include/__tree - llvm-project/libcxx - Git at Google

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #ifndef _LIBCPP___TREE
 #define _LIBCPP___TREE

 #include <__algorithm/min.h>
 #include <__assert>
 #include <__config>
 #include <__fwd/pair.h>
 #include <__iterator/distance.h>
 #include <__iterator/iterator_traits.h>
 #include <__iterator/next.h>
 #include <__memory/addressof.h>
 #include <__memory/allocator_traits.h>
 #include <__memory/compressed_pair.h>
 #include <__memory/construct_at.h>
 #include <__memory/pointer_traits.h>
 #include <__memory/swap_allocator.h>
 #include <__memory/unique_ptr.h>
 #include <__new/launder.h>
 #include <__type_traits/copy_cvref.h>
 #include <__type_traits/enable_if.h>
 #include <__type_traits/invoke.h>
 #include <__type_traits/is_constructible.h>
 #include <__type_traits/is_nothrow_assignable.h>
 #include <__type_traits/is_nothrow_constructible.h>
 #include <__type_traits/is_same.h>
 #include <__type_traits/is_specialization.h>
 #include <__type_traits/is_swappable.h>
 #include <__type_traits/remove_const.h>
 #include <__utility/forward.h>
 #include <__utility/lazy_synth_three_way_comparator.h>
 #include <__utility/move.h>
 #include <__utility/pair.h>
 #include <__utility/swap.h>
 #include <__utility/try_key_extraction.h>
 #include <limits>

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif

 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>

 _LIBCPP_DIAGNOSTIC_PUSH
 // GCC complains about the backslashes at the end, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121528
 _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wcomment")
 // __tree is a red-black-tree implementation used for the associative containers (i.e. (multi)map/set). It stores
 // - (1) a pointer to the node with the smallest (i.e. leftmost) element, namely __begin_node_
 // - (2) the number of nodes in the tree, namely __size_
 // - (3) a pointer to the root of the tree, namely __end_node_
 //
 // Storing (1) and (2) is required to allow for constant time lookups. A tree looks like this in memory:
 //
 //      __end_node_
 //           |
 //          root
 //         /    \
 //       l1       r1
 //      /  \     /  \
 //    ...  ... ...  ...
 //
 // All nodes except __end_node_ have a __left_ and __right_ pointer as well as a __parent_ pointer.
 // __end_node_ only contains a __left_ pointer, which points to the root of the tree.
 // This layout allows for iteration through the tree without a need for special handling of the end node. See
 // __tree_next_iter and __tree_prev_iter for more details.
 _LIBCPP_DIAGNOSTIC_POP

 _LIBCPP_BEGIN_NAMESPACE_STD

 template <class _Pointer>
 class __tree_end_node;
 template <class _VoidPtr>
 class __tree_node_base;
 template <class _Tp, class _VoidPtr>
 class __tree_node;

 template <class _Key, class _Value>
 struct __value_type;

 /*

 _NodePtr algorithms

 The algorithms taking _NodePtr are red black tree algorithms.  Those
 algorithms taking a parameter named __root should assume that __root
 points to a proper red black tree (unless otherwise specified).

 Each algorithm herein assumes that __root->__parent_ points to a non-null
 structure which has a member __left_ which points back to __root.  No other
 member is read or written to at __root->__parent_.

 __root->__parent_ will be referred to below (in comments only) as end_node.
 end_node->__left_ is an externably accessible lvalue for __root, and can be
 changed by node insertion and removal (without explicit reference to end_node).

 All nodes (with the exception of end_node), even the node referred to as
 __root, have a non-null __parent_ field.

 */

 // Returns:  true if __x is a left child of its parent, else false
 // Precondition:  __x != nullptr.
 template <class _NodePtr>
 inline _LIBCPP_HIDE_FROM_ABI bool __tree_is_left_child(_NodePtr __x) _NOEXCEPT {
   return __x == __x->__parent_->__left_;
 }

 // Determines if the subtree rooted at __x is a proper red black subtree.  If
 //    __x is a proper subtree, returns the black height (null counts as 1).  If
 //    __x is an improper subtree, returns 0.
 template <class _NodePtr>
 unsigned __tree_sub_invariant(_NodePtr __x) {
   if (__x == nullptr)
     return 1;
   // parent consistency checked by caller
   // check __x->__left_ consistency
   if (__x->__left_ != nullptr && __x->__left_->__parent_ != __x)
     return 0;
   // check __x->__right_ consistency
   if (__x->__right_ != nullptr && __x->__right_->__parent_ != __x)
     return 0;
   // check __x->__left_ != __x->__right_ unless both are nullptr
   if (__x->__left_ == __x->__right_ && __x->__left_ != nullptr)
     return 0;
   // If this is red, neither child can be red
   if (!__x->__is_black_) {
     if (__x->__left_ && !__x->__left_->__is_black_)
       return 0;
     if (__x->__right_ && !__x->__right_->__is_black_)
       return 0;
   }
   unsigned __h = std::__tree_sub_invariant(__x->__left_);
   if (__h == 0)
     return 0; // invalid left subtree
   if (__h != std::__tree_sub_invariant(__x->__right_))
     return 0;                    // invalid or different height right subtree
   return __h + __x->__is_black_; // return black height of this node
 }

 // Determines if the red black tree rooted at __root is a proper red black tree.
 //    __root == nullptr is a proper tree.  Returns true if __root is a proper
 //    red black tree, else returns false.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI bool __tree_invariant(_NodePtr __root) {
   if (__root == nullptr)
     return true;
   // check __x->__parent_ consistency
   if (__root->__parent_ == nullptr)
     return false;
   if (!std::__tree_is_left_child(__root))
     return false;
   // root must be black
   if (!__root->__is_black_)
     return false;
   // do normal node checks
   return std::__tree_sub_invariant(__root) != 0;
 }

 // Returns:  pointer to the left-most node under __x.
 template <class _NodePtr>
 inline _LIBCPP_HIDE_FROM_ABI _NodePtr __tree_min(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "Root node shouldn't be null");
   while (__x->__left_ != nullptr)
     __x = __x->__left_;
   return __x;
 }

 // Returns:  pointer to the right-most node under __x.
 template <class _NodePtr>
 inline _LIBCPP_HIDE_FROM_ABI _NodePtr __tree_max(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "Root node shouldn't be null");
   while (__x->__right_ != nullptr)
     __x = __x->__right_;
   return __x;
 }

 // Returns:  pointer to the next in-order node after __x.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI _NodePtr __tree_next(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   if (__x->__right_ != nullptr)
     return std::__tree_min(__x->__right_);
   while (!std::__tree_is_left_child(__x))
     __x = __x->__parent_unsafe();
   return __x->__parent_unsafe();
 }

 // __tree_next_iter and __tree_prev_iter implement iteration through the tree. The order is as follows:
 // left sub-tree -> node -> right sub-tree. When the right-most node of a sub-tree is reached, we walk up the tree until
 // we find a node where we were in the left sub-tree. We are _always_ in a left sub-tree, since the __end_node_ points
 // to the actual root of the tree through a __left_ pointer. Incrementing the end() pointer is UB, so we can assume that
 // never happens.
 template <class _EndNodePtr, class _NodePtr>
 inline _LIBCPP_HIDE_FROM_ABI _EndNodePtr __tree_next_iter(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   if (__x->__right_ != nullptr)
     return static_cast<_EndNodePtr>(std::__tree_min(__x->__right_));
   while (!std::__tree_is_left_child(__x))
     __x = __x->__parent_unsafe();
   return static_cast<_EndNodePtr>(__x->__parent_);
 }

 // Returns:  pointer to the previous in-order node before __x.
 // Note: __x may be the end node.
 template <class _NodePtr, class _EndNodePtr>
 inline _LIBCPP_HIDE_FROM_ABI _NodePtr __tree_prev_iter(_EndNodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   if (__x->__left_ != nullptr)
     return std::__tree_max(__x->__left_);
   _NodePtr __xx = static_cast<_NodePtr>(__x);
   while (std::__tree_is_left_child(__xx))
     __xx = __xx->__parent_unsafe();
   return __xx->__parent_unsafe();
 }

 // Returns:  pointer to a node which has no children
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI _NodePtr __tree_leaf(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   while (true) {
     if (__x->__left_ != nullptr) {
       __x = __x->__left_;
       continue;
     }
     if (__x->__right_ != nullptr) {
       __x = __x->__right_;
       continue;
     }
     break;
   }
   return __x;
 }

 // Effects:  Makes __x->__right_ the subtree root with __x as its left child
 //           while preserving in-order order.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI void __tree_left_rotate(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   _LIBCPP_ASSERT_INTERNAL(__x->__right_ != nullptr, "node should have a right child");
   _NodePtr __y  = __x->__right_;
   __x->__right_ = __y->__left_;
   if (__x->__right_ != nullptr)
     __x->__right_->__set_parent(__x);
   __y->__parent_ = __x->__parent_;
   if (std::__tree_is_left_child(__x))
     __x->__parent_->__left_ = __y;
   else
     __x->__parent_unsafe()->__right_ = __y;
   __y->__left_ = __x;
   __x->__set_parent(__y);
 }

 // Effects:  Makes __x->__left_ the subtree root with __x as its right child
 //           while preserving in-order order.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI void __tree_right_rotate(_NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "node shouldn't be null");
   _LIBCPP_ASSERT_INTERNAL(__x->__left_ != nullptr, "node should have a left child");
   _NodePtr __y = __x->__left_;
   __x->__left_ = __y->__right_;
   if (__x->__left_ != nullptr)
     __x->__left_->__set_parent(__x);
   __y->__parent_ = __x->__parent_;
   if (std::__tree_is_left_child(__x))
     __x->__parent_->__left_ = __y;
   else
     __x->__parent_unsafe()->__right_ = __y;
   __y->__right_ = __x;
   __x->__set_parent(__y);
 }

 // Effects:  Rebalances __root after attaching __x to a leaf.
 // Precondition:  __x has no children.
 //                __x == __root or == a direct or indirect child of __root.
 //                If __x were to be unlinked from __root (setting __root to
 //                  nullptr if __root == __x), __tree_invariant(__root) == true.
 // Postcondition: __tree_invariant(end_node->__left_) == true.  end_node->__left_
 //                may be different than the value passed in as __root.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI void __tree_balance_after_insert(_NodePtr __root, _NodePtr __x) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__root != nullptr, "Root of the tree shouldn't be null");
   _LIBCPP_ASSERT_INTERNAL(__x != nullptr, "Can't attach null node to a leaf");
   __x->__is_black_ = __x == __root;
   while (__x != __root && !__x->__parent_unsafe()->__is_black_) {
     // __x->__parent_ != __root because __x->__parent_->__is_black == false
     if (std::__tree_is_left_child(__x->__parent_unsafe())) {
       _NodePtr __y = __x->__parent_unsafe()->__parent_unsafe()->__right_;
       if (__y != nullptr && !__y->__is_black_) {
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = true;
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = __x == __root;
         __y->__is_black_ = true;
       } else {
         if (!std::__tree_is_left_child(__x)) {
           __x = __x->__parent_unsafe();
           std::__tree_left_rotate(__x);
         }
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = true;
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = false;
         std::__tree_right_rotate(__x);
         break;
       }
     } else {
       _NodePtr __y = __x->__parent_unsafe()->__parent_->__left_;
       if (__y != nullptr && !__y->__is_black_) {
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = true;
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = __x == __root;
         __y->__is_black_ = true;
       } else {
         if (std::__tree_is_left_child(__x)) {
           __x = __x->__parent_unsafe();
           std::__tree_right_rotate(__x);
         }
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = true;
         __x              = __x->__parent_unsafe();
         __x->__is_black_ = false;
         std::__tree_left_rotate(__x);
         break;
       }
     }
   }
 }

