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Section: 24.6.7 [priority.queue] Status: WP Submitter: Tim Song Opened: 2020-11-21 Last modified: 2021-06-07
Priority: 3
View all other issues in [priority.queue].
View all issues with WP status.
Discussion:
priority_queue has two constructor templates taking a pair of input iterators in addition to a comparator and a container, but it does not have allocator-extended constructors corresponding to these constructor templates:
template<class InputIterator>
priority_queue(InputIterator first, InputIterator last, const Compare& x,
const Container&);
template<class InputIterator>
priority_queue(InputIterator first, InputIterator last,
const Compare& x = Compare(), Container&& = Container());
[2020-11-29; Reflector prioritization]
Set priority to 3 during reflector discussions. It has been pointed out that this issue is related to LWG 1199, LWG 2210, and LWG 2713.
[2021-02-17 Tim adds PR]
[2021-02-26; LWG telecon]
Set status to Tentatively Ready after discussion and poll.
| F | A | N |
|---|---|---|
| 11 | 0 | 0 |
[2021-06-07 Approved at June 2021 virtual plenary. Status changed: Voting → WP.]
Proposed resolution:
This wording is relative to N4878.
Add the following paragraph at the end of 24.6.1 [container.adaptors.general]:
-6- The exposition-only alias template iter-value-type defined in 24.3.1 [sequences.general] may appear in deduction guides for container adaptors.
Modify 24.6.7 [priority.queue], class template priority_queue synopsis, as indicated:
namespace std {
template<class T, class Container = vector<T>,
class Compare = less<typename Container::value_type>>
class priority_queue {
// […]
public:
priority_queue() : priority_queue(Compare()) {}
explicit priority_queue(const Compare& x) : priority_queue(x, Container()) {}
priority_queue(const Compare& x, const Container&);
priority_queue(const Compare& x, Container&&);
template<class InputIterator>
priority_queue(InputIterator first, InputIterator last, const Compare& x,
const Container&);
template<class InputIterator>
priority_queue(InputIterator first, InputIterator last,
const Compare& x = Compare(), Container&& = Container());
template<class Alloc> explicit priority_queue(const Alloc&);
template<class Alloc> priority_queue(const Compare&, const Alloc&);
template<class Alloc> priority_queue(const Compare&, const Container&, const Alloc&);
template<class Alloc> priority_queue(const Compare&, Container&&, const Alloc&);
template<class Alloc> priority_queue(const priority_queue&, const Alloc&);
template<class Alloc> priority_queue(priority_queue&&, const Alloc&);
template<class InputIterator, class Alloc>
priority_queue(InputIterator, InputIterator, const Alloc&);
template<class InputIterator, class Alloc>
priority_queue(InputIterator, InputIterator, const Compare&, const Alloc&);
template<class InputIterator, class Alloc>
priority_queue(InputIterator, InputIterator, const Compare&, const Container&, const Alloc&);
template<class InputIterator, class Alloc>
priority_queue(InputIterator, InputIterator, const Compare&, Container&&, const Alloc&);
// […]
};
template<class Compare, class Container>
priority_queue(Compare, Container)
-> priority_queue<typename Container::value_type, Container, Compare>;
template<class InputIterator,
class Compare = less<typename iterator_traitsiter-value-type<InputIterator>::value_type>,
class Container = vector<typename iterator_traitsiter-value-type<InputIterator>::value_type>>
priority_queue(InputIterator, InputIterator, Compare = Compare(), Container = Container())
-> priority_queue<typename iterator_traitsiter-value-type<InputIterator>::value_type, Container, Compare>;
template<class Compare, class Container, class Allocator>
priority_queue(Compare, Container, Allocator)
-> priority_queue<typename Container::value_type, Container, Compare>;
template<class InputIterator, class Allocator>
priority_queue(InputIterator, InputIterator, Allocator)
-> priority_queue<iter-value-type<InputIterator>,
vector<iter-value-type<InputIterator>, Allocator>,
less<iter-value-type<InputIterator>>>;
template<class InputIterator, class Compare, class Allocator>
priority_queue(InputIterator, InputIterator, Compare, Allocator)
-> priority_queue<iter-value-type<InputIterator>,
vector<iter-value-type<InputIterator>, Allocator>, Compare>;
template<class InputIterator, class Compare, class Container, class Allocator>
priority_queue(InputIterator, InputIterator, Compare, Container, Allocator)
-> priority_queue<typename Container::value_type, Container, Compare>;
// […]
}
Add the following paragraphs to 24.6.7.3 [priqueue.cons.alloc]:
template<class InputIterator, class Alloc> priority_queue(InputIterator first, InputIterator last, const Alloc& a);-?- Effects: Initializes c with first as the first argument, last as the second argument, and a as the third argument, and value-initializes comp; calls make_heap(c.begin(), c.end(), comp).
template<class InputIterator, class Alloc> priority_queue(InputIterator first, InputIterator last, const Compare& compare, const Alloc& a);-?- Effects: Initializes c with first as the first argument, last as the second argument, and a as the third argument, and initializes comp with compare; calls make_heap(c.begin(), c.end(), comp).
template<class InputIterator, class Alloc> priority_queue(InputIterator first, InputIterator last, const Compare& compare, const Container& cont, const Alloc& a);-?- Effects: Initializes c with cont as the first argument and a as the second argument, and initializes comp with compare; calls c.insert(c.end(), first, last); and finally calls make_heap(c.begin(), c.end(), comp).
template<class InputIterator, class Alloc> priority_queue(InputIterator first, InputIterator last, const Compare& compare, Container&& cont, const Alloc& a);-?- Effects: Initializes c with std::move(cont) as the first argument and a as the second argument, and initializes comp with compare; calls c.insert(c.end(), first, last); and finally calls make_heap(c.begin(), c.end(), comp).