std::ranges::views::transform, std::ranges::transform_view
From cppreference.com
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Ranges library
(C++23)(C++23)
transform_viewviews::transform
(C++26)(C++26)
(C++23)(C++23)
(C++26)(C++26)
(C++26)(C++26)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)
(C++23)(C++23)
(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
std::ranges::transform_view
(C++26)
Defined in header
<ranges>
(1)
template< ranges::input_range V,
(since C++20) 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<V>>& is a valid type */
class transform_view
(until C++23)
template< ranges::input_range V,
(since C++23)
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<V>>& is a valid type */
class transform_view
namespace views {
(2)
(since C++20)
inline constexpr /*unspecified*/ transform = /*unspecified*/;
Call signature
template< ranges::viewable_range R, class F >
(since C++20)
requires /* see below */
template< class F >
constexpr /*range adaptor closure*/ transform( F&& fun );
(since C++20)
constexpr /*range adaptor closure*/ transform( F&& fun );
1) A range adaptor that represents
view of an underlying sequence after applying a transformation function to each element.2) RangeAdaptorObject. The expression views::transform(e, f) is expression-equivalent to transform_view(e, f) for any suitable subexpressions e and f.
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 <F>(until C++23)movable-box <F>(since C++23) fun_ (private)
the underlying function object(exposition-only member object*)
[edit] Member functions
returns the number of elements, provided only if the underlying (adapted) range satisfies
(public member function) [edit]
sized_range (public member function) [edit]
(C++26)
approximately_sized_range (public member function) [edit]
Inherited from std::ranges::view_interface
returns whether the derived view is empty, provided only if it satisfies
(public member function of
sized_range or forward_range (public member function of
std::ranges::view_interface<D>) [edit]
(C++23)
(public member function of
std::ranges::view_interface<D>) [edit]
(C++23)
(public member function of
std::ranges::view_interface<D>) [edit]
returns whether the derived view is not empty, provided only if ranges::empty is applicable to it
(public member function of
(public member function of
std::ranges::view_interface<D>) [edit]
returns the first element in the derived view, provided if it satisfies
(public member function of
forward_range (public member function of
std::ranges::view_interface<D>) [edit]
returns the last element in the derived view, provided only if it satisfies
(public member function of
bidirectional_range and common_range (public member function of
std::ranges::view_interface<D>) [edit]
returns the
(public member function of
nth element in the derived view, provided only if it satisfies random_access_range (public member function of
std::ranges::view_interface<D>) [edit]
[edit] Deduction guides
[edit] Nested classes
[edit] Example
Run this code
#include <algorithm> #include <cstdio> #include <iterator> #include <ranges> #include <string> 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