• Log in

#include <compare>
#include <initializer_list>
 
namespace std {
 // class template flat_map
 template<class Key,
 class T,
 class Compare = less<Key>,
 class KeyContainer = vector<Key>,
 class MappedContainer = vector<T>>
 class flat_map;
 
 struct sorted_unique_t
 {
 explicit sorted_unique_t() = default;
 };
 inline constexpr sorted_unique_t sorted_unique{};
 
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Allocator>
 struct uses_allocator<flat_map<Key, T, Compare, KeyContainer, MappedContainer>,
 Allocator>;
 
 // erasure for flat_map
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Predicate>
 typename flat_map<Key, T, Compare, KeyContainer, MappedContainer>::size_type erase_if(
 flat_map<Key, T, Compare, KeyContainer, MappedContainer>& c,
 Predicate pred);
 
 // class template flat_multimap
 template<class Key,
 class T,
 class Compare = less<Key>,
 class KeyContainer = vector<Key>,
 class MappedContainer = vector<T>>
 class flat_multimap;
 
 struct sorted_equivalent_t
 {
 explicit sorted_equivalent_t() = default;
 };
 inline constexpr sorted_equivalent_t sorted_equivalent{};
 
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Allocator>
 struct uses_allocator<flat_multimap<Key, T, Compare, KeyContainer, MappedContainer>,
 Allocator>;
 
 // erasure for flat_multimap
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Predicate>
 typename flat_multimap<Key, T, Compare, KeyContainer, MappedContainer>::size_type
 erase_if(flat_multimap<Key, T, Compare, KeyContainer, MappedContainer>& c,
 Predicate pred);
}

namespace std {
 template<class Key,
 class T,
 class Compare = less<Key>,
 class KeyContainer = vector<Key>,
 class MappedContainer = vector<T>>
 class flat_map
 {
 public:
 // types
 using key_type = Key;
 using mapped_type = T;
 using value_type = pair<key_type, mapped_type>;
 using key_compare = Compare;
 using reference = pair<const key_type&, mapped_type&>;
 using const_reference = pair<const key_type&, const mapped_type&>;
 using size_type = size_t;
 using difference_type = ptrdiff_t;
 using iterator = /* implementation-defined */;
 using const_iterator = /* implementation-defined */;
 using reverse_iterator = std::reverse_iterator <iterator>;
 using const_reverse_iterator = std::reverse_iterator <const_iterator>;
 using key_container_type = KeyContainer;
 using mapped_container_type = MappedContainer;
 
 class value_compare
 {
 private:
 key_compare comp; // exposition only
 value_compare(key_compare c)
 : comp(c)
 {
 } // exposition only
 
 public:
 bool operator()(const_reference x, const_reference y) const
 {
 return comp(x.first, y.first);
 }
 };
 
 struct containers
 {
 key_container_type keys;
 mapped_container_type values;
 };
 
 // constructors
 flat_map()
 : flat_map(key_compare())
 {
 }
 
 explicit flat_map(const key_compare& comp)
 : c()
 , compare(comp)
 {
 }
 
 flat_map(key_container_type key_cont,
 mapped_container_type mapped_cont,
 const key_compare& comp = key_compare());
 
 flat_map(sorted_unique_t,
 key_container_type key_cont,
 mapped_container_type mapped_cont,
 const key_compare& comp = key_compare());
 
 template<class InputIter>
 flat_map(InputIter first, InputIter last, const key_compare& comp = key_compare())
 : c()
 , compare(comp)
 {
 insert(first, last);
 }
 
 template<class InputIter>
 flat_map(sorted_unique_t s,
 InputIter first,
 InputIter last,
 const key_compare& comp = key_compare())
 : c()
 , compare(comp)
 {
 insert(s, first, last);
 }
 
 template<container-compatible-range <value_type> R>
 flat_map(from_range_t fr, R&& rg)
 : flat_map(fr, std::forward <R>(rg), key_compare())
 {
 }
 template<container-compatible-range <value_type> R>
 flat_map(from_range_t, R&& rg, const key_compare& comp)
 : flat_map(comp)
 {
 insert_range(std::forward <R>(rg));
 }
 
 flat_map(initializer_list<value_type> il, const key_compare& comp = key_compare())
 : flat_map(il.begin(), il.end(), comp)
 {
 }
 
 flat_map(sorted_unique_t s,
 initializer_list<value_type> il,
 const key_compare& comp = key_compare())
 : flat_map(s, il.begin(), il.end(), comp)
 {
 }
 
