std::ranges::views::transform, std::ranges::transform_view - cppreference.com (original) (raw)
std::ranges::transform_view
| Defined in header | ||
|---|---|---|
| (1) | ||
| template< ranges::input_range V, std::copy_constructible F > requires ranges::view<V> && std::is_object_v<F> && std::regular_invocable<F&, ranges::range_reference_t<V>> && /* invoke_result_t<F&, range_reference_t>& is a valid type */ class transform_view : public ranges::view_interface<transform_view<V, F>> | (since C++20) (until C++23) | |
| template< ranges::input_range V, std::move_constructible F > requires ranges::view<V> && std::is_object_v<F> && std::regular_invocable<F&, ranges::range_reference_t<V>> && /* invoke_result_t<F&, range_reference_t>& is a valid type */ class transform_view : public ranges::view_interface<transform_view<V, F>> | (since C++23) | |
| namespace views { inline constexpr /*unspecified*/ transform = /*unspecified*/; } | (2) | (since C++20) |
| Call signature | ||
| template< ranges::viewable_range R, class F > requires /* see below */ constexpr ranges::view auto transform( R&& r, F&& fun ); | (since C++20) | |
| template< class F > constexpr /*range adaptor closure*/ transform( F&& fun ); | (since C++20) |
- A range adaptor that represents view of an underlying sequence after applying a transformation function to each element.
transform_view models the concepts random_access_range, bidirectional_range, forward_range, input_range, common_range, and sized_range when the underlying view V models respective concepts.
Contents
[edit] Data members
| Member | Description |
|---|---|
| V base_ (private) | the underlying view(exposition-only member object*) |
| copyable-box(until C++23)movable-box(since C++23) fun_ (private) | the underlying function object(exposition-only member object*) |
[edit] Member functions
| (constructor) | constructs a transform_view (public member function) [edit] |
|---|---|
| base | returns a copy of the underlying (adapted) view (public member function) [edit] |
| begin | returns an iterator to the beginning (public member function) [edit] |
| end | returns an iterator or a sentinel to the end (public member function) [edit] |
| size | returns the number of elements, provided only if the underlying (adapted) range satisfies sized_range (public member function) [edit] |
| reserve_hint(C++26) | returns the approximate size of the resulting approximately_sized_range (public member function) [edit] |
| Inherited from std::ranges::view_interface | |
| empty | returns whether the derived view is empty, provided only if it satisfies sized_range or forward_range (public member function of std::ranges::view_interface) [edit] |
| cbegin(C++23) | returns a constant iterator to the beginning of the range (public member function of std::ranges::view_interface) [edit] |
| cend(C++23) | returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface) [edit] |
| operator bool | returns whether the derived view is not empty, provided only if ranges::empty is applicable to it (public member function of std::ranges::view_interface) [edit] |
| front | returns the first element in the derived view, provided if it satisfies forward_range (public member function of std::ranges::view_interface) [edit] |
| back | returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range (public member function of std::ranges::view_interface) [edit] |
| operator[] | returns the nth element in the derived view, provided only if it satisfies random_access_range (public member function of std::ranges::view_interface) [edit] |
[edit] Deduction guides
[edit] Nested classes
| | the iterator type(exposition-only member class template*) | | ------------------------------------------------------------- | | | the sentinel type(exposition-only member class template*) |
[edit] Example
#include #include #include #include #include char rot13a(const char x, const char a) { return a + (x - a + 13) % 26; } char rot13(const char x) { if ('Z' >= x and x >= 'A') return rot13a(x, 'A'); if ('z' >= x and x >= 'a') return rot13a(x, 'a'); return x; } int main() { auto show = [](const unsigned char x) { std::putchar(x); }; std::string in{"cppreference.com\n"}; std::ranges::for_each(in, show); std::ranges::for_each(in | std::views::transform(rot13), show); std::string out; std::ranges::copy(std::views::transform(in, rot13), std::back_inserter(out)); std::ranges::for_each(out, show); std::ranges::for_each(out | std::views::transform(rot13), show); }
Output:
cppreference.com pccersrerapr.pbz pccersrerapr.pbz cppreference.com