[libc++] NFC: Move unwrap_iter to its own header
NOKEYCHECK=True
GitOrigin-RevId: 9968896cd62a62b11ac61085534dd598c4bd3c60
diff --git a/include/algorithm b/include/algorithm
index 65655d7..dbe7d5d 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -645,6 +645,7 @@
*/
+#include <__algorithm/unwrap_iter.h>
#include <__config>
#include <initializer_list>
#include <type_traits>
@@ -1639,65 +1640,6 @@
__value_, __equal_to<__v, _Tp>());
}
-// __unwrap_iter, __rewrap_iter
-
-// The job of __unwrap_iter is to lower contiguous iterators (such as
-// vector<T>::iterator) into pointers, to reduce the number of template
-// instantiations and to enable pointer-based optimizations e.g. in std::copy.
-// For iterators that are not contiguous, it must be a no-op.
-// In debug mode, we don't do this.
-//
-// __unwrap_iter is non-constexpr for user-defined iterators whose
-// `to_address` and/or `operator->` is non-constexpr. This is okay; but we
-// try to avoid doing __unwrap_iter in constant-evaluated contexts anyway.
-//
-// Some algorithms (e.g. std::copy, but not std::sort) need to convert an
-// "unwrapped" result back into a contiguous iterator. Since contiguous iterators
-// are random-access, we can do this portably using iterator arithmetic; this
-// is the job of __rewrap_iter.
-
-template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value>
-struct __unwrap_iter_impl {
- static _LIBCPP_CONSTEXPR _Iter
- __apply(_Iter __i) _NOEXCEPT {
- return __i;
- }
-};
-
-#if _LIBCPP_DEBUG_LEVEL < 2
-
-template <class _Iter>
-struct __unwrap_iter_impl<_Iter, true> {
- static _LIBCPP_CONSTEXPR decltype(_VSTD::__to_address(declval<_Iter>()))
- __apply(_Iter __i) _NOEXCEPT {
- return _VSTD::__to_address(__i);
- }
-};
-
-#endif // _LIBCPP_DEBUG_LEVEL < 2
-
-template<class _Iter, class _Impl = __unwrap_iter_impl<_Iter> >
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-decltype(_Impl::__apply(declval<_Iter>()))
-__unwrap_iter(_Iter __i) _NOEXCEPT
-{
- return _Impl::__apply(__i);
-}
-
-template<class _OrigIter>
-_OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
-{
- return __result;
-}
-
-template<class _OrigIter, class _UnwrappedIter>
-_OrigIter __rewrap_iter(_OrigIter __first, _UnwrappedIter __result)
-{
- // Precondition: __result is reachable from __first
- // Precondition: _OrigIter is a contiguous iterator
- return __first + (__result - _VSTD::__unwrap_iter(__first));
-}
-
// copy
template <class _InputIterator, class _OutputIterator>