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f76f739805
GSL/include/span.h
Neil MacIntosh f76f739805 Addressing #178: wrong return type for function.
2015-11-30 18:20:14 -08:00

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///////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
//
// This code is licensed under the MIT License (MIT).
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
///////////////////////////////////////////////////////////////////////////////
#pragma once
#ifndef GSL_SPAN_H
#define GSL_SPAN_H
#include "gsl_assert.h"
#include "gsl_util.h"
#include <algorithm>
#include <array>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <iterator>
#include <limits>
#include <new>
#include <numeric>
#include <stdexcept>
#include <type_traits>
#include <utility>
#ifdef _MSC_VER
// turn off some warnings that are noisy about our Expects statements
#pragma warning(push)
#pragma warning(disable : 4127) // conditional expression is constant
// No MSVC does constexpr fully yet
#pragma push_macro("constexpr")
#define constexpr
// VS 2013 workarounds
#if _MSC_VER <= 1800
#define GSL_MSVC_HAS_VARIADIC_CTOR_BUG
#define GSL_MSVC_NO_SUPPORT_FOR_MOVE_CTOR_DEFAULT
// noexcept is not understood
#ifndef GSL_THROWS_ON_CONTRACT_VIOLATION
#pragma push_macro("noexcept")
#define noexcept /* nothing */
#endif
// turn off some misguided warnings
#pragma warning(push)
#pragma warning(disable : 4351) // warns about newly introduced aggregate initializer behavior
#pragma warning(disable : 4512) // warns that assignment op could not be generated
#endif // _MSC_VER <= 1800
#endif // _MSC_VER
#ifdef GSL_THROW_ON_CONTRACT_VIOLATION
#ifdef _MSC_VER
#pragma push_macro("noexcept")
#endif
#define noexcept /* nothing */
#endif // GSL_THROW_ON_CONTRACT_VIOLATION
namespace gsl
{
/*
** begin definitions of index and bounds
*/
namespace details
{
template <typename SizeType>
struct SizeTypeTraits
{
static const SizeType max_value = std::numeric_limits<SizeType>::max();
};
template <typename... Ts>
class are_integral : public std::integral_constant<bool, true>
{
};
template <typename T, typename... Ts>
class are_integral<T, Ts...>
: public std::integral_constant<bool,
std::is_integral<T>::value && are_integral<Ts...>::value>
{
};
}
template <size_t Rank>
class index final
{
static_assert(Rank > 0, "Rank must be greater than 0!");
template <size_t OtherRank>
friend class index;
public:
static const size_t rank = Rank;
using value_type = std::ptrdiff_t;
using size_type = value_type;
using reference = std::add_lvalue_reference_t<value_type>;
using const_reference = std::add_lvalue_reference_t<std::add_const_t<value_type>>;
constexpr index() noexcept {}
constexpr index(const value_type (&values)[Rank]) noexcept
{
std::copy(values, values + Rank, elems);
}
#ifdef GSL_MSVC_HAS_VARIADIC_CTOR_BUG
template <
typename T, typename... Ts,
typename = std::enable_if_t<((sizeof...(Ts) + 1) == Rank) && std::is_integral<T>::value &&
details::are_integral<Ts...>::value>>
constexpr index(T t, Ts... ds)
: index({narrow_cast<value_type>(t), narrow_cast<value_type>(ds)...})
{
}
#else
template <typename... Ts, typename = std::enable_if_t<(sizeof...(Ts) == Rank) &&
details::are_integral<Ts...>::value>>
constexpr index(Ts... ds) noexcept : elems{narrow_cast<value_type>(ds)...}
{
}
#endif
constexpr index(const index& other) noexcept = default;
constexpr index& operator=(const index& rhs) noexcept = default;
// Preconditions: component_idx < rank
constexpr reference operator[](size_t component_idx)
{
Expects(component_idx < Rank); // Component index must be less than rank
return elems[component_idx];
}
// Preconditions: component_idx < rank
constexpr const_reference operator[](size_t component_idx) const noexcept
{
Expects(component_idx < Rank); // Component index must be less than rank
