/* Reference for a nice read: https://medium.com/@vgasparyan1995/what-is-an-allocator-c8df15a93ed */ #include #include namespace nge { static std::size_t memory_used { 0 }; template < typename T > struct allocator { using value_type = T; using size_type = std::size_t; using difference_type = std::ptrdiff_t; allocator() noexcept = default; allocator( const allocator& ) noexcept = default; ~allocator() = default; T* allocate( const size_type ) const; void deallocate( T*, const size_type ) const; }; template < typename T > T* allocator< T >::allocate( const size_type n ) const { memory_used += ( n * sizeof( T ) ); return static_cast< T* >( ::operator new( n * sizeof( T ) ) ); } template < typename T > void allocator< T >::deallocate( T* ptr, const size_type n ) const { memory_used -= ( n * sizeof( T ) ); ::operator delete( ptr, n * sizeof( T ) ); } } #include #include #include #include template < typename T, typename Allocator > using default_set = std::set< T, std::less< T >, Allocator >; template < typename T, template < typename U, typename Allocator > typename Container, std::size_t N = 100 > void test_allocation() { std::cout << __PRETTY_FUNCTION__ << std::endl; std::cout << "Memory allocated before: " << nge::memory_used << std::endl; Container< T, nge::allocator< T > > _tmp; for ( std::size_t i { 0 }; i < N; ++i ) { _tmp.insert( std::end( _tmp ), i ); } std::cout << "Memory allocated after: " << nge::memory_used << std::endl; } int main( int argc, char* argv[] ) { std::cout << "From " << __FILE__ << ":" << std::endl << __PRETTY_FUNCTION__ << "\nMemory Allocation Test" << " [with " << "C++ = " << __cplusplus << "; " << "GNU = " << __GNUC__ << "." << __GNUC_MINOR__ << "." << __GNUC_PATCHLEVEL__ << "]" << std::endl; std::cout << std::endl; test_allocation< int, std::vector >(); std::cout << std::endl; test_allocation< int, std::list >(); std::cout << std::endl; test_allocation< int, default_set >(); return EXIT_SUCCESS; }