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deductiongu...iority_queue(3)  C++ Standard Libary deductiongu...iority_queue(3)

NAME
     deductionguidesforstd::priority_queue    -    deductionguidesforstd::prior-
     ity_queue

Synopsis
	Defined in header <queue>
	template< class Comp, class Container >

	priority_queue( Comp, Container  )				     (1)
     (since C++17)

	    -> priority_queue<typename Container::value_type, Container,
	Comp>;
	template< class InputIt,

		  class Comp = std::less</*iter-value-type*/<InputIt>>,
		  class Container =
	std::vector</*iter-value-type*/<InputIt>  >			     (2)
     (since C++17)
	priority_queue( InputIt, InputIt, Comp = Comp(), Container =
	Container() )

	    -> priority_queue</*iter-value-type*/<InputIt>, Container,
	Comp>;
	template< class Comp, class Container, class Alloc >

	priority_queue( Comp, Container, Alloc	)			     (3)
     (since C++17)

	    -> priority_queue<typename Container::value_type, Container,
	Comp>;
	template< class InputIt, class Alloc >

	priority_queue( InputIt, InputIt, Alloc )
	    ->	priority_queue</*iter-value-type*/<InputIt>,		     (4)
     (since C++17)
			      std::vector</*iter-value-type*/<InputIt>,
	Alloc>,

			      std::less</*iter-value-type*/<InputIt>>>;
	template< class InputIt, class Comp, class Alloc >

	priority_queue( InputIt, InputIt, Comp, Alloc )
	    ->	priority_queue</*iter-value-type*/<InputIt>,		     (5)
     (since C++17)

			      std::vector</*iter-value-type*/<InputIt>,
	Alloc>, Comp>;
	template< class InputIt, class Comp, class Container, class Alloc
	>

	priority_queue(  InputIt,  InputIt, Comp, Container, Alloc )	     (6)
     (since C++17)

	    -> priority_queue<typename Container::value_type, Container,
	Comp>;
	template< ranges::input_range R,

		  class Comp = std::less<ranges::range_value_t<R>> >
	priority_queue( std::from_range_t, R&&, Comp = Comp()  )	     (7)
     (since C++23)
	    -> priority_queue<ranges::range_value_t<R>,

			      std::vector<ranges::range_value_t<R>>,
	Comp>;
	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>,		     (8)
     (since C++23)

			      std::vector<ranges::range_value_t<R>,
	Alloc>, Comp>;
	template< ranges::input_range R, class Alloc >

	priority_queue( std::from_range_t, R&&, Alloc )
	    ->	priority_queue<ranges::range_value_t<R>,		     (9)
     (since C++23)

			      std::vector<ranges::range_value_t<R>,
	Alloc>>;

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

	1-6) Allow deduction from underlying container type and from an iterator
     range.
	/*iter-value-type*/<It>        denotes	      typename	     std::itera-
     tor_traits<It>::value_type for
	any type It.
	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()
      {
	  const std::vector<int> v = {1, 2, 3, 4};
	  std::priority_queue  pq1{std::greater<int>{}, v}; // deduces std::pri-
     ority_queue<
							   //	  int, std::vec-
     tor<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::prior-
     ity_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 retroac-
     tively to
	previously published C++ standards.

	   DR	 Applied to		 Behavior as published		    Cor-
     rect behavior
	LWG  3506  C++17       deduction  guides  from	iterator  and  allocator
     added
			    were missing

http://cppreference.com 	   2024.06.10	   deductiongu...iority_queue(3)
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