 // constructors with allocators
 
 template<class Alloc>
 explicit flat_map(const Alloc& a);
 template<class Alloc>
 flat_map(const key_compare& comp, const Alloc& a);
 template<class Alloc>
 flat_map(const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const Alloc& a);
 template<class Alloc>
 flat_map(const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const key_compare& comp,
 const Alloc& a);
 template<class Alloc>
 flat_map(sorted_unique_t,
 const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const Alloc& a);
 template<class Alloc>
 flat_map(sorted_unique_t,
 const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const key_compare& comp,
 const Alloc& a);
 template<class Alloc>
 flat_map(const flat_map&, const Alloc& a);
 template<class Alloc>
 flat_map(flat_map&&, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_map(InputIter first, InputIter last, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_map(InputIter first, InputIter last, const key_compare& comp, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_map(sorted_unique_t, InputIter first, InputIter last, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_map(sorted_unique_t,
 InputIter first,
 InputIter last,
 const key_compare& comp,
 const Alloc& a);
 template<container-compatible-range <value_type> R, class Alloc>
 flat_map(from_range_t, R&& rg, const Alloc& a);
 template<container-compatible-range <value_type> R, class Alloc>
 flat_map(from_range_t, R&& rg, const key_compare& comp, const Alloc& a);
 template<class Alloc>
 flat_map(initializer_list<value_type> il, const Alloc& a);
 template<class Alloc>
 flat_map(initializer_list<value_type> il, const key_compare& comp, const Alloc& a);
 template<class Alloc>
 flat_map(sorted_unique_t, initializer_list<value_type> il, const Alloc& a);
 template<class Alloc>
 flat_map(sorted_unique_t,
 initializer_list<value_type> il,
 const key_compare& comp,
 const Alloc& a);
 
 flat_map& operator=(initializer_list<value_type>);
 
 // iterators
 iterator begin() noexcept;
 const_iterator begin() const noexcept;
 iterator end() noexcept;
 const_iterator end() const noexcept;
 
 reverse_iterator rbegin() noexcept;
 const_reverse_iterator rbegin() const noexcept;
 reverse_iterator rend() noexcept;
 const_reverse_iterator rend() const noexcept;
 
 const_iterator cbegin() const noexcept;
 const_iterator cend() const noexcept;
 const_reverse_iterator crbegin() const noexcept;
 const_reverse_iterator crend() const noexcept;
 
 // capacity
 bool empty() const noexcept;
 size_type size() const noexcept;
 size_type max_size() const noexcept;
 
 // element access
 mapped_type& operator[](const key_type& x);
 mapped_type& operator[](key_type&& x);
 template<class K>
 mapped_type& operator[](K&& x);
 mapped_type& at(const key_type& x);
 const mapped_type& at(const key_type& x) const;
 template<class K>
 mapped_type& at(const K& x);
 template<class K>
 const mapped_type& at(const K& x) const;
 
 // modifiers
 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& x) { return emplace(x); }
 pair<iterator, bool> insert(value_type&& x) { return emplace(std::move(x)); }
 iterator insert(const_iterator position, const value_type& x)
 {
 return emplace_hint(position, x);
 }
 iterator insert(const_iterator position, value_type&& x)
 {
 return emplace_hint(position, std::move(x));
 }
 
 template<class P>
 pair<iterator, bool> insert(P&& x);
 template<class P>
 iterator insert(const_iterator position, P&&);
 template<class InputIter>
 void insert(InputIter first, InputIter last);
 template<class InputIter>
 void insert(sorted_unique_t, InputIter first, InputIter last);
 template<container-compatible-range <value_type> R>
 void insert_range(R&& rg);
 
