llvm-project/libcxx/include/unordered_map

// -*- 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_UNORDERED_MAP
#define _LIBCPP_UNORDERED_MAP

/*

    unordered_map synopsis

#include <initializer_list>

namespace std
{

template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
          class Alloc = allocator<pair<const Key, T>>>
class unordered_map
{
public:
    // types
    typedef Key                                                        key_type;
    typedef T                                                          mapped_type;
    typedef Hash                                                       hasher;
    typedef Pred                                                       key_equal;
    typedef Alloc                                                      allocator_type;
    typedef pair<const key_type, mapped_type>                          value_type;
    typedef value_type&                                                reference;
    typedef const value_type&                                          const_reference;
    typedef typename allocator_traits<allocator_type>::pointer         pointer;
    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
    typedef typename allocator_traits<allocator_type>::size_type       size_type;
    typedef typename allocator_traits<allocator_type>::difference_type difference_type;

    typedef /unspecified/ iterator;
    typedef /unspecified/ const_iterator;
    typedef /unspecified/ local_iterator;
    typedef /unspecified/ const_local_iterator;

    typedef unspecified                             node_type;            // C++17
    typedef INSERT_RETURN_TYPE<iterator, node_type> insert_return_type;   // C++17

    unordered_map()
        noexcept(
            is_nothrow_default_constructible<hasher>::value &&
            is_nothrow_default_constructible<key_equal>::value &&
            is_nothrow_default_constructible<allocator_type>::value);
    explicit unordered_map(size_type n, const hasher& hf = hasher(),
                           const key_equal& eql = key_equal(),
                           const allocator_type& a = allocator_type());
    template <class InputIterator>
        unordered_map(InputIterator f, InputIterator l,
                      size_type n = 0, const hasher& hf = hasher(),
                      const key_equal& eql = key_equal(),
                      const allocator_type& a = allocator_type());
    explicit unordered_map(const allocator_type&);
    unordered_map(const unordered_map&);
    unordered_map(const unordered_map&, const Allocator&);
    unordered_map(unordered_map&&)
        noexcept(
            is_nothrow_move_constructible<hasher>::value &&
            is_nothrow_move_constructible<key_equal>::value &&
            is_nothrow_move_constructible<allocator_type>::value);
    unordered_map(unordered_map&&, const Allocator&);
    unordered_map(initializer_list<value_type>, size_type n = 0,
                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
                  const allocator_type& a = allocator_type());
    unordered_map(size_type n, const allocator_type& a)
      : unordered_map(n, hasher(), key_equal(), a) {}  // C++14
    unordered_map(size_type n, const hasher& hf, const allocator_type& a)
      : unordered_map(n, hf, key_equal(), a) {}  // C++14
    template <class InputIterator>
      unordered_map(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
      : unordered_map(f, l, n, hasher(), key_equal(), a) {}  // C++14
    template <class InputIterator>
      unordered_map(InputIterator f, InputIterator l, size_type n, const hasher& hf,
        const allocator_type& a)
      : unordered_map(f, l, n, hf, key_equal(), a) {}  // C++14
    unordered_map(initializer_list<value_type> il, size_type n, const allocator_type& a)
      : unordered_map(il, n, hasher(), key_equal(), a) {}  // C++14
    unordered_map(initializer_list<value_type> il, size_type n, const hasher& hf,
      const allocator_type& a)
      : unordered_map(il, n, hf, key_equal(), a) {}  // C++14
    ~unordered_map();
    unordered_map& operator=(const unordered_map&);
    unordered_map& operator=(unordered_map&&)
        noexcept(
            allocator_type::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<allocator_type>::value &&
            is_nothrow_move_assignable<hasher>::value &&
            is_nothrow_move_assignable<key_equal>::value);
    unordered_map& operator=(initializer_list<value_type>);

    allocator_type get_allocator() const noexcept;

    bool      empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;

    iterator       begin() noexcept;
    iterator       end() noexcept;
    const_iterator begin()  const noexcept;
    const_iterator end()    const noexcept;
    const_iterator cbegin() const noexcept;
    const_iterator cend()   const noexcept;

    template <class... Args>
        pair<iterator, bool> emplace(Args&&... args);
    template <class... Args>
        iterator emplace_hint(const_iterator position, Args&&... args);
    pair<iterator, bool> insert(const value_type& obj);
    template <class P>
        pair<iterator, bool> insert(P&& obj);
    iterator insert(const_iterator hint, const value_type& obj);
    template <class P>
        iterator insert(const_iterator hint, P&& obj);
    template <class InputIterator>
        void insert(InputIterator first, InputIterator last);
    void insert(initializer_list<value_type>);

    node_type extract(const_iterator position);                                       // C++17
    node_type extract(const key_type& x);                                             // C++17
    insert_return_type insert(node_type&& nh);                                        // C++17
    iterator           insert(const_iterator hint, node_type&& nh);                   // C++17

    template <class... Args>
        pair<iterator, bool> try_emplace(const key_type& k, Args&&... args);          // C++17
    template <class... Args>
        pair<iterator, bool> try_emplace(key_type&& k, Args&&... args);               // C++17
    template <class... Args>
        iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args); // C++17
    template <class... Args>
        iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args);      // C++17
    template <class M>
        pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj);            // C++17
    template <class M>
        pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj);                 // C++17
    template <class M>
        iterator insert_or_assign(const_iterator hint, const key_type& k, M&& obj);   // C++17
    template <class M>
        iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj);        // C++17

    iterator erase(const_iterator position);
    iterator erase(iterator position);  // C++14
    size_type erase(const key_type& k);
    iterator erase(const_iterator first, const_iterator last);
    void clear() noexcept;

    template<class H2, class P2>
      void merge(unordered_map<Key, T, H2, P2, Allocator>& source);         // C++17
    template<class H2, class P2>
      void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);        // C++17
    template<class H2, class P2>
      void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);    // C++17
    template<class H2, class P2>
      void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);   // C++17

    void swap(unordered_map&)
        noexcept(
            (!allocator_type::propagate_on_container_swap::value ||
             __is_nothrow_swappable<allocator_type>::value) &&
            __is_nothrow_swappable<hasher>::value &&
            __is_nothrow_swappable<key_equal>::value);

    hasher hash_function() const;
    key_equal key_eq() const;

    iterator       find(const key_type& k);
    const_iterator find(const key_type& k) const;
    template<typename K>
        iterator find(const K& x);              // C++20
    template<typename K>
        const_iterator find(const K& x) const;  // C++20
    size_type count(const key_type& k) const;
    template<typename K>
        size_type count(const K& k) const; // C++20
    bool contains(const key_type& k) const; // C++20
    template<typename K>
        bool contains(const K& k) const; // C++20
    pair<iterator, iterator>             equal_range(const key_type& k);
    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
    template<typename K>
        pair<iterator, iterator>             equal_range(const K& k); // C++20
    template<typename K>
        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20

    mapped_type& operator[](const key_type& k);
    mapped_type& operator[](key_type&& k);

    mapped_type&       at(const key_type& k);
    const mapped_type& at(const key_type& k) const;

    size_type bucket_count() const noexcept;
    size_type max_bucket_count() const noexcept;

    size_type bucket_size(size_type n) const;
    size_type bucket(const key_type& k) const;

    local_iterator       begin(size_type n);
    local_iterator       end(size_type n);
    const_local_iterator begin(size_type n) const;
    const_local_iterator end(size_type n) const;
    const_local_iterator cbegin(size_type n) const;
    const_local_iterator cend(size_type n) const;

    float load_factor() const noexcept;
    float max_load_factor() const noexcept;
    void max_load_factor(float z);
    void rehash(size_type n);
    void reserve(size_type n);
};

template<class InputIterator,
    class Hash = hash<iter_key_t<InputIterator>>, class Pred = equal_to<iter_key_t<InputIterator>>,
    class Allocator = allocator<iter_to_alloc_t<InputIterator>>>
unordered_map(InputIterator, InputIterator, typename see below::size_type = see below,
    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
  -> unordered_map<iter_key_t<InputIterator>, iter_value_t<InputIterator>, Hash, Pred,
    Allocator>; // C++17

template<class Key, class T, class Hash = hash<Key>,
    class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>>
unordered_map(initializer_list<pair<const Key, T>>, typename see below::size_type = see below,
    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
  -> unordered_map<Key, T, Hash, Pred, Allocator>; // C++17

template<class InputIterator, class Allocator>
unordered_map(InputIterator, InputIterator, typename see below::size_type, Allocator)
  -> unordered_map<iter_key_t<InputIterator>, iter_val_t<InputIterator>,
        hash<iter_key_t<InputIterator>>, equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class InputIterator, class Allocator>
unordered_map(InputIterator, InputIterator, Allocator)
  -> unordered_map<iter_key_t<InputIterator>, iter_val_t<InputIterator>,
        hash<iter_key_t<InputIterator>>, equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class InputIterator, class Hash, class Allocator>
unordered_map(InputIterator, InputIterator, typename see below::size_type, Hash, Allocator)
  -> unordered_map<iter_key_t<InputIterator>, iter_val_t<InputIterator>, Hash,
          equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class Key, class T, typename Allocator>
unordered_map(initializer_list<pair<const Key, T>>, typename see below::size_type, Allocator)
  -> unordered_map<Key, T, hash<Key>, equal_to<Key>, Allocator>; // C++17

template<class Key, class T, typename Allocator>
unordered_map(initializer_list<pair<const Key, T>>, Allocator)
  -> unordered_map<Key, T, hash<Key>, equal_to<Key>, Allocator>; // C++17

template<class Key, class T, class Hash, class Allocator>
unordered_map(initializer_list<pair<const Key, T>>, typename see below::size_type, Hash, Allocator)
  -> unordered_map<Key, T, Hash, equal_to<Key>, Allocator>; // C++17

template <class Key, class T, class Hash, class Pred, class Alloc>
    void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x,
              unordered_map<Key, T, Hash, Pred, Alloc>& y)
              noexcept(noexcept(x.swap(y)));

template <class Key, class T, class Hash, class Pred, class Alloc>
    bool
    operator==(const unordered_map<Key, T, Hash, Pred, Alloc>& x,
               const unordered_map<Key, T, Hash, Pred, Alloc>& y);

template <class Key, class T, class Hash, class Pred, class Alloc>
    bool
    operator!=(const unordered_map<Key, T, Hash, Pred, Alloc>& x,
               const unordered_map<Key, T, Hash, Pred, Alloc>& y);

