std::ranges::view_interface<D>::data
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constexpr auto data()
requires std::contiguous_iterator <ranges::iterator_t <D>>;
(1)
(since C++20)
requires std::contiguous_iterator <ranges::iterator_t <D>>;
constexpr auto data() const
(2)
(since C++20)
requires ranges::range <const D> &&
The default implementation of data() member function obtains the address denoted by the beginning iterator via std::to_address, which is also the lowest address of the contiguous storage (implied by contiguous_iterator) referenced by the view of the derived type when the view is not empty.
1) Let
derived be static_cast<D&>(*this). Equivalent to return std::to_address (ranges::begin (derived));.2) Same as (1), except that
derived is static_cast<const D&>(*this).Contents
[edit] Return value
The address denoted by the beginning iterator.
[edit] Notes
Following derived types may use the default implementation of data():
- std::ranges::common_view
- std::ranges::drop_view
- std::ranges::drop_while_view
- std::ranges::ref_view
- std::ranges::subrange
- std::ranges::take_view
- std::ranges::take_while_view
Following types are derived from std::ranges::view_interface and do not declare their own data() member function, but they cannot use the default implementation, because their iterator types never satisfy contiguous_iterator:
- std::ranges::basic_istream_view
- std::ranges::elements_view
- std::ranges::filter_view
- std::ranges::iota_view
- std::ranges::join_view
- std::ranges::lazy_split_view
- std::ranges::reverse_view
- std::ranges::split_view
- std::ranges::transform_view
[edit] Example
Run this code
#include <array> #include <iostream> #include <ranges> #include <string_view> int main() { constexpr std::string_view str { "Hello, C++20!" }; std::cout << (str | std::views::drop (7)).data() << '\n'; constexpr static std::array a { 1,2,3,4,5 }; constexpr auto v { a | std::views::take (3) }; static_assert( &a[0] == v.data() ); }
Output:
C++20!
[edit] See also
(C++20)
(customization point object)[edit]