 void insert(initializer_list<value_type> il) { insert(il.begin(), il.end()); }
 void insert(sorted_unique_t s, initializer_list<value_type> il)
 {
 insert(s, il.begin(), il.end());
 }
 
 containers extract() &&;
 void replace(key_container_type&& key_cont, mapped_container_type&& mapped_cont);
 
 template<class... Args>
 pair<iterator, bool> try_emplace(const key_type& k, Args&&... args);
 template<class... Args>
 pair<iterator, bool> try_emplace(key_type&& k, Args&&... args);
 template<class K, class... Args>
 pair<iterator, bool> try_emplace(K&& k, Args&&... args);
 template<class... Args>
 iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args);
 template<class... Args>
 iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args);
 template<class K, class... Args>
 iterator try_emplace(const_iterator hint, K&& k, Args&&... args);
 template<class M>
 pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj);
 template<class M>
 pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj);
 template<class K, class M>
 pair<iterator, bool> insert_or_assign(K&& k, M&& obj);
 template<class M>
 iterator insert_or_assign(const_iterator hint, const key_type& k, M&& obj);
 template<class M>
 iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj);
 template<class K, class M>
 iterator insert_or_assign(const_iterator hint, K&& k, M&& obj);
 
 iterator erase(iterator position);
 iterator erase(const_iterator position);
 size_type erase(const key_type& x);
 template<class K>
 size_type erase(K&& x);
 iterator erase(const_iterator first, const_iterator last);
 
 void swap(flat_map& y) noexcept;
 void clear() noexcept;
 
 // observers
 key_compare key_comp() const;
 value_compare value_comp() const;
 
 const key_container_type& keys() const noexcept { return c.keys; }
 const mapped_container_type& values() const noexcept { return c.values; }
 
 // map operations
 iterator find(const key_type& x);
 const_iterator find(const key_type& x) const;
 template<class K>
 iterator find(const K& x);
 template<class K>
 const_iterator find(const K& x) const;
 
 size_type count(const key_type& x) const;
 template<class K>
 size_type count(const K& x) const;
 
 bool contains(const key_type& x) const;
 template<class K>
 bool contains(const K& x) const;
 
 iterator lower_bound(const key_type& x);
 const_iterator lower_bound(const key_type& x) const;
 template<class K>
 iterator lower_bound(const K& x);
 template<class K>
 const_iterator lower_bound(const K& x) const;
 
 iterator upper_bound(const key_type& x);
 const_iterator upper_bound(const key_type& x) const;
 template<class K>
 iterator upper_bound(const K& x);
 template<class K>
 const_iterator upper_bound(const K& x) const;
 
 pair<iterator, iterator> equal_range(const key_type& x);
 pair<const_iterator, const_iterator> equal_range(const key_type& x) const;
 template<class K>
 pair<iterator, iterator> equal_range(const K& x);
 template<class K>
 pair<const_iterator, const_iterator> equal_range(const K& x) const;
 
 friend bool operator==(const flat_map& x, const flat_map& y);
 
 friend /*synth-three-way-result*/<value_type> operator<=>(const flat_map& x,
 const flat_map& y);
 
 friend void swap(flat_map& x, flat_map& y) noexcept { x.swap(y); }
 
 private:
 containers c; // exposition only
 key_compare compare; // exposition only
 
 struct key_equiv
 { // exposition only
 key_equiv(key_compare c)
 : comp(c)
 {
 }
 bool operator()(const_reference x, const_reference y) const
 {
 return !comp(x.first, y.first) && !comp(y.first, x.first);
 }
 key_compare comp;
 };
 };
 
