std::ranges::views::zip_transform, std::ranges::zip_transform_view - cppreference.com

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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>...> && /can-reference/<std::invoke_result_t< 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 i^th element is the result of applying the invocable object to the i^th 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:

FD models copy_constructible,
FD& models regular_invocable, and
std::invoke_result_t<FD&> is an object type,

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. See CustomizationPointObject for details.

Member functions

(constructor)	constructs a `zip_transform_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 each underlying (adapted) range satisfies `sized_range` (public member function) [edit]
Inherited from 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<D>`) [edit]
cbegin (C++23)	returns a constant iterator to the beginning of the range (public member function of `std::ranges::view_interface<D>`) [edit]
cend (C++23)	returns a sentinel for the constant iterator of the range (public member function of `std::ranges::view_interface<D>`) [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<D>`) [edit]
front	returns the first element in the derived view, provided if it satisfies `forward_range` (public member function of `std::ranges::view_interface<D>`) [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<D>`) [edit]
operator[]	returns the `n`^th element in the derived view, provided only if it satisfies `random_access_range` (public member function of `std::ranges::view_interface<D>`) [edit]

Deduction guides

Member types

Type	Definition
`InnerView` (private)	`ranges::zip_view<Views...>`. (exposition-only member type*)
`ziperator` (private)	`ranges::iterator_t<const InnerView>` if `Const` is `true`, otherwise `ranges::iterator_t<InnerView>`. (exposition-only member type*)
`zentinel` (private)	`ranges::sentinel_t<const InnerView>` if `Const` is `true`, otherwise `ranges::sentinel_t<InnerView>`. (exposition-only member type*)

Data members

Member	Description
`InnerView` `zip_` (private)	an underlying view object (exposition-only member object*)
`movable-box<F>` `fun_` (private)	a wrapped invocable object (exposition-only member object*)

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*)

Notes

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

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);
}

Output:

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