 // Precondition:  __z == __root or == a direct or indirect child of __root.
 // Effects:  unlinks __z from the tree rooted at __root, rebalancing as needed.
 // Postcondition: __tree_invariant(end_node->__left_) == true && end_node->__left_
 //                nor any of its children refer to __z.  end_node->__left_
 //                may be different than the value passed in as __root.
 template <class _NodePtr>
 _LIBCPP_HIDE_FROM_ABI void __tree_remove(_NodePtr __root, _NodePtr __z) _NOEXCEPT {
   _LIBCPP_ASSERT_INTERNAL(__root != nullptr, "Root node should not be null");
   _LIBCPP_ASSERT_INTERNAL(__z != nullptr, "The node to remove should not be null");
   _LIBCPP_ASSERT_INTERNAL(std::__tree_invariant(__root), "The tree invariants should hold");
   // __z will be removed from the tree.  Client still needs to destruct/deallocate it
   // __y is either __z, or if __z has two children, __tree_next(__z).
   // __y will have at most one child.
   // __y will be the initial hole in the tree (make the hole at a leaf)
   _NodePtr __y = (__z->__left_ == nullptr || __z->__right_ == nullptr) ? __z : std::__tree_next(__z);
   // __x is __y's possibly null single child
   _NodePtr __x = __y->__left_ != nullptr ? __y->__left_ : __y->__right_;
   // __w is __x's possibly null uncle (will become __x's sibling)
   _NodePtr __w = nullptr;
   // link __x to __y's parent, and find __w
   if (__x != nullptr)
     __x->__parent_ = __y->__parent_;
   if (std::__tree_is_left_child(__y)) {
     __y->__parent_->__left_ = __x;
     if (__y != __root)
       __w = __y->__parent_unsafe()->__right_;
     else
       __root = __x; // __w == nullptr
   } else {
     __y->__parent_unsafe()->__right_ = __x;
     // __y can't be root if it is a right child
     __w = __y->__parent_->__left_;
   }
   bool __removed_black = __y->__is_black_;
   // If we didn't remove __z, do so now by splicing in __y for __z,
   //    but copy __z's color.  This does not impact __x or __w.
   if (__y != __z) {
     // __z->__left_ != nulptr but __z->__right_ might == __x == nullptr
     __y->__parent_ = __z->__parent_;
     if (std::__tree_is_left_child(__z))
       __y->__parent_->__left_ = __y;
     else
       __y->__parent_unsafe()->__right_ = __y;
     __y->__left_ = __z->__left_;
     __y->__left_->__set_parent(__y);
     __y->__right_ = __z->__right_;
     if (__y->__right_ != nullptr)
       __y->__right_->__set_parent(__y);
     __y->__is_black_ = __z->__is_black_;
     if (__root == __z)
       __root = __y;
   }
   // There is no need to rebalance if we removed a red, or if we removed
   //     the last node.
   if (__removed_black && __root != nullptr) {
     // Rebalance:
     // __x has an implicit black color (transferred from the removed __y)
     //    associated with it, no matter what its color is.
     // If __x is __root (in which case it can't be null), it is supposed
     //    to be black anyway, and if it is doubly black, then the double
     //    can just be ignored.
     // If __x is red (in which case it can't be null), then it can absorb
     //    the implicit black just by setting its color to black.
     // Since __y was black and only had one child (which __x points to), __x
     //   is either red with no children, else null, otherwise __y would have
     //   different black heights under left and right pointers.
     // if (__x == __root || __x != nullptr && !__x->__is_black_)
     if (__x != nullptr)
       __x->__is_black_ = true;
     else {
       //  Else __x isn't root, and is "doubly black", even though it may
       //     be null.  __w can not be null here, else the parent would
       //     see a black height >= 2 on the __x side and a black height
       //     of 1 on the __w side (__w must be a non-null black or a red
       //     with a non-null black child).
       while (true) {
         if (!std::__tree_is_left_child(__w)) // if x is left child
         {
           if (!__w->__is_black_) {
             __w->__is_black_                    = true;
             __w->__parent_unsafe()->__is_black_ = false;
             std::__tree_left_rotate(__w->__parent_unsafe());
             // __x is still valid
             // reset __root only if necessary
             if (__root == __w->__left_)
               __root = __w;
             // reset sibling, and it still can't be null
             __w = __w->__left_->__right_;
           }
           // __w->__is_black_ is now true, __w may have null children
           if ((__w->__left_ == nullptr || __w->__left_->__is_black_) &&
               (__w->__right_ == nullptr || __w->__right_->__is_black_)) {
             __w->__is_black_ = false;
             __x              = __w->__parent_unsafe();
             // __x can no longer be null
             if (__x == __root || !__x->__is_black_) {
               __x->__is_black_ = true;
               break;
             }
             // reset sibling, and it still can't be null
             __w = std::__tree_is_left_child(__x) ? __x->__parent_unsafe()->__right_ : __x->__parent_->__left_;
             // continue;
           } else // __w has a red child
           {
             if (__w->__right_ == nullptr || __w->__right_->__is_black_) {
               // __w left child is non-null and red
               __w->__left_->__is_black_ = true;
               __w->__is_black_          = false;
               std::__tree_right_rotate(__w);
               // __w is known not to be root, so root hasn't changed
               // reset sibling, and it still can't be null
               __w = __w->__parent_unsafe();
             }
             // __w has a right red child, left child may be null
             __w->__is_black_                    = __w->__parent_unsafe()->__is_black_;
             __w->__parent_unsafe()->__is_black_ = true;
             __w->__right_->__is_black_          = true;
             std::__tree_left_rotate(__w->__parent_unsafe());
             break;
           }
         } else {
           if (!__w->__is_black_) {
             __w->__is_black_                    = true;
             __w->__parent_unsafe()->__is_black_ = false;
             std::__tree_right_rotate(__w->__parent_unsafe());
             // __x is still valid
             // reset __root only if necessary
             if (__root == __w->__right_)
               __root = __w;
             // reset sibling, and it still can't be null
             __w = __w->__right_->__left_;
           }
           // __w->__is_black_ is now true, __w may have null children
           if ((__w->__left_ == nullptr || __w->__left_->__is_black_) &&
               (__w->__right_ == nullptr || __w->__right_->__is_black_)) {
             __w->__is_black_ = false;
             __x              = __w->__parent_unsafe();
             // __x can no longer be null
             if (!__x->__is_black_ || __x == __root) {
               __x->__is_black_ = true;
               break;
             }
             // reset sibling, and it still can't be null
             __w = std::__tree_is_left_child(__x) ? __x->__parent_unsafe()->__right_ : __x->__parent_->__left_;
             // continue;
           } else // __w has a red child
           {
             if (__w->__left_ == nullptr || __w->__left_->__is_black_) {
               // __w right child is non-null and red
               __w->__right_->__is_black_ = true;
               __w->__is_black_           = false;
               std::__tree_left_rotate(__w);
               // __w is known not to be root, so root hasn't changed
               // reset sibling, and it still can't be null
               __w = __w->__parent_unsafe();
             }
             // __w has a left red child, right child may be null
             __w->__is_black_                    = __w->__parent_unsafe()->__is_black_;
             __w->__parent_unsafe()->__is_black_ = true;
             __w->__left_->__is_black_           = true;
             std::__tree_right_rotate(__w->__parent_unsafe());
             break;
           }
         }
       }
     }
   }
 }

 // node traits

 template <class _Tp>
 inline const bool __is_tree_value_type_v = __is_specialization_v<_Tp, __value_type>;

 template <class _Tp>
 struct __get_tree_key_type {
   using type _LIBCPP_NODEBUG = _Tp;
 };

 template <class _Key, class _ValueT>
 struct __get_tree_key_type<__value_type<_Key, _ValueT> > {
   using type _LIBCPP_NODEBUG = _Key;
 };

 template <class _Tp>
 using __get_tree_key_type_t _LIBCPP_NODEBUG = typename __get_tree_key_type<_Tp>::type;

 template <class _Tp>
 struct __get_node_value_type {
   using type _LIBCPP_NODEBUG = _Tp;
 };

 template <class _Key, class _ValueT>
 struct __get_node_value_type<__value_type<_Key, _ValueT> > {
   using type _LIBCPP_NODEBUG = pair<const _Key, _ValueT>;
 };

 template <class _Tp>
 using __get_node_value_type_t _LIBCPP_NODEBUG = typename __get_node_value_type<_Tp>::type;

 template <class _NodePtr, class _NodeT = typename pointer_traits<_NodePtr>::element_type>
 struct __tree_node_types;

 template <class _NodePtr, class _Tp, class _VoidPtr>
 struct __tree_node_types<_NodePtr, __tree_node<_Tp, _VoidPtr> > {
   using __node_base_pointer _LIBCPP_NODEBUG = __rebind_pointer_t<_VoidPtr, __tree_node_base<_VoidPtr> >;
   using __end_node_pointer _LIBCPP_NODEBUG  = __rebind_pointer_t<_VoidPtr, __tree_end_node<__node_base_pointer> >;

 private:
   static_assert(is_same<typename pointer_traits<_VoidPtr>::element_type, void>::value,
                 "_VoidPtr does not point to unqualified void type");
 };

 // node

 template <class _Pointer>
 class __tree_end_node {
 public:
   using pointer = _Pointer;
   pointer __left_;

   _LIBCPP_HIDE_FROM_ABI __tree_end_node() _NOEXCEPT : __left_() {}
 };

 template <class _VoidPtr>
 class __tree_node_base : public __tree_end_node<__rebind_pointer_t<_VoidPtr, __tree_node_base<_VoidPtr> > > {
 public:
   using pointer                            = __rebind_pointer_t<_VoidPtr, __tree_node_base>;
   using __end_node_pointer _LIBCPP_NODEBUG = __rebind_pointer_t<_VoidPtr, __tree_end_node<pointer> >;

   pointer __right_;
   __end_node_pointer __parent_;
   bool __is_black_;

   _LIBCPP_HIDE_FROM_ABI pointer __parent_unsafe() const { return static_cast<pointer>(__parent_); }

   _LIBCPP_HIDE_FROM_ABI void __set_parent(pointer __p) { __parent_ = static_cast<__end_node_pointer>(__p); }

   _LIBCPP_HIDE_FROM_ABI __tree_node_base()             = default;
   __tree_node_base(__tree_node_base const&)            = delete;
   __tree_node_base& operator=(__tree_node_base const&) = delete;
 };

 template <class _Tp, class _VoidPtr>
 class __tree_node : public __tree_node_base<_VoidPtr> {
 public:
   using __node_value_type _LIBCPP_NODEBUG = __get_node_value_type_t<_Tp>;