 template<class KeyContainer,
 class MappedContainer,
 class Compare = less<typename KeyContainer::value_type>>
 flat_map(KeyContainer, MappedContainer, Compare = Compare())
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer, class MappedContainer, class Allocator>
 flat_map(KeyContainer, MappedContainer, Allocator)
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 less<typename KeyContainer::value_type>,
 KeyContainer,
 MappedContainer>;
 template<class KeyContainer, class MappedContainer, class Compare, class Allocator>
 flat_map(KeyContainer, MappedContainer, Compare, Allocator)
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer,
 class MappedContainer,
 class Compare = less<typename KeyContainer::value_type>>
 flat_map(sorted_unique_t, KeyContainer, MappedContainer, Compare = Compare())
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer, class MappedContainer, class Allocator>
 flat_map(sorted_unique_t, KeyContainer, MappedContainer, Allocator)
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 less<typename KeyContainer::value_type>,
 KeyContainer,
 MappedContainer>;
 template<class KeyContainer, class MappedContainer, class Compare, class Allocator>
 flat_map(sorted_unique_t, KeyContainer, MappedContainer, Compare, Allocator)
 -> flat_map<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class InputIter, class Compare = less</*iter-key-type*/<InputIter>>>
 flat_map(InputIter, InputIter, Compare = Compare())
 -> flat_map</*iter-key-type*/<InputIter>, /*iter-mapped-type*/<InputIter>, Compare>;
 
 template<class InputIter, class Compare = less</*iter-key-type*/<InputIter>>>
 flat_map(sorted_unique_t, InputIter, InputIter, Compare = Compare())
 -> flat_map</*iter-key-type*/<InputIter>, /*iter-mapped-type*/<InputIter>, Compare>;
 
 template<ranges::input_range R,
 class Compare = less</*range-key-type*/<R>>,
 class Allocator = allocator<byte>>
 flat_map(from_range_t, R&&, Compare = Compare(), Allocator = Allocator()) -> flat_map<
 /*range-key-type*/<R>,
 /*range-mapped-type*/<R>,
 Compare,
 vector</*range-key-type*/<R>, /*alloc-rebind*/<Allocator, /*range-key-type*/<R>>>,
 vector</*range-mapped-type*/<R>,
 /*alloc-rebind*/<Allocator, /*range-mapped-type*/<R>>>>;
 
 template<ranges::input_range R, class Allocator>
 flat_map(from_range_t, R&&, Allocator) -> flat_map<
 /*range-key-type*/<R>,
 /*range-mapped-type*/<R>,
 less</*range-key-type*/<R>>,
 vector</*range-key-type*/<R>, /*alloc-rebind*/<Allocator, /*range-key-type*/<R>>>,
 vector</*range-mapped-type*/<R>,
 /*alloc-rebind*/<Allocator, /*range-mapped-type*/<R>>>>;
 
 template<class Key, class T, class Compare = less<Key>>
 flat_map(initializer_list<pair<Key, T>>, Compare = Compare())
 -> flat_map<Key, T, Compare>;
 
 template<class Key, class T, class Compare = less<Key>>
 flat_map(sorted_unique_t, initializer_list<pair<Key, T>>, Compare = Compare())
 -> flat_map<Key, T, Compare>;
 
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Allocator>
 struct uses_allocator<flat_map<Key, T, Compare, KeyContainer, MappedContainer>,
 Allocator>
 : bool_constant<uses_allocator_v<KeyContainer, Allocator> &&
 uses_allocator_v<MappedContainer, Allocator>>
 {};
}

namespace std {
 template<class Key,
 class T,
 class Compare = less<Key>,
 class KeyContainer = vector<Key>,
 class MappedContainer = vector<T>>
 class flat_multimap
 {
 public:
 // types
 using key_type = Key;
 using mapped_type = T;
 using value_type = pair<key_type, mapped_type>;
 using key_compare = Compare;
 using reference = pair<const key_type&, mapped_type&>;
 using const_reference = pair<const key_type&, const mapped_type&>;
 using size_type = size_t;
 using difference_type = ptrdiff_t;
 using iterator = /* implementation-defined */;
 using const_iterator = /* implementation-defined */;
 using reverse_iterator = std::reverse_iterator <iterator>;
 using const_reverse_iterator = std::reverse_iterator <const_iterator>;
 using key_container_type = KeyContainer;
 using mapped_container_type = MappedContainer;
 
 class value_compare
 {
 private:
 key_compare comp; // exposition only
 value_compare(key_compare c)
 : comp(c)
 {
 } // exposition only
 
 public:
 bool operator()(const_reference x, const_reference y) const
 {
 return comp(x.first, y.first);
 }
 };
 
 struct containers
 {
 key_container_type keys;
 mapped_container_type values;
 };
 