template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
          class Alloc = allocator<pair<const Key, T>>>
class unordered_multimap
{
public:
    // types
    typedef Key                                                        key_type;
    typedef T                                                          mapped_type;
    typedef Hash                                                       hasher;
    typedef Pred                                                       key_equal;
    typedef Alloc                                                      allocator_type;
    typedef pair<const key_type, mapped_type>                          value_type;
    typedef value_type&                                                reference;
    typedef const value_type&                                          const_reference;
    typedef typename allocator_traits<allocator_type>::pointer         pointer;
    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
    typedef typename allocator_traits<allocator_type>::size_type       size_type;
    typedef typename allocator_traits<allocator_type>::difference_type difference_type;

    typedef /unspecified/ iterator;
    typedef /unspecified/ const_iterator;
    typedef /unspecified/ local_iterator;
    typedef /unspecified/ const_local_iterator;

    typedef unspecified node_type;    // C++17

    unordered_multimap()
        noexcept(
            is_nothrow_default_constructible<hasher>::value &&
            is_nothrow_default_constructible<key_equal>::value &&
            is_nothrow_default_constructible<allocator_type>::value);
    explicit unordered_multimap(size_type n, const hasher& hf = hasher(),
                           const key_equal& eql = key_equal(),
                           const allocator_type& a = allocator_type());
    template <class InputIterator>
        unordered_multimap(InputIterator f, InputIterator l,
                      size_type n = 0, const hasher& hf = hasher(),
                      const key_equal& eql = key_equal(),
                      const allocator_type& a = allocator_type());
    explicit unordered_multimap(const allocator_type&);
    unordered_multimap(const unordered_multimap&);
    unordered_multimap(const unordered_multimap&, const Allocator&);
    unordered_multimap(unordered_multimap&&)
        noexcept(
            is_nothrow_move_constructible<hasher>::value &&
            is_nothrow_move_constructible<key_equal>::value &&
            is_nothrow_move_constructible<allocator_type>::value);
    unordered_multimap(unordered_multimap&&, const Allocator&);
    unordered_multimap(initializer_list<value_type>, size_type n = 0,
                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
                  const allocator_type& a = allocator_type());
    unordered_multimap(size_type n, const allocator_type& a)
      : unordered_multimap(n, hasher(), key_equal(), a) {}  // C++14
    unordered_multimap(size_type n, const hasher& hf, const allocator_type& a)
      : unordered_multimap(n, hf, key_equal(), a) {}  // C++14
    template <class InputIterator>
      unordered_multimap(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
      : unordered_multimap(f, l, n, hasher(), key_equal(), a) {}  // C++14
    template <class InputIterator>
      unordered_multimap(InputIterator f, InputIterator l, size_type n, const hasher& hf,
        const allocator_type& a)
      : unordered_multimap(f, l, n, hf, key_equal(), a) {}  // C++14
    unordered_multimap(initializer_list<value_type> il, size_type n, const allocator_type& a)
      : unordered_multimap(il, n, hasher(), key_equal(), a) {}  // C++14
    unordered_multimap(initializer_list<value_type> il, size_type n, const hasher& hf,
      const allocator_type& a)
      : unordered_multimap(il, n, hf, key_equal(), a) {}  // C++14
    ~unordered_multimap();
    unordered_multimap& operator=(const unordered_multimap&);
    unordered_multimap& operator=(unordered_multimap&&)
        noexcept(
            allocator_type::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<allocator_type>::value &&
            is_nothrow_move_assignable<hasher>::value &&
            is_nothrow_move_assignable<key_equal>::value);
    unordered_multimap& operator=(initializer_list<value_type>);

    allocator_type get_allocator() const noexcept;

    bool      empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;

    iterator       begin() noexcept;
    iterator       end() noexcept;
    const_iterator begin()  const noexcept;
    const_iterator end()    const noexcept;
    const_iterator cbegin() const noexcept;
    const_iterator cend()   const noexcept;

    template <class... Args>
        iterator emplace(Args&&... args);
    template <class... Args>
        iterator emplace_hint(const_iterator position, Args&&... args);
    iterator insert(const value_type& obj);
    template <class P>
        iterator insert(P&& obj);
    iterator insert(const_iterator hint, const value_type& obj);
    template <class P>
        iterator insert(const_iterator hint, P&& obj);
    template <class InputIterator>
        void insert(InputIterator first, InputIterator last);
    void insert(initializer_list<value_type>);

    node_type extract(const_iterator position);                // C++17
    node_type extract(const key_type& x);                      // C++17
    iterator insert(node_type&& nh);                           // C++17
    iterator insert(const_iterator hint, node_type&& nh);      // C++17

    iterator erase(const_iterator position);
    iterator erase(iterator position);  // C++14
    size_type erase(const key_type& k);
    iterator erase(const_iterator first, const_iterator last);
    void clear() noexcept;

    template<class H2, class P2>
      void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);    // C++17
    template<class H2, class P2>
      void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);   // C++17
    template<class H2, class P2>
      void merge(unordered_map<Key, T, H2, P2, Allocator>& source);         // C++17
    template<class H2, class P2>
      void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);        // C++17

    void swap(unordered_multimap&)
        noexcept(
            (!allocator_type::propagate_on_container_swap::value ||
             __is_nothrow_swappable<allocator_type>::value) &&
            __is_nothrow_swappable<hasher>::value &&
            __is_nothrow_swappable<key_equal>::value);

    hasher hash_function() const;
    key_equal key_eq() const;

    iterator       find(const key_type& k);
    const_iterator find(const key_type& k) const;
    template<typename K>
        iterator find(const K& x);              // C++20
    template<typename K>
        const_iterator find(const K& x) const;  // C++20
    size_type count(const key_type& k) const;
    template<typename K>
        size_type count(const K& k) const; // C++20
    bool contains(const key_type& k) const; // C++20
    template<typename K>
        bool contains(const K& k) const; // C++20
    pair<iterator, iterator>             equal_range(const key_type& k);
    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
    template<typename K>
        pair<iterator, iterator>             equal_range(const K& k); // C++20
    template<typename K>
        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20

    size_type bucket_count() const noexcept;
    size_type max_bucket_count() const noexcept;

    size_type bucket_size(size_type n) const;
    size_type bucket(const key_type& k) const;

    local_iterator       begin(size_type n);
    local_iterator       end(size_type n);
    const_local_iterator begin(size_type n) const;
    const_local_iterator end(size_type n) const;
    const_local_iterator cbegin(size_type n) const;
    const_local_iterator cend(size_type n) const;

    float load_factor() const noexcept;
    float max_load_factor() const noexcept;
    void max_load_factor(float z);
    void rehash(size_type n);
    void reserve(size_type n);
};

template<class InputIterator,
    class Hash = hash<iter_key_t<InputIterator>>, class Pred = equal_to<iter_key_t<InputIterator>>,
    class Allocator = allocator<iter_to_alloc_t<InputIterator>>>
unordered_multimap(InputIterator, InputIterator, typename see below::size_type = see below,
    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
  -> unordered_multimap<iter_key_t<InputIterator>, iter_value_t<InputIterator>, Hash, Pred,
    Allocator>; // C++17

template<class Key, class T, class Hash = hash<Key>,
    class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>>
unordered_multimap(initializer_list<pair<const Key, T>>, typename see below::size_type = see below,
    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
  -> unordered_multimap<Key, T, Hash, Pred, Allocator>; // C++17

template<class InputIterator, class Allocator>
unordered_multimap(InputIterator, InputIterator, typename see below::size_type, Allocator)
  -> unordered_multimap<iter_key_t<InputIterator>, iter_val_t<InputIterator>,
        hash<iter_key_t<InputIterator>>, equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class InputIterator, class Allocator>
unordered_multimap(InputIterator, InputIterator, Allocator)
  -> unordered_multimap<iter_key_t<InputIterator>, iter_val_t<InputIterator>,
        hash<iter_key_t<InputIterator>>, equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class InputIterator, class Hash, class Allocator>
unordered_multimap(InputIterator, InputIterator, typename see below::size_type, Hash, Allocator)
  -> unordered_multimap<iter_key_t<InputIterator>, iter_val_t<InputIterator>, Hash,
          equal_to<iter_key_t<InputIterator>>, Allocator>; // C++17

template<class Key, class T, typename Allocator>
unordered_multimap(initializer_list<pair<const Key, T>>, typename see below::size_type, Allocator)
  -> unordered_multimap<Key, T, hash<Key>, equal_to<Key>, Allocator>; // C++17

template<class Key, class T, typename Allocator>
unordered_multimap(initializer_list<pair<const Key, T>>, Allocator)
  -> unordered_multimap<Key, T, hash<Key>, equal_to<Key>, Allocator>; // C++17

template<class Key, class T, class Hash, class Allocator>
unordered_multimap(initializer_list<pair<const Key, T>>, typename see below::size_type, Hash,
    Allocator)
  -> unordered_multimap<Key, T, Hash, equal_to<Key>, Allocator>; // C++17

template <class Key, class T, class Hash, class Pred, class Alloc>
    void swap(unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
              unordered_multimap<Key, T, Hash, Pred, Alloc>& y)
              noexcept(noexcept(x.swap(y)));

template <class K, class T, class H, class P, class A, class Predicate>
    typename unordered_map<K, T, H, P, A>::size_type
    erase_if(unordered_map<K, T, H, P, A>& c, Predicate pred);       // C++20

template <class K, class T, class H, class P, class A, class Predicate>
    typename unordered_multimap<K, T, H, P, A>::size_type
    erase_if(unordered_multimap<K, T, H, P, A>& c, Predicate pred);  // C++20

template <class Key, class T, class Hash, class Pred, class Alloc>
    bool
    operator==(const unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
               const unordered_multimap<Key, T, Hash, Pred, Alloc>& y);

template <class Key, class T, class Hash, class Pred, class Alloc>
    bool
    operator!=(const unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
               const unordered_multimap<Key, T, Hash, Pred, Alloc>& y);

}  // std

*/

#include <__algorithm/is_permutation.h>
#include <__assert> // all public C++ headers provide the assertion handler
#include <__config>
#include <__debug>
#include <__functional/is_transparent.h>
#include <__functional/operations.h>
#include <__hash_table>
#include <__iterator/distance.h>
#include <__iterator/erase_if_container.h>
#include <__iterator/iterator_traits.h>
#include <__memory/addressof.h>
#include <__node_handle>
#include <__utility/forward.h>
#include <stdexcept>
#include <tuple>
#include <version>

