Intel® oneAPI Threading Building Blocks Developer Guide and API Reference
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{});
}