return elems[component_idx];
}
constexpr bool operator==(const index& rhs) const noexcept
{
return std::equal(elems, elems + rank, rhs.elems);
}
constexpr bool operator!=(const index& rhs) const noexcept { return !(this == rhs); }
constexpr index operator+() const noexcept { return *this; }
constexpr index operator-() const noexcept
{
index ret = *this;
std::transform(ret, ret + rank, ret, std::negate<value_type>{});
return ret;
}
constexpr index operator+(const index& rhs) const noexcept
{
index ret = *this;
ret += rhs;
return ret;
}
constexpr index operator-(const index& rhs) const noexcept
{
index ret = *this;
ret -= rhs;
return ret;
}
constexpr index& operator+=(const index& rhs) noexcept
{
std::transform(elems, elems + rank, rhs.elems, elems, std::plus<value_type>{});
return *this;
}
constexpr index& operator-=(const index& rhs) noexcept
{
std::transform(elems, elems + rank, rhs.elems, elems, std::minus<value_type>{});
return *this;
}
constexpr index operator*(value_type v) const noexcept
{
index ret = *this;
ret *= v;
return ret;
}
constexpr index operator/(value_type v) const noexcept
{
index ret = *this;
ret /= v;
return ret;
}
friend constexpr index operator*(value_type v, const index& rhs) noexcept
{
return rhs * v;
}
constexpr index& operator*=(value_type v) noexcept
{
std::transform(elems, elems + rank, elems,
[v](value_type x) { return std::multiplies<value_type>{}(x, v); });
return *this;
}
constexpr index& operator/=(value_type v) noexcept
{
std::transform(elems, elems + rank, elems,
[v](value_type x) { return std::divides<value_type>{}(x, v); });
return *this;
}
private:
value_type elems[Rank] = {};
};
#ifndef _MSC_VER
struct static_bounds_dynamic_range_t
{
template <typename T, typename Dummy = std::enable_if_t<std::is_integral<T>::value>>
constexpr operator T() const noexcept
{
return narrow_cast<T>(-1);
}
template <typename T, typename Dummy = std::enable_if_t<std::is_integral<T>::value>>
constexpr bool operator==(T other) const noexcept
{
return narrow_cast<T>(-1) == other;
}
template <typename T, typename Dummy = std::enable_if_t<std::is_integral<T>::value>>
constexpr bool operator!=(T other) const noexcept
{
return narrow_cast<T>(-1) != other;
}
};
template <typename T, typename Dummy = std::enable_if_t<std::is_integral<T>::value>>
constexpr bool operator==(T left, static_bounds_dynamic_range_t right) noexcept
{
return right == left;
}
template <typename T, typename Dummy = std::enable_if_t<std::is_integral<T>::value>>
constexpr bool operator!=(T left, static_bounds_dynamic_range_t right) noexcept
{
return right != left;
}
constexpr static_bounds_dynamic_range_t dynamic_range{};
#else
const std::ptrdiff_t dynamic_range = -1;
#endif
struct generalized_mapping_tag
{
};
struct contiguous_mapping_tag : generalized_mapping_tag
{
};
namespace details
{
template <std::ptrdiff_t Left, std::ptrdiff_t Right>
struct LessThan
{
static const bool value = Left < Right;
};
template <std::ptrdiff_t... Ranges>
struct BoundsRanges
{
using size_type = std::ptrdiff_t;
static const size_type Depth = 0;
static const size_type DynamicNum = 0;
static const size_type CurrentRange = 1;
static const size_type TotalSize = 1;
// TODO : following signature is for work around VS bug
template <typename OtherRange>
BoundsRanges(const OtherRange&, bool /* firstLevel */)
{
}
BoundsRanges(const BoundsRanges&) = default;
BoundsRanges& operator=(const BoundsRanges&) = default;
BoundsRanges(const std::ptrdiff_t* const) {}
BoundsRanges() = default;
template <typename T, size_t Dim>
void serialize(T&) const
{
}
template <typename T, size_t Dim>
size_type linearize(const T&) const
{
return 0;
}
template <typename T, size_t Dim>
size_type contains(const T&) const
{
return -1;
}
