std::priority_queue<T,Container,Compare>::swap
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Tables
std::priority_queue void swap( priority_queue& other ) noexcept(/* see below */);
(since C++11)
other. Effectively calls using std::swap ; swap(c, other.c); swap(comp, other.comp);
Contents
[edit] Parameters
other
-
container adaptor to exchange the contents with
[edit] Return value
(none)
[edit] Exceptions
noexcept specification:
noexcept(noexcept(swap(c, other.c)) && noexcept(swap(comp, other.comp)))
In the expression above, the identifier swap is looked up in the same manner as the one used by the C++17 std::is_nothrow_swappable trait.
(until C++17)
noexcept specification:
(since C++17)noexcept(std::is_nothrow_swappable_v <Container> &&
std::is_nothrow_swappable_v <Compare>)
std::is_nothrow_swappable_v <Compare>)
[edit] Complexity
Same as underlying container (typically constant).
Notes
Some implementations (e.g. libc++) provide the swap member function as an extension to pre-C++11 modes.
[edit] Example
Run this code
#include <iostream> #include <concepts> #include <functional> #include <queue> #include <string> #include <string_view> #include <vector> template<typename Adaptor> requires (std::ranges::input_range <typename Adaptor::container_type>) void print(std::string_view name, const Adaptor& adaptor) { struct Printer : Adaptor // to use protected Adaptor::Container c; { void print(std::string_view name) const { std::cout << name << " [" << std::size (this->c) << "]: "; for (auto const& elem : this->c) std::cout << elem << ' '; std::cout << '\n'; } }; static_cast<Printer const&>(adaptor).print(name); } int main() { std::vector <std::string > v1{"1","2","3","4"}, v2{"Ɐ","B","Ɔ","D","Ǝ"}; std::priority_queue s1(std::less <>(), std::move(v1)); std::priority_queue s2(std::less <>(), std::move(v2)); print("s1", s1); print("s2", s2); s1.swap(s2); print("s1", s1); print("s2", s2); }
Output:
s1 [4]: 4 3 2 1 s2 [5]: Ǝ D Ɔ B Ɐ s1 [5]: Ǝ D Ɔ B Ɐ s2 [4]: 4 3 2 1
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2456 | C++11 | the noexcept specification is ill-formed
|
made to work |