std::ranges::Range
Defined in header <ranges>
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template< class T > concept Range = __RangeImpl<T&>; // exposition-only definition |
(1) | |
// exposition-only helper concept template< class T > |
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// exposition-only helper concept template< class T > |
(3) | |
1) The
Range
concept defines the requirements of a type that allows iteration over its elements by providing an iterator and sentinel that denote the elements of the range.
Formally, given an expression E such that decltype((E)) is T, T models Range only if
- [ranges::begin(E), ranges::end(E)) denotes a range, and
- both ranges::begin(E) and ranges::end(E) are amortized constant time and non-modifying, and
- if the type of ranges::begin(E) models
ForwardIterator
, ranges::begin(E) is equality-preserving (in other words, forward iterators support multi-pass algorithms)
ranges::begin(std::forward<T>(t))
and ranges::end(std::forward<T>(t))
do not require implicit expression variations.3) The exposition-only concept __ForwardingRange defines the requirements of a range such that a function can take it by value and return iterators obtained from it without danger of dangling.
Formally, given an expression E such that decltype((E)) is T and an lvalue t that denotes the same object as E, T models __ForwardingRange only if
- ranges::begin(E) and ranges::begin(t) are expression-equivalent (have the same effect when evaluated, and both or neither are potentially-throwing, both or neither are constant subexpressions), and
- ranges::end(E) and ranges::end(t) are expression-equivalent, and
- the validity of iterators obtained from the object denoted by E is not tied to the lifetime of that object.