Revert "[libc++] NFC: Move unwrap_iter to its own header"
This reverts commit 9968896cd62a62b11ac61085534dd598c4bd3c60.
This commit seems to cause the build failures of main.
NOKEYCHECK=True
GitOrigin-RevId: b13edf6e907b32d0b8da09dfe08fa271638eca3c
diff --git a/include/algorithm b/include/algorithm
index dbe7d5d..65655d7 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -645,7 +645,6 @@
*/
-#include <__algorithm/unwrap_iter.h>
#include <__config>
#include <initializer_list>
#include <type_traits>
@@ -1640,6 +1639,65 @@
__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>