std::common_iterator<I,S>::common_iterator
constexpr common_iterator() requires std::default_initializable<I> = default; |
(1) | (since C++20) |
constexpr common_iterator( I i ); |
(2) | (since C++20) |
constexpr common_iterator( S s ); |
(3) | (since C++20) |
template< class I2, class S2 >
requires std::convertible_to<const I2&, I> &&
std::convertible_to<const S2&, S>
constexpr common_iterator( const common_iterator<I2, S2>& x ); |
(4) | (since C++20) |
Constructs a new iterator adaptor, effectively initializes the underlying std::variant<I, S> member object var to hold an I (iterator) or S (sentinel) object.
1) Default constructor. Default-initializes
var. After construction,
var holds a value-initialized
I object. Operations on the resulting iterator adaptor have defined behavior if and only if the corresponding operations on a value-initialized
I also have defined behavior.
2) After construction,
var holds an
I object move-constructed from
i.
3) After construction,
var holds an
S object move-constructed from
s.
4) After construction,
var holds an
I or
S object initialized from the
I2 or
S2 held by
x.var, if
x.var holds that alternative, respectively. The behavior is undefined if
x is in an invalid state, that is,
x.var.valueless_by_exception() is equal to
true.
Parameters
| i | - | iterator to adapt |
| s | - | sentinel to adapt |
| x | - | iterator adaptor to copy |
Example
#include <algorithm>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>
int main()
{
std::vector v {3,1,4,1,5,9,2};
using CI = std::common_iterator<
std::counted_iterator<std::vector<int>::iterator>,
std::default_sentinel_t
>;
CI unused; // (1)
CI start { std::counted_iterator{std::next(begin(v)), ssize(v)-2} }; // (2)
CI finish { std::default_sentinel }; // (3)
CI first { start }; // (4)
CI last { finish }; // (4)
std::copy(first, last, std::ostream_iterator<int>{std::cout, " "});
std::cout << '\n';
std::common_iterator<
std::counted_iterator<
std::ostream_iterator<double>>,
std::default_sentinel_t>
beg { std::counted_iterator{std::ostream_iterator<double>{std::cout,"; "}, 5} },
end { std::default_sentinel };
std::iota(beg, end, 3.1);
std::cout << '\n';
}
Output:
1 4 1 5 9 3.1; 4.1; 5.1; 6.1; 7.1;
See also
|
(C++20)
|
assigns another iterator adaptor (public member function) |
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