[span.overview] (original) (raw)

A span is a view over a contiguous sequence of objects, the storage of which is owned by some other object.

All member functions of span have constant time complexity.

namespace std { template<class ElementType, size_t Extent = dynamic_extent> class span { public: using element_type = ElementType;using value_type = remove_cv_t<ElementType>;using size_type = size_t;using difference_type = ptrdiff_t;using pointer = element_type*;using const_pointer = const element_type*;using reference = element_type&;using const_reference = const element_type&;using iterator = implementation-defined; using const_iterator = std::const_iterator<iterator>;using reverse_iterator = std::reverse_iterator<iterator>;using const_reverse_iterator = std::const_iterator<reverse_iterator>;static constexpr size_type extent = Extent;constexpr span() noexcept;template<class It> constexpr explicit(extent != dynamic_extent) span(It first, size_type count);template<class It, class End> constexpr explicit(extent != dynamic_extent) span(It first, End last);template<size_t N> constexpr span(type_identity_t<element_type> (&arr)[N]) noexcept;template<class T, size_t N> constexpr span(array<T, N>& arr) noexcept;template<class T, size_t N> constexpr span(const array<T, N>& arr) noexcept;template<class R> constexpr explicit(extent != dynamic_extent) span(R&& r);constexpr explicit(extent != dynamic_extent) span(std::initializer_list<value_type> il);constexpr span(const span& other) noexcept = default;template<class OtherElementType, size_t OtherExtent> constexpr explicit(see below) span(const span<OtherElementType, OtherExtent>& s) noexcept;constexpr span& operator=(const span& other) noexcept = default;template<size_t Count> constexpr span<element_type, Count> first() const;template<size_t Count> constexpr span<element_type, Count> last() const;template<size_t Offset, size_t Count = dynamic_extent> constexpr span<element_type, _see below_> subspan() const;constexpr span<element_type, dynamic_extent> first(size_type count) const;constexpr span<element_type, dynamic_extent> last(size_type count) const;constexpr span<element_type, dynamic_extent> subspan( size_type offset, size_type count = dynamic_extent) const;constexpr size_type size() const noexcept;constexpr size_type size_bytes() const noexcept;constexpr bool empty() const noexcept;constexpr reference operator[](size_type idx) const;constexpr reference at(size_type idx) const; constexpr reference front() const;constexpr reference back() const;constexpr pointer data() const noexcept;constexpr iterator begin() const noexcept;constexpr iterator end() const noexcept;constexpr const_iterator cbegin() const noexcept { return begin(); } constexpr const_iterator cend() const noexcept { return end(); } constexpr reverse_iterator rbegin() const noexcept;constexpr reverse_iterator rend() const noexcept;constexpr const_reverse_iterator crbegin() const noexcept { return rbegin(); } constexpr const_reverse_iterator crend() const noexcept { return rend(); } private: pointer data_; size_type size_; };template<class It, class EndOrSize> span(It, EndOrSize) -> span<remove_reference_t<iter_reference_t<It>>,maybe-static-ext<EndOrSize>>;template<class T, size_t N> span(T (&)[N]) -> span<T, N>;template<class T, size_t N> span(array<T, N>&) -> span<T, N>;template<class T, size_t N> span(const array<T, N>&) -> span<const T, N>;template<class R> span(R&&) -> span<remove_reference_t<ranges::range_reference_t<R>>>;}

ElementType is required to be a complete object type that is not an abstract class type.

For a span s, any operation that invalidates a pointer in the range [s.data(), s.data() + s.size()) invalidates pointers, iterators, and references to elements of s.