Deduction guides¶
If possible, concurrent_map 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_key_t<InputIterator>>,
typename Allocator = tbb_allocator<iterator_alloc_value_t<InputIterator>>>
concurrent_map( InputIterator, InputIterator,
Compare = Compare(),
Allocator = Allocator() )
-> concurrent_map<iterator_key_t<InputIterator>,
iterator_mapped_t<InputIterator>,
Compare,
Allocator>;
template <typename InputIterator,
typename Allocator>
concurrent_map( InputIterator, InputIterator,
Allocator )
-> concurrent_map<iterator_key_t<InputIterator>,
iterator_mapped_t<InputIterator>,
std::less<iterator_key_t<InputIterator>>,
Allocator>;
template <typename Key, typename T,
typename Compare = std::less<std::remove_const_t<Key>>,
typename Allocator = tbb_allocator<std::pair<const Key, T>>>
concurrent_map( std::initializer_list<std::pair<Key, T>>,
Compare = Compare(),
Allocator = Allocator() )
-> concurrent_map<std::remove_const_t<Key>,
T,
Compare,
Allocator>;
template <typename Key, typename T,
typename Allocator>
concurrent_map( std::initializer_list<std::pair<Key, T>>, Allocator )
-> concurrent_map<std::remove_const_t<Key>,
T,
std::less<std::remove_const_t<Key>>,
Allocator>;
where the type aliases iterator_key_t, iterator_mapped_t, iterator_alloc_value_t are defined as follows:
template <typename InputIterator>
using iterator_key_t = std::remove_const_t<typename std::iterator_traits<InputIterator>::value_type::first_type>;
template <typename InputIterator>
using iterator_mapped_t = typename std::iterator_traits<InputIterator>::value_type::second_type;
template <typename InputIterator>
using iterator_alloc_value_t = std::pair<std::add_const_t<iterator_key_t<InputIterator>>,
iterator_mapped_t<InputIterator>>;
These deduction guides only participate in the overload resolution if the following requirements are met:
The
InputIteratortype meets theInputIteratorrequirements described in the [input.iterators] section of the ISO C++ Standard.The
Allocatortype meets theAllocatorrequirements described in the [allocator.requirements] section of the ISO C++ Standard.The
Comparetype does not meet theAllocatorrequirements.
Example
#include <oneapi/tbb/concurrent_map.h>
#include <vector>
int main() {
std::vector<std::pair<int, float>> v;
// Deduces cm1 as concurrent_map<int, float>
oneapi::tbb::concurrent_map cm1(v.begin(), v.end());
// Deduces cm2 as concurrent_map<int, float>
oneapi::tbb::concurrent_map cm2({std::pair(1, 2f), std::pair(2, 3f)});
}