std::ranges::views::zip_transform, std::ranges::zip_transform_view

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(until C++23)(C++23)

Defined in header <ranges>
template< std::move_constructible F, ranges::input_range... Views >

    requires (ranges::view<Views> && ...) && (sizeof...(Views) > 0) &&
              std::is_object_v<F> && std::regular_invocable<
                  F&, ranges::range_reference_t<Views>...> &&
                  F&, ranges::range_reference_t<Views>...>>
class zip_transform_view

     : public ranges::view_interface<zip_transform_view<F, Views...>>
(1) (since C++23)
namespace views {

    inline constexpr /*unspecified*/ zip_transform = /*unspecified*/;

(2) (since C++23)
Call signature
template< class F, ranges::viewable_range... Rs >

    requires /* see below */

constexpr auto zip_transform( F&& f, Rs&&... rs );
(since C++23)
1) zip_transform_view is a range adaptor that takes an invocable object and one or more views, and produces a view whose ith element is the result of applying the invocable object to the ith elements of all views.
A type T models the exposition-only concept /*can-reference*/ if and only if T& is a valid type.
2) views::zip_transform is a customization point object.

When calling with one argument f, let FD be std::decay_t<decltype(f)>, if:

then views::zip_transform(f) is expression-equivalent to ((void)f, auto(views::empty<std::decay_t<std::invoke_result_t<FD&>>>)). Otherwise, the call to views::zip_transform is ill-formed.

When calling with more than one arguments f and rs..., views::zip_transform(f, rs...) is expression-equivalent to ranges::zip_transform_view(f, rs...).

zip_transform_view models the concepts random_access_range, bidirectional_range, forward_range, input_range, common_range, and sized_range when the underlying ranges::zip_view<Views...> models respective concepts.


Customization point objects

The name views::zip_transform denotes a customization point object, which is a const function object of a literal semiregular class type. For exposition purposes, the cv-unqualified version of its type is denoted as __zip_transform_fn.

All instances of __zip_transform_fn are equal. The effects of invoking different instances of type __zip_transform_fn on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus, views::zip_transform can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to views::zip_transform above, __zip_transform_fn models

Otherwise, no function call operator of __zip_transform_fn participates in overload resolution.

[edit] Member functions

constructs a zip_transform_view
(public member function) [edit]
returns an iterator to the beginning
(public member function) [edit]
returns an iterator or a sentinel to the end
(public member function) [edit]
returns the number of elements. Provided only if each underlying (adapted) range satisfies sized_range.
(public member function) [edit]
Inherited from std::ranges::view_interface
returns whether the derived view is empty. Provided if it satisfies sized_range or forward_range.
(public member function of std::ranges::view_interface<D>) [edit]
returns a constant iterator to the beginning of the range.
(public member function of std::ranges::view_interface<D>) [edit]
returns a sentinel for the constant iterator of the range.
(public member function of std::ranges::view_interface<D>) [edit]
returns whether the derived view is not empty. Provided if ranges::empty is applicable to it.
(public member function of std::ranges::view_interface<D>) [edit]
returns the first element in the derived view. Provided if it satisfies forward_range.
(public member function of std::ranges::view_interface<D>) [edit]
returns the last element in the derived view. Provided if it satisfies bidirectional_range and common_range.
(public member function of std::ranges::view_interface<D>) [edit]
returns the nth element in the derived view. Provided if it satisfies random_access_range.
(public member function of std::ranges::view_interface<D>) [edit]

[edit] Deduction guides

[edit] Member types

Member type Definition
InnerView (private) ranges::zip_view<Views...>.
(exposition-only member type*)
ziperator (private)
zentinel (private)

[edit] Data members

Member object Definition
zip_ (private) An underlying view object of type InnerView
(exposition-only member object*)
fun_ (private) A wrapped invocable object of type movable-box<F>
(exposition-only member object*)

[edit] Nested classes

the iterator type
(exposition-only member class template*)
the sentinel type used when the underlying zip_view is not a common_range
(exposition-only member class template*)

[edit] Notes

Feature-test macro Value Std Feature
__cpp_lib_ranges_zip 202110L (C++23) std::ranges::zip_view,

[edit] Example

#include <array>
#include <iostream>
#include <list>
#include <ranges>
#include <vector>
void print(auto const rem, auto const& r)
    std::cout << rem << '{'; 
    for (char o[]{0,' ',0}; auto const& e : r)
        std::cout << o << e, *o = ',';
    std::cout << "}\n";
int main()
    auto v1 = std::vector<float>{1, 2, 3};
    auto v2 = std::list<short>{1, 2, 3, 4};
    auto v3 = std::to_array({1, 2, 3, 4, 5});
    auto add = [](auto a, auto b, auto c) { return a + b + c; };
    auto sum = std::views::zip_transform(add, v1, v2, v3);
    print("v1:  ", v1);
    print("v2:  ", v2);
    print("v3:  ", v3);
    print("sum: ", sum);


v1:  {1, 2, 3}
v2:  {1, 2, 3, 4}
v3:  {1, 2, 3, 4, 5}
sum: {3, 6, 9}

[edit] See also

a view consisting of tuples of references to corresponding elements of the adapted views
(class template) (customization point object)[edit]
a view of a sequence that applies a transformation function to each element
(class template) (range adaptor object)[edit]
takes a view consisting of tuple-like values and a number N and produces a view of Nth element of each tuple
(class template) (range adaptor object)[edit]