#ifndef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
#  include <algorithm>
#  include <bit>
#  include <iterator>
#endif

// standard-mandated includes

// [iterator.range]
#include <__iterator/access.h>
#include <__iterator/data.h>
#include <__iterator/empty.h>
#include <__iterator/reverse_access.h>
#include <__iterator/size.h>

// [unord.map.syn]
#include <compare>
#include <initializer_list>

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

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Key, class _Cp, class _Hash, class _Pred,
          bool = is_empty<_Hash>::value && !__libcpp_is_final<_Hash>::value>
class __unordered_map_hasher
    : private _Hash
{
public:
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_hasher()
        _NOEXCEPT_(is_nothrow_default_constructible<_Hash>::value)
        : _Hash() {}
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_hasher(const _Hash& __h)
        _NOEXCEPT_(is_nothrow_copy_constructible<_Hash>::value)
        : _Hash(__h) {}
    _LIBCPP_INLINE_VISIBILITY
    const _Hash& hash_function() const _NOEXCEPT {return *this;}
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _Cp& __x) const
        {return static_cast<const _Hash&>(*this)(__x.__get_value().first);}
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _Key& __x) const
        {return static_cast<const _Hash&>(*this)(__x);}
#if _LIBCPP_STD_VER > 17
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _K2& __x) const
        {return static_cast<const _Hash&>(*this)(__x);}
#endif
    _LIBCPP_INLINE_VISIBILITY
    void swap(__unordered_map_hasher& __y)
        _NOEXCEPT_(__is_nothrow_swappable<_Hash>::value)
    {
        using _VSTD::swap;
        swap(static_cast<_Hash&>(*this), static_cast<_Hash&>(__y));
    }
};

template <class _Key, class _Cp, class _Hash, class _Pred>
class __unordered_map_hasher<_Key, _Cp, _Hash, _Pred, false>
{
    _Hash __hash_;
public:
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_hasher()
        _NOEXCEPT_(is_nothrow_default_constructible<_Hash>::value)
        : __hash_() {}
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_hasher(const _Hash& __h)
        _NOEXCEPT_(is_nothrow_copy_constructible<_Hash>::value)
        : __hash_(__h) {}
    _LIBCPP_INLINE_VISIBILITY
    const _Hash& hash_function() const _NOEXCEPT {return __hash_;}
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _Cp& __x) const
        {return __hash_(__x.__get_value().first);}
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _Key& __x) const
        {return __hash_(__x);}
#if _LIBCPP_STD_VER > 17
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    size_t operator()(const _K2& __x) const
        {return __hash_(__x);}
#endif
    _LIBCPP_INLINE_VISIBILITY
    void swap(__unordered_map_hasher& __y)
        _NOEXCEPT_(__is_nothrow_swappable<_Hash>::value)
    {
        using _VSTD::swap;
        swap(__hash_, __y.__hash_);
    }
};

template <class _Key, class _Cp, class _Hash, class _Pred, bool __b>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(__unordered_map_hasher<_Key, _Cp, _Hash, _Pred, __b>& __x,
     __unordered_map_hasher<_Key, _Cp, _Hash, _Pred, __b>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

template <class _Key, class _Cp, class _Pred, class _Hash,
          bool = is_empty<_Pred>::value && !__libcpp_is_final<_Pred>::value>
class __unordered_map_equal
    : private _Pred
{
public:
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_equal()
        _NOEXCEPT_(is_nothrow_default_constructible<_Pred>::value)
        : _Pred() {}
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_equal(const _Pred& __p)
        _NOEXCEPT_(is_nothrow_copy_constructible<_Pred>::value)
        : _Pred(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    const _Pred& key_eq() const _NOEXCEPT {return *this;}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _Cp& __y) const
        {return static_cast<const _Pred&>(*this)(__x.__get_value().first, __y.__get_value().first);}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _Key& __y) const
        {return static_cast<const _Pred&>(*this)(__x.__get_value().first, __y);}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Key& __x, const _Cp& __y) const
        {return static_cast<const _Pred&>(*this)(__x, __y.__get_value().first);}
#if _LIBCPP_STD_VER > 17
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _K2& __y) const
        {return static_cast<const _Pred&>(*this)(__x.__get_value().first, __y);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _K2& __x, const _Cp& __y) const
        {return static_cast<const _Pred&>(*this)(__x, __y.__get_value().first);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Key& __x, const _K2& __y) const
        {return static_cast<const _Pred&>(*this)(__x, __y);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _K2& __x, const _Key& __y) const
        {return static_cast<const _Pred&>(*this)(__x, __y);}
#endif
    _LIBCPP_INLINE_VISIBILITY
    void swap(__unordered_map_equal& __y)
        _NOEXCEPT_(__is_nothrow_swappable<_Pred>::value)
    {
        using _VSTD::swap;
        swap(static_cast<_Pred&>(*this), static_cast<_Pred&>(__y));
    }
};

template <class _Key, class _Cp, class _Pred, class _Hash>
class __unordered_map_equal<_Key, _Cp, _Pred, _Hash, false>
{
    _Pred __pred_;
public:
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_equal()
        _NOEXCEPT_(is_nothrow_default_constructible<_Pred>::value)
        : __pred_() {}
    _LIBCPP_INLINE_VISIBILITY
    __unordered_map_equal(const _Pred& __p)
        _NOEXCEPT_(is_nothrow_copy_constructible<_Pred>::value)
        : __pred_(__p) {}
    _LIBCPP_INLINE_VISIBILITY
    const _Pred& key_eq() const _NOEXCEPT {return __pred_;}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _Cp& __y) const
        {return __pred_(__x.__get_value().first, __y.__get_value().first);}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _Key& __y) const
        {return __pred_(__x.__get_value().first, __y);}
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Key& __x, const _Cp& __y) const
        {return __pred_(__x, __y.__get_value().first);}
#if _LIBCPP_STD_VER > 17
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Cp& __x, const _K2& __y) const
        {return __pred_(__x.__get_value().first, __y);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _K2& __x, const _Cp& __y) const
        {return __pred_(__x, __y.__get_value().first);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _Key& __x, const _K2& __y) const
        {return __pred_(__x, __y);}
    template <typename _K2>
    _LIBCPP_INLINE_VISIBILITY
    bool operator()(const _K2& __x, const _Key& __y) const
        {return __pred_(__x, __y);}
#endif
    _LIBCPP_INLINE_VISIBILITY
    void swap(__unordered_map_equal& __y)
        _NOEXCEPT_(__is_nothrow_swappable<_Pred>::value)
    {
        using _VSTD::swap;
        swap(__pred_, __y.__pred_);
    }
};

template <class _Key, class _Cp, class _Pred, class _Hash, bool __b>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(__unordered_map_equal<_Key, _Cp, _Pred, _Hash, __b>& __x,
     __unordered_map_equal<_Key, _Cp, _Pred, _Hash, __b>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

template <class _Alloc>
class __hash_map_node_destructor
{
    typedef _Alloc                              allocator_type;
    typedef allocator_traits<allocator_type>    __alloc_traits;

public:

    typedef typename __alloc_traits::pointer       pointer;
private:

    allocator_type& __na_;

    __hash_map_node_destructor& operator=(const __hash_map_node_destructor&);

public:
    bool __first_constructed;
    bool __second_constructed;

    _LIBCPP_INLINE_VISIBILITY
    explicit __hash_map_node_destructor(allocator_type& __na) _NOEXCEPT
        : __na_(__na),
          __first_constructed(false),
          __second_constructed(false)
        {}

#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    __hash_map_node_destructor(__hash_node_destructor<allocator_type>&& __x)
        _NOEXCEPT
        : __na_(__x.__na_),
          __first_constructed(__x.__value_constructed),
          __second_constructed(__x.__value_constructed)
        {
            __x.__value_constructed = false;
        }
#else  // _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    __hash_map_node_destructor(const __hash_node_destructor<allocator_type>& __x)
        : __na_(__x.__na_),
          __first_constructed(__x.__value_constructed),
          __second_constructed(__x.__value_constructed)
        {
            const_cast<bool&>(__x.__value_constructed) = false;
        }
#endif // _LIBCPP_CXX03_LANG

    _LIBCPP_INLINE_VISIBILITY
    void operator()(pointer __p) _NOEXCEPT
    {
        if (__second_constructed)
            __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__get_value().second));
        if (__first_constructed)
            __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__get_value().first));
        if (__p)
            __alloc_traits::deallocate(__na_, __p, 1);
    }
};

#ifndef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp>
struct _LIBCPP_STANDALONE_DEBUG __hash_value_type
{
    typedef _Key                                     key_type;
    typedef _Tp                                      mapped_type;
    typedef pair<const key_type, mapped_type>        value_type;
    typedef pair<key_type&, mapped_type&>            __nc_ref_pair_type;
    typedef pair<key_type&&, mapped_type&&>          __nc_rref_pair_type;

private:
    value_type __cc;

public:
    _LIBCPP_INLINE_VISIBILITY
    value_type& __get_value()
    {
#if _LIBCPP_STD_VER > 14
        return *_VSTD::launder(_VSTD::addressof(__cc));
#else
        return __cc;
#endif
    }

    _LIBCPP_INLINE_VISIBILITY
    const value_type& __get_value() const
    {
#if _LIBCPP_STD_VER > 14
        return *_VSTD::launder(_VSTD::addressof(__cc));
#else
        return __cc;
#endif
    }

    _LIBCPP_INLINE_VISIBILITY
    __nc_ref_pair_type __ref()
    {
        value_type& __v = __get_value();
        return __nc_ref_pair_type(const_cast<key_type&>(__v.first), __v.second);
    }

    _LIBCPP_INLINE_VISIBILITY
    __nc_rref_pair_type __move()
    {
        value_type& __v = __get_value();
        return __nc_rref_pair_type(
            _VSTD::move(const_cast<key_type&>(__v.first)),
            _VSTD::move(__v.second));
    }

    _LIBCPP_INLINE_VISIBILITY
    __hash_value_type& operator=(const __hash_value_type& __v)
    {
        __ref() = __v.__get_value();
        return *this;
    }

