Difference between revisions of "cpp/ranges/contiguous range"
From cppreference.com
m (fmt.) |
m (+ more cases [example]) |
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Line 24: | Line 24: | ||
#include <deque> | #include <deque> | ||
#include <list> | #include <list> | ||
+ | #include <mdspan> | ||
#include <ranges> | #include <ranges> | ||
#include <set> | #include <set> | ||
+ | #include <span> | ||
+ | #include <string_view> | ||
#include <valarray> | #include <valarray> | ||
#include <vector> | #include <vector> | ||
Line 31: | Line 34: | ||
template<typename T> | template<typename T> | ||
concept CR = std::ranges::contiguous_range<T>; | concept CR = std::ranges::contiguous_range<T>; | ||
+ | |||
+ | // zstring being a ranges::contiguous_range doesn't have to be a ranges::sized_range | ||
+ | struct zstring | ||
+ | { | ||
+ | struct sentinel | ||
+ | { | ||
+ | friend constexpr bool operator==(const char* str, sentinel) noexcept | ||
+ | { return *str == '\0'; } | ||
+ | }; | ||
+ | |||
+ | const char* str; | ||
+ | |||
+ | const char* begin() const noexcept { return str; } | ||
+ | sentinel end() const noexcept { return {}; } | ||
+ | }; | ||
int main() | int main() | ||
Line 43: | Line 61: | ||
not CR<std::list<int>> and | not CR<std::list<int>> and | ||
not CR<std::set<int>> and | not CR<std::set<int>> and | ||
− | CR<std::array<std::list<int>,42>> | + | CR<std::array<std::list<int>,42>> and |
+ | CR<std::string_view> and | ||
+ | CR<zstring> and | ||
+ | CR<std::span<const int>> and | ||
+ | not CR<std::mdspan<int, std::dims<1>>> | ||
); | ); | ||
} | } |
Latest revision as of 00:59, 3 November 2024
Defined in header <ranges>
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template< class T > concept contiguous_range = |
(since C++20) | |
The contiguous_range
concept is a refinement of range
for which ranges::begin returns a model of contiguous_iterator
and the customization point ranges::data is usable.
[edit] Semantic requirements
T
models contiguous_range
only if given an expression e
such that decltype((e)) is T&, std::to_address(ranges::begin(e)) == ranges::data(e).
[edit] Example
Run this code
#include <array> #include <deque> #include <list> #include <mdspan> #include <ranges> #include <set> #include <span> #include <string_view> #include <valarray> #include <vector> template<typename T> concept CR = std::ranges::contiguous_range<T>; // zstring being a ranges::contiguous_range doesn't have to be a ranges::sized_range struct zstring { struct sentinel { friend constexpr bool operator==(const char* str, sentinel) noexcept { return *str == '\0'; } }; const char* str; const char* begin() const noexcept { return str; } sentinel end() const noexcept { return {}; } }; int main() { int a[4]; static_assert( CR<std::vector<int>> and not CR<std::vector<bool>> and not CR<std::deque<int>> and CR<std::valarray<int>> and CR<decltype(a)> and not CR<std::list<int>> and not CR<std::set<int>> and CR<std::array<std::list<int>,42>> and CR<std::string_view> and CR<zstring> and CR<std::span<const int>> and not CR<std::mdspan<int, std::dims<1>>> ); }
[edit] See also
(C++20) |
specifies that a range knows its size in constant time (concept) |
(C++20) |
specifies a range whose iterator type satisfies random_access_iterator (concept) |