Deduction guides

If possible, concurrent_multiset constructors support class template argument deduction (since C++17). Copy and move constructors, including constructors with an explicit allocator_type argument, provide implicitly-generated deduction guides. In addition, the following explicit deduction guides are provided:

template <typename InputIterator,
          typename Compare = std::less<iterator_value_t<InputIterator>>,
          typename Allocator = tbb::tbb_allocator<iterator_value_t<InputIterator>>>
concurrent_multiset( InputIterator, InputIterator,
                     Compare = Compare(),
                     Allocator = Allocator() )
-> concurrent_multiset<iterator_value_t<InputIterator>,
                       Compare,
                       Allocator>;

template <typename InputIterator,
          typename Allocator>
concurrent_multiset( InputIterator, InputIterator,
                     Allocator )
-> concurrent_multiset<iterator_value_t<InputIterator>,
                       std::less<iterator_value_t<InputIterator>>,
                       Allocator>;

template <typename Key,
          typename Compare = std::less<Key>,
          typename Allocator = tbb::tbb_allocator<Key>>
concurrent_multiset( std::initializer_list<Key>,
                     Compare = Compare(),
                     Allocator = Allocator() )
-> concurrent_multiset<Key,
                       Compare,
                       Allocator>;

template <typename Key,
          typename Allocator>
concurrent_multiset( std::initializer_list<Key>,
                     Allocator )
-> concurrent_multiset<Key,
                       std::less<Key>,
                       Allocator>;

Where the type alias iterator_value_t is defined as follows:

template <typename InputIterator>
using iterator_value_t = typename std::iterator_traits<InputIterator>::value_type;

These deduction guides only participate in the overload resolution if the following requirements are met:

  • The InputIterator type meets the InputIterator requirements described in the [input.iterators] section of the ISO C++ Standard.

  • The Allocator type meets the Allocator requirements described in the [allocator.requirements] section of the ISO C++ Standard.

  • The Compare type does not meet the Allocator requirements.

Example

#include <oneapi/tbb/concurrent_set.h>
#include <vector>

int main() {
    std::vector<int> v;

    // Deduces cs1 as concurrent_multiset<int>
    oneapi::tbb::concurrent_multiset cs1(v.begin(), v.end());

    // Deduces cs2 as concurrent_multiset<int>
    oneapi::tbb::concurrent_multiset cs2({1, 2, 3});
}

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