std::experimental::apply
From cppreference.com
< cpp | experimental
| Defined in header <experimental/tuple>
|
||
template< class F, class Tuple > constexpr decltype(auto) apply(F&& f, Tuple&& t); |
(library fundamentals TS) | |
Invoke the Callable object f with a tuple of arguments.
Parameters
| f | - | Callable object to be invoked |
| t | - | tuple whose elements to be used as arguments to f
|
Return value
What returned by f.
Possible implementation
namespace detail
{
template<class F, class Tuple, std::size_t... I>
constexpr decltype(auto) apply_impl(F&& f, Tuple&& t, std::index_sequence<I...>)
{
return std::invoke(std::forward<F>(f), std::get<I>(std::forward<Tuple>(t))...);
// Note: std::invoke is a C++17 feature
}
} // namespace detail
template<class F, class Tuple>
constexpr decltype(auto) apply(F&& f, Tuple&& t)
{
return detail::apply_impl(std::forward<F>(f), std::forward<Tuple>(t),
std::make_index_sequence<std::tuple_size_v<std::decay_t<Tuple>>>{});
}
|
Example
Run this code
#include <iostream>
#include <tuple>
template<typename... Ts>
void print_tuple(const std::tuple<Ts...> &tuple)
{
std::apply([](const auto&... elem)
{
((std::cout << elem << '\n'), ...);
}, tuple);
}
int main()
{
const std::tuple<int, char> t = std::make_tuple(5, 'a');
print_tuple(t);
}
Output:
5
a
See also
(C++11) |
creates a tuple object of the type defined by the argument types (function template) |
(C++11) |
creates a tuple of forwarding references (function template) |