Deduction guides

If possible, oneapi::tbb::concurrent_priority_queue 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::cache_aligned_allocator<iterator_value_t<InputIterator>>>
concurrent_priority_queue( InputIterator, InputIterator,
                           Compare = Compare(),
                           Allocator = Allocator() )
-> concurrent_priority_queue<iterator_value_t<InputIterator>,
                             Compare,
                             Allocator>;

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

template <typename T,
          typename Compare = std::less<T>,
          typename Allocator = tbb::cache_aligned_allocator<T>>
concurrent_priority_queue( std::initializer_list<T>,
                           Compare = Compare(),
                           Allocator = Allocator() )
-> concurrent_priority_queue<T,
                             Compare,
                             Allocator>;

template <typename T,
          typename Allocator>
concurrent_priority_queue( std::initializer_list<T>,
                           Allocator )
-> concurrent_priority_queue<T,
                             std::less<T>,
                             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_priority_queue.h>
#include <vector>
#include <functional>

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

    // Deduces cpq1 as oneapi::tbb::concurrent_priority_queue<int>
    oneapi::tbb::concurrent_priority_queue cpq1(vec.begin(), vec.end());

    // Deduces cpq2 as oneapi::tbb::concurrent_priority_queue<int, std::greater>
    oneapi::tbb::concurrent_priority_queue cpq2(vec.begin(), vec.end(), std::greater{});
}

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