deduction guides for std::priority_queue

 

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priority_queue

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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::push_range (C++23)

priority_queue::emplace (C++11)

priority_queue::pop

priority_queue::swap (C++11)

Non-member functions

swap(std::priority_queue) (C++11)

Helper classes

uses_allocator<std::priority_queue> (C++11)

formatter<std::priority_queue> (C++23)

Deduction guides(C++17)

 

Defined in header <queue>
template<class Comp, class Container > priority_queue( Comp, Container )     -> priority_queue<typename Container::value_type, Container, Comp>;	(1)	(since C++17)
template<class InputIt,           class Comp =std::less</*iter-val-t*/<InputIt>>,           class Container =std::vector</*iter-val-t*/<InputIt>> priority_queue( InputIt, InputIt, Comp = Comp(), Container = Container())     -> priority_queue</*iter-val-t*/<InputIt>, 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>;	(3)	(since C++17)
template<class InputIt, class Alloc > priority_queue( InputIt, InputIt, Alloc )     -> priority_queue</*iter-val-t*/<InputIt>,                       std::vector</*iter-val-t*/<InputIt>, Alloc>,                       std::less</*iter-val-t*/<InputIt>>>;	(4)	(since C++17)
template<class InputIt, class Comp, class Alloc > priority_queue( InputIt, InputIt, Comp, Alloc )     -> priority_queue</*iter-val-t*/<InputIt>,                       std::vector</*iter-val-t*/<InputIt>, Alloc>, Comp>;	(5)	(since C++17)
template<class InputIt, class Comp, class Container, class Alloc > priority_queue( InputIt, InputIt, Comp, Container, Alloc )     -> priority_queue<typename Container::value_type, Container, Comp>;	(6)	(since C++17)
template<ranges::input_range R,           class Comp =std::less<ranges::range_value_t<R>>> priority_queue(std::from_range_t, R&&, Comp = Comp())     -> priority_queue<ranges::range_value_t<R>,                       std::vector<ranges::range_value_t<R>>, Comp>;	(7)	(since C++23)
template<ranges::input_range R, class Comp, class Alloc > priority_queue(std::from_range_t, R&&, Comp, Alloc )     -> priority_queue<ranges::range_value_t<R>,                       std::vector<ranges::range_value_t<R>, Alloc>, Comp>;	(8)	(since C++23)
template<ranges::input_range R, class Alloc > priority_queue(std::from_range_t, R&&, Alloc )     -> priority_queue<ranges::range_value_t<R>,                       std::vector<ranges::range_value_t<R>, Alloc>>;	(9)	(since C++23)
Exposition-only helper type aliases
template<class InputIt > using/*iter-val-t*/=     typenamestd::iterator_traits<InputIt>::value_type;		(exposition only*)

The following deduction guides are provided for std::priority_queue:

1-6) Allow deduction from underlying container type and from an iterator range.

7-9) Allow deduction from a std::from_range_t tag and an input_range.

These overloads participate in overload resolution only if

• InputIt satisfies LegacyInputIterator,
• Comp does not satisfy Allocator,
• Container does not satisfy Allocator,
• for overloads (4,5),(since C++23)Alloc satisfies Allocator, and
• for overloads (3,6), 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.

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_containers_ranges	202202L	(C++23)	Ranges-aware construction and insertion; overloads (7-9)

Example

Run this code

#include <functional>#include <iostream>#include <queue>#include <vector>   int main(){conststd::vector<int> v ={1, 2, 3, 4};std::priority_queue pq1{std::greater<int>{}, v};// deduces std::priority_queue<// int, std::vector<int>,// std::greater<int>>for(;!pq1.empty(); pq1.pop())std::cout<< pq1.top()<<' ';std::cout<<'\n';   std::priority_queue pq2{v.begin(), v.end()};// deduces std::priority_queue<int>   for(;!pq2.empty(); pq2.pop())std::cout<< pq2.top()<<' ';std::cout<<'\n';}

Output:

1 2 3 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 3506	C++17	deduction guides from iterator and allocator were missing	added, (4-6)