std::ranges::views::adjacent_transform, std::ranges::adjacent_transform_view, std::ranges::views::pairwise_transform
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
(public member function) [edit]
returns a constant iterator to the beginning of the range
(public member function of
returns a sentinel for the constant iterator of the range
(public member function of
(C++23)(C++23)
(C++23)(C++23)
(C++23)(C++23)
(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)
adjacent_transform_viewviews::adjacent_transform
(C++23)(C++23)
views::pairwise_transform
(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::adjacent_transform_view
Member functions
Non-member functions
Member functions
Non-member functions
Defined in header
<ranges>
template< ranges::forward_range V, std::move_constructible F, std::size_t N >
(1)
(since C++23)
requires ranges::view <V> && (N > 0) && std::is_object_v <F> &&
std::regular_invocable <F&,
/*REPEAT*/(ranges::range_reference_t <V>, N)...> &&
/*can-reference*/<std::invoke_result_t <F&,
/*REPEAT*/(ranges::range_reference_t <V>, N)...>>
class adjacent_transform_view
namespace views {
(2)
(since C++23)
template< std::size_t N >
constexpr /* unspecified */ adjacent_transform = /* unspecified */;
namespace views {
(3)
(since C++23)
inline constexpr auto pairwise_transform = adjacent_transform<2>;
Call signature
template< ranges::viewable_range R, class F >
(since C++23)
requires /* see below */
template< class F >
constexpr /*range adaptor closure*/ adjacent_transform<N>( F&& fun );
(since C++23)
constexpr /*range adaptor closure*/ adjacent_transform<N>( F&& fun );
1)
adjacent_transform_view is a range adaptor that takes a view and an invocable object fun, and produces a view whose ith element is a value that is the result of applying fun to each element in [i, i + N) of the original view. F always has arity N. Let
S be the size of the original view. Then the size of produced view is:
- S - N + 1, if S >= N,
- 0 otherwise, and the resulting view is empty.
2) The name views::adjacent_transform<N> denotes a RangeAdaptorObject. Given subexpressions e and f, and a constant expression
N, the expression views::adjacent_transform<N>(e, f) is expression-equivalent to:
- ((void)e, views::zip_transform (f)), if
Nis equal to 0 and decltype((e)) modelsforward_range(except that the evaluations of e and f are indeterminately sequenced), - adjacent_transform_view<views::all_t <decltype((e))>, std::decay_t <decltype((f))>, N>(e, f) otherwise.
3) The name views::pairwise_transform denotes a RangeAdaptorObject that behaves exactly as views::adjacent_transform<2>. In particular, the arity of
F is also 2 and fun is a binary invocable object.adjacent_transform_view always models forward_range, and models bidirectional_range, random_access_range, or sized_range, if adapted view type models the corresponding concept.
Contents
[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] Nested types
Type
Definition
inner_iterator (private)
- ranges::iterator_t <const InnerView>, if
Constis true. Otherwise, - ranges::iterator_t <InnerView>
(exposition-only member type*)
inner_sentinel (private)
- ranges::sentinel_t <const InnerView>, if
Constis true. Otherwise, - ranges::sentinel_t <InnerView>
(exposition-only member type*)
[edit] Data members
Member
Description
/*movable-box*/<F>
(exposition-only member object*)
fun_ (private)
the transforming invocable object(exposition-only member object*)
[edit] Nested classes
the sentinel type used when
(exposition-only member class template*)
adjacent_transform_view is not a common_range (exposition-only member class template*)
[edit] Notes
views::adjacent_transform only accepts foward ranges even when N is 0.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_ranges_zip |
202110L |
(C++23) | ranges::zip_view , ranges::zip_transform_view , ranges::adjacent_view , ranges::adjacent_transform_view
|
[edit] Example
Run this code
#include <array> #include <iostream> #include <ranges> int main() { constexpr static std::array data{1, 2, 3, 4, 5, 6}; constexpr int window{3}; auto Fun = [](auto... ints) { return (... + ints); }; // Alternatively, the Fun could be any ternary (if window == 3) callable, e.g.: // auto Fun = [](int x, int y, int z) { return x + y + z; }; constexpr auto view = data | std::views::adjacent_transform<window>(Fun); static_assert( view.size() == (data.size() - window + 1) && std::array {6, 9, 12, 15} == std::array {view[0], view[1], view[2], view[3]} && view[0] == Fun(data[0], data[1], data[2]) && view[1] == Fun(data[1], data[2], data[3]) && view[2] == Fun(data[2], data[3], data[4]) && view[3] == Fun(data[3], data[4], data[5]) ); for (int x : view) std::cout << x << ' '; std::cout << '\n'; }
Output:
6 9 12 15
[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 4098 | C++23 | views::adjacent_transform<0> used to accept input-only ranges | made rejected |
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 26.7.27 Adjacent transform view [range.adjacent.transform]
[edit] See also
a
(class template) (range adaptor object)[edit]
view consisting of tuples of references to adjacent elements of the adapted view(class template) (range adaptor object)[edit]
a
(class template) (range adaptor object)[edit]
view of a sequence that applies a transformation function to each element(class template) (range adaptor object)[edit]
a
(class template) (customization point object)[edit]
view consisting of results of application of a transformation function to corresponding elements of the adapted views(class template) (customization point object)[edit]