 // We use a union to avoid initialization during member initialization, which allows us
 // to use the allocator from the container to construct the `__node_value_type` in the
 // memory provided by the union member
 #ifndef _LIBCPP_CXX03_LANG

 private:
   union {
     __node_value_type __value_;
   };

 public:
   _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return __value_; }
 #else

 private:
   _ALIGNAS_TYPE(__node_value_type) unsigned char __buffer_[sizeof(__node_value_type)];

 public:
   _LIBCPP_HIDE_FROM_ABI __node_value_type& __get_value() { return *reinterpret_cast<__node_value_type*>(__buffer_); }
 #endif

   template <class _Alloc, class... _Args>
   _LIBCPP_HIDE_FROM_ABI explicit __tree_node(_Alloc& __na, _Args&&... __args) {
     allocator_traits<_Alloc>::construct(__na, std::addressof(__get_value()), std::forward<_Args>(__args)...);
   }
   ~__tree_node()                             = delete;
   __tree_node(__tree_node const&)            = delete;
   __tree_node& operator=(__tree_node const&) = delete;
 };

 template <class _Allocator>
 class __tree_node_destructor {
   using allocator_type                 = _Allocator;
   using __alloc_traits _LIBCPP_NODEBUG = allocator_traits<allocator_type>;

 public:
   using pointer = typename __alloc_traits::pointer;

 private:
   allocator_type& __na_;

 public:
   bool __value_constructed;

   _LIBCPP_HIDE_FROM_ABI __tree_node_destructor(const __tree_node_destructor&) = default;
   __tree_node_destructor& operator=(const __tree_node_destructor&)            = delete;

   _LIBCPP_HIDE_FROM_ABI explicit __tree_node_destructor(allocator_type& __na, bool __val = false) _NOEXCEPT
       : __na_(__na),
         __value_constructed(__val) {}

   _LIBCPP_HIDE_FROM_ABI void operator()(pointer __p) _NOEXCEPT {
     if (__value_constructed)
       __alloc_traits::destroy(__na_, std::addressof(__p->__get_value()));
     if (__p)
       __alloc_traits::deallocate(__na_, __p, 1);
   }

   template <class>
   friend class __map_node_destructor;
 };

 #if _LIBCPP_STD_VER >= 17
 template <class _NodeType, class _Alloc>
 struct __generic_container_node_destructor;
 template <class _Tp, class _VoidPtr, class _Alloc>
 struct __generic_container_node_destructor<__tree_node<_Tp, _VoidPtr>, _Alloc> : __tree_node_destructor<_Alloc> {
   using __tree_node_destructor<_Alloc>::__tree_node_destructor;
 };
 #endif

 template <class _Tp, class _NodePtr, class _DiffType>
 class __tree_iterator {
   using _NodeTypes _LIBCPP_NODEBUG = __tree_node_types<_NodePtr>;
   // NOLINTNEXTLINE(libcpp-nodebug-on-aliases) lldb relies on this alias for pretty printing
   using __node_pointer                      = _NodePtr;
   using __node_base_pointer _LIBCPP_NODEBUG = typename _NodeTypes::__node_base_pointer;
   using __end_node_pointer _LIBCPP_NODEBUG  = typename _NodeTypes::__end_node_pointer;

   __end_node_pointer __ptr_;

 public:
   using iterator_category = bidirectional_iterator_tag;
   using value_type        = __get_node_value_type_t<_Tp>;
   using difference_type   = _DiffType;
   using reference         = value_type&;
   using pointer           = __rebind_pointer_t<_NodePtr, value_type>;

   _LIBCPP_HIDE_FROM_ABI __tree_iterator() _NOEXCEPT : __ptr_(nullptr) {}

   _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __get_np()->__get_value(); }
   _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
     return pointer_traits<pointer>::pointer_to(__get_np()->__get_value());
   }

   _LIBCPP_HIDE_FROM_ABI __tree_iterator& operator++() {
     __ptr_ = std::__tree_next_iter<__end_node_pointer>(static_cast<__node_base_pointer>(__ptr_));
     return *this;
   }
   _LIBCPP_HIDE_FROM_ABI __tree_iterator operator++(int) {
     __tree_iterator __t(*this);
     ++(*this);
     return __t;
   }

   _LIBCPP_HIDE_FROM_ABI __tree_iterator& operator--() {
     __ptr_ = static_cast<__end_node_pointer>(std::__tree_prev_iter<__node_base_pointer>(__ptr_));
     return *this;
   }
   _LIBCPP_HIDE_FROM_ABI __tree_iterator operator--(int) {
     __tree_iterator __t(*this);
     --(*this);
     return __t;
   }

   friend _LIBCPP_HIDE_FROM_ABI bool operator==(const __tree_iterator& __x, const __tree_iterator& __y) {
     return __x.__ptr_ == __y.__ptr_;
   }
   friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const __tree_iterator& __x, const __tree_iterator& __y) {
     return !(__x == __y);
   }

 private:
   _LIBCPP_HIDE_FROM_ABI explicit __tree_iterator(__node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
   _LIBCPP_HIDE_FROM_ABI explicit __tree_iterator(__end_node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
   _LIBCPP_HIDE_FROM_ABI __node_pointer __get_np() const { return static_cast<__node_pointer>(__ptr_); }
   template <class, class, class>
   friend class __tree;
   template <class, class, class>
   friend class __tree_const_iterator;
 };

 template <class _Tp, class _NodePtr, class _DiffType>
 class __tree_const_iterator {
   using _NodeTypes _LIBCPP_NODEBUG = __tree_node_types<_NodePtr>;
   // NOLINTNEXTLINE(libcpp-nodebug-on-aliases) lldb relies on this alias for pretty printing
   using __node_pointer                      = _NodePtr;
   using __node_base_pointer _LIBCPP_NODEBUG = typename _NodeTypes::__node_base_pointer;
   using __end_node_pointer _LIBCPP_NODEBUG  = typename _NodeTypes::__end_node_pointer;

   __end_node_pointer __ptr_;

 public:
   using iterator_category                    = bidirectional_iterator_tag;
   using value_type                           = __get_node_value_type_t<_Tp>;
   using difference_type                      = _DiffType;
   using reference                            = const value_type&;
   using pointer                              = __rebind_pointer_t<_NodePtr, const value_type>;
   using __non_const_iterator _LIBCPP_NODEBUG = __tree_iterator<_Tp, __node_pointer, difference_type>;

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator() _NOEXCEPT : __ptr_(nullptr) {}

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator(__non_const_iterator __p) _NOEXCEPT : __ptr_(__p.__ptr_) {}

   _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __get_np()->__get_value(); }
   _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
     return pointer_traits<pointer>::pointer_to(__get_np()->__get_value());
   }

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator& operator++() {
     __ptr_ = std::__tree_next_iter<__end_node_pointer>(static_cast<__node_base_pointer>(__ptr_));
     return *this;
   }

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator operator++(int) {
     __tree_const_iterator __t(*this);
     ++(*this);
     return __t;
   }

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator& operator--() {
     __ptr_ = static_cast<__end_node_pointer>(std::__tree_prev_iter<__node_base_pointer>(__ptr_));
     return *this;
   }

   _LIBCPP_HIDE_FROM_ABI __tree_const_iterator operator--(int) {
     __tree_const_iterator __t(*this);
     --(*this);
     return __t;
   }

   friend _LIBCPP_HIDE_FROM_ABI bool operator==(const __tree_const_iterator& __x, const __tree_const_iterator& __y) {
     return __x.__ptr_ == __y.__ptr_;
   }
   friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const __tree_const_iterator& __x, const __tree_const_iterator& __y) {
     return !(__x == __y);
   }

 private:
   _LIBCPP_HIDE_FROM_ABI explicit __tree_const_iterator(__node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
   _LIBCPP_HIDE_FROM_ABI explicit __tree_const_iterator(__end_node_pointer __p) _NOEXCEPT : __ptr_(__p) {}
   _LIBCPP_HIDE_FROM_ABI __node_pointer __get_np() const { return static_cast<__node_pointer>(__ptr_); }

   template <class, class, class>
   friend class __tree;
 };

 template <class _Tp, class _Compare>
 #ifndef _LIBCPP_CXX03_LANG
 _LIBCPP_DIAGNOSE_WARNING(!__is_invocable_v<_Compare const&, _Tp const&, _Tp const&>,
                          "the specified comparator type does not provide a viable const call operator")
 #endif
 int __diagnose_non_const_comparator();

 template <class _Tp, class _Compare, class _Allocator>
 class __tree {
 public:
   using value_type     = __get_node_value_type_t<_Tp>;
   using value_compare  = _Compare;
   using allocator_type = _Allocator;

 private:
   using __alloc_traits _LIBCPP_NODEBUG = allocator_traits<allocator_type>;
   using key_type                       = __get_tree_key_type_t<_Tp>;

 public:
   using pointer         = typename __alloc_traits::pointer;
   using const_pointer   = typename __alloc_traits::const_pointer;
   using size_type       = typename __alloc_traits::size_type;
   using difference_type = typename __alloc_traits::difference_type;

   using __void_pointer _LIBCPP_NODEBUG = typename __alloc_traits::void_pointer;

   using __node _LIBCPP_NODEBUG = __tree_node<_Tp, __void_pointer>;
   // NOLINTNEXTLINE(libcpp-nodebug-on-aliases) lldb relies on this alias for pretty printing
   using __node_pointer = __rebind_pointer_t<__void_pointer, __node>;

   using __node_base _LIBCPP_NODEBUG         = __tree_node_base<__void_pointer>;
   using __node_base_pointer _LIBCPP_NODEBUG = __rebind_pointer_t<__void_pointer, __node_base>;

   using __end_node_t _LIBCPP_NODEBUG       = __tree_end_node<__node_base_pointer>;
   using __end_node_pointer _LIBCPP_NODEBUG = __rebind_pointer_t<__void_pointer, __end_node_t>;

   using __parent_pointer _LIBCPP_NODEBUG = __end_node_pointer; // TODO: Remove this once the uses in <map> are removed

   using __node_allocator _LIBCPP_NODEBUG = __rebind_alloc<__alloc_traits, __node>;
   using __node_traits _LIBCPP_NODEBUG    = allocator_traits<__node_allocator>;

