23 Containers library [containers]

23.6 Container adaptors [container.adaptors]

23.6.8 Class template flat_map [flat.map]

23.6.8.7 Modifiers [flat.map.modifiers]

template<class... Args> pair<iterator, bool> emplace(Args&&... args);

Constraints: is_constructible_v<pair<key_type, mapped_type>, Args...> is true.

Effects: Initializes an object t of type pair<key_type, mapped_type> with std::forward<Args>(args)...; if the map already contains an element whose key is equivalent to t.first, *this is unchanged.

Otherwise, equivalent to: auto key_it = ranges::upper_bound(c.keys, t.first, compare); auto value_it = c.values.begin() + distance(c.keys.begin(), key_it); c.keys.insert(key_it, std::move(t.first)); c.values.insert(value_it, std::move(t.second));

Returns: The bool component of the returned pair is true if and only if the insertion took place, and the iterator component of the pair points to the element with key equivalent to t.first.

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template<class P> pair<iterator, bool> insert(P&& x);
template<class P> iterator insert(const_iterator position, P&& x);

Constraints: is_constructible_v<pair<key_type, mapped_type>, P> is true.

Effects: The first form is equivalent to return emplace(std::forward<P>(x));.

The second form is equivalent to return emplace_hint(position, std::forward<P>(x));.

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template<class InputIterator>
  void insert(InputIterator first, InputIterator last);

Effects: Adds elements to c as if by: for (; first != last; ++first) { value_type value = *first; c.keys.insert(c.keys.end(), std::move(value.first)); c.values.insert(c.values.end(), std::move(value.second)); }

Then, sorts the range of newly inserted elements with respect to value_comp(); merges the resulting sorted range and the sorted range of pre-existing elements into a single sorted range; and finally erases the duplicate elements as if by: auto zv = views::zip(c.keys, c.values); auto it = ranges::unique(zv, key_equiv(compare)).begin(); auto dist = distance(zv.begin(), it); c.keys.erase(c.keys.begin() + dist, c.keys.end()); c.values.erase(c.values.begin() + dist, c.values.end());

Complexity: N +

M log M

, where N is size() before the operation and M is distance(first, last).

Remarks: Since this operation performs an in-place merge, it may allocate memory.

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template<class InputIterator>
  void insert(sorted_unique_t, InputIterator first, InputIterator last);

Then, merges the sorted range of newly added elements and the sorted range of pre-existing elements into a single sorted range; and finally erases the duplicate elements as if by: auto zv = views::zip(c.keys, c.values); auto it = ranges::unique(zv, key_equiv(compare)).begin(); auto dist = distance(zv.begin(), it); c.keys.erase(c.keys.begin() + dist, c.keys.end()); c.values.erase(c.values.begin() + dist, c.values.end());

Complexity: Linear in N, where N is size() after the operation.

Remarks: Since this operation performs an in-place merge, it may allocate memory.

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template<container-compatible-range<value_type> R>
  void insert_range(R&& rg);

Effects: Adds elements to c as if by: for (const auto& e : rg) { c.keys.insert(c.keys.end(), e.first); c.values.insert(c.values.end(), e.second); }

Complexity: N +

M log M

, where N is size() before the operation and M is ranges::distance(rg).

Remarks: Since this operation performs an in-place merge, it may allocate memory.

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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... 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);

Constraints: is_constructible_v<mapped_type, Args...> is true.

Effects: If the map already contains an element whose key is equivalent to k, *this and args... are unchanged.

Otherwise equivalent to: auto key_it = ranges::upper_bound(c.keys, k, compare); auto value_it = c.values.begin() + distance(c.keys.begin(), key_it); c.keys.insert(key_it, std::forward<decltype(k)>(k)); c.values.emplace(value_it, std::forward<Args>(args)...);

Returns: In the first two overloads, the bool component of the returned pair is true if and only if the insertion took place.

