std::ranges::transform_view<V,F>::iterator<Const>::base
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std::ranges::transform_view
(C++26)
transform_view::iterator::base
constexpr const ranges::iterator_t <Base>& base() const & noexcept;
(1)
(since C++20)
constexpr ranges::iterator_t <Base> base() &&;
(2)
(since C++20)
Returns the underlying iterator.
1) Returns a reference to the underlying iterator.
2) Move constructs the result from the underlying iterator.
[edit] Parameters
(none)
[edit] Return value
1) A reference to the underlying iterator.
2) An iterator move constructed from the underlying iterator.
[edit] Example
Run this code
#include <algorithm> #include <iostream> #include <iterator> #include <ranges> int main() { const auto v = { 0, 1, 2, 3, 4 }; auto x2 = [](int x) { return x << 1; }; std::ranges::transform_view tv{ v, x2 }; std::ostream_iterator <int> ostr{ std::cout, " " }; std::ranges::copy (v, ostr), std::cout << '\n'; std::ranges::copy (tv.base(), ostr), std::cout << '\n'; std::ranges::copy (tv, ostr), std::cout << '\n'; }
Output:
0 1 2 3 4 0 1 2 3 4 0 2 4 6 8
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3533 | C++20 | the const& overload of base returns a copy of the underlying iterator
|
returns a reference |
| LWG 3593 | C++20 | the const& overload of base might not be noexcept
|
made noexcept |