 // TODO(LLVM 22): Remove this check
 #ifndef _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
   static_assert(sizeof(__node_base_pointer) == sizeof(__end_node_pointer) && _LIBCPP_ALIGNOF(__node_base_pointer) ==
                     _LIBCPP_ALIGNOF(__end_node_pointer),
                 "It looks like you are using std::__tree (an implementation detail for (multi)map/set) with a fancy "
                 "pointer type that thas a different representation depending on whether it points to a __tree base "
                 "pointer or a __tree node pointer (both of which are implementation details of the standard library). "
                 "This means that your ABI is being broken between LLVM 19 and LLVM 20. If you don't care about your "
                 "ABI being broken, define the _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB macro to silence this "
                 "diagnostic.");
 #endif

 private:
   // check for sane allocator pointer rebinding semantics. Rebinding the
   // allocator for a new pointer type should be exactly the same as rebinding
   // the pointer using 'pointer_traits'.
   static_assert(is_same<__node_pointer, typename __node_traits::pointer>::value,
                 "Allocator does not rebind pointers in a sane manner.");
   using __node_base_allocator _LIBCPP_NODEBUG = __rebind_alloc<__node_traits, __node_base>;
   using __node_base_traits _LIBCPP_NODEBUG    = allocator_traits<__node_base_allocator>;
   static_assert(is_same<__node_base_pointer, typename __node_base_traits::pointer>::value,
                 "Allocator does not rebind pointers in a sane manner.");

 private:
   __end_node_pointer __begin_node_;
   _LIBCPP_COMPRESSED_PAIR(__end_node_t, __end_node_, __node_allocator, __node_alloc_);
   _LIBCPP_COMPRESSED_PAIR(size_type, __size_, value_compare, __value_comp_);

 public:
   _LIBCPP_HIDE_FROM_ABI __end_node_pointer __end_node() _NOEXCEPT {
     return pointer_traits<__end_node_pointer>::pointer_to(__end_node_);
   }
   _LIBCPP_HIDE_FROM_ABI __end_node_pointer __end_node() const _NOEXCEPT {
     return pointer_traits<__end_node_pointer>::pointer_to(const_cast<__end_node_t&>(__end_node_));
   }
   _LIBCPP_HIDE_FROM_ABI __node_allocator& __node_alloc() _NOEXCEPT { return __node_alloc_; }

 private:
   _LIBCPP_HIDE_FROM_ABI const __node_allocator& __node_alloc() const _NOEXCEPT { return __node_alloc_; }

 public:
   _LIBCPP_HIDE_FROM_ABI allocator_type __alloc() const _NOEXCEPT { return allocator_type(__node_alloc()); }

   _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size_; }
   _LIBCPP_HIDE_FROM_ABI value_compare& value_comp() _NOEXCEPT { return __value_comp_; }
   _LIBCPP_HIDE_FROM_ABI const value_compare& value_comp() const _NOEXCEPT { return __value_comp_; }

 public:
   _LIBCPP_HIDE_FROM_ABI __node_pointer __root() const _NOEXCEPT {
     return static_cast<__node_pointer>(__end_node()->__left_);
   }

   _LIBCPP_HIDE_FROM_ABI __node_base_pointer* __root_ptr() const _NOEXCEPT {
     return std::addressof(__end_node()->__left_);
   }

   using iterator       = __tree_iterator<_Tp, __node_pointer, difference_type>;
   using const_iterator = __tree_const_iterator<_Tp, __node_pointer, difference_type>;

   _LIBCPP_HIDE_FROM_ABI explicit __tree(const value_compare& __comp) _NOEXCEPT_(
       is_nothrow_default_constructible<__node_allocator>::value&& is_nothrow_copy_constructible<value_compare>::value)
       : __size_(0), __value_comp_(__comp) {
     __begin_node_ = __end_node();
   }

   _LIBCPP_HIDE_FROM_ABI explicit __tree(const allocator_type& __a)
       : __begin_node_(), __node_alloc_(__node_allocator(__a)), __size_(0) {
     __begin_node_ = __end_node();
   }

   _LIBCPP_HIDE_FROM_ABI __tree(const value_compare& __comp, const allocator_type& __a)
       : __begin_node_(), __node_alloc_(__node_allocator(__a)), __size_(0), __value_comp_(__comp) {
     __begin_node_ = __end_node();
   }

   _LIBCPP_HIDE_FROM_ABI __tree(const __tree& __t);
   _LIBCPP_HIDE_FROM_ABI __tree& operator=(const __tree& __t);
   template <class _ForwardIterator>
   _LIBCPP_HIDE_FROM_ABI void __assign_unique(_ForwardIterator __first, _ForwardIterator __last);
   template <class _InputIterator>
   _LIBCPP_HIDE_FROM_ABI void __assign_multi(_InputIterator __first, _InputIterator __last);
   _LIBCPP_HIDE_FROM_ABI __tree(__tree&& __t) _NOEXCEPT_(
       is_nothrow_move_constructible<__node_allocator>::value&& is_nothrow_move_constructible<value_compare>::value);
   _LIBCPP_HIDE_FROM_ABI __tree(__tree&& __t, const allocator_type& __a);

   _LIBCPP_HIDE_FROM_ABI __tree& operator=(__tree&& __t)
       _NOEXCEPT_(is_nothrow_move_assignable<value_compare>::value &&
                  ((__node_traits::propagate_on_container_move_assignment::value &&
                    is_nothrow_move_assignable<__node_allocator>::value) ||
                   allocator_traits<__node_allocator>::is_always_equal::value)) {
     __move_assign(__t, integral_constant<bool, __node_traits::propagate_on_container_move_assignment::value>());
     return *this;
   }

   _LIBCPP_HIDE_FROM_ABI ~__tree() {
     static_assert(is_copy_constructible<value_compare>::value, "Comparator must be copy-constructible.");
     destroy(__root());
   }

   _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return iterator(__begin_node_); }
   _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return const_iterator(__begin_node_); }
   _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return iterator(__end_node()); }
   _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return const_iterator(__end_node()); }

   _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
     return std::min<size_type>(__node_traits::max_size(__node_alloc()), numeric_limits<difference_type >::max());
   }

   _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT;

   _LIBCPP_HIDE_FROM_ABI void swap(__tree& __t)
 #if _LIBCPP_STD_VER <= 11
       _NOEXCEPT_(__is_nothrow_swappable_v<value_compare> &&
                  (!__node_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<__node_allocator>));
 #else
       _NOEXCEPT_(__is_nothrow_swappable_v<value_compare>);
 #endif

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI iterator __emplace_multi(_Args&&... __args);

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI iterator __emplace_hint_multi(const_iterator __p, _Args&&... __args);

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> __emplace_unique(_Args&&... __args) {
     return std::__try_key_extraction<key_type>(
         [this](const key_type& __key, _Args&&... __args2) {
           auto [__parent, __child] = __find_equal(__key);
           __node_pointer __r       = static_cast<__node_pointer>(__child);
           bool __inserted          = false;
           if (__child == nullptr) {
             __node_holder __h = __construct_node(std::forward<_Args>(__args2)...);
             __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
             __r        = __h.release();
             __inserted = true;
           }
           return pair<iterator, bool>(iterator(__r), __inserted);
         },
         [this](_Args&&... __args2) {
           __node_holder __h        = __construct_node(std::forward<_Args>(__args2)...);
           auto [__parent, __child] = __find_equal(__h->__get_value());
           __node_pointer __r       = static_cast<__node_pointer>(__child);
           bool __inserted          = false;
           if (__child == nullptr) {
             __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
             __r        = __h.release();
             __inserted = true;
           }
           return pair<iterator, bool>(iterator(__r), __inserted);
         },
         std::forward<_Args>(__args)...);
   }

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> __emplace_hint_unique(const_iterator __p, _Args&&... __args) {
     return std::__try_key_extraction<key_type>(
         [this, __p](const key_type& __key, _Args&&... __args2) {
           __node_base_pointer __dummy;
           auto [__parent, __child] = __find_equal(__p, __dummy, __key);
           __node_pointer __r       = static_cast<__node_pointer>(__child);
           bool __inserted          = false;
           if (__child == nullptr) {
             __node_holder __h = __construct_node(std::forward<_Args>(__args2)...);
             __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
             __r        = __h.release();
             __inserted = true;
           }
           return pair<iterator, bool>(iterator(__r), __inserted);
         },
         [this, __p](_Args&&... __args2) {
           __node_holder __h = __construct_node(std::forward<_Args>(__args2)...);
           __node_base_pointer __dummy;
           auto [__parent, __child] = __find_equal(__p, __dummy, __h->__get_value());
           __node_pointer __r       = static_cast<__node_pointer>(__child);
           if (__child == nullptr) {
             __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
             __r = __h.release();
           }
           return pair<iterator, bool>(iterator(__r), __child == nullptr);
         },
         std::forward<_Args>(__args)...);
   }

   template <class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void
   __insert_unique_from_orphaned_node(const_iterator __p, __get_node_value_type_t<_Tp>&& __value) {
     __emplace_hint_unique(__p, const_cast<key_type&&>(__value.first), std::move(__value.second));
   }

   template <class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __insert_unique_from_orphaned_node(const_iterator __p, _Tp&& __value) {
     __emplace_hint_unique(__p, std::move(__value));
   }

   template <class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __insert_multi_from_orphaned_node(const_iterator __p, value_type&& __value) {
     __emplace_hint_multi(__p, const_cast<key_type&&>(__value.first), std::move(__value.second));
   }

   template <class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI void __insert_multi_from_orphaned_node(const_iterator __p, _Tp&& __value) {
     __emplace_hint_multi(__p, std::move(__value));
   }

   template <class _InIter, class _Sent>
   _LIBCPP_HIDE_FROM_ABI void __insert_range_multi(_InIter __first, _Sent __last) {
     if (__first == __last)
       return;

     if (__root() == nullptr) { // Make sure we always have a root node
       __insert_node_at(
           __end_node(), __end_node()->__left_, static_cast<__node_base_pointer>(__construct_node(*__first).release()));
       ++__first;
     }

     auto __max_node = static_cast<__node_pointer>(std::__tree_max(static_cast<__node_base_pointer>(__root())));

     for (; __first != __last; ++__first) {
       __node_holder __nd = __construct_node(*__first);
       // Always check the max node first. This optimizes for sorted ranges inserted at the end.
       if (!value_comp()(__nd->__get_value(), __max_node->__get_value())) { // __node >= __max_val
         __insert_node_at(static_cast<__end_node_pointer>(__max_node),
                          __max_node->__right_,
                          static_cast<__node_base_pointer>(__nd.get()));
         __max_node = __nd.release();
       } else {
         __end_node_pointer __parent;
         __node_base_pointer& __child = __find_leaf_high(__parent, __nd->__get_value());
         __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd.release()));
       }
     }
   }

   _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> __node_assign_unique(const value_type& __v, __node_pointer __dest);

   _LIBCPP_HIDE_FROM_ABI iterator __node_insert_multi(__node_pointer __nd);
   _LIBCPP_HIDE_FROM_ABI iterator __node_insert_multi(const_iterator __p, __node_pointer __nd);

   template <class _InIter, class _Sent>
   _LIBCPP_HIDE_FROM_ABI void __insert_range_unique(_InIter __first, _Sent __last) {
     if (__first == __last)
       return;

     if (__root() == nullptr) {
       __insert_node_at(
           __end_node(), __end_node()->__left_, static_cast<__node_base_pointer>(__construct_node(*__first).release()));
       ++__first;
     }

     auto __max_node = static_cast<__node_pointer>(std::__tree_max(static_cast<__node_base_pointer>(__root())));

     using __reference = decltype(*__first);

     for (; __first != __last; ++__first) {
       std::__try_key_extraction<key_type>(
           [this, &__max_node](const key_type& __key, __reference&& __val) {
             if (value_comp()(__max_node->__get_value(), __key)) { // __key > __max_node
               __node_holder __nd = __construct_node(std::forward<__reference>(__val));
               __insert_node_at(static_cast<__end_node_pointer>(__max_node),
                                __max_node->__right_,
                                static_cast<__node_base_pointer>(__nd.get()));
               __max_node = __nd.release();
             } else {
               auto [__parent, __child] = __find_equal(__key);
               if (__child == nullptr) {
                 __node_holder __nd = __construct_node(std::forward<__reference>(__val));
                 __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd.release()));
               }
             }
           },
           [this, &__max_node](__reference&& __val) {
             __node_holder __nd = __construct_node(std::forward<__reference>(__val));
             if (value_comp()(__max_node->__get_value(), __nd->__get_value())) { // __node > __max_node
               __insert_node_at(static_cast<__end_node_pointer>(__max_node),
                                __max_node->__right_,
                                static_cast<__node_base_pointer>(__nd.get()));
               __max_node = __nd.release();
             } else {
               auto [__parent, __child] = __find_equal(__nd->__get_value());
               if (__child == nullptr) {
                 __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd.release()));
               }
             }
           },
           *__first);
     }
   }

