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std::ranges::views::cartesian_product, std::ranges::cartesian_product_view

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< cpp‎ | ranges
 
 
Ranges library
Range primitives
Range concepts
Views

Range factories
Range adaptors
(C++23)(C++23)
(C++23)(C++23)
cartesian_product_viewviews::cartesian_product
(C++23)(C++23)

 
std::ranges::cartesian_product_view
Member functions
Deduction guides
Iterator
Member functions
Non-member functions
 
Defined in header <ranges>
template< ranges::input_range First, ranges::forward_range... Vs >

    requires (ranges::view <First> && ... && ranges::view <Vs>)
class cartesian_product_view

    : public ranges::view_interface <cartesian_product_view<First, Vs...>>
(1) (since C++23)
namespace views {

    inline constexpr /*unspecified*/ cartesian_product = /*unspecified*/;

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

    requires /* see below */

constexpr ranges::view auto cartesian_product( Rs&&... rs );
(since C++23)
Helper concepts
template< bool Const, class First, class... Vs >

concept /*cartesian-product-is-random-access*/ =
    (ranges::random_access_range </*maybe-const*/<Const, First>> && ... &&
        (ranges::random_access_range </*maybe-const*/<Const, Vs>> &&

            ranges::sized_range </*maybe-const*/<Const, Vs>>));
(3) (exposition only*)
template< class R >

concept /*cartesian-product-common-arg*/ =
    ranges::common_range <R> ||

        (ranges::sized_range <R> && ranges::random_access_range <R>);
(4) (exposition only*)
template< bool Const, class First, class... Vs >

concept /*cartesian-product-is-bidirectional*/ =
    (ranges::bidirectional_range </*maybe-const*/<Const, First>> && ... &&
        (ranges::bidirectional_range </*maybe-const*/<Const, Vs>> &&

            /*cartesian-product-common-arg*/</*maybe-const*/<Const, Vs>>));
(5) (exposition only*)
template< class First, class... Vs >

concept /*cartesian-product-is-common*/ =

    /*cartesian-product-common-arg*/<First>;
(6) (exposition only*)
template< class... Vs >

concept /*cartesian-product-is-sized*/ =

    (ranges::sized_range <Vs> && ...);
(7) (exposition only*)
template< bool Const, template<class> class FirstSent, class First, class... Vs >

concept /*cartesian-is-sized-sentinel*/ =
    (std::sized_sentinel_for <FirstSent</*maybe-const*/<Const, First>>,
        ranges::iterator_t </*maybe-const*/<Const, First>>> && ... &&
            (ranges::sized_range </*maybe-const*/<Const, Vs>> &&
                std::sized_sentinel_for <ranges::iterator_t <
                    /*maybe-const*/<Const, Vs>>,

                        ranges::iterator_t </*maybe-const*/<Const, Vs>>>));
(8) (exposition only*)
Helper function templates
template< /*cartesian-product-common-arg*/ R >

constexpr auto /*cartesian-common-arg-end*/( R& r )
{
    if constexpr (ranges::common_range <R>)
        return ranges::end (r);
    else
        return ranges::begin (r) + ranges::distance (r);

}
(9) (exposition only*)
1) cartesian_product_view is a range adaptor that takes n views, where n > 0, and produces a view of tuples calculated by the n-ary cartesian product of the provided ranges. The size of produced view is a multiple of sizes of provided ranges, while each element is a tuple (of references) of the size n.
2) views::cartesian_product is a customization point object.
3) Determines if cartesian_product is a random access range (see also random_access_range).
4) Determines if cartesian_product is a common range (see also common_range).
5) Determines if cartesian_product is a bidirectional range (see also bidirectional_range).
6) Determines if cartesian_product satisfies the helper concept /*cartesian-product-is-common*/ (see also common_range).
7) Determines if cartesian_product is a sized range (see also sized_range).
8) Determines if cartesian_product uses sized sentinel.
9) Returns the end of the produced view. Participates in overload resolution only if cartesian_product satisfies the helper concept /*cartesian-product-common-arg*/.

The First range passed to cartesian_product_view is treated specially, since it is only passed through a single time. As a result, several constrains are relaxed on it:

Contents

Customization point objects

The name views::cartesian_product denotes a customization point object, which is a const function object of a literal semiregular class type. See CustomizationPointObject for details.

[edit] Data members

Member Definition
std::tuple <First, Vs...> base_ (private) An object that holds all adapted view objects.
(exposition-only member object*)

[edit] Member functions

constructs a cartesian_product_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 the underlying (adapted) range satisfies sized_range
(public member function) [edit]
Inherited from std::ranges::view_interface
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]
(C++23)
returns a constant iterator to the beginning of the range
(public member function of std::ranges::view_interface<D>) [edit]
(C++23)
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 only 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 only 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 only if it satisfies random_access_range
(public member function of std::ranges::view_interface<D>) [edit]

[edit] Deduction guides

[edit] Nested classes

the iterator type
(exposition-only member class template*)

[edit] Notes

Feature-test macro Value Std Feature
__cpp_lib_ranges_cartesian_product 202207L (C++23) std::ranges::cartesian_product_view

[edit] Example

Run this code
#include <array>
#include <iostream>
#include <list>
#include <ranges>
#include <string>
#include <vector>
 
void print(std::tuple <char const&, int const&, std::string const&> t, int pos)
{
 const auto& [a, b, c] = t;
 std::cout << '(' << a << ' ' << b << ' ' << c << ')' << (pos % 4 ? " " : "\n");
}
 
int main()
{
 const auto x = std::array {'A', 'B'};
 const auto y = std::vector {1, 2, 3};
 const auto z = std::list <std::string >{"α", "β", "γ", "δ"};
 
 for (int i{1}; auto const& tuple : std::views::cartesian_product(x, y, z))
 print(tuple, i++);
}

Output: 

(A 1 α) (A 1 β) (A 1 γ) (A 1 δ)
(A 2 α) (A 2 β) (A 2 γ) (A 2 δ)
(A 3 α) (A 3 β) (A 3 γ) (A 3 δ)
(B 1 α) (B 1 β) (B 1 γ) (B 1 δ)
(B 2 α) (B 2 β) (B 2 γ) (B 2 δ)
(B 3 α) (B 3 β) (B 3 γ) (B 3 δ)

[edit] References

  • C++23 standard (ISO/IEC 14882:2024):
  • 26.7.31 Cartesian product view [range.stride]

[edit] See also

a view consisting of tuples of references to corresponding elements of the adapted views
(class template) (customization point object)[edit]

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