 // constructors
 flat_multimap()
 : flat_multimap(key_compare())
 {
 }
 
 explicit flat_multimap(const key_compare& comp)
 : c()
 , compare(comp)
 {
 }
 
 flat_multimap(key_container_type key_cont,
 mapped_container_type mapped_cont,
 const key_compare& comp = key_compare());
 
 flat_multimap(sorted_equivalent_t,
 key_container_type key_cont,
 mapped_container_type mapped_cont,
 const key_compare& comp = key_compare());
 
 template<class InputIter>
 flat_multimap(InputIter first,
 InputIter last,
 const key_compare& comp = key_compare())
 : c()
 , compare(comp)
 {
 insert(first, last);
 }
 
 template<class InputIter>
 flat_multimap(sorted_equivalent_t s,
 InputIter first,
 InputIter last,
 const key_compare& comp = key_compare())
 : c()
 , compare(comp)
 {
 insert(s, first, last);
 }
 
 template<container-compatible-range <value_type> R>
 flat_multimap(from_range_t fr, R&& rg)
 : flat_multimap(fr, std::forward <R>(rg), key_compare())
 {
 }
 template<container-compatible-range <value_type> R>
 flat_multimap(from_range_t, R&& rg, const key_compare& comp)
 : flat_multimap(comp)
 {
 insert_range(std::forward <R>(rg));
 }
 
 flat_multimap(initializer_list<value_type> il,
 const key_compare& comp = key_compare())
 : flat_multimap(il.begin(), il.end(), comp)
 {
 }
 
 flat_multimap(sorted_equivalent_t s,
 initializer_list<value_type> il,
 const key_compare& comp = key_compare())
 : flat_multimap(s, il.begin(), il.end(), comp)
 {
 }
 
 // constructors with allocators
 
 template<class Alloc>
 explicit flat_multimap(const Alloc& a);
 template<class Alloc>
 flat_multimap(const key_compare& comp, const Alloc& a);
 template<class Alloc>
 flat_multimap(const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const Alloc& a);
 template<class Alloc>
 flat_multimap(const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const key_compare& comp,
 const Alloc& a);
 template<class Alloc>
 flat_multimap(sorted_equivalent_t,
 const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const Alloc& a);
 template<class Alloc>
 flat_multimap(sorted_equivalent_t,
 const key_container_type& key_cont,
 const mapped_container_type& mapped_cont,
 const key_compare& comp,
 const Alloc& a);
 template<class Alloc>
 flat_multimap(const flat_multimap&, const Alloc& a);
 template<class Alloc>
 flat_multimap(flat_multimap&&, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_multimap(InputIter first, InputIter last, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_multimap(InputIter first,
 InputIter last,
 const key_compare& comp,
 const Alloc& a);
 template<class InputIter, class Alloc>
 flat_multimap(sorted_equivalent_t, InputIter first, InputIter last, const Alloc& a);
 template<class InputIter, class Alloc>
 flat_multimap(sorted_equivalent_t,
 InputIter first,
 InputIter last,
 const key_compare& comp,
 const Alloc& a);
 template<container-compatible-range <value_type> R, class Alloc>
 flat_multimap(from_range_t, R&& rg, const Alloc& a);
 template<container-compatible-range <value_type> R, class Alloc>
 flat_multimap(from_range_t, R&& rg, const key_compare& comp, const Alloc& a);
 template<class Alloc>
 flat_multimap(initializer_list<value_type> il, const Alloc& a);
 template<class Alloc>
 flat_multimap(initializer_list<value_type> il,
 const key_compare& comp,
 const Alloc& a);
 template<class Alloc>
 flat_multimap(sorted_equivalent_t, initializer_list<value_type> il, const Alloc& a);
 template<class Alloc>
 flat_multimap(sorted_equivalent_t,
 initializer_list<value_type> il,
 const key_compare& comp,
 const Alloc& a);
 
 flat_multimap& operator=(initializer_list<value_type>);
 
 // iterators
 iterator begin() noexcept;
 const_iterator begin() const noexcept;
 iterator end() noexcept;
 const_iterator end() const noexcept;
 
 reverse_iterator rbegin() noexcept;
 const_reverse_iterator rbegin() const noexcept;
 reverse_iterator rend() noexcept;
 const_reverse_iterator rend() const noexcept;
 
 const_iterator cbegin() const noexcept;
 const_iterator cend() const noexcept;
 const_reverse_iterator crbegin() const noexcept;
 const_reverse_iterator crend() const noexcept;
 
 // capacity
 bool empty() const noexcept;
 size_type size() const noexcept;
 size_type max_size() const noexcept;
 
 // modifiers
 template<class... Args>
 iterator emplace(Args&&... args);
 template<class... Args>
 iterator emplace_hint(const_iterator position, Args&&... args);
 
 iterator insert(const value_type& x) { return emplace(x); }
 iterator insert(value_type&& x) { return emplace(std::move(x)); }
 iterator insert(const_iterator position, const value_type& x)
 {
 return emplace_hint(position, x);
 }
 iterator insert(const_iterator position, value_type&& x)
 {
 return emplace_hint(position, std::move(x));
 }
 
 template<class P>
 iterator insert(P&& x);
 template<class P>
 iterator insert(const_iterator position, P&&);
 template<class InputIter>
 void insert(InputIter first, InputIter last);
 template<class InputIter>
 void insert(sorted_equivalent_t, InputIter first, InputIter last);
 template<container-compatible-range <value_type> R>
 void insert_range(R&& rg);
 
 void insert(initializer_list<value_type> il) { insert(il.begin(), il.end()); }
 void insert(sorted_equivalent_t s, initializer_list<value_type> il)
 {
 insert(s, il.begin(), il.end());
 }
 
 containers extract() &&;
 void replace(key_container_type&& key_cont, mapped_container_type&& mapped_cont);
 
 iterator erase(iterator position);
 iterator erase(const_iterator position);
 size_type erase(const key_type& x);
 template<class K>
 size_type erase(K&& x);
 iterator erase(const_iterator first, const_iterator last);
 
 void swap(flat_multimap&) noexcept;
 void clear() noexcept;
 
 // observers
 key_compare key_comp() const;
 value_compare value_comp() const;
 
 const key_container_type& keys() const noexcept { return c.keys; }
 const mapped_container_type& values() const noexcept { return c.values; }
 
 // map operations
 iterator find(const key_type& x);
 const_iterator find(const key_type& x) const;
 template<class K>
 iterator find(const K& x);
 template<class K>
 const_iterator find(const K& x) const;
 
 size_type count(const key_type& x) const;
 template<class K>
 size_type count(const K& x) const;
 
 bool contains(const key_type& x) const;
 template<class K>
 bool contains(const K& x) const;
 
 iterator lower_bound(const key_type& x);
 const_iterator lower_bound(const key_type& x) const;
 template<class K>
 iterator lower_bound(const K& x);
 template<class K>
 const_iterator lower_bound(const K& x) const;
 
 iterator upper_bound(const key_type& x);
 const_iterator upper_bound(const key_type& x) const;
 template<class K>
 iterator upper_bound(const K& x);
 template<class K>
 const_iterator upper_bound(const K& x) const;
 
 pair<iterator, iterator> equal_range(const key_type& x);
 pair<const_iterator, const_iterator> equal_range(const key_type& x) const;
 template<class K>
 pair<iterator, iterator> equal_range(const K& x);
 template<class K>
 pair<const_iterator, const_iterator> equal_range(const K& x) const;
 
 friend bool operator==(const flat_multimap& x, const flat_multimap& y);
 
 friend /*synth-three-way-result*/<value_type> operator<=>(const flat_multimap& x,
 const flat_multimap& y);
 
 friend void swap(flat_multimap& x, flat_multimap& y) noexcept { x.swap(y); }
 
 private:
 containers c; // exposition only
 key_compare compare; // exposition only
 };
 
 template<class KeyContainer,
 class MappedContainer,
 class Compare = less<typename KeyContainer::value_type>>
 flat_multimap(KeyContainer, MappedContainer, Compare = Compare())
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer, class MappedContainer, class Allocator>
 flat_multimap(KeyContainer, MappedContainer, Allocator)
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 less<typename KeyContainer::value_type>,
 KeyContainer,
 MappedContainer>;
 template<class KeyContainer, class MappedContainer, class Compare, class Allocator>
 flat_multimap(KeyContainer, MappedContainer, Compare, Allocator)
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer,
 class MappedContainer,
 class Compare = less<typename KeyContainer::value_type>>
 flat_multimap(sorted_equivalent_t, KeyContainer, MappedContainer, Compare = Compare())
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class KeyContainer, class MappedContainer, class Allocator>
 flat_multimap(sorted_equivalent_t, KeyContainer, MappedContainer, Allocator)
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 less<typename KeyContainer::value_type>,
 KeyContainer,
 MappedContainer>;
 template<class KeyContainer, class MappedContainer, class Compare, class Allocator>
 flat_multimap(sorted_equivalent_t, KeyContainer, MappedContainer, Compare, Allocator)
 -> flat_multimap<typename KeyContainer::value_type,
 typename MappedContainer::value_type,
 Compare,
 KeyContainer,
 MappedContainer>;
 
 template<class InputIter, class Compare = less</*iter-key-type*/<InputIter>>>
 flat_multimap(InputIter, InputIter, Compare = Compare())
 -> flat_multimap</*iter-key-type*/<InputIter>,
 /*iter-mapped-type*/<InputIter>,
 Compare>;
 
 template<class InputIter, class Compare = less</*iter-key-type*/<InputIter>>>
 flat_multimap(sorted_equivalent_t, InputIter, InputIter, Compare = Compare())
 -> flat_multimap</*iter-key-type*/<InputIter>,
 /*iter-mapped-type*/<InputIter>,
 Compare>;
 
 template<ranges::input_range R,
 class Compare = less</*range-key-type*/<R>>,
 class Allocator = allocator<byte>>
 flat_multimap(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
 -> flat_multimap<
 /*range-key-type*/<R>,
 /*range-mapped-type*/<R>,
 Compare,
 vector</*range-key-type*/<R>, /*alloc-rebind*/<Allocator, /*range-key-type*/<R>>>,
 vector</*range-mapped-type*/<R>,
 /*alloc-rebind*/<Allocator, /*range-mapped-type*/<R>>>>;
 
 template<ranges::input_range R, class Allocator>
 flat_multimap(from_range_t, R&&, Allocator) -> flat_multimap<
 /*range-key-type*/<R>,
 /*range-mapped-type*/<R>,
 less</*range-key-type*/<R>>,
 vector</*range-key-type*/<R>, /*alloc-rebind*/<Allocator, /*range-key-type*/<R>>>,
 vector</*range-mapped-type*/<R>,
 /*alloc-rebind*/<Allocator, /*range-mapped-type*/<R>>>>;
 
 template<class Key, class T, class Compare = less<Key>>
 flat_multimap(initializer_list<pair<Key, T>>, Compare = Compare())
 -> flat_multimap<Key, T, Compare>;
 
 template<class Key, class T, class Compare = less<Key>>
 flat_multimap(sorted_equivalent_t, initializer_list<pair<Key, T>>, Compare = Compare())
 -> flat_multimap<Key, T, Compare>;
 
 template<class Key,
 class T,
 class Compare,
 class KeyContainer,
 class MappedContainer,
 class Allocator>
 struct uses_allocator<flat_multimap<Key, T, Compare, KeyContainer, MappedContainer>,
 Allocator>
 : bool_constant<uses_allocator_v<KeyContainer, Allocator> &&
 uses_allocator_v<MappedContainer, Allocator>>
 {};
}