   _LIBCPP_HIDE_FROM_ABI iterator __remove_node_pointer(__node_pointer) _NOEXCEPT;

 #if _LIBCPP_STD_VER >= 17
   template <class _NodeHandle, class _InsertReturnType>
   _LIBCPP_HIDE_FROM_ABI _InsertReturnType __node_handle_insert_unique(_NodeHandle&&);
   template <class _NodeHandle>
   _LIBCPP_HIDE_FROM_ABI iterator __node_handle_insert_unique(const_iterator, _NodeHandle&&);
   template <class _Tree>
   _LIBCPP_HIDE_FROM_ABI void __node_handle_merge_unique(_Tree& __source);

   template <class _NodeHandle>
   _LIBCPP_HIDE_FROM_ABI iterator __node_handle_insert_multi(_NodeHandle&&);
   template <class _NodeHandle>
   _LIBCPP_HIDE_FROM_ABI iterator __node_handle_insert_multi(const_iterator, _NodeHandle&&);
   template <class _Tree>
   _LIBCPP_HIDE_FROM_ABI void __node_handle_merge_multi(_Tree& __source);

   template <class _NodeHandle>
   _LIBCPP_HIDE_FROM_ABI _NodeHandle __node_handle_extract(key_type const&);
   template <class _NodeHandle>
   _LIBCPP_HIDE_FROM_ABI _NodeHandle __node_handle_extract(const_iterator);
 #endif

   _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p);
   _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI size_type __erase_unique(const _Key& __k);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI size_type __erase_multi(const _Key& __k);

   _LIBCPP_HIDE_FROM_ABI void
   __insert_node_at(__end_node_pointer __parent, __node_base_pointer& __child, __node_base_pointer __new_node) _NOEXCEPT;

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI iterator find(const _Key& __key) {
     auto [__, __match] = __find_equal(__key);
     if (__match == nullptr)
       return end();
     return iterator(static_cast<__node_pointer>(__match));
   }

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI const_iterator find(const _Key& __key) const {
     auto [__, __match] = __find_equal(__key);
     if (__match == nullptr)
       return end();
     return const_iterator(static_cast<__node_pointer>(__match));
   }

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI size_type __count_unique(const _Key& __k) const;
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI size_type __count_multi(const _Key& __k) const;

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI iterator lower_bound(const _Key& __v) {
     return __lower_bound(__v, __root(), __end_node());
   }
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI iterator __lower_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI const_iterator lower_bound(const _Key& __v) const {
     return __lower_bound(__v, __root(), __end_node());
   }
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI const_iterator
   __lower_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result) const;
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI iterator upper_bound(const _Key& __v) {
     return __upper_bound(__v, __root(), __end_node());
   }
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI iterator __upper_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI const_iterator upper_bound(const _Key& __v) const {
     return __upper_bound(__v, __root(), __end_node());
   }
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI const_iterator
   __upper_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result) const;
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> __equal_range_unique(const _Key& __k);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> __equal_range_unique(const _Key& __k) const;

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> __equal_range_multi(const _Key& __k);
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> __equal_range_multi(const _Key& __k) const;

   using _Dp _LIBCPP_NODEBUG           = __tree_node_destructor<__node_allocator>;
   using __node_holder _LIBCPP_NODEBUG = unique_ptr<__node, _Dp>;

   _LIBCPP_HIDE_FROM_ABI __node_holder remove(const_iterator __p) _NOEXCEPT;

   // FIXME: Make this function const qualified. Unfortunately doing so
   // breaks existing code which uses non-const callable comparators.
   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<__end_node_pointer, __node_base_pointer&> __find_equal(const _Key& __v);

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<__end_node_pointer, __node_base_pointer&> __find_equal(const _Key& __v) const {
     return const_cast<__tree*>(this)->__find_equal(__v);
   }

   template <class _Key>
   _LIBCPP_HIDE_FROM_ABI pair<__end_node_pointer, __node_base_pointer&>
   __find_equal(const_iterator __hint, __node_base_pointer& __dummy, const _Key& __v);

   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __tree& __t) {
     __copy_assign_alloc(__t, integral_constant<bool, __node_traits::propagate_on_container_copy_assignment::value>());
   }

   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __tree& __t, true_type) {
     if (__node_alloc() != __t.__node_alloc())
       clear();
     __node_alloc() = __t.__node_alloc();
   }
   _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __tree&, false_type) {}

 private:
   _LIBCPP_HIDE_FROM_ABI __node_base_pointer& __find_leaf_low(__end_node_pointer& __parent, const value_type& __v);

   _LIBCPP_HIDE_FROM_ABI __node_base_pointer& __find_leaf_high(__end_node_pointer& __parent, const value_type& __v);

   _LIBCPP_HIDE_FROM_ABI __node_base_pointer&
   __find_leaf(const_iterator __hint, __end_node_pointer& __parent, const value_type& __v);

   template <class... _Args>
   _LIBCPP_HIDE_FROM_ABI __node_holder __construct_node(_Args&&... __args);

   // TODO: Make this _LIBCPP_HIDE_FROM_ABI
   _LIBCPP_HIDDEN void destroy(__node_pointer __nd) _NOEXCEPT { (__tree_deleter(__node_alloc_))(__nd); }

   _LIBCPP_HIDE_FROM_ABI void __move_assign(__tree& __t, false_type);
   _LIBCPP_HIDE_FROM_ABI void __move_assign(__tree& __t, true_type) _NOEXCEPT_(
       is_nothrow_move_assignable<value_compare>::value&& is_nothrow_move_assignable<__node_allocator>::value);

   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__tree& __t)
       _NOEXCEPT_(!__node_traits::propagate_on_container_move_assignment::value ||
                  is_nothrow_move_assignable<__node_allocator>::value) {
     __move_assign_alloc(__t, integral_constant<bool, __node_traits::propagate_on_container_move_assignment::value>());
   }

   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__tree& __t, true_type)
       _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value) {
     __node_alloc() = std::move(__t.__node_alloc());
   }
   _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__tree&, false_type) _NOEXCEPT {}

   template <class _From, class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI static void __assign_value(__get_node_value_type_t<value_type>& __lhs, _From&& __rhs) {
     using __key_type = __remove_const_t<typename value_type::first_type>;

     // This is technically UB, since the object was constructed as `const`.
     // Clang doesn't optimize on this currently though.
     const_cast<__key_type&>(__lhs.first) = const_cast<__copy_cvref_t<_From, __key_type>&&>(__rhs.first);
     __lhs.second                         = std::forward<_From>(__rhs).second;
   }

   template <class _To, class _From, class _ValueT = _Tp, __enable_if_t<!__is_tree_value_type_v<_ValueT>, int> = 0>
   _LIBCPP_HIDE_FROM_ABI static void __assign_value(_To& __lhs, _From&& __rhs) {
     __lhs = std::forward<_From>(__rhs);
   }

   struct _DetachedTreeCache {
     _LIBCPP_HIDE_FROM_ABI explicit _DetachedTreeCache(__tree* __t) _NOEXCEPT
         : __t_(__t),
           __cache_root_(__detach_from_tree(__t)) {
       __advance();
     }

     _LIBCPP_HIDE_FROM_ABI __node_pointer __get() const _NOEXCEPT { return __cache_elem_; }

     _LIBCPP_HIDE_FROM_ABI void __advance() _NOEXCEPT {
       __cache_elem_ = __cache_root_;
       if (__cache_root_) {
         __cache_root_ = __detach_next(__cache_root_);
       }
     }

     _LIBCPP_HIDE_FROM_ABI ~_DetachedTreeCache() {
       __t_->destroy(__cache_elem_);
       if (__cache_root_) {
         while (__cache_root_->__parent_ != nullptr)
           __cache_root_ = static_cast<__node_pointer>(__cache_root_->__parent_);
         __t_->destroy(__cache_root_);
       }
     }

     _DetachedTreeCache(_DetachedTreeCache const&)            = delete;
     _DetachedTreeCache& operator=(_DetachedTreeCache const&) = delete;

   private:
     _LIBCPP_HIDE_FROM_ABI static __node_pointer __detach_from_tree(__tree* __t) _NOEXCEPT;
     _LIBCPP_HIDE_FROM_ABI static __node_pointer __detach_next(__node_pointer) _NOEXCEPT;

     __tree* __t_;
     __node_pointer __cache_root_;
     __node_pointer __cache_elem_;
   };

   class __tree_deleter {
     __node_allocator& __alloc_;

   public:
     using pointer = __node_pointer;

     _LIBCPP_HIDE_FROM_ABI __tree_deleter(__node_allocator& __alloc) : __alloc_(__alloc) {}

 #ifdef _LIBCPP_COMPILER_CLANG_BASED // FIXME: GCC complains about not being able to always_inline a recursive function
     _LIBCPP_HIDE_FROM_ABI
 #endif
     void
     operator()(__node_pointer __ptr) {
       if (!__ptr)
         return;

       (*this)(static_cast<__node_pointer>(__ptr->__left_));

       auto __right = __ptr->__right_;

       __node_traits::destroy(__alloc_, std::addressof(__ptr->__get_value()));
       __node_traits::deallocate(__alloc_, __ptr, 1);

       (*this)(static_cast<__node_pointer>(__right));
     }
   };

   // This copy construction will always produce a correct red-black-tree assuming the incoming tree is correct, since we
   // copy the exact structure 1:1. Since this is for copy construction _only_ we know that we get a correct tree. If we
   // didn't get a correct tree, the invariants of __tree are broken and we have a much bigger problem than an improperly
   // balanced tree.
 #ifdef _LIBCPP_COMPILER_CLANG_BASED // FIXME: GCC complains about not being able to always_inline a recursive function
   _LIBCPP_HIDE_FROM_ABI
 #endif
   __node_pointer
   __copy_construct_tree(__node_pointer __src) {
     if (!__src)
       return nullptr;

     __node_holder __new_node = __construct_node(__src->__get_value());

     unique_ptr<__node, __tree_deleter> __left(
         __copy_construct_tree(static_cast<__node_pointer>(__src->__left_)), __node_alloc_);
     __node_pointer __right = __copy_construct_tree(static_cast<__node_pointer>(__src->__right_));