size_type elementNum(size_t) const noexcept { return 0; }
size_type totalSize() const noexcept { return TotalSize; }
bool operator==(const BoundsRanges&) const noexcept { return true; }
};
template <std::ptrdiff_t... RestRanges>
struct BoundsRanges<dynamic_range, RestRanges...> : BoundsRanges<RestRanges...>
{
using Base = BoundsRanges<RestRanges...>;
using size_type = std::ptrdiff_t;
static const size_t Depth = Base::Depth + 1;
static const size_t DynamicNum = Base::DynamicNum + 1;
static const size_type CurrentRange = dynamic_range;
static const size_type TotalSize = dynamic_range;
const size_type m_bound;
BoundsRanges(const BoundsRanges&) = default;
BoundsRanges(const std::ptrdiff_t* const arr)
: Base(arr + 1), m_bound(*arr * this->Base::totalSize())
{
Expects(0 <= *arr);
}
BoundsRanges() : m_bound(0) {}
template <std::ptrdiff_t OtherRange, std::ptrdiff_t... RestOtherRanges>
BoundsRanges(const BoundsRanges<OtherRange, RestOtherRanges...>& other,
bool /* firstLevel */ = true)
: Base(static_cast<const BoundsRanges<RestOtherRanges...>&>(other), false)
, m_bound(other.totalSize())
{
}
template <typename T, size_t Dim = 0>
void serialize(T& arr) const
{
arr[Dim] = elementNum();
this->Base::template serialize<T, Dim + 1>(arr);
}
template <typename T, size_t Dim = 0>
size_type linearize(const T& arr) const
{
const size_type index = this->Base::totalSize() * arr[Dim];
Expects(index < m_bound);
return index + this->Base::template linearize<T, Dim + 1>(arr);
}
template <typename T, size_t Dim = 0>
size_type contains(const T& arr) const
{
const ptrdiff_t last = this->Base::template contains<T, Dim + 1>(arr);
if (last == -1) return -1;
const ptrdiff_t cur = this->Base::totalSize() * arr[Dim];
return cur < m_bound ? cur + last : -1;
}
size_type totalSize() const noexcept { return m_bound; }
size_type elementNum() const noexcept { return totalSize() / this->Base::totalSize(); }
size_type elementNum(size_t dim) const noexcept
{
if (dim > 0)
return this->Base::elementNum(dim - 1);
else
return elementNum();
}
bool operator==(const BoundsRanges& rhs) const noexcept
{
return m_bound == rhs.m_bound &&
static_cast<const Base&>(*this) == static_cast<const Base&>(rhs);
}
};
template <std::ptrdiff_t CurRange, std::ptrdiff_t... RestRanges>
struct BoundsRanges<CurRange, RestRanges...> : BoundsRanges<RestRanges...>
{
using Base = BoundsRanges<RestRanges...>;
using size_type = std::ptrdiff_t;
static const size_t Depth = Base::Depth + 1;
static const size_t DynamicNum = Base::DynamicNum;
static const size_type CurrentRange = CurRange;
static const size_type TotalSize =
Base::TotalSize == dynamic_range ? dynamic_range : CurrentRange * Base::TotalSize;
BoundsRanges(const BoundsRanges&) = default;
BoundsRanges(const std::ptrdiff_t* const arr) : Base(arr) {}
BoundsRanges() = default;
template <std::ptrdiff_t OtherRange, std::ptrdiff_t... RestOtherRanges>
BoundsRanges(const BoundsRanges<OtherRange, RestOtherRanges...>& other,
bool firstLevel = true)
: Base(static_cast<const BoundsRanges<RestOtherRanges...>&>(other), false)
{
(void) firstLevel;
}
template <typename T, size_t Dim = 0>
void serialize(T& arr) const
{
arr[Dim] = elementNum();
this->Base::template serialize<T, Dim + 1>(arr);
}
template <typename T, size_t Dim = 0>
size_type linearize(const T& arr) const
{
Expects(arr[Dim] < CurrentRange); // Index is out of range
return this->Base::totalSize() * arr[Dim] +
this->Base::template linearize<T, Dim + 1>(arr);
}
template <typename T, size_t Dim = 0>
size_type contains(const T& arr) const
{
if (arr[Dim] >= CurrentRange) return -1;
const size_type last = this->Base::template contains<T, Dim + 1>(arr);
if (last == -1) return -1;
return this->Base::totalSize() * arr[Dim] + last;
}
size_type totalSize() const noexcept { return CurrentRange * this->Base::totalSize(); }
