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std::ranges::transform_view<V,F>::iterator

template< bool Const >
class /*iterator*/

(since C++20)

The return type of transform_view::begin, and of transform_view::end when the underlying view is a common_range.

The type /*iterator*/<true> is returned by the const-qualified overloads. The type /*iterator*/<false> is returned by the non-const-qualified overloads.

The name of this class template (shown here as iterator) is unspecified.

Typical implementation holds two data members: an iterator into (possibly const-qualified) V, and a pointer to parent transform_view.

Member types

Member type	Definition
`Parent` (private)	`const ranges::transform_view<V, F>` if `Const` is `true`, otherwise `ranges::transform_view<V, F>`. The name is for exposition only.
`Base` (private)	`const V` if `Const` is `true`, otherwise `V`. The name is for exposition only.
`iterator_concept`	`std::random_access_iterator_tag` if `Base` models `random_access_range`, `std::bidirectional_iterator_tag` if `Base` models `bidirectional_range`, `std::forward_iterator_tag` if `Base` models `forward_range`, `std::input_iterator_tag` otherwise.
`iterator_category`	Not defined if `Base` does not model `forward_range`. Otherwise, if `std::invoke_result_t<F&, ranges::range_reference_t<Base>>` is not a reference, `std::input_iterator_tag`. Else, let `C` be `std::iterator_traits<ranges::iterator_t<Base>>::iterator_category`. If `C` is `std::contiguous_iterator_tag`, the type is `std::random_access_iterator_tag`; otherwise, the type is `C`.
`value_type`	`std::remove_cvref_t<std::invoke_result_t<F&, ranges::range_reference_t<Base>>>`
`difference_type`	`ranges::range_difference_t<Base>`

Member functions

(constructor) (C++20)	constructs an iterator (public member function)
base (C++20)	returns the underlying iterator (public member function)
operator* (C++20)	accesses the transformed element (public member function)
operator[] (C++20)	accesses an element by index (public member function)
operator++operator++(int)operator--operator--(int)operator+=operator-= (C++20)	advances or decrements the underlying iterator (public member function)

Non-member functions

operator==operator<operator>operator<=operator>=operator<=> (C++20)	compares the underlying iterators (function)
operator+operator- (C++20)	performs iterator arithmetic (function)
iter_move (C++20)	obtains an rvalue reference to the transformed element (function)

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
P2259R1	C++20	member `iterator_category` is always defined	defined only if `Base` models `forward_range`
LWG 3555	C++20	the definition of `iterator_concept` ignores const	made to consider
LWG 3798	C++20	`iterator_category` is input-only if transformation result is rvalue reference	may have a stronger category

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