort<_Comp_ref>(__first, __last, _Comp_ref(__comp));
-}
-
-template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
-{
- _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-sort(_Tp** __first, _Tp** __last)
-{
- _VSTD::sort((uintptr_t*)__first, (uintptr_t*)__last, __less<uintptr_t>());
-}
-
-template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last)
-{
- _VSTD::sort(__first.base(), __last.base());
-}
-
-template <class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
-void
-sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last, _Compare __comp)
-{
- typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
- _VSTD::sort<_Tp*, _Comp_ref>(__first.base(), __last.base(), __comp);
+ __less<uintptr_t> __comp;
+ _VSTD::__sort<__less<uintptr_t>&, uintptr_t*>((uintptr_t*)__first, (uintptr_t*)__last, __comp);
}
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
@@ -5478,6 +5443,29 @@
_VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
}
+// sort
+
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
+{
+ typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
+ if (__libcpp_is_constant_evaluated()) {
+ _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
+ } else {
+ _VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
+ }
+}
+
+template <class _RandomAccessIterator>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+void
+sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
+{
+ _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+}
+
// includes
template <class _Compare, class _InputIterator1, class _InputIterator2>
