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

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< cpp‎ | ranges
C++
Ranges library
Range adaptors
(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)
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 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

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. For exposition purposes, the cv-unqualified version of its type is denoted as __cartesian_product_fn

All instances of __cartesian_product_fn are equal. The effects of invoking different instances of type __cartesian_product_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::cartesian_product

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

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

Data members

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

Member functions

 constructs a cartesian_product_view
(public member function)
returns an iterator to the beginning
(public member function)
returns an iterator or a sentinel to the end
(public member function)
returns the number of elements. Provided only if the underlying (adapted) range satisfies sized_range.
(public member function)
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>)
(C++23)
 returns a constant iterator to the beginning of the range.
(public member function of std::ranges::view_interface<D>)
(C++23)
 returns a sentinel for the constant iterator of the range.
(public member function of std::ranges::view_interface<D>)
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>)
returns the first element in the derived view. Provided if it satisfies forward_range.
(public member function of std::ranges::view_interface<D>)
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>)
returns the n th element in the derived view. Provided if it satisfies random_access_range.
(public member function of std::ranges::view_interface<D>)

Deduction guides

Nested classes

 the iterator type
(exposition-only member class template*

Notes

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

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)

References

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

See also

(C++23)
 a view consisting of tuples of references to corresponding elements of the adapted views
(class template) (customization point object)
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