Utility Span

group utility_span

Variables

constexpr std::size_t dynamic_extent = std::numeric_limits<std::size_t>::max()

A constant used to differentiate std::span of static and dynamic extent.

template<typename T>
struct is_host_span_supported_container : public std::false_type

template<typename T, typename Alloc>
struct is_host_span_supported_container<std::vector<T, Alloc>> : public std::true_type

template<typename T, typename Alloc>
struct is_host_span_supported_container<thrust::host_vector<T, Alloc>> : public std::true_type

template<typename T, typename Alloc>
struct is_host_span_supported_container<std::basic_string<T, std::char_traits<T>, Alloc>> : public std::true_type

template<typename T, std::size_t Extent = cudf::dynamic_extent>
struct host_span : public cudf::detail::span_base<T, cudf::dynamic_extent, host_span<T, cudf::dynamic_extent>>

#include <span.hpp>

C++20 std::span with reduced feature set.

Public Types

using base = cudf::detail::span_base<T, Extent, host_span<T, Extent>>

Base type.

Public Functions

inline constexpr host_span(T *data, std::size_t size, bool is_device_accessible)

Constructor from pointer and size

Parameters:

• data – Pointer to the first element in the span

• size – The number of elements in the span

• is_device_accessible – Whether the data is device accessible (e.g. pinned memory)

template<typename C>
inline constexpr host_span(C &in)

Constructor from container

Parameters:

in – The container to construct the span from

template<typename C>
inline constexpr host_span(C const &in)

Constructor from const container

Parameters:

in – The container to construct the span from

template<typename OtherT>
inline constexpr host_span(cudf::detail::host_vector<OtherT> &in)

Constructor from a host_vector

Parameters:

in – The host_vector to construct the span from

template<typename OtherT>
inline constexpr host_span(cudf::detail::host_vector<OtherT> const &in)

Constructor from a const host_vector

Parameters:

in – The host_vector to construct the span from

template<typename OtherT, std::size_t OtherExtent>
inline constexpr host_span(host_span<OtherT, OtherExtent> const &other) noexcept

Parameters:

other – The span to copy

inline constexpr base::reference operator[](size_type idx) const

Returns a reference to the idx-th element of the sequence.

The behavior is undefined if idx is out of range (i.e., if it is greater than or equal to size()).

Parameters:

idx – the index of the element to access

Returns:

A reference to the idx-th element of the sequence, i.e., data()[idx]

inline constexpr base::reference front() const

Returns a reference to the first element in the span.

Calling front on an empty span results in undefined behavior.

Returns:

Reference to the first element in the span

inline constexpr base::reference back() const

Returns a reference to the last element in the span.

Calling last on an empty span results in undefined behavior.

Returns:

Reference to the last element in the span

inline bool is_device_accessible() const

Returns whether the data is device accessible (e.g. pinned memory)

Returns:

true if the data is device accessible

inline constexpr host_span subspan(typename base::size_type offset, typename base::size_type count) const noexcept

Obtains a span that is a view over the count elements of this span starting at offset.

Parameters:

• offset – The offset of the first element in the subspan

• count – The number of elements in the subspan

Returns:

A subspan of the sequence, of requested count and offset

template<typename T>
struct is_device_span_supported_container : public std::false_type

template<typename T, typename Alloc>
struct is_device_span_supported_container<thrust::device_vector<T, Alloc>> : public std::true_type

template<typename T>
struct is_device_span_supported_container<rmm::device_vector<T>> : public std::true_type

template<typename T>
struct is_device_span_supported_container<rmm::device_uvector<T>> : public std::true_type

template<typename T, std::size_t Extent = cudf::dynamic_extent>
struct device_span : public cudf::detail::span_base<T, cudf::dynamic_extent, device_span<T, cudf::dynamic_extent>>

#include <span.hpp>

Device version of C++20 std::span with reduced feature set.

Public Types

using base = cudf::detail::span_base<T, Extent, device_span<T, Extent>>

Base type.

Public Functions

template<typename C>
inline constexpr device_span(C &in)

Constructor from container

Parameters:

in – The container to construct the span from

template<typename C>
inline constexpr device_span(C const &in)

Constructor from const container

Parameters:

in – The container to construct the span from

template<typename OtherT, std::size_t OtherExtent>
inline constexpr device_span(device_span<OtherT, OtherExtent> const &other) noexcept

Parameters:

other – The span to copy

inline constexpr base::reference operator[](size_type idx) const

Returns a reference to the idx-th element of the sequence.

The behavior is undefined if idx is out of range (i.e., if it is greater than or equal to size()).

Parameters:

idx – the index of the element to access

Returns:

A reference to the idx-th element of the sequence, i.e., data()[idx]

inline constexpr base::reference front() const

Returns a reference to the first element in the span.

Calling front on an empty span results in undefined behavior.

Returns:

Reference to the first element in the span

inline constexpr base::reference back() const

Returns a reference to the last element in the span.

Calling last on an empty span results in undefined behavior.

Returns:

Reference to the last element in the span

inline constexpr device_span subspan(typename base::size_type offset, typename base::size_type count) const noexcept

Obtains a span that is a view over the count elements of this span starting at offset.

Parameters:

• offset – The offset of the first element in the subspan

• count – The number of elements in the subspan

Returns:

A subspan of the sequence, of requested count and offset