size_type elementNum() const noexcept { return CurrentRange; }
size_type elementNum(size_t dim) const noexcept
{
if (dim > 0)
return this->Base::elementNum(dim - 1);
else
return elementNum();
}
bool operator==(const BoundsRanges& rhs) const noexcept
{
return static_cast<const Base&>(*this) == static_cast<const Base&>(rhs);
}
};
template <typename SourceType, typename TargetType>
struct BoundsRangeConvertible
: public std::integral_constant<bool, (SourceType::TotalSize >= TargetType::TotalSize ||
TargetType::TotalSize == dynamic_range ||
SourceType::TotalSize == dynamic_range ||
TargetType::TotalSize == 0)>
{
};
template <typename TypeChain>
struct TypeListIndexer
{
const TypeChain& obj_;
TypeListIndexer(const TypeChain& obj) : obj_(obj) {}
template <size_t N>
const TypeChain& getObj(std::true_type)
{
return obj_;
}
template <size_t N, typename MyChain = TypeChain, typename MyBase = typename MyChain::Base>
auto getObj(std::false_type)
-> decltype(TypeListIndexer<MyBase>(static_cast<const MyBase&>(obj_)).template get<N>())
{
return TypeListIndexer<MyBase>(static_cast<const MyBase&>(obj_)).template get<N>();
}
template <size_t N>
auto get() -> decltype(getObj<N - 1>(std::integral_constant<bool, N == 0>()))
{
return getObj<N - 1>(std::integral_constant<bool, N == 0>());
}
};
template <typename TypeChain>
TypeListIndexer<TypeChain> createTypeListIndexer(const TypeChain& obj)
{
return TypeListIndexer<TypeChain>(obj);
}
template <size_t Rank, bool Enabled = (Rank > 1),
typename Ret = std::enable_if_t<Enabled, index<Rank - 1>>>
constexpr Ret shift_left(const index<Rank>& other) noexcept
{
Ret ret{};
for (size_t i = 0; i < Rank - 1; ++i) {
ret[i] = other[i + 1];
}
return ret;
}
}
template <typename IndexType>
class bounds_iterator;
template <std::ptrdiff_t... Ranges>
class static_bounds
{
public:
static_bounds(const details::BoundsRanges<Ranges...>&) {}
};
template <std::ptrdiff_t FirstRange, std::ptrdiff_t... RestRanges>
class static_bounds<FirstRange, RestRanges...>
{
using MyRanges = details::BoundsRanges<FirstRange, RestRanges...>;
MyRanges m_ranges;
constexpr static_bounds(const MyRanges& range) : m_ranges(range) {}
template <std::ptrdiff_t... OtherRanges>
friend class static_bounds;
public:
static const size_t rank = MyRanges::Depth;
static const size_t dynamic_rank = MyRanges::DynamicNum;
static const std::ptrdiff_t static_size = MyRanges::TotalSize;
using size_type = std::ptrdiff_t;
using index_type = index<rank>;
using const_index_type = std::add_const_t<index_type>;
using iterator = bounds_iterator<const_index_type>;
using const_iterator = bounds_iterator<const_index_type>;
using difference_type = std::ptrdiff_t;
using sliced_type = static_bounds<RestRanges...>;
using mapping_type = contiguous_mapping_tag;
constexpr static_bounds(const static_bounds&) = default;
template <typename SourceType, typename TargetType, size_t Rank>
struct BoundsRangeConvertible2;
template <size_t Rank, typename SourceType, typename TargetType,
typename Ret = BoundsRangeConvertible2<typename SourceType::Base,
typename TargetType::Base, Rank>>
static auto helpBoundsRangeConvertible(SourceType, TargetType, std::true_type) -> Ret;
template <size_t Rank, typename SourceType, typename TargetType>
static auto helpBoundsRangeConvertible(SourceType, TargetType, ...) -> std::false_type;
template <typename SourceType, typename TargetType, size_t Rank>
struct BoundsRangeConvertible2
: decltype(helpBoundsRangeConvertible<Rank - 1>(
SourceType(), TargetType(),
std::integral_constant<bool,
SourceType::Depth == TargetType::Depth &&
(SourceType::CurrentRange == TargetType::CurrentRange ||
TargetType::CurrentRange == dynamic_range ||
SourceType::CurrentRange == dynamic_range)>()))
{
};
template <typename SourceType, typename TargetType>
