deduction guides for std::priority_queue

 

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Technical Specifications

 

Containers library

array (C++11)

vector

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list

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std::priority_queue

Member functions

priority_queue::priority_queue

priority_queue::~priority_queue

priority_queue::operator=

Element access

priority_queue::top

Capacity

priority_queue::empty

priority_queue::size

Modifiers

priority_queue::push

priority_queue::emplace

priority_queue::pop

priority_queue::swap

Deduction guides(C++17)

 

Defined in header <queue>
template <class Compare, class Container> priority_queue(Compare, Container)  -> priority_queue<typename Container::value_type, Container, Compare>;	(1)	(since C++17)
template<class InputIt,          class Comp = std::less<typename std::iterator_traits<InputIt>::value_type>,          class Container = std::vector<typename iterator_traits<InputIt>::value_type>> priority_queue(InputIt, InputIt, Comp = Comp(), Container = Container())   -> priority_queue<typename std::iterator_traits<InputIt>::value_type, Container, Comp>;	(2)	(since C++17)
template<class Comp, class Container, class Alloc> priority_queue(Comp, Container, Alloc)   -> priority_queue<typename Container::value_type, Container, Comp>;	(2)	(since C++17)

These deduction guides are provided for std::priority_queue to allow deduction from underlying container type (overloads (1,3)) and from an iterator range (overload (2)) This overload only participates in overload resolution if InputIt satisfies LegacyInputIterator, Alloc satisfies Allocator, Comp does not satisfy Allocator, Container does not satisfy Allocator and, for overload (3), if std::uses_allocator_v<Container, Alloc> is true

Note: the extent to which the library determines that a type does not satisfy LegacyInputIterator is unspecified, except that as a minimum integral types do not qualify as input iterators. Likewise, the extent to which it determines that a type does not satisfy Allocator is unspecified, except that as a minimum the member type Alloc::value_type must exist and the expression std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as an unevaluated operand.

Example

Run this code

#include <vector>
#include <queue>
int main() {
   std::vector<int> v = {1,2,3,4};
   std::priority_queue pq1{v};                  // deduces std::priority_queue<int>
   std::priority_queue pq2{v.begin(), v.end()}; // deduces std::priority_queue<int>
}