Deduction guides#

If possible, concurrent_bounded_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 guide is provided:

template <typename InputIterator,
          typename Allocator = tbb::cache_aligned_allocator<iterator_value_t<InputIterator>>
concurrent_bounded_queue( InputIterator, InputIterator,
                          Allocator = Allocator() )
-> concurrent_bounded_queue<iterator_value_t<InputIterator>,

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;

This 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.


#include <oneapi/tbb/concurrent_queue.h>
#include <vector>
#include <memory>

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

    // Deduces cq1 as oneapi::tbb::concurrent_bounded_queue<int>
    oneapi::tbb::concurrent_bounded_queue cq1(vec.begin(), vec.end());

    // Deduces cq2 as oneapi::tbb::concurrent_bounded_queue<int, std::allocator<int>>
    oneapi::tbb::concurrent_bounded_queue cq2(vec.begin(), vec.end(), std::allocator<int>{})