struct BoundsRangeConvertible2<SourceType, TargetType, 0> : std::true_type
{
};
template <typename SourceType, typename TargetType, std::ptrdiff_t Rank = TargetType::Depth>
struct BoundsRangeConvertible
: decltype(helpBoundsRangeConvertible<Rank - 1>(
SourceType(), TargetType(),
std::integral_constant<bool,
SourceType::Depth == TargetType::Depth &&
(!details::LessThan<SourceType::CurrentRange,
TargetType::CurrentRange>::value ||
TargetType::CurrentRange == dynamic_range ||
SourceType::CurrentRange == dynamic_range)>()))
{
};
template <typename SourceType, typename TargetType>
struct BoundsRangeConvertible<SourceType, TargetType, 0> : std::true_type
{
};
template <std::ptrdiff_t... Ranges,
typename = std::enable_if_t<details::BoundsRangeConvertible<
details::BoundsRanges<Ranges...>,
details::BoundsRanges<FirstRange, RestRanges...>>::value>>
constexpr static_bounds(const static_bounds<Ranges...>& other) : m_ranges(other.m_ranges)
{
Expects((MyRanges::DynamicNum == 0 && details::BoundsRanges<Ranges...>::DynamicNum == 0) ||
MyRanges::DynamicNum > 0 || other.m_ranges.totalSize() >= m_ranges.totalSize());
}
constexpr static_bounds(std::initializer_list<size_type> il)
: m_ranges(static_cast<const std::ptrdiff_t*>(il.begin()))
{
// Size of the initializer list must match the rank of the array
Expects((MyRanges::DynamicNum == 0 && il.size() == 1 && *il.begin() == static_size) ||
MyRanges::DynamicNum == il.size());
// Size of the range must be less than the max element of the size type
Expects(m_ranges.totalSize() <= PTRDIFF_MAX);
}
constexpr static_bounds() = default;
constexpr static_bounds& operator=(const static_bounds& otherBounds)
{
new (&m_ranges) MyRanges(otherBounds.m_ranges);
return *this;
}
constexpr sliced_type slice() const noexcept
{
return sliced_type{static_cast<const details::BoundsRanges<RestRanges...>&>(m_ranges)};
}
constexpr size_type stride() const noexcept { return rank > 1 ? slice().size() : 1; }
constexpr size_type size() const noexcept { return m_ranges.totalSize(); }
constexpr size_type total_size() const noexcept { return m_ranges.totalSize(); }
constexpr size_type linearize(const index_type& idx) const { return m_ranges.linearize(idx); }
constexpr bool contains(const index_type& idx) const noexcept
{
return m_ranges.contains(idx) != -1;
}
constexpr size_type operator[](size_t index) const noexcept
{
return m_ranges.elementNum(index);
}
template <size_t Dim = 0>
constexpr size_type extent() const noexcept
{
static_assert(Dim < rank,
"dimension should be less than rank (dimension count starts from 0)");
return details::createTypeListIndexer(m_ranges).template get<Dim>().elementNum();
}
template <typename IntType>
constexpr size_type extent(IntType dim) const noexcept
{
static_assert(std::is_integral<IntType>::value,
"Dimension parameter must be supplied as an integral type.");
auto real_dim = narrow_cast<size_t>(dim);
Expects(real_dim < rank);
return m_ranges.elementNum(real_dim);
}
constexpr index_type index_bounds() const noexcept
{
size_type extents[rank] = {};
m_ranges.serialize(extents);
return {extents};
}
template <std::ptrdiff_t... Ranges>
constexpr bool operator==(const static_bounds<Ranges...>& rhs) const noexcept
{
return this->size() == rhs.size();
}
template <std::ptrdiff_t... Ranges>
constexpr bool operator!=(const static_bounds<Ranges...>& rhs) const noexcept
{
return !(*this == rhs);
}
constexpr const_iterator begin() const noexcept { return const_iterator(*this, index_type{}); }
constexpr const_iterator end() const noexcept
{
return const_iterator(*this, this->index_bounds());
}
};
template <size_t Rank>
class strided_bounds
{
template <size_t OtherRank>
friend class strided_bounds;
public:
static const size_t rank = Rank;
using value_type = std::ptrdiff_t;
using reference = std::add_lvalue_reference_t<value_type>;