    _LIBCPP_INLINE_VISIBILITY
    __hash_value_type& operator=(__hash_value_type&& __v)
    {
        __ref() = __v.__move();
        return *this;
    }

    template <class _ValueTp,
              class = typename enable_if<
                    __is_same_uncvref<_ValueTp, value_type>::value
                 >::type
             >
    _LIBCPP_INLINE_VISIBILITY
    __hash_value_type& operator=(_ValueTp&& __v)
    {
        __ref() = _VSTD::forward<_ValueTp>(__v);
        return *this;
    }

private:
    __hash_value_type(const __hash_value_type& __v) = delete;
    __hash_value_type(__hash_value_type&& __v) = delete;
    template <class ..._Args>
    explicit __hash_value_type(_Args&& ...__args) = delete;

    ~__hash_value_type() = delete;
};

#else

template <class _Key, class _Tp>
struct __hash_value_type
{
    typedef _Key                                     key_type;
    typedef _Tp                                      mapped_type;
    typedef pair<const key_type, mapped_type>        value_type;

private:
    value_type __cc;

public:
    _LIBCPP_INLINE_VISIBILITY
    value_type& __get_value() { return __cc; }
    _LIBCPP_INLINE_VISIBILITY
    const value_type& __get_value() const { return __cc; }

private:
   ~__hash_value_type();
};

#endif

template <class _HashIterator>
class _LIBCPP_TEMPLATE_VIS __hash_map_iterator
{
    _HashIterator __i_;

    typedef  __hash_node_types_from_iterator<_HashIterator> _NodeTypes;

public:
    typedef forward_iterator_tag                                 iterator_category;
    typedef typename _NodeTypes::__map_value_type                value_type;
    typedef typename _NodeTypes::difference_type                 difference_type;
    typedef value_type&                                          reference;
    typedef typename _NodeTypes::__map_value_type_pointer       pointer;

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_iterator() _NOEXCEPT {}

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_iterator(_HashIterator __i) _NOEXCEPT : __i_(__i) {}

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

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_iterator& operator++() {++__i_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __hash_map_iterator operator++(int)
    {
        __hash_map_iterator __t(*this);
        ++(*this);
        return __t;
    }

    friend _LIBCPP_INLINE_VISIBILITY
        bool operator==(const __hash_map_iterator& __x, const __hash_map_iterator& __y)
        {return __x.__i_ == __y.__i_;}
    friend _LIBCPP_INLINE_VISIBILITY
        bool operator!=(const __hash_map_iterator& __x, const __hash_map_iterator& __y)
        {return __x.__i_ != __y.__i_;}

    template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_map;
    template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_iterator;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_local_iterator;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_map_const_iterator;
};

template <class _HashIterator>
class _LIBCPP_TEMPLATE_VIS __hash_map_const_iterator
{
    _HashIterator __i_;

    typedef  __hash_node_types_from_iterator<_HashIterator> _NodeTypes;

public:
    typedef forward_iterator_tag                                 iterator_category;
    typedef typename _NodeTypes::__map_value_type                value_type;
    typedef typename _NodeTypes::difference_type                 difference_type;
    typedef const value_type&                                    reference;
    typedef typename _NodeTypes::__const_map_value_type_pointer  pointer;

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_const_iterator() _NOEXCEPT {}

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_const_iterator(_HashIterator __i) _NOEXCEPT : __i_(__i) {}
    _LIBCPP_INLINE_VISIBILITY
    __hash_map_const_iterator(
            __hash_map_iterator<typename _HashIterator::__non_const_iterator> __i)
                 _NOEXCEPT
                : __i_(__i.__i_) {}

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

    _LIBCPP_INLINE_VISIBILITY
    __hash_map_const_iterator& operator++() {++__i_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __hash_map_const_iterator operator++(int)
    {
        __hash_map_const_iterator __t(*this);
        ++(*this);
        return __t;
    }

    friend _LIBCPP_INLINE_VISIBILITY
        bool operator==(const __hash_map_const_iterator& __x, const __hash_map_const_iterator& __y)
        {return __x.__i_ == __y.__i_;}
    friend _LIBCPP_INLINE_VISIBILITY
        bool operator!=(const __hash_map_const_iterator& __x, const __hash_map_const_iterator& __y)
        {return __x.__i_ != __y.__i_;}

    template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_map;
    template <class, class, class, class, class> friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_iterator;
    template <class> friend class _LIBCPP_TEMPLATE_VIS __hash_const_local_iterator;
};

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
class unordered_multimap;

template <class _Key, class _Tp, class _Hash = hash<_Key>, class _Pred = equal_to<_Key>,
          class _Alloc = allocator<pair<const _Key, _Tp> > >
class _LIBCPP_TEMPLATE_VIS unordered_map
{
public:
    // types
    typedef _Key                                           key_type;
    typedef _Tp                                            mapped_type;
    typedef __type_identity_t<_Hash>                       hasher;
    typedef __type_identity_t<_Pred>                       key_equal;
    typedef __type_identity_t<_Alloc>                      allocator_type;
    typedef pair<const key_type, mapped_type>              value_type;
    typedef value_type&                                    reference;
    typedef const value_type&                              const_reference;
    static_assert((is_same<value_type, typename allocator_type::value_type>::value),
                  "Invalid allocator::value_type");

private:
    typedef __hash_value_type<key_type, mapped_type>                          __value_type;
    typedef __unordered_map_hasher<key_type, __value_type, hasher, key_equal> __hasher;
    typedef __unordered_map_equal<key_type, __value_type, key_equal, hasher>  __key_equal;
    typedef typename __rebind_alloc_helper<allocator_traits<allocator_type>,
                                                 __value_type>::type          __allocator_type;

    typedef __hash_table<__value_type, __hasher,
                         __key_equal,  __allocator_type>   __table;

    __table __table_;

    typedef typename __table::_NodeTypes                   _NodeTypes;
    typedef typename __table::__node_pointer               __node_pointer;
    typedef typename __table::__node_const_pointer         __node_const_pointer;
    typedef typename __table::__node_traits                __node_traits;
    typedef typename __table::__node_allocator             __node_allocator;
    typedef typename __table::__node                       __node;
    typedef __hash_map_node_destructor<__node_allocator>   _Dp;
    typedef unique_ptr<__node, _Dp>                         __node_holder;
    typedef allocator_traits<allocator_type>               __alloc_traits;

    static_assert((is_same<typename __table::__container_value_type, value_type>::value), "");
    static_assert((is_same<typename __table::__node_value_type, __value_type>::value), "");
public:
    typedef typename __alloc_traits::pointer         pointer;
    typedef typename __alloc_traits::const_pointer   const_pointer;
    typedef typename __table::size_type              size_type;
    typedef typename __table::difference_type        difference_type;

    typedef __hash_map_iterator<typename __table::iterator>       iterator;
    typedef __hash_map_const_iterator<typename __table::const_iterator> const_iterator;
    typedef __hash_map_iterator<typename __table::local_iterator> local_iterator;
    typedef __hash_map_const_iterator<typename __table::const_local_iterator> const_local_iterator;

#if _LIBCPP_STD_VER > 14
    typedef __map_node_handle<__node, allocator_type> node_type;
    typedef __insert_return_type<iterator, node_type> insert_return_type;
#endif

    template <class _Key2, class _Tp2, class _Hash2, class _Pred2, class _Alloc2>
        friend class _LIBCPP_TEMPLATE_VIS unordered_map;
    template <class _Key2, class _Tp2, class _Hash2, class _Pred2, class _Alloc2>
        friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;

    _LIBCPP_INLINE_VISIBILITY
    unordered_map()
        _NOEXCEPT_(is_nothrow_default_constructible<__table>::value)
    {
        _VSTD::__debug_db_insert_c(this);
    }
    explicit unordered_map(size_type __n, const hasher& __hf = hasher(),
                           const key_equal& __eql = key_equal());
    unordered_map(size_type __n, const hasher& __hf,
                  const key_equal& __eql,
                  const allocator_type& __a);
    template <class _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last);
    template <class _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      size_type __n, const hasher& __hf = hasher(),
                      const key_equal& __eql = key_equal());
    template <class _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      size_type __n, const hasher& __hf,
                      const key_equal& __eql,
                      const allocator_type& __a);
    _LIBCPP_INLINE_VISIBILITY
    explicit unordered_map(const allocator_type& __a);
    unordered_map(const unordered_map& __u);
    unordered_map(const unordered_map& __u, const allocator_type& __a);
#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    unordered_map(unordered_map&& __u)
        _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
    unordered_map(unordered_map&& __u, const allocator_type& __a);
    unordered_map(initializer_list<value_type> __il);
    unordered_map(initializer_list<value_type> __il, size_type __n,
                  const hasher& __hf = hasher(), const key_equal& __eql = key_equal());
    unordered_map(initializer_list<value_type> __il, size_type __n,
                  const hasher& __hf, const key_equal& __eql,
                  const allocator_type& __a);
#endif // _LIBCPP_CXX03_LANG
#if _LIBCPP_STD_VER > 11
    _LIBCPP_INLINE_VISIBILITY
    unordered_map(size_type __n, const allocator_type& __a)
      : unordered_map(__n, hasher(), key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_map(size_type __n, const hasher& __hf, const allocator_type& __a)
      : unordered_map(__n, __hf, key_equal(), __a) {}
    template <class _InputIterator>
    _LIBCPP_INLINE_VISIBILITY
      unordered_map(_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type& __a)
      : unordered_map(__first, __last, __n, hasher(), key_equal(), __a) {}
    template <class _InputIterator>
    _LIBCPP_INLINE_VISIBILITY
      unordered_map(_InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf,
        const allocator_type& __a)
      : unordered_map(__first, __last, __n, __hf, key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_map(initializer_list<value_type> __il, size_type __n, const allocator_type& __a)
      : unordered_map(__il, __n, hasher(), key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_map(initializer_list<value_type> __il, size_type __n, const hasher& __hf,
      const allocator_type& __a)
      : unordered_map(__il, __n, __hf, key_equal(), __a) {}
#endif
    _LIBCPP_INLINE_VISIBILITY
    ~unordered_map() {
        static_assert(sizeof(__diagnose_unordered_container_requirements<_Key, _Hash, _Pred>(0)), "");
    }

