std::ranges::concat_view<Views...>::iterator
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< cpp | ranges | concat view
template< bool Const > class /*iterator*/ |
(1) | (exposition only*) |
| Helper concepts |
||
template< bool Const, class... Rs > concept /*concat-is-random-access*/ = /* see description */; |
(2) | (exposition only*) |
template< bool Const, class... Rs > concept /*concat-is-bidirectional*/ = /* see description */; |
(3) | (exposition only*) |
1) ranges::concat_view<Views...>::
iterator is the type of the iterators returned by begin() and end() of ranges::concat_view<Views...>.2) Let
Fs be the pack that consists of all elements of Rs except the last element. Equivalent totemplate<bool Const, class... Rs>
concept concat-is-random-access = // exposition only
all-random-access <Const, Rs...> &&
(ranges::common_range<maybe-const <Const, Fs>> && ...);
3) Let
Fs be the pack that consists of all elements of Rs except the last element. Equivalent totemplate<bool Const, class... Rs>
concept concat-is-bidirectional = // exposition only
all-bidirectional <Const, Rs...> &&
(ranges::common_range<maybe-const <Const, Fs>> && ...);
Template parameters
| Const | - | whether the iterator is a constant iterator |
Nested types
Exposition-only types | |
| Type | Definition |
base-iter
|
std::variant<ranges::iterator_t<maybe-const <Const, Views>>...>(exposition-only member type*) |
Iterator property types | |
| Type | Definition |
iterator_concept
|
an iterator tag, see below |
iterator_category(conditionally present) |
an iterator tag, see below |
value_type
|
concat-value-t <maybe-const <Const, Views>...>
|
difference_type
|
std::common_type_t<ranges::range_difference_t< |
Determining the iterator concept
iterator_concept is defined as follows:
- If
concat-is-random-access<Const, Views...> is modeled,iterator_conceptdenotes std::random_access_iterator_tag. - Otherwise, if
concat-is-bidirectional<Const, Views...> is modeled,iterator_conceptdenotes std::bidirectional_iterator_tag. - Otherwise, if
all-forward<Const, Views...> is modeled,iterator_conceptdenotes std::forward_iterator_tag. - Otherwise,
iterator_conceptdenotes std::input_iterator_tag.
Determining the iterator category
iterator_category is defined if and only if all-forward <Const, Views...> is modeled. In this case, it is defined as follows:
- If std::is_reference_v<
concat-reference-t<maybe-const<Const, Views>...>> is false,iterator_categorydenotes std::input_iterator_tag. - Otherwise, let
Csdenote the pack of types std::iterator_traits<ranges::iterator_t<maybe-const<Const, Views>>>::iterator_category...:- If (std::derived_from<Cs, std::random_access_iterator_tag> && ...) &&
concat-is-random-access<Const, Views...> is true,iterator_categorydenotes std::random_access_iterator_tag. - Otherwise, if (std::derived_from<Cs, std::bidirectional_iterator_tag> && ...) &&
concat-is-bidirectional<Const, Views...> is true,iterator_categorydenotes std::bidirectional_iterator_tag. - Otherwise, if (std::derived_from<Cs, std::forward_iterator_tag> && ...) is true,
iterator_categorydenotes std::forward_iterator_tag. - Otherwise,
iterator_categorydenotes std::input_iterator_tag.
- If (std::derived_from<Cs, std::random_access_iterator_tag> && ...) &&
Data members
| Member | Definition |
maybe-const <Const, ranges::concat_view>* parent_
|
a pointer to the parent concat_view(exposition-only member object*) |
base-iter it_
|
an iterator into the current view (exposition-only member object*) |
Member functions
| constructs an iterator (public member function) | |
| accesses the element (public member function) | |
| accesses an element by index (public member function) | |
| advances or decrements the underlying iterator (public member function) | |
Exposition-only function templates | |
replaces it_ with the beginning of the next view, if it_ is the end of current view(exposition-only member function*) | |
decrements it_ such that it points to the previous position(exposition-only member function*) | |
| advances the current position on given offset (exposition-only member function*) | |
| decrements the current position on given value (exposition-only member function*) | |
Non-member functions
| compares the underlying iterators (function) | |
| (C++26) |
performs iterator arithmetic (function) |
| (C++26) |
casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function) |
| (C++26) |
swaps the objects pointed to by two underlying iterators (function) |
Example
The preliminary version can be checked out on Compiler Explorer.
Run this code
#include <iostream> #include <iterator> #include <ranges> int main() { namespace views = std::views; static constexpr int p[]{1, 2, 3}; static constexpr auto e = {4, 5}; auto t = views::iota(6, 9); auto cat = views::concat(p, e, t); auto dog = views::concat(cat, cat); for (auto i{dog.begin()}; i != std::default_sentinel; ++i) std::cout << *i << ' '; std::cout << '\n'; }
Output:
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
References
- C++26 standard (ISO/IEC 14882:2026):
- 26.7.18.3 Class template
concat_view::iterator[range.concat.iterator]
- 26.7.18.3 Class template