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polymorphic-allocator.cpp
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polymorphic-allocator.cpp
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/*
* In C++17, polymorphic memory management is introduced with the following
* classes in the namespace pmr:
*
* - std::pmr::polymorphic_allocator
* - std::pmr::memory_resource
* - std::pmr::pool_options
* - std::pmr::synchronized_pool_resource
* - std::pmr::unsynchronized_pool_resource
* - std::pmr::monotonic_buffer_resource
*
* Before C++17,
* An object declared with an allocator cannot be assigned to another declared
* with a different allocator.
*
* To resolve such a problem, a class can now use
* std::pmr::polymorphic_allocator for high-level memory management and
* std::pmr::memory_resource for low-level memory_management so that instances
* of a class that adopt different memory management policies are compatible
* one another.
*
* Note that the implementation of std::pmr::vector is as follows:
*
* namespace pmr {
* template<class T>
* using vector = std::vector<T, std::pmr::polymorphic_allocator<T>>;
* }
*/
#include <iostream>
#include <memory_resource>
#include <vector>
int main()
{
std::pmr::synchronized_pool_resource sync_pool;
std::pmr::unsynchronized_pool_resource unsync_pool;
std::pmr::vector<int> v0{{0, 1, 2, 3, 4}, &sync_pool};
std::pmr::vector<int> v1{{5, 6, 7, 8, 9}, &unsync_pool};
for (const auto& elem : v0)
std::cout << elem << ' ';
std::cout << '\n';
v0 = v1;
for (const auto& elem : v0)
std::cout << elem << ' ';
}