    _LIBCPP_INLINE_VISIBILITY
    unordered_map& operator=(const unordered_map& __u)
    {
#ifndef _LIBCPP_CXX03_LANG
        __table_ = __u.__table_;
#else
        if (this != _VSTD::addressof(__u)) {
            __table_.clear();
            __table_.hash_function() = __u.__table_.hash_function();
            __table_.key_eq() = __u.__table_.key_eq();
            __table_.max_load_factor() = __u.__table_.max_load_factor();
            __table_.__copy_assign_alloc(__u.__table_);
            insert(__u.begin(), __u.end());
        }
#endif
        return *this;
    }
#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    unordered_map& operator=(unordered_map&& __u)
        _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
    _LIBCPP_INLINE_VISIBILITY
    unordered_map& operator=(initializer_list<value_type> __il);
#endif // _LIBCPP_CXX03_LANG

    _LIBCPP_INLINE_VISIBILITY
    allocator_type get_allocator() const _NOEXCEPT
        {return allocator_type(__table_.__node_alloc());}

    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
    bool      empty() const _NOEXCEPT {return __table_.size() == 0;}
    _LIBCPP_INLINE_VISIBILITY
    size_type size() const _NOEXCEPT  {return __table_.size();}
    _LIBCPP_INLINE_VISIBILITY
    size_type max_size() const _NOEXCEPT {return __table_.max_size();}

    _LIBCPP_INLINE_VISIBILITY
    iterator       begin() _NOEXCEPT        {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    iterator       end() _NOEXCEPT          {return __table_.end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator begin()  const _NOEXCEPT {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator end()    const _NOEXCEPT {return __table_.end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cbegin() const _NOEXCEPT {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cend()   const _NOEXCEPT {return __table_.end();}

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> insert(const value_type& __x)
        {return __table_.__insert_unique(__x);}

    iterator insert(const_iterator __p, const value_type& __x) {
        _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                             "unordered_map::insert(const_iterator, const value_type&) called with an iterator not "
                             "referring to this unordered_map");
        ((void)__p);
        return insert(__x).first;
    }

    template <class _InputIterator>
        _LIBCPP_INLINE_VISIBILITY
        void insert(_InputIterator __first, _InputIterator __last);

#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    void insert(initializer_list<value_type> __il)
        {insert(__il.begin(), __il.end());}

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> insert(value_type&& __x)
        {return __table_.__insert_unique(_VSTD::move(__x));}

    iterator insert(const_iterator __p, value_type&& __x) {
        _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                             "unordered_map::insert(const_iterator, const value_type&) called with an iterator not"
                             " referring to this unordered_map");
        ((void)__p);
        return __table_.__insert_unique(_VSTD::move(__x)).first;
    }

    template <class _Pp,
              class = typename enable_if<is_constructible<value_type, _Pp>::value>::type>
        _LIBCPP_INLINE_VISIBILITY
        pair<iterator, bool> insert(_Pp&& __x)
            {return __table_.__insert_unique(_VSTD::forward<_Pp>(__x));}

    template <class _Pp,
              class = typename enable_if<is_constructible<value_type, _Pp>::value>::type>
        _LIBCPP_INLINE_VISIBILITY
        iterator insert(const_iterator __p, _Pp&& __x)
        {
            _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                                 "unordered_map::insert(const_iterator, value_type&&) called with an iterator not"
                                 " referring to this unordered_map");
          ((void)__p);
            return insert(_VSTD::forward<_Pp>(__x)).first;
        }

    template <class... _Args>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, bool> emplace(_Args&&... __args) {
        return __table_.__emplace_unique(_VSTD::forward<_Args>(__args)...);
    }

    template <class... _Args>
    _LIBCPP_INLINE_VISIBILITY
    iterator emplace_hint(const_iterator __p, _Args&&... __args) {
        _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__p)) == this,
                             "unordered_map::emplace_hint(const_iterator, args...) called with an iterator not"
                             " referring to this unordered_map");
          ((void)__p);
        return __table_.__emplace_unique(_VSTD::forward<_Args>(__args)...).first;
    }

#endif // _LIBCPP_CXX03_LANG

#if _LIBCPP_STD_VER > 14
    template <class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        pair<iterator, bool> try_emplace(const key_type& __k, _Args&&... __args)
    {
        return __table_.__emplace_unique_key_args(__k, piecewise_construct,
            _VSTD::forward_as_tuple(__k),
            _VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
    }

    template <class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        pair<iterator, bool> try_emplace(key_type&& __k, _Args&&... __args)
    {
        return __table_.__emplace_unique_key_args(__k, piecewise_construct,
            _VSTD::forward_as_tuple(_VSTD::move(__k)),
            _VSTD::forward_as_tuple(_VSTD::forward<_Args>(__args)...));
    }

    template <class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        iterator try_emplace(const_iterator __h, const key_type& __k, _Args&&... __args)
    {
        _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__h)) == this,
                             "unordered_map::try_emplace(const_iterator, key, args...) called with an iterator not"
                             " referring to this unordered_map");
        ((void)__h);
        return try_emplace(__k, _VSTD::forward<_Args>(__args)...).first;
    }

    template <class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        iterator try_emplace(const_iterator __h, key_type&& __k, _Args&&... __args)
    {
        _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(_VSTD::addressof(__h)) == this,
                             "unordered_map::try_emplace(const_iterator, key, args...) called with an iterator not"
                             " referring to this unordered_map");
        ((void)__h);
        return try_emplace(_VSTD::move(__k), _VSTD::forward<_Args>(__args)...).first;
    }

    template <class _Vp>
        _LIBCPP_INLINE_VISIBILITY
        pair<iterator, bool> insert_or_assign(const key_type& __k, _Vp&& __v)
    {
        pair<iterator, bool> __res = __table_.__emplace_unique_key_args(__k,
            __k, _VSTD::forward<_Vp>(__v));
        if (!__res.second) {
            __res.first->second = _VSTD::forward<_Vp>(__v);
        }
        return __res;
    }

    template <class _Vp>
        _LIBCPP_INLINE_VISIBILITY
        pair<iterator, bool> insert_or_assign(key_type&& __k, _Vp&& __v)
    {
        pair<iterator, bool> __res = __table_.__emplace_unique_key_args(__k,
            _VSTD::move(__k), _VSTD::forward<_Vp>(__v));
        if (!__res.second) {
            __res.first->second = _VSTD::forward<_Vp>(__v);
        }
        return __res;
    }

    template <class _Vp>
        _LIBCPP_INLINE_VISIBILITY
        iterator insert_or_assign(const_iterator, const key_type& __k, _Vp&& __v)
     {
          // FIXME: Add debug mode checking for the iterator input
          return insert_or_assign(__k, _VSTD::forward<_Vp>(__v)).first;
     }

    template <class _Vp>
        _LIBCPP_INLINE_VISIBILITY
        iterator insert_or_assign(const_iterator, key_type&& __k, _Vp&& __v)
     {
        // FIXME: Add debug mode checking for the iterator input
        return insert_or_assign(_VSTD::move(__k), _VSTD::forward<_Vp>(__v)).first;
     }
#endif // _LIBCPP_STD_VER > 14

    _LIBCPP_INLINE_VISIBILITY
    iterator erase(const_iterator __p) {return __table_.erase(__p.__i_);}
    _LIBCPP_INLINE_VISIBILITY
    iterator erase(iterator __p)       {return __table_.erase(__p.__i_);}
    _LIBCPP_INLINE_VISIBILITY
    size_type erase(const key_type& __k) {return __table_.__erase_unique(__k);}
    _LIBCPP_INLINE_VISIBILITY
    iterator erase(const_iterator __first, const_iterator __last)
        {return __table_.erase(__first.__i_, __last.__i_);}
    _LIBCPP_INLINE_VISIBILITY
        void clear() _NOEXCEPT {__table_.clear();}

#if _LIBCPP_STD_VER > 14
    _LIBCPP_INLINE_VISIBILITY
    insert_return_type insert(node_type&& __nh)
    {
        _LIBCPP_ASSERT(__nh.empty() || __nh.get_allocator() == get_allocator(),
            "node_type with incompatible allocator passed to unordered_map::insert()");
        return __table_.template __node_handle_insert_unique<
            node_type, insert_return_type>(_VSTD::move(__nh));
    }
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __hint, node_type&& __nh)
    {
        _LIBCPP_ASSERT(__nh.empty() || __nh.get_allocator() == get_allocator(),
            "node_type with incompatible allocator passed to unordered_map::insert()");
        return __table_.template __node_handle_insert_unique<node_type>(
            __hint.__i_, _VSTD::move(__nh));
    }
    _LIBCPP_INLINE_VISIBILITY
    node_type extract(key_type const& __key)
    {
        return __table_.template __node_handle_extract<node_type>(__key);
    }
    _LIBCPP_INLINE_VISIBILITY
    node_type extract(const_iterator __it)
    {
        return __table_.template __node_handle_extract<node_type>(
            __it.__i_);
    }

    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_map<key_type, mapped_type, _H2, _P2, allocator_type>& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_unique(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_map<key_type, mapped_type, _H2, _P2, allocator_type>&& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_unique(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_multimap<key_type, mapped_type, _H2, _P2, allocator_type>& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_unique(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_multimap<key_type, mapped_type, _H2, _P2, allocator_type>&& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_unique(__source.__table_);
    }
#endif

    _LIBCPP_INLINE_VISIBILITY
    void swap(unordered_map& __u)
        _NOEXCEPT_(__is_nothrow_swappable<__table>::value)
        { __table_.swap(__u.__table_);}

    _LIBCPP_INLINE_VISIBILITY
    hasher hash_function() const
        {return __table_.hash_function().hash_function();}
    _LIBCPP_INLINE_VISIBILITY
    key_equal key_eq() const
        {return __table_.key_eq().key_eq();}

    _LIBCPP_INLINE_VISIBILITY
    iterator       find(const key_type& __k)       {return __table_.find(__k);}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator find(const key_type& __k) const {return __table_.find(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    iterator       find(const _K2& __k)            {return __table_.find(__k);}
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    const_iterator find(const _K2& __k) const      {return __table_.find(__k);}
#endif // _LIBCPP_STD_VER > 17

    _LIBCPP_INLINE_VISIBILITY
    size_type count(const key_type& __k) const {return __table_.__count_unique(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    size_type count(const _K2& __k) const      {return __table_.__count_unique(__k);}
#endif // _LIBCPP_STD_VER > 17

#if _LIBCPP_STD_VER > 17
    _LIBCPP_INLINE_VISIBILITY
    bool contains(const key_type& __k) const {return find(__k) != end();}

    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    bool contains(const _K2& __k) const      {return find(__k) != end();}
#endif // _LIBCPP_STD_VER > 17

