std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::insert_range
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Tables
std::flat_map
flat_map::insert_range
template< container-compatible-range <value_type> R >
void insert_range( R&& rg );
(since C++23) void insert_range( R&& rg );
(constexpr since C++26)
Inserts a copy of each element in the range rg into underlying containers 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); }
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. 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 = std::distance (zv.begin(), it); c.keys.erase(c.keys.begin() + dist, c.keys.end()); c.values.erase(c.values.begin() + dist, c.values.end());
Each iterator in the range rg is dereferenced exactly once.
If any of the following conditions is satisfied, the behavior is undefined:
-
value_typeis not EmplaceConstructible intoflat_mapfrom *ranges::begin (rg) - rg and *this overlap.
Information on iterator invalidation is copied from here
Contents
[edit] Parameters
[edit] Complexity
\(\scriptsize S + N \cdot \log(N)\)S+N·log(N), where \(\scriptsize S\)S is size() and \(\scriptsize N\)N is ranges::distance (rg).
[edit] Notes
Since insert_range performs an in-place merge operation, that may allocate memory.
[edit] Example
Run this code
#include <iostream> #include <flat_map> #include <utility> void println(auto, const auto& container) { for (const auto& [key, value] : container) std::cout << '{' << key << ',' << value << '}' << ' '; std::cout << '\n'; } int main() { auto container = std::flat_map {std::pair {1, 11}, {3, 33}, {2, 22}, {4, 44}}; const auto rg = {std::pair {-1, -11}, {3, -33}, {-2, -22}}; #ifdef __cpp_lib_containers_ranges container.insert_range(rg); #else container.insert(rg.begin(), rg.end()); #endif println("{}", container); }
Output:
{-2,-22} {-1,-11} {1,11} {2,22} {3,33} {4,44}