promise_base( std::allocator_arg_t, Allocator alloc) {
typedef detail::shared_state_object< R, Allocator > object_type;
typedef std::allocator_traits< typename object_type::allocator_type > traits_type;
typedef pointer_traits< typename traits_type::pointer > ptrait_type;
typename object_type::allocator_type a{ alloc };
typename traits_type::pointer ptr{ traits_type::allocate( a, 1) };
typename ptrait_type::element_type* p = ptrait_type::to_address(ptr);
try {
traits_type::construct( a, p, a);
} catch (...) {
traits_type::deallocate( a, ptr, 1);
throw;
}
future_.reset(p);
}
explicit packaged_task( std::allocator_arg_t, Allocator const& alloc, Fn && fn) {
typedef detail::task_object<
typename std::decay< Fn >::type, Allocator, R, Args ...
> object_type;
typedef std::allocator_traits<
typename object_type::allocator_type
> traits_type;
typedef pointer_traits< typename traits_type::pointer > ptrait_type;
typename object_type::allocator_type a{ alloc };
typename traits_type::pointer ptr{ traits_type::allocate( a, 1) };
typename ptrait_type::element_type* p = boost::to_address(ptr);
try {
traits_type::construct( a, p, a, std::forward< Fn >( fn) );
} catch (...) {
traits_type::deallocate( a, ptr, 1);
throw;
}
task_.reset(p);
}
polymorphic_holder& operator=(Derived const& rhs) {
ptr_.reset(boost::make_shared<Derived>(rhs));
return *this;
}