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, iterator>             equal_range(const key_type& __k)
        {return __table_.__equal_range_unique(__k);}
    _LIBCPP_INLINE_VISIBILITY
    pair<const_iterator, const_iterator> equal_range(const key_type& __k) const
        {return __table_.__equal_range_unique(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, iterator>             equal_range(const _K2& __k)
        {return __table_.__equal_range_unique(__k);}
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    pair<const_iterator, const_iterator> equal_range(const _K2& __k) const
        {return __table_.__equal_range_unique(__k);}
#endif // _LIBCPP_STD_VER > 17

    mapped_type& operator[](const key_type& __k);
#ifndef _LIBCPP_CXX03_LANG
    mapped_type& operator[](key_type&& __k);
#endif

    mapped_type&       at(const key_type& __k);
    const mapped_type& at(const key_type& __k) const;

    _LIBCPP_INLINE_VISIBILITY
    size_type bucket_count() const _NOEXCEPT {return __table_.bucket_count();}
    _LIBCPP_INLINE_VISIBILITY
    size_type max_bucket_count() const _NOEXCEPT {return __table_.max_bucket_count();}

    _LIBCPP_INLINE_VISIBILITY
    size_type bucket_size(size_type __n) const
        {return __table_.bucket_size(__n);}
    _LIBCPP_INLINE_VISIBILITY
    size_type bucket(const key_type& __k) const {return __table_.bucket(__k);}

    _LIBCPP_INLINE_VISIBILITY
    local_iterator       begin(size_type __n)        {return __table_.begin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    local_iterator       end(size_type __n)          {return __table_.end(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator begin(size_type __n) const  {return __table_.cbegin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator end(size_type __n) const    {return __table_.cend(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator cbegin(size_type __n) const {return __table_.cbegin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator cend(size_type __n) const   {return __table_.cend(__n);}

    _LIBCPP_INLINE_VISIBILITY
    float load_factor() const _NOEXCEPT {return __table_.load_factor();}
    _LIBCPP_INLINE_VISIBILITY
    float max_load_factor() const _NOEXCEPT {return __table_.max_load_factor();}
    _LIBCPP_INLINE_VISIBILITY
    void max_load_factor(float __mlf) {__table_.max_load_factor(__mlf);}
    _LIBCPP_INLINE_VISIBILITY
    void rehash(size_type __n) {__table_.rehash(__n);}
    _LIBCPP_INLINE_VISIBILITY
    void reserve(size_type __n) {__table_.reserve(__n);}

#ifdef _LIBCPP_ENABLE_DEBUG_MODE

    bool __dereferenceable(const const_iterator* __i) const
        {return __table_.__dereferenceable(_VSTD::addressof(__i->__i_));}
    bool __decrementable(const const_iterator* __i) const
        {return __table_.__decrementable(_VSTD::addressof(__i->__i_));}
    bool __addable(const const_iterator* __i, ptrdiff_t __n) const
        {return __table_.__addable(_VSTD::addressof(__i->__i_), __n);}
    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const
        {return __table_.__addable(_VSTD::addressof(__i->__i_), __n);}

#endif // _LIBCPP_ENABLE_DEBUG_MODE

private:

#ifdef _LIBCPP_CXX03_LANG
    __node_holder __construct_node_with_key(const key_type& __k);
#endif
};

#if _LIBCPP_STD_VER >= 17
template<class _InputIterator,
         class _Hash = hash<__iter_key_type<_InputIterator>>,
         class _Pred = equal_to<__iter_key_type<_InputIterator>>,
         class _Allocator = allocator<__iter_to_alloc_type<_InputIterator>>,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<!__is_allocator<_Pred>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type = 0,
              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
  -> unordered_map<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>, _Hash, _Pred, _Allocator>;

template<class _Key, class _Tp, class _Hash = hash<remove_const_t<_Key>>,
         class _Pred = equal_to<remove_const_t<_Key>>,
         class _Allocator = allocator<pair<const _Key, _Tp>>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<!__is_allocator<_Pred>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type = 0,
              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
  -> unordered_map<remove_const_t<_Key>, _Tp, _Hash, _Pred, _Allocator>;

template<class _InputIterator, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Allocator)
  -> unordered_map<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                   hash<__iter_key_type<_InputIterator>>, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _InputIterator, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(_InputIterator, _InputIterator, _Allocator)
  -> unordered_map<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                   hash<__iter_key_type<_InputIterator>>, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _InputIterator, class _Hash, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
  -> unordered_map<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                   _Hash, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _Key, class _Tp, class _Allocator,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type, _Allocator)
  -> unordered_map<remove_const_t<_Key>, _Tp,
                   hash<remove_const_t<_Key>>,
                   equal_to<remove_const_t<_Key>>, _Allocator>;

template<class _Key, class _Tp, class _Allocator,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(initializer_list<pair<_Key, _Tp>>, _Allocator)
  -> unordered_map<remove_const_t<_Key>, _Tp,
                   hash<remove_const_t<_Key>>,
                   equal_to<remove_const_t<_Key>>, _Allocator>;

template<class _Key, class _Tp, class _Hash, class _Allocator,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_map(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
  -> unordered_map<remove_const_t<_Key>, _Tp, _Hash,
                   equal_to<remove_const_t<_Key>>, _Allocator>;
#endif

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        size_type __n, const hasher& __hf, const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        size_type __n, const hasher& __hf, const key_equal& __eql,
        const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        const allocator_type& __a)
    : __table_(typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        _InputIterator __first, _InputIterator __last)
{
    _VSTD::__debug_db_insert_c(this);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        _InputIterator __first, _InputIterator __last, size_type __n,
        const hasher& __hf, const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        _InputIterator __first, _InputIterator __last, size_type __n,
        const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        const unordered_map& __u)
    : __table_(__u.__table_)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__u.bucket_count());
    insert(__u.begin(), __u.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        const unordered_map& __u, const allocator_type& __a)
    : __table_(__u.__table_, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__u.bucket_count());
    insert(__u.begin(), __u.end());
}

#ifndef _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        unordered_map&& __u)
    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
    : __table_(_VSTD::move(__u.__table_))
{
    _VSTD::__debug_db_insert_c(this);
    std::__debug_db_swap(this, std::addressof(__u));
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        unordered_map&& __u, const allocator_type& __a)
    : __table_(_VSTD::move(__u.__table_), typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    if (__a != __u.get_allocator())
    {
        iterator __i = __u.begin();
        while (__u.size() != 0) {
            __table_.__emplace_unique(
                __u.__table_.remove((__i++).__i_)->__value_.__move());
        }
    }
    else
        std::__debug_db_swap(this, std::addressof(__u));
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        initializer_list<value_type> __il)
{
    _VSTD::__debug_db_insert_c(this);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
        const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_map(
        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
        const key_equal& __eql, const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator=(unordered_map&& __u)
    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value)
{
    __table_ = _VSTD::move(__u.__table_);
    return *this;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator=(
        initializer_list<value_type> __il)
{
    __table_.__assign_unique(__il.begin(), __il.end());
    return *this;
}

#endif // _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
inline
void
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(_InputIterator __first,
                                                       _InputIterator __last)
{
    for (; __first != __last; ++__first)
        __table_.__insert_unique(*__first);
}

#ifndef _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](const key_type& __k)
{
    return __table_.__emplace_unique_key_args(__k,
        piecewise_construct, _VSTD::forward_as_tuple(__k),
                             _VSTD::forward_as_tuple()).first->__get_value().second;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](key_type&& __k)
{
    return __table_.__emplace_unique_key_args(__k,
        piecewise_construct, _VSTD::forward_as_tuple(_VSTD::move(__k)),
                             _VSTD::forward_as_tuple()).first->__get_value().second;
}
#else // _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node_with_key(const key_type& __k)
{
    __node_allocator& __na = __table_.__node_alloc();
    __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__get_value().first), __k);
    __h.get_deleter().__first_constructed = true;
    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__get_value().second));
    __h.get_deleter().__second_constructed = true;
    return __h;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](const key_type& __k)
{
    iterator __i = find(__k);
    if (__i != end())
        return __i->second;
    __node_holder __h = __construct_node_with_key(__k);
    pair<iterator, bool> __r = __table_.__node_insert_unique(__h.get());
    __h.release();
    return __r.first->second;
}

#endif // _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
_Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::at(const key_type& __k)
{
    iterator __i = find(__k);
    if (__i == end())
        __throw_out_of_range("unordered_map::at: key not found");
    return __i->second;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
const _Tp&
unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::at(const key_type& __k) const
{
    const_iterator __i = find(__k);
    if (__i == end())
        __throw_out_of_range("unordered_map::at: key not found");
    return __i->second;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
     unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

#if _LIBCPP_STD_VER > 17
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc,
          class _Predicate>
inline _LIBCPP_INLINE_VISIBILITY
    typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::size_type
    erase_if(unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __c,
             _Predicate __pred) {
  return _VSTD::__libcpp_erase_if_container(__c, __pred);
}
#endif

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
bool
operator==(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
           const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
{
    if (__x.size() != __y.size())
        return false;
    typedef typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::const_iterator
                                                                 const_iterator;
    for (const_iterator __i = __x.begin(), __ex = __x.end(), __ey = __y.end();
            __i != __ex; ++__i)
    {
        const_iterator __j = __y.find(__i->first);
        if (__j == __ey || !(*__i == *__j))
            return false;
    }
    return true;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
           const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
{
    return !(__x == __y);
}

template <class _Key, class _Tp, class _Hash = hash<_Key>, class _Pred = equal_to<_Key>,
          class _Alloc = allocator<pair<const _Key, _Tp> > >
class _LIBCPP_TEMPLATE_VIS unordered_multimap
{
public:
    // types
    typedef _Key                                           key_type;
    typedef _Tp                                            mapped_type;
    typedef __type_identity_t<_Hash>                       hasher;
    typedef __type_identity_t<_Pred>                       key_equal;
    typedef __type_identity_t<_Alloc>                      allocator_type;
    typedef pair<const key_type, mapped_type>              value_type;
    typedef value_type&                                    reference;
    typedef const value_type&                              const_reference;
    static_assert((is_same<value_type, typename allocator_type::value_type>::value),
                  "Invalid allocator::value_type");

private:
    typedef __hash_value_type<key_type, mapped_type>                          __value_type;
    typedef __unordered_map_hasher<key_type, __value_type, hasher, key_equal> __hasher;
    typedef __unordered_map_equal<key_type, __value_type, key_equal, hasher>  __key_equal;
    typedef typename __rebind_alloc_helper<allocator_traits<allocator_type>,
                                                 __value_type>::type          __allocator_type;

    typedef __hash_table<__value_type, __hasher,
                         __key_equal,  __allocator_type>   __table;