     __node_pointer __new_node_ptr = __new_node.release();

     __new_node_ptr->__is_black_ = __src->__is_black_;
     __new_node_ptr->__left_     = static_cast<__node_base_pointer>(__left.release());
     __new_node_ptr->__right_    = static_cast<__node_base_pointer>(__right);
     if (__new_node_ptr->__left_)
       __new_node_ptr->__left_->__parent_ = static_cast<__end_node_pointer>(__new_node_ptr);
     if (__new_node_ptr->__right_)
       __new_node_ptr->__right_->__parent_ = static_cast<__end_node_pointer>(__new_node_ptr);
     return __new_node_ptr;
   }

   // This copy assignment will always produce a correct red-black-tree assuming the incoming tree is correct, since our
   // own tree is a red-black-tree and the incoming tree is a red-black-tree. The invariants of a red-black-tree are
   // temporarily not met until all of the incoming red-black tree is copied.
 #ifdef _LIBCPP_COMPILER_CLANG_BASED // FIXME: GCC complains about not being able to always_inline a recursive function
   _LIBCPP_HIDE_FROM_ABI
 #endif
   __node_pointer
   __copy_assign_tree(__node_pointer __dest, __node_pointer __src) {
     if (!__src) {
       destroy(__dest);
       return nullptr;
     }

     __assign_value(__dest->__get_value(), __src->__get_value());
     __dest->__is_black_ = __src->__is_black_;

     // If we already have a left node in the destination tree, reuse it and copy-assign recursively
     if (__dest->__left_) {
       __dest->__left_ = static_cast<__node_base_pointer>(__copy_assign_tree(
           static_cast<__node_pointer>(__dest->__left_), static_cast<__node_pointer>(__src->__left_)));

       // Otherwise, we must create new nodes; copy-construct from here on
     } else if (__src->__left_) {
       auto __new_left       = __copy_construct_tree(static_cast<__node_pointer>(__src->__left_));
       __dest->__left_       = static_cast<__node_base_pointer>(__new_left);
       __new_left->__parent_ = static_cast<__end_node_pointer>(__dest);
     }

     // Identical to the left case above, just for the right nodes
     if (__dest->__right_) {
       __dest->__right_ = static_cast<__node_base_pointer>(__copy_assign_tree(
           static_cast<__node_pointer>(__dest->__right_), static_cast<__node_pointer>(__src->__right_)));
     } else if (__src->__right_) {
       auto __new_right       = __copy_construct_tree(static_cast<__node_pointer>(__src->__right_));
       __dest->__right_       = static_cast<__node_base_pointer>(__new_right);
       __new_right->__parent_ = static_cast<__end_node_pointer>(__dest);
     }

     return __dest;
   }
 };

 // Precondition:  __size_ != 0
 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_pointer
 __tree<_Tp, _Compare, _Allocator>::_DetachedTreeCache::__detach_from_tree(__tree* __t) _NOEXCEPT {
   __node_pointer __cache                = static_cast<__node_pointer>(__t->__begin_node_);
   __t->__begin_node_                    = __t->__end_node();
   __t->__end_node()->__left_->__parent_ = nullptr;
   __t->__end_node()->__left_            = nullptr;
   __t->__size_                          = 0;
   // __cache->__left_ == nullptr
   if (__cache->__right_ != nullptr)
     __cache = static_cast<__node_pointer>(__cache->__right_);
   // __cache->__left_ == nullptr
   // __cache->__right_ == nullptr
   return __cache;
 }

 // Precondition:  __cache != nullptr
 //    __cache->left_ == nullptr
 //    __cache->right_ == nullptr
 //    This is no longer a red-black tree
 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_pointer
 __tree<_Tp, _Compare, _Allocator>::_DetachedTreeCache::__detach_next(__node_pointer __cache) _NOEXCEPT {
   if (__cache->__parent_ == nullptr)
     return nullptr;
   if (std::__tree_is_left_child(static_cast<__node_base_pointer>(__cache))) {
     __cache->__parent_->__left_ = nullptr;
     __cache                     = static_cast<__node_pointer>(__cache->__parent_);
     if (__cache->__right_ == nullptr)
       return __cache;
     return static_cast<__node_pointer>(std::__tree_leaf(__cache->__right_));
   }
   // __cache is right child
   __cache->__parent_unsafe()->__right_ = nullptr;
   __cache                              = static_cast<__node_pointer>(__cache->__parent_);
   if (__cache->__left_ == nullptr)
     return __cache;
   return static_cast<__node_pointer>(std::__tree_leaf(__cache->__left_));
 }

 template <class _Tp, class _Compare, class _Allocator>
 __tree<_Tp, _Compare, _Allocator>& __tree<_Tp, _Compare, _Allocator>::operator=(const __tree& __t) {
   if (this == std::addressof(__t))
     return *this;

   value_comp() = __t.value_comp();
   __copy_assign_alloc(__t);

   if (__size_ != 0) {
     *__root_ptr() = static_cast<__node_base_pointer>(__copy_assign_tree(__root(), __t.__root()));
   } else {
     *__root_ptr() = static_cast<__node_base_pointer>(__copy_construct_tree(__t.__root()));
     if (__root())
       __root()->__parent_ = __end_node();
   }
   __begin_node_ =
       __end_node()->__left_ ? static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_)) : __end_node();
   __size_ = __t.size();

   return *this;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _ForwardIterator>
 void __tree<_Tp, _Compare, _Allocator>::__assign_unique(_ForwardIterator __first, _ForwardIterator __last) {
   using _ITraits     = iterator_traits<_ForwardIterator>;
   using _ItValueType = typename _ITraits::value_type;
   static_assert(
       is_same<_ItValueType, value_type>::value, "__assign_unique may only be called with the containers value type");
   static_assert(
       __has_forward_iterator_category<_ForwardIterator>::value, "__assign_unique requires a forward iterator");
   if (__size_ != 0) {
     _DetachedTreeCache __cache(this);
     for (; __cache.__get() != nullptr && __first != __last; ++__first) {
       if (__node_assign_unique(*__first, __cache.__get()).second)
         __cache.__advance();
     }
   }
   for (; __first != __last; ++__first)
     __emplace_unique(*__first);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _InputIterator>
 void __tree<_Tp, _Compare, _Allocator>::__assign_multi(_InputIterator __first, _InputIterator __last) {
   using _ITraits     = iterator_traits<_InputIterator>;
   using _ItValueType = typename _ITraits::value_type;
   static_assert(
       is_same<_ItValueType, value_type>::value, "__assign_multi may only be called with the containers value_type");
   if (__size_ != 0) {
     _DetachedTreeCache __cache(this);
     for (; __cache.__get() && __first != __last; ++__first) {
       __assign_value(__cache.__get()->__get_value(), *__first);
       __node_insert_multi(__cache.__get());
       __cache.__advance();
     }
   }
   const_iterator __e = end();
   for (; __first != __last; ++__first)
     __emplace_hint_multi(__e, *__first);
 }

 template <class _Tp, class _Compare, class _Allocator>
 __tree<_Tp, _Compare, _Allocator>::__tree(const __tree& __t)
     : __begin_node_(__end_node()),
       __node_alloc_(__node_traits::select_on_container_copy_construction(__t.__node_alloc())),
       __size_(0),
       __value_comp_(__t.value_comp()) {
   if (__t.size() == 0)
     return;

   *__root_ptr()       = static_cast<__node_base_pointer>(__copy_construct_tree(__t.__root()));
   __root()->__parent_ = __end_node();
   __begin_node_       = static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_));
   __size_             = __t.size();
 }

 template <class _Tp, class _Compare, class _Allocator>
 __tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t) _NOEXCEPT_(
     is_nothrow_move_constructible<__node_allocator>::value&& is_nothrow_move_constructible<value_compare>::value)
     : __begin_node_(std::move(__t.__begin_node_)),
       __end_node_(std::move(__t.__end_node_)),
       __node_alloc_(std::move(__t.__node_alloc_)),
       __size_(__t.__size_),
       __value_comp_(std::move(__t.__value_comp_)) {
   if (__size_ == 0)
     __begin_node_ = __end_node();
   else {
     __end_node()->__left_->__parent_ = static_cast<__end_node_pointer>(__end_node());
     __t.__begin_node_                = __t.__end_node();
     __t.__end_node()->__left_        = nullptr;
     __t.__size_                      = 0;
   }
 }

 template <class _Tp, class _Compare, class _Allocator>
 __tree<_Tp, _Compare, _Allocator>::__tree(__tree&& __t, const allocator_type& __a)
     : __node_alloc_(__node_allocator(__a)), __size_(0), __value_comp_(std::move(__t.value_comp())) {
   if (__a == __t.__alloc()) {
     if (__t.__size_ == 0)
       __begin_node_ = __end_node();
     else {
       __begin_node_                    = __t.__begin_node_;
       __end_node()->__left_            = __t.__end_node()->__left_;
       __end_node()->__left_->__parent_ = static_cast<__end_node_pointer>(__end_node());
       __size_                          = __t.__size_;
       __t.__begin_node_                = __t.__end_node();
       __t.__end_node()->__left_        = nullptr;
       __t.__size_                      = 0;
     }
   } else {
     __begin_node_ = __end_node();
   }
 }

 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, true_type)
     _NOEXCEPT_(is_nothrow_move_assignable<value_compare>::value&& is_nothrow_move_assignable<__node_allocator>::value) {
   destroy(static_cast<__node_pointer>(__end_node()->__left_));
   __begin_node_ = __t.__begin_node_;
   __end_node_   = __t.__end_node_;
   __move_assign_alloc(__t);
   __size_       = __t.__size_;
   __value_comp_ = std::move(__t.__value_comp_);
   if (__size_ == 0)
     __begin_node_ = __end_node();
   else {
     __end_node()->__left_->__parent_ = static_cast<__end_node_pointer>(__end_node());
     __t.__begin_node_                = __t.__end_node();
     __t.__end_node()->__left_        = nullptr;
     __t.__size_                      = 0;
   }
 }

 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::__move_assign(__tree& __t, false_type) {
   if (__node_alloc() == __t.__node_alloc())
     __move_assign(__t, true_type());
   else {
     value_comp()       = std::move(__t.value_comp());
     const_iterator __e = end();
     if (__size_ != 0) {
       _DetachedTreeCache __cache(this);
       while (__cache.__get() != nullptr && __t.__size_ != 0) {
         __assign_value(__cache.__get()->__get_value(), std::move(__t.remove(__t.begin())->__get_value()));
         __node_insert_multi(__cache.__get());
         __cache.__advance();
       }
     }
     while (__t.__size_ != 0) {
       __insert_multi_from_orphaned_node(__e, std::move(__t.remove(__t.begin())->__get_value()));
     }
   }
 }

 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::swap(__tree& __t)
 #if _LIBCPP_STD_VER <= 11
     _NOEXCEPT_(__is_nothrow_swappable_v<value_compare> &&
                (!__node_traits::propagate_on_container_swap::value || __is_nothrow_swappable_v<__node_allocator>))
 #else
     _NOEXCEPT_(__is_nothrow_swappable_v<value_compare>)
 #endif
 {
   using std::swap;
   swap(__begin_node_, __t.__begin_node_);
   swap(__end_node_, __t.__end_node_);
   std::__swap_allocator(__node_alloc(), __t.__node_alloc());
   swap(__size_, __t.__size_);
   swap(__value_comp_, __t.__value_comp_);
   if (__size_ == 0)
     __begin_node_ = __end_node();
   else
     __end_node()->__left_->__parent_ = __end_node();
   if (__t.__size_ == 0)
     __t.__begin_node_ = __t.__end_node();
   else
     __t.__end_node()->__left_->__parent_ = __t.__end_node();
 }

