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std::ranges::views::join_with, std::ranges::join_with_view - cppreference.com

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Defined in header <ranges>

template< ranges::input_range V, ranges::forward_range Pattern > requires ranges::view<V> && ranges::input_range<ranges::range_reference_t<V>> && ranges::view<Pattern> && /*concatable*/<ranges::range_reference_t<V>, Pattern> class join_with_view : ranges::view_interface<join_with_view<V, Pattern>>

 (1) (since C++23)

namespace views { inline constexpr /* unspecified */ join_with = /* unspecified */; }

 (2) (since C++23)

Call signature

template< ranges::viewable_range R, class Pattern > requires /* see below */ constexpr ranges::view auto join_with( R&& r, Pattern&& pattern );

 (since C++23)

template< class Pattern > constexpr /* range adaptor closure */ join_with( Pattern&& pattern );

 (since C++23)

1) A range adaptor that represents view consisting of the sequence obtained from flattening a view of ranges, with every element of the delimiter inserted in between elements of the view. The delimiter can be a single element or a view of elements.

join_with_view models input_range.

join_with_view models forward_range when:

  • ranges::range_reference_t<V> is a reference, and
  • V and ranges::range_reference_t<V> each model forward_range.

join_with_view models bidirectional_range when:

  • ranges::range_reference_t<V> is a reference,
  • V, ranges::range_reference_t<V>, and Pattern each models bidirectional_range, and
  • ranges::range_reference_t<V> and Pattern each model common_range.

join_with_view models common_range when:

  • ranges::range_reference_t<V> is a reference, and
  • V and ranges::range_reference_t<V> each model forward_range and common_range.

Nested types

Type Definition
InnerRng ranges::range_reference_t<V>
(exposition-only member type*)

Data members

Member Definition
V base_ the underlying (adapted) view
(exposition-only member object*)
Pattern pattern_ the pattern object
(exposition-only member object*)
non-propagating-cache <ranges::iterator_t<V>> outer_it_
(present only if V does not model forward_range) 		the cache of the outer iterator
(exposition-only member object*)
non-propagating-cache <std::remove_cv_t<InnerRng >> inner_
(present only if std::is_reference_v<InnerRng > is false) 		the cache of the inner range
(exposition-only member object*)

Member functions

constructs a join_with_view
(public member function) [edit]
returns a copy of the underlying (adapted) 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]
Inherited from 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]

Deduction guides

Nested classes

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

Notes

Feature-test macro Value Std Feature
__cpp_lib_ranges_join_with 202202L (C++23) std::ranges::join_with_view

Example

#include <iostream>
#include <ranges>
#include <string_view>
#include <vector>

int main()
{
    using namespace std::literals;
    
    std::vector v{"This"sv, "is"sv, "a"sv, "test."sv};
    auto joined = v | std::views::join_with(' ');
    
    for (auto c : joined)
        std::cout << c;
    std::cout << '\n';
}

Output:

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 4074 C++23 join_with_view was underconstrained updated the constraints

See also