    __table __table_;

    typedef typename __table::_NodeTypes                   _NodeTypes;
    typedef typename __table::__node_traits                __node_traits;
    typedef typename __table::__node_allocator             __node_allocator;
    typedef typename __table::__node                       __node;
    typedef __hash_map_node_destructor<__node_allocator>   _Dp;
    typedef unique_ptr<__node, _Dp>                         __node_holder;
    typedef allocator_traits<allocator_type>               __alloc_traits;
    static_assert((is_same<typename __node_traits::size_type,
                          typename __alloc_traits::size_type>::value),
                 "Allocator uses different size_type for different types");
public:
    typedef typename __alloc_traits::pointer         pointer;
    typedef typename __alloc_traits::const_pointer   const_pointer;
    typedef typename __table::size_type              size_type;
    typedef typename __table::difference_type        difference_type;

    typedef __hash_map_iterator<typename __table::iterator>       iterator;
    typedef __hash_map_const_iterator<typename __table::const_iterator> const_iterator;
    typedef __hash_map_iterator<typename __table::local_iterator> local_iterator;
    typedef __hash_map_const_iterator<typename __table::const_local_iterator> const_local_iterator;

#if _LIBCPP_STD_VER > 14
    typedef __map_node_handle<__node, allocator_type> node_type;
#endif

    template <class _Key2, class _Tp2, class _Hash2, class _Pred2, class _Alloc2>
        friend class _LIBCPP_TEMPLATE_VIS unordered_map;
    template <class _Key2, class _Tp2, class _Hash2, class _Pred2, class _Alloc2>
        friend class _LIBCPP_TEMPLATE_VIS unordered_multimap;

    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap()
        _NOEXCEPT_(is_nothrow_default_constructible<__table>::value)
    {
        _VSTD::__debug_db_insert_c(this);
    }
    explicit unordered_multimap(size_type __n, const hasher& __hf = hasher(),
                                const key_equal& __eql = key_equal());
    unordered_multimap(size_type __n, const hasher& __hf,
                                const key_equal& __eql,
                                const allocator_type& __a);
    template <class _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last);
    template <class _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                      size_type __n, const hasher& __hf = hasher(),
                      const key_equal& __eql = key_equal());
    template <class _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                      size_type __n, const hasher& __hf,
                      const key_equal& __eql,
                      const allocator_type& __a);
    _LIBCPP_INLINE_VISIBILITY
    explicit unordered_multimap(const allocator_type& __a);
    unordered_multimap(const unordered_multimap& __u);
    unordered_multimap(const unordered_multimap& __u, const allocator_type& __a);
#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap(unordered_multimap&& __u)
        _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
    unordered_multimap(unordered_multimap&& __u, const allocator_type& __a);
    unordered_multimap(initializer_list<value_type> __il);
    unordered_multimap(initializer_list<value_type> __il, size_type __n,
                       const hasher& __hf = hasher(),
                       const key_equal& __eql = key_equal());
    unordered_multimap(initializer_list<value_type> __il, size_type __n,
                       const hasher& __hf, const key_equal& __eql,
                       const allocator_type& __a);
#endif // _LIBCPP_CXX03_LANG
#if _LIBCPP_STD_VER > 11
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap(size_type __n, const allocator_type& __a)
      : unordered_multimap(__n, hasher(), key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap(size_type __n, const hasher& __hf, const allocator_type& __a)
      : unordered_multimap(__n, __hf, key_equal(), __a) {}
    template <class _InputIterator>
    _LIBCPP_INLINE_VISIBILITY
      unordered_multimap(_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type& __a)
      : unordered_multimap(__first, __last, __n, hasher(), key_equal(), __a) {}
    template <class _InputIterator>
    _LIBCPP_INLINE_VISIBILITY
      unordered_multimap(_InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf,
        const allocator_type& __a)
      : unordered_multimap(__first, __last, __n, __hf, key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap(initializer_list<value_type> __il, size_type __n, const allocator_type& __a)
      : unordered_multimap(__il, __n, hasher(), key_equal(), __a) {}
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap(initializer_list<value_type> __il, size_type __n, const hasher& __hf,
      const allocator_type& __a)
      : unordered_multimap(__il, __n, __hf, key_equal(), __a) {}
#endif
    _LIBCPP_INLINE_VISIBILITY
    ~unordered_multimap() {
        static_assert(sizeof(__diagnose_unordered_container_requirements<_Key, _Hash, _Pred>(0)), "");
    }

    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap& operator=(const unordered_multimap& __u)
    {
#ifndef _LIBCPP_CXX03_LANG
        __table_ = __u.__table_;
#else
        if (this != _VSTD::addressof(__u)) {
            __table_.clear();
            __table_.hash_function() = __u.__table_.hash_function();
            __table_.key_eq() = __u.__table_.key_eq();
            __table_.max_load_factor() = __u.__table_.max_load_factor();
            __table_.__copy_assign_alloc(__u.__table_);
            insert(__u.begin(), __u.end());
        }
#endif
        return *this;
    }
#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap& operator=(unordered_multimap&& __u)
        _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
    _LIBCPP_INLINE_VISIBILITY
    unordered_multimap& operator=(initializer_list<value_type> __il);
#endif // _LIBCPP_CXX03_LANG

    _LIBCPP_INLINE_VISIBILITY
    allocator_type get_allocator() const _NOEXCEPT
        {return allocator_type(__table_.__node_alloc());}

    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
    bool      empty() const _NOEXCEPT {return __table_.size() == 0;}
    _LIBCPP_INLINE_VISIBILITY
    size_type size() const _NOEXCEPT  {return __table_.size();}
    _LIBCPP_INLINE_VISIBILITY
    size_type max_size() const _NOEXCEPT {return __table_.max_size();}

    _LIBCPP_INLINE_VISIBILITY
    iterator       begin() _NOEXCEPT        {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    iterator       end() _NOEXCEPT          {return __table_.end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator begin()  const _NOEXCEPT {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator end()    const _NOEXCEPT {return __table_.end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cbegin() const _NOEXCEPT {return __table_.begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cend()   const _NOEXCEPT {return __table_.end();}

    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const value_type& __x) {return __table_.__insert_multi(__x);}

    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __p, const value_type& __x)
        {return __table_.__insert_multi(__p.__i_, __x);}

    template <class _InputIterator>
    _LIBCPP_INLINE_VISIBILITY
    void insert(_InputIterator __first, _InputIterator __last);

#ifndef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    void insert(initializer_list<value_type> __il)
        {insert(__il.begin(), __il.end());}
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(value_type&& __x) {return __table_.__insert_multi(_VSTD::move(__x));}

    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __p, value_type&& __x)
        {return __table_.__insert_multi(__p.__i_, _VSTD::move(__x));}

    template <class _Pp,
              class = typename enable_if<is_constructible<value_type, _Pp>::value>::type>
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(_Pp&& __x)
        {return __table_.__insert_multi(_VSTD::forward<_Pp>(__x));}

    template <class _Pp,
              class = typename enable_if<is_constructible<value_type, _Pp>::value>::type>
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __p, _Pp&& __x)
        {return __table_.__insert_multi(__p.__i_, _VSTD::forward<_Pp>(__x));}

    template <class... _Args>
    iterator emplace(_Args&&... __args) {
        return __table_.__emplace_multi(_VSTD::forward<_Args>(__args)...);
    }

    template <class... _Args>
    iterator emplace_hint(const_iterator __p, _Args&&... __args) {
        return __table_.__emplace_hint_multi(__p.__i_, _VSTD::forward<_Args>(__args)...);
    }
#endif // _LIBCPP_CXX03_LANG


    _LIBCPP_INLINE_VISIBILITY
    iterator erase(const_iterator __p) {return __table_.erase(__p.__i_);}
    _LIBCPP_INLINE_VISIBILITY
    iterator erase(iterator __p)       {return __table_.erase(__p.__i_);}
    _LIBCPP_INLINE_VISIBILITY
    size_type erase(const key_type& __k) {return __table_.__erase_multi(__k);}
    _LIBCPP_INLINE_VISIBILITY
    iterator erase(const_iterator __first, const_iterator __last)
        {return __table_.erase(__first.__i_, __last.__i_);}
    _LIBCPP_INLINE_VISIBILITY
    void clear() _NOEXCEPT {__table_.clear();}

#if _LIBCPP_STD_VER > 14
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(node_type&& __nh)
    {
        _LIBCPP_ASSERT(__nh.empty() || __nh.get_allocator() == get_allocator(),
            "node_type with incompatible allocator passed to unordered_multimap::insert()");
        return __table_.template __node_handle_insert_multi<node_type>(
            _VSTD::move(__nh));
    }
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __hint, node_type&& __nh)
    {
        _LIBCPP_ASSERT(__nh.empty() || __nh.get_allocator() == get_allocator(),
            "node_type with incompatible allocator passed to unordered_multimap::insert()");
        return __table_.template __node_handle_insert_multi<node_type>(
            __hint.__i_, _VSTD::move(__nh));
    }
    _LIBCPP_INLINE_VISIBILITY
    node_type extract(key_type const& __key)
    {
        return __table_.template __node_handle_extract<node_type>(__key);
    }
    _LIBCPP_INLINE_VISIBILITY
    node_type extract(const_iterator __it)
    {
        return __table_.template __node_handle_extract<node_type>(
            __it.__i_);
    }

    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_multimap<key_type, mapped_type, _H2, _P2, allocator_type>& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_multi(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_multimap<key_type, mapped_type, _H2, _P2, allocator_type>&& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_multi(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_map<key_type, mapped_type, _H2, _P2, allocator_type>& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_multi(__source.__table_);
    }
    template <class _H2, class _P2>
    _LIBCPP_INLINE_VISIBILITY
    void merge(unordered_map<key_type, mapped_type, _H2, _P2, allocator_type>&& __source)
    {
        _LIBCPP_ASSERT(__source.get_allocator() == get_allocator(),
                       "merging container with incompatible allocator");
        return __table_.__node_handle_merge_multi(__source.__table_);
    }
#endif

    _LIBCPP_INLINE_VISIBILITY
    void swap(unordered_multimap& __u)
        _NOEXCEPT_(__is_nothrow_swappable<__table>::value)
        {__table_.swap(__u.__table_);}