 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::clear() _NOEXCEPT {
   destroy(__root());
   __size_               = 0;
   __begin_node_         = __end_node();
   __end_node()->__left_ = nullptr;
 }

 // Find lower_bound place to insert
 // Set __parent to parent of null leaf
 // Return reference to null leaf
 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
 __tree<_Tp, _Compare, _Allocator>::__find_leaf_low(__end_node_pointer& __parent, const value_type& __v) {
   __node_pointer __nd = __root();
   if (__nd != nullptr) {
     while (true) {
       if (value_comp()(__nd->__get_value(), __v)) {
         if (__nd->__right_ != nullptr)
           __nd = static_cast<__node_pointer>(__nd->__right_);
         else {
           __parent = static_cast<__end_node_pointer>(__nd);
           return __nd->__right_;
         }
       } else {
         if (__nd->__left_ != nullptr)
           __nd = static_cast<__node_pointer>(__nd->__left_);
         else {
           __parent = static_cast<__end_node_pointer>(__nd);
           return __parent->__left_;
         }
       }
     }
   }
   __parent = __end_node();
   return __parent->__left_;
 }

 // Find upper_bound place to insert
 // Set __parent to parent of null leaf
 // Return reference to null leaf
 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&
 __tree<_Tp, _Compare, _Allocator>::__find_leaf_high(__end_node_pointer& __parent, const value_type& __v) {
   __node_pointer __nd = __root();
   if (__nd != nullptr) {
     while (true) {
       if (value_comp()(__v, __nd->__get_value())) {
         if (__nd->__left_ != nullptr)
           __nd = static_cast<__node_pointer>(__nd->__left_);
         else {
           __parent = static_cast<__end_node_pointer>(__nd);
           return __parent->__left_;
         }
       } else {
         if (__nd->__right_ != nullptr)
           __nd = static_cast<__node_pointer>(__nd->__right_);
         else {
           __parent = static_cast<__end_node_pointer>(__nd);
           return __nd->__right_;
         }
       }
     }
   }
   __parent = __end_node();
   return __parent->__left_;
 }

 // Find leaf place to insert closest to __hint
 // First check prior to __hint.
 // Next check after __hint.
 // Next do O(log N) search.
 // Set __parent to parent of null leaf
 // Return reference to null leaf
 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer& __tree<_Tp, _Compare, _Allocator>::__find_leaf(
     const_iterator __hint, __end_node_pointer& __parent, const value_type& __v) {
   if (__hint == end() || !value_comp()(*__hint, __v)) // check before
   {
     // __v <= *__hint
     const_iterator __prior = __hint;
     if (__prior == begin() || !value_comp()(__v, *--__prior)) {
       // *prev(__hint) <= __v <= *__hint
       if (__hint.__ptr_->__left_ == nullptr) {
         __parent = static_cast<__end_node_pointer>(__hint.__ptr_);
         return __parent->__left_;
       } else {
         __parent = static_cast<__end_node_pointer>(__prior.__ptr_);
         return static_cast<__node_base_pointer>(__prior.__ptr_)->__right_;
       }
     }
     // __v < *prev(__hint)
     return __find_leaf_high(__parent, __v);
   }
   // else __v > *__hint
   return __find_leaf_low(__parent, __v);
 }

 // Find __v
 // If __v exists, return the parent of the node of __v and a reference to the pointer to the node of __v.
 // If __v doesn't exist, return the parent of the null leaf and a reference to the pointer to the null leaf.
 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 _LIBCPP_HIDE_FROM_ABI pair<typename __tree<_Tp, _Compare, _Allocator>::__end_node_pointer,
                            typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&>
 __tree<_Tp, _Compare, _Allocator>::__find_equal(const _Key& __v) {
   using _Pair = pair<__end_node_pointer, __node_base_pointer&>;

   __node_pointer __nd = __root();

   if (__nd == nullptr) {
     auto __end = __end_node();
     return _Pair(__end, __end->__left_);
   }

   __node_base_pointer* __node_ptr = __root_ptr();
   auto __comp                     = __lazy_synth_three_way_comparator<_Compare, _Key, value_type>(value_comp());

   while (true) {
     auto __comp_res = __comp(__v, __nd->__get_value());

     if (__comp_res.__less()) {
       if (__nd->__left_ == nullptr)
         return _Pair(static_cast<__end_node_pointer>(__nd), __nd->__left_);

       __node_ptr = std::addressof(__nd->__left_);
       __nd       = static_cast<__node_pointer>(__nd->__left_);
     } else if (__comp_res.__greater()) {
       if (__nd->__right_ == nullptr)
         return _Pair(static_cast<__end_node_pointer>(__nd), __nd->__right_);

       __node_ptr = std::addressof(__nd->__right_);
       __nd       = static_cast<__node_pointer>(__nd->__right_);
     } else {
       return _Pair(static_cast<__end_node_pointer>(__nd), *__node_ptr);
     }
   }
 }

 // Find __v
 // First check prior to __hint.
 // Next check after __hint.
 // Next do O(log N) search.
 // If __v exists, return the parent of the node of __v and a reference to the pointer to the node of __v.
 // If __v doesn't exist, return the parent of the null leaf and a reference to the pointer to the null leaf.
 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 _LIBCPP_HIDE_FROM_ABI pair<typename __tree<_Tp, _Compare, _Allocator>::__end_node_pointer,
                            typename __tree<_Tp, _Compare, _Allocator>::__node_base_pointer&>
 __tree<_Tp, _Compare, _Allocator>::__find_equal(const_iterator __hint, __node_base_pointer& __dummy, const _Key& __v) {
   using _Pair = pair<__end_node_pointer, __node_base_pointer&>;

   if (__hint == end() || value_comp()(__v, *__hint)) { // check before
     // __v < *__hint
     const_iterator __prior = __hint;
     if (__prior == begin() || value_comp()(*--__prior, __v)) {
       // *prev(__hint) < __v < *__hint
       if (__hint.__ptr_->__left_ == nullptr)
         return _Pair(__hint.__ptr_, __hint.__ptr_->__left_);
       return _Pair(__prior.__ptr_, static_cast<__node_pointer>(__prior.__ptr_)->__right_);
     }
     // __v <= *prev(__hint)
     return __find_equal(__v);
   }

   if (value_comp()(*__hint, __v)) { // check after
     // *__hint < __v
     const_iterator __next = std::next(__hint);
     if (__next == end() || value_comp()(__v, *__next)) {
       // *__hint < __v < *std::next(__hint)
       if (__hint.__get_np()->__right_ == nullptr)
         return _Pair(__hint.__ptr_, static_cast<__node_pointer>(__hint.__ptr_)->__right_);
       return _Pair(__next.__ptr_, __next.__ptr_->__left_);
     }
     // *next(__hint) <= __v
     return __find_equal(__v);
   }

   // else __v == *__hint
   __dummy = static_cast<__node_base_pointer>(__hint.__ptr_);
   return _Pair(__hint.__ptr_, __dummy);
 }

 template <class _Tp, class _Compare, class _Allocator>
 void __tree<_Tp, _Compare, _Allocator>::__insert_node_at(
     __end_node_pointer __parent, __node_base_pointer& __child, __node_base_pointer __new_node) _NOEXCEPT {
   __new_node->__left_   = nullptr;
   __new_node->__right_  = nullptr;
   __new_node->__parent_ = __parent;
   // __new_node->__is_black_ is initialized in __tree_balance_after_insert
   __child = __new_node;
   if (__begin_node_->__left_ != nullptr)
     __begin_node_ = static_cast<__end_node_pointer>(__begin_node_->__left_);
   std::__tree_balance_after_insert(__end_node()->__left_, __child);
   ++__size_;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class... _Args>
 typename __tree<_Tp, _Compare, _Allocator>::__node_holder
 __tree<_Tp, _Compare, _Allocator>::__construct_node(_Args&&... __args) {
   __node_allocator& __na = __node_alloc();
   __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
   std::__construct_at(std::addressof(*__h), __na, std::forward<_Args>(__args)...);
   __h.get_deleter().__value_constructed = true;
   return __h;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class... _Args>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__emplace_multi(_Args&&... __args) {
   __node_holder __h = __construct_node(std::forward<_Args>(__args)...);
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf_high(__parent, __h->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
   return iterator(static_cast<__node_pointer>(__h.release()));
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class... _Args>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__emplace_hint_multi(const_iterator __p, _Args&&... __args) {
   __node_holder __h = __construct_node(std::forward<_Args>(__args)...);
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf(__p, __parent, __h->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
   return iterator(static_cast<__node_pointer>(__h.release()));
 }

 template <class _Tp, class _Compare, class _Allocator>
 pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, bool>
 __tree<_Tp, _Compare, _Allocator>::__node_assign_unique(const value_type& __v, __node_pointer __nd) {
   auto [__parent, __child] = __find_equal(__v);
   __node_pointer __r       = static_cast<__node_pointer>(__child);
   bool __inserted          = false;
   if (__child == nullptr) {
     __assign_value(__nd->__get_value(), __v);
     __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
     __r        = __nd;
     __inserted = true;
   }
   return pair<iterator, bool>(iterator(__r), __inserted);
 }

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__node_insert_multi(__node_pointer __nd) {
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf_high(__parent, __nd->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
   return iterator(__nd);
 }

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__node_insert_multi(const_iterator __p, __node_pointer __nd) {
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf(__p, __parent, __nd->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__nd));
   return iterator(__nd);
 }

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__remove_node_pointer(__node_pointer __ptr) _NOEXCEPT {
   iterator __r(__ptr);
   ++__r;
   if (__begin_node_ == __ptr)
     __begin_node_ = __r.__ptr_;
   --__size_;
   std::__tree_remove(__end_node()->__left_, static_cast<__node_base_pointer>(__ptr));
   return __r;
 }

 #if _LIBCPP_STD_VER >= 17
 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle, class _InsertReturnType>
 _LIBCPP_HIDE_FROM_ABI _InsertReturnType
 __tree<_Tp, _Compare, _Allocator>::__node_handle_insert_unique(_NodeHandle&& __nh) {
   if (__nh.empty())
     return _InsertReturnType{end(), false, _NodeHandle()};

   __node_pointer __ptr = __nh.__ptr_;
   auto [__parent, __child] = __find_equal(__ptr->__get_value());
   if (__child != nullptr)
     return _InsertReturnType{iterator(static_cast<__node_pointer>(__child)), false, std::move(__nh)};

   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
   __nh.__release_ptr();
   return _InsertReturnType{iterator(__ptr), true, _NodeHandle()};
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle>
 _LIBCPP_HIDE_FROM_ABI typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__node_handle_insert_unique(const_iterator __hint, _NodeHandle&& __nh) {
   if (__nh.empty())
     return end();