The returned iterator points to the map element whose key is equivalent to k.

Complexity: The same as emplace for the first two overloads, and the same as emplace_hint for the last two overloads.

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template<class K, class... Args>
  pair<iterator, bool> try_emplace(K&& k, Args&&... args);
template<class K, class... Args>
  iterator try_emplace(const_iterator hint, K&& k, Args&&... args);

Constraints:

(19.1)
The qualified-id Compare::is_transparent is valid and denotes a type.
(19.2)
is_constructible_v<key_type, K> is true.
(19.3)
is_constructible_v<mapped_type, Args...> is true.
(19.4)
For the first overload, is_convertible_v<K&&, const_iterator> and is_convertible_v<K&&, iterator> are both false.

Preconditions: The conversion from k into key_type constructs an object u, for which find(k) == find(u) is true.

Effects: If the map already contains an element whose key is equivalent to k, *this and args... are unchanged.

Otherwise equivalent to: auto key_it = ranges::upper_bound(c.keys, k, compare); auto value_it = c.values.begin() + distance(c.keys.begin(), key_it); c.keys.emplace(key_it, std::forward<K>(k)); c.values.emplace(value_it, std::forward<Args>(args)...);

Returns: In the first overload, the bool component of the returned pair is true if and only if the insertion took place.

The returned iterator points to the map element whose key is equivalent to k.

Complexity: The same as emplace and emplace_hint, respectively.

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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 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);

Constraints: is_assignable_v<mapped_type&, M> is true and is_constructible_v<mapped_type, M> is true.

Effects: If the map already contains an element e whose key is equivalent to k, assigns std::forward<M>(obj) to e.second.

Otherwise, equivalent to try_emplace(std::forward<decltype(k)>(k), std::forward<M>(obj)) for the first two overloads or try_emplace(hint, std::forward<decltype(k)>(k), std::forward<M>(obj)) for the last two overloads.

Returns: In the first two overloads, the bool component of the returned pair is true if and only if the insertion took place.

The returned iterator points to the map element whose key is equivalent to k.

Complexity: The same as emplace for the first two overloads and the same as emplace_hint for the last two overloads.

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template<class K, class M>
  pair<iterator, bool> insert_or_assign(K&& k, M&& obj);
template<class K, class M>
  iterator insert_or_assign(const_iterator hint, K&& k, M&& obj);

Constraints:

(28.1)
The qualified-id Compare::is_transparent is valid and denotes a type.
(28.2)
is_constructible_v<key_type, K> is true.
(28.3)
is_assignable_v<mapped_type&, M> is true.
(28.4)
is_constructible_v<mapped_type, M> is true.

Preconditions: The conversion from k into key_type constructs an object u, for which find(k) == find(u) is true.

Effects: If the map already contains an element e whose key is equivalent to k, assigns std::forward<M>(obj) to e.second.

Otherwise, equivalent to try_emplace(std::forward<K>(k), std::forward<M>(obj)) for the first overload or try_emplace(hint, std::forward<K>(k), std::forward<M>(obj)) for the second overload.

Returns: In the first overload, the bool component of the returned pair is true if and only if the insertion took place.

The returned iterator points to the map element whose key is equivalent to k.

Complexity: The same as emplace and emplace_hint, respectively.

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void swap(flat_map& y) noexcept;

Effects: Equivalent to: ranges::swap(compare, y.compare); ranges::swap(c.keys, y.c.keys); ranges::swap(c.values, y.c.values);

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containers extract() &&;

Postconditions: *this is emptied, even if the function exits via an exception.

Returns: std::move(c).

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void replace(key_container_type&& key_cont, mapped_container_type&& mapped_cont);

Preconditions: key_cont.size() == mapped_cont.size() is true, the elements of key_cont are sorted with respect to compare, and key_cont contains no equal elements.

Effects: Equivalent to: c.keys = std::move(key_cont); c.values = std::move(mapped_cont);