    _LIBCPP_INLINE_VISIBILITY
    hasher hash_function() const
        {return __table_.hash_function().hash_function();}
    _LIBCPP_INLINE_VISIBILITY
    key_equal key_eq() const
        {return __table_.key_eq().key_eq();}

    _LIBCPP_INLINE_VISIBILITY
    iterator       find(const key_type& __k)       {return __table_.find(__k);}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator find(const key_type& __k) const {return __table_.find(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    iterator       find(const _K2& __k)            {return __table_.find(__k);}
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    const_iterator find(const _K2& __k) const      {return __table_.find(__k);}
#endif // _LIBCPP_STD_VER > 17

    _LIBCPP_INLINE_VISIBILITY
    size_type count(const key_type& __k) const {return __table_.__count_multi(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    size_type count(const _K2& __k) const      {return __table_.__count_multi(__k);}
#endif // _LIBCPP_STD_VER > 17

#if _LIBCPP_STD_VER > 17
    _LIBCPP_INLINE_VISIBILITY
    bool contains(const key_type& __k) const {return find(__k) != end();}

    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    bool contains(const _K2& __k) const      {return find(__k) != end();}
#endif // _LIBCPP_STD_VER > 17

    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, iterator>             equal_range(const key_type& __k)
        {return __table_.__equal_range_multi(__k);}
    _LIBCPP_INLINE_VISIBILITY
    pair<const_iterator, const_iterator> equal_range(const key_type& __k) const
        {return __table_.__equal_range_multi(__k);}
#if _LIBCPP_STD_VER > 17
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    pair<iterator, iterator>             equal_range(const _K2& __k)
        {return __table_.__equal_range_multi(__k);}
    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
    _LIBCPP_INLINE_VISIBILITY
    pair<const_iterator, const_iterator> equal_range(const _K2& __k) const
        {return __table_.__equal_range_multi(__k);}
#endif // _LIBCPP_STD_VER > 17

    _LIBCPP_INLINE_VISIBILITY
    size_type bucket_count() const _NOEXCEPT {return __table_.bucket_count();}
    _LIBCPP_INLINE_VISIBILITY
    size_type max_bucket_count() const _NOEXCEPT
        {return __table_.max_bucket_count();}

    _LIBCPP_INLINE_VISIBILITY
    size_type bucket_size(size_type __n) const
        {return __table_.bucket_size(__n);}
    _LIBCPP_INLINE_VISIBILITY
    size_type bucket(const key_type& __k) const {return __table_.bucket(__k);}

    _LIBCPP_INLINE_VISIBILITY
    local_iterator       begin(size_type __n)        {return __table_.begin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    local_iterator       end(size_type __n)          {return __table_.end(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator begin(size_type __n) const  {return __table_.cbegin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator end(size_type __n) const    {return __table_.cend(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator cbegin(size_type __n) const {return __table_.cbegin(__n);}
    _LIBCPP_INLINE_VISIBILITY
    const_local_iterator cend(size_type __n) const   {return __table_.cend(__n);}

    _LIBCPP_INLINE_VISIBILITY
    float load_factor() const _NOEXCEPT {return __table_.load_factor();}
    _LIBCPP_INLINE_VISIBILITY
    float max_load_factor() const _NOEXCEPT {return __table_.max_load_factor();}
    _LIBCPP_INLINE_VISIBILITY
    void max_load_factor(float __mlf) {__table_.max_load_factor(__mlf);}
    _LIBCPP_INLINE_VISIBILITY
    void rehash(size_type __n) {__table_.rehash(__n);}
    _LIBCPP_INLINE_VISIBILITY
    void reserve(size_type __n) {__table_.reserve(__n);}

#ifdef _LIBCPP_ENABLE_DEBUG_MODE

    bool __dereferenceable(const const_iterator* __i) const
        {return __table_.__dereferenceable(_VSTD::addressof(__i->__i_));}
    bool __decrementable(const const_iterator* __i) const
        {return __table_.__decrementable(_VSTD::addressof(__i->__i_));}
    bool __addable(const const_iterator* __i, ptrdiff_t __n) const
        {return __table_.__addable(_VSTD::addressof(__i->__i_), __n);}
    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const
        {return __table_.__addable(_VSTD::addressof(__i->__i_), __n);}

#endif // _LIBCPP_ENABLE_DEBUG_MODE


};

#if _LIBCPP_STD_VER >= 17
template<class _InputIterator,
         class _Hash = hash<__iter_key_type<_InputIterator>>,
         class _Pred = equal_to<__iter_key_type<_InputIterator>>,
         class _Allocator = allocator<__iter_to_alloc_type<_InputIterator>>,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<!__is_allocator<_Pred>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type = 0,
                   _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
  -> unordered_multimap<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>, _Hash, _Pred, _Allocator>;

template<class _Key, class _Tp, class _Hash = hash<remove_const_t<_Key>>,
         class _Pred = equal_to<remove_const_t<_Key>>,
         class _Allocator = allocator<pair<const _Key, _Tp>>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<!__is_allocator<_Pred>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type = 0,
                   _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
  -> unordered_multimap<remove_const_t<_Key>, _Tp, _Hash, _Pred, _Allocator>;

template<class _InputIterator, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Allocator)
  -> unordered_multimap<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                        hash<__iter_key_type<_InputIterator>>, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _InputIterator, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(_InputIterator, _InputIterator, _Allocator)
  -> unordered_multimap<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                        hash<__iter_key_type<_InputIterator>>, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _InputIterator, class _Hash, class _Allocator,
         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
  -> unordered_multimap<__iter_key_type<_InputIterator>, __iter_mapped_type<_InputIterator>,
                        _Hash, equal_to<__iter_key_type<_InputIterator>>, _Allocator>;

template<class _Key, class _Tp, class _Allocator,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type, _Allocator)
  -> unordered_multimap<remove_const_t<_Key>, _Tp,
                        hash<remove_const_t<_Key>>,
                        equal_to<remove_const_t<_Key>>, _Allocator>;

template<class _Key, class _Tp, class _Allocator,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(initializer_list<pair<_Key, _Tp>>, _Allocator)
  -> unordered_multimap<remove_const_t<_Key>, _Tp,
                        hash<remove_const_t<_Key>>,
                        equal_to<remove_const_t<_Key>>, _Allocator>;

template<class _Key, class _Tp, class _Hash, class _Allocator,
         class = enable_if_t<!__is_allocator<_Hash>::value>,
         class = enable_if_t<!is_integral<_Hash>::value>,
         class = enable_if_t<__is_allocator<_Allocator>::value>>
unordered_multimap(initializer_list<pair<_Key, _Tp>>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
  -> unordered_multimap<remove_const_t<_Key>, _Tp, _Hash,
                        equal_to<remove_const_t<_Key>>, _Allocator>;
#endif

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        size_type __n, const hasher& __hf, const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        size_type __n, const hasher& __hf, const key_equal& __eql,
        const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        _InputIterator __first, _InputIterator __last)
{
    _VSTD::__debug_db_insert_c(this);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        _InputIterator __first, _InputIterator __last, size_type __n,
        const hasher& __hf, const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        _InputIterator __first, _InputIterator __last, size_type __n,
        const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__first, __last);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        const allocator_type& __a)
    : __table_(typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        const unordered_multimap& __u)
    : __table_(__u.__table_)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__u.bucket_count());
    insert(__u.begin(), __u.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        const unordered_multimap& __u, const allocator_type& __a)
    : __table_(__u.__table_, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__u.bucket_count());
    insert(__u.begin(), __u.end());
}

#ifndef _LIBCPP_CXX03_LANG

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        unordered_multimap&& __u)
    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
    : __table_(_VSTD::move(__u.__table_))
{
    _VSTD::__debug_db_insert_c(this);
    std::__debug_db_swap(this, std::addressof(__u));
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        unordered_multimap&& __u, const allocator_type& __a)
    : __table_(_VSTD::move(__u.__table_), typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    if (__a != __u.get_allocator())
    {
        iterator __i = __u.begin();
        while (__u.size() != 0)
        {
            __table_.__insert_multi(
                __u.__table_.remove((__i++).__i_)->__value_.__move());
        }
    }
    else
        std::__debug_db_swap(this, std::addressof(__u));
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        initializer_list<value_type> __il)
{
    _VSTD::__debug_db_insert_c(this);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
        const key_equal& __eql)
    : __table_(__hf, __eql)
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::unordered_multimap(
        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
        const key_equal& __eql, const allocator_type& __a)
    : __table_(__hf, __eql, typename __table::allocator_type(__a))
{
    _VSTD::__debug_db_insert_c(this);
    __table_.rehash(__n);
    insert(__il.begin(), __il.end());
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>&
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::operator=(unordered_multimap&& __u)
    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value)
{
    __table_ = _VSTD::move(__u.__table_);
    return *this;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>&
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::operator=(
        initializer_list<value_type> __il)
{
    __table_.__assign_multi(__il.begin(), __il.end());
    return *this;
}

#endif // _LIBCPP_CXX03_LANG



template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
template <class _InputIterator>
inline
void
unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(_InputIterator __first,
                                                            _InputIterator __last)
{
    for (; __first != __last; ++__first)
        __table_.__insert_multi(*__first);
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
     unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

#if _LIBCPP_STD_VER > 17
template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc,
          class _Predicate>
inline _LIBCPP_INLINE_VISIBILITY
    typename unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::size_type
    erase_if(unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __c,
             _Predicate __pred) {
  return _VSTD::__libcpp_erase_if_container(__c, __pred);
}
#endif

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
bool
operator==(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
           const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
{
    if (__x.size() != __y.size())
        return false;
    typedef typename unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::const_iterator
                                                                 const_iterator;
    typedef pair<const_iterator, const_iterator> _EqRng;
    for (const_iterator __i = __x.begin(), __ex = __x.end(); __i != __ex;)
    {
        _EqRng __xeq = __x.equal_range(__i->first);
        _EqRng __yeq = __y.equal_range(__i->first);
        if (_VSTD::distance(__xeq.first, __xeq.second) !=
            _VSTD::distance(__yeq.first, __yeq.second) ||
                  !_VSTD::is_permutation(__xeq.first, __xeq.second, __yeq.first))
            return false;
        __i = __xeq.second;
    }
    return true;
}

template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
           const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
{
    return !(__x == __y);
}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP_UNORDERED_MAP