   __node_pointer __ptr = __nh.__ptr_;
   __node_base_pointer __dummy;
   auto [__parent, __child] = __find_equal(__hint, __dummy, __ptr->__get_value());
   __node_pointer __r       = static_cast<__node_pointer>(__child);
   if (__child == nullptr) {
     __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
     __r = __ptr;
     __nh.__release_ptr();
   }
   return iterator(__r);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle>
 _LIBCPP_HIDE_FROM_ABI _NodeHandle __tree<_Tp, _Compare, _Allocator>::__node_handle_extract(key_type const& __key) {
   iterator __it = find(__key);
   if (__it == end())
     return _NodeHandle();
   return __node_handle_extract<_NodeHandle>(__it);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle>
 _LIBCPP_HIDE_FROM_ABI _NodeHandle __tree<_Tp, _Compare, _Allocator>::__node_handle_extract(const_iterator __p) {
   __node_pointer __np = __p.__get_np();
   __remove_node_pointer(__np);
   return _NodeHandle(__np, __alloc());
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Tree>
 _LIBCPP_HIDE_FROM_ABI void __tree<_Tp, _Compare, _Allocator>::__node_handle_merge_unique(_Tree& __source) {
   static_assert(is_same<typename _Tree::__node_pointer, __node_pointer>::value, "");

   for (typename _Tree::iterator __i = __source.begin(); __i != __source.end();) {
     __node_pointer __src_ptr = __i.__get_np();
     auto [__parent, __child] = __find_equal(__src_ptr->__get_value());
     ++__i;
     if (__child != nullptr)
       continue;
     __source.__remove_node_pointer(__src_ptr);
     __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__src_ptr));
   }
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle>
 _LIBCPP_HIDE_FROM_ABI typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__node_handle_insert_multi(_NodeHandle&& __nh) {
   if (__nh.empty())
     return end();
   __node_pointer __ptr = __nh.__ptr_;
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf_high(__parent, __ptr->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
   __nh.__release_ptr();
   return iterator(__ptr);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _NodeHandle>
 _LIBCPP_HIDE_FROM_ABI typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__node_handle_insert_multi(const_iterator __hint, _NodeHandle&& __nh) {
   if (__nh.empty())
     return end();

   __node_pointer __ptr = __nh.__ptr_;
   __end_node_pointer __parent;
   __node_base_pointer& __child = __find_leaf(__hint, __parent, __ptr->__get_value());
   __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__ptr));
   __nh.__release_ptr();
   return iterator(__ptr);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Tree>
 _LIBCPP_HIDE_FROM_ABI void __tree<_Tp, _Compare, _Allocator>::__node_handle_merge_multi(_Tree& __source) {
   static_assert(is_same<typename _Tree::__node_pointer, __node_pointer>::value, "");

   for (typename _Tree::iterator __i = __source.begin(); __i != __source.end();) {
     __node_pointer __src_ptr = __i.__get_np();
     __end_node_pointer __parent;
     __node_base_pointer& __child = __find_leaf_high(__parent, __src_ptr->__get_value());
     ++__i;
     __source.__remove_node_pointer(__src_ptr);
     __insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__src_ptr));
   }
 }

 #endif // _LIBCPP_STD_VER >= 17

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::iterator __tree<_Tp, _Compare, _Allocator>::erase(const_iterator __p) {
   __node_pointer __np    = __p.__get_np();
   iterator __r           = __remove_node_pointer(__np);
   __node_allocator& __na = __node_alloc();
   __node_traits::destroy(__na, std::addressof(const_cast<value_type&>(*__p)));
   __node_traits::deallocate(__na, __np, 1);
   return __r;
 }

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::erase(const_iterator __f, const_iterator __l) {
   while (__f != __l)
     __f = erase(__f);
   return iterator(__l.__ptr_);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::size_type
 __tree<_Tp, _Compare, _Allocator>::__erase_unique(const _Key& __k) {
   iterator __i = find(__k);
   if (__i == end())
     return 0;
   erase(__i);
   return 1;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::size_type
 __tree<_Tp, _Compare, _Allocator>::__erase_multi(const _Key& __k) {
   pair<iterator, iterator> __p = __equal_range_multi(__k);
   size_type __r                = 0;
   for (; __p.first != __p.second; ++__r)
     __p.first = erase(__p.first);
   return __r;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::size_type
 __tree<_Tp, _Compare, _Allocator>::__count_unique(const _Key& __k) const {
   __node_pointer __rt = __root();
   auto __comp         = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __rt = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return 1;
   }
   return 0;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::size_type
 __tree<_Tp, _Compare, _Allocator>::__count_multi(const _Key& __k) const {
   __end_node_pointer __result = __end_node();
   __node_pointer __rt         = __root();
   auto __comp                 = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __result = static_cast<__end_node_pointer>(__rt);
       __rt     = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return std::distance(
           __lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__end_node_pointer>(__rt)),
           __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result));
   }
   return 0;
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__lower_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result) {
   while (__root != nullptr) {
     if (!value_comp()(__root->__get_value(), __v)) {
       __result = static_cast<__end_node_pointer>(__root);
       __root   = static_cast<__node_pointer>(__root->__left_);
     } else
       __root = static_cast<__node_pointer>(__root->__right_);
   }
   return iterator(__result);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::const_iterator __tree<_Tp, _Compare, _Allocator>::__lower_bound(
     const _Key& __v, __node_pointer __root, __end_node_pointer __result) const {
   while (__root != nullptr) {
     if (!value_comp()(__root->__get_value(), __v)) {
       __result = static_cast<__end_node_pointer>(__root);
       __root   = static_cast<__node_pointer>(__root->__left_);
     } else
       __root = static_cast<__node_pointer>(__root->__right_);
   }
   return const_iterator(__result);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::iterator
 __tree<_Tp, _Compare, _Allocator>::__upper_bound(const _Key& __v, __node_pointer __root, __end_node_pointer __result) {
   while (__root != nullptr) {
     if (value_comp()(__v, __root->__get_value())) {
       __result = static_cast<__end_node_pointer>(__root);
       __root   = static_cast<__node_pointer>(__root->__left_);
     } else
       __root = static_cast<__node_pointer>(__root->__right_);
   }
   return iterator(__result);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 typename __tree<_Tp, _Compare, _Allocator>::const_iterator __tree<_Tp, _Compare, _Allocator>::__upper_bound(
     const _Key& __v, __node_pointer __root, __end_node_pointer __result) const {
   while (__root != nullptr) {
     if (value_comp()(__v, __root->__get_value())) {
       __result = static_cast<__end_node_pointer>(__root);
       __root   = static_cast<__node_pointer>(__root->__left_);
     } else
       __root = static_cast<__node_pointer>(__root->__right_);
   }
   return const_iterator(__result);
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, typename __tree<_Tp, _Compare, _Allocator>::iterator>
 __tree<_Tp, _Compare, _Allocator>::__equal_range_unique(const _Key& __k) {
   using _Pp                   = pair<iterator, iterator>;
   __end_node_pointer __result = __end_node();
   __node_pointer __rt         = __root();
   auto __comp                 = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __result = static_cast<__end_node_pointer>(__rt);
       __rt     = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return _Pp(iterator(__rt),
                  iterator(__rt->__right_ != nullptr ? static_cast<__end_node_pointer>(std::__tree_min(__rt->__right_))
                                                     : __result));
   }
   return _Pp(iterator(__result), iterator(__result));
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 pair<typename __tree<_Tp, _Compare, _Allocator>::const_iterator,
      typename __tree<_Tp, _Compare, _Allocator>::const_iterator>
 __tree<_Tp, _Compare, _Allocator>::__equal_range_unique(const _Key& __k) const {
   using _Pp                   = pair<const_iterator, const_iterator>;
   __end_node_pointer __result = __end_node();
   __node_pointer __rt         = __root();
   auto __comp                 = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __result = static_cast<__end_node_pointer>(__rt);
       __rt     = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return _Pp(
           const_iterator(__rt),
           const_iterator(
               __rt->__right_ != nullptr ? static_cast<__end_node_pointer>(std::__tree_min(__rt->__right_)) : __result));
   }
   return _Pp(const_iterator(__result), const_iterator(__result));
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 pair<typename __tree<_Tp, _Compare, _Allocator>::iterator, typename __tree<_Tp, _Compare, _Allocator>::iterator>
 __tree<_Tp, _Compare, _Allocator>::__equal_range_multi(const _Key& __k) {
   using _Pp                   = pair<iterator, iterator>;
   __end_node_pointer __result = __end_node();
   __node_pointer __rt         = __root();
   auto __comp                 = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __result = static_cast<__end_node_pointer>(__rt);
       __rt     = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return _Pp(__lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__end_node_pointer>(__rt)),
                  __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result));
   }
   return _Pp(iterator(__result), iterator(__result));
 }

 template <class _Tp, class _Compare, class _Allocator>
 template <class _Key>
 pair<typename __tree<_Tp, _Compare, _Allocator>::const_iterator,
      typename __tree<_Tp, _Compare, _Allocator>::const_iterator>
 __tree<_Tp, _Compare, _Allocator>::__equal_range_multi(const _Key& __k) const {
   using _Pp                   = pair<const_iterator, const_iterator>;
   __end_node_pointer __result = __end_node();
   __node_pointer __rt         = __root();
   auto __comp                 = __lazy_synth_three_way_comparator<value_compare, _Key, value_type>(value_comp());
   while (__rt != nullptr) {
     auto __comp_res = __comp(__k, __rt->__get_value());
     if (__comp_res.__less()) {
       __result = static_cast<__end_node_pointer>(__rt);
       __rt     = static_cast<__node_pointer>(__rt->__left_);
     } else if (__comp_res.__greater())
       __rt = static_cast<__node_pointer>(__rt->__right_);
     else
       return _Pp(__lower_bound(__k, static_cast<__node_pointer>(__rt->__left_), static_cast<__end_node_pointer>(__rt)),
                  __upper_bound(__k, static_cast<__node_pointer>(__rt->__right_), __result));
   }
   return _Pp(const_iterator(__result), const_iterator(__result));
 }

 template <class _Tp, class _Compare, class _Allocator>
 typename __tree<_Tp, _Compare, _Allocator>::__node_holder
 __tree<_Tp, _Compare, _Allocator>::remove(const_iterator __p) _NOEXCEPT {
   __node_pointer __np = __p.__get_np();
   if (__begin_node_ == __p.__ptr_) {
     if (__np->__right_ != nullptr)
       __begin_node_ = static_cast<__end_node_pointer>(__np->__right_);
     else
       __begin_node_ = static_cast<__end_node_pointer>(__np->__parent_);
   }
   --__size_;
   std::__tree_remove(__end_node()->__left_, static_cast<__node_base_pointer>(__np));
   return __node_holder(__np, _Dp(__node_alloc(), true));
 }

 template <class _Tp, class _Compare, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI void swap(__tree<_Tp, _Compare, _Allocator>& __x, __tree<_Tp, _Compare, _Allocator>& __y)
     _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
   __x.swap(__y);
 }

 _LIBCPP_END_NAMESPACE_STD

 _LIBCPP_POP_MACROS

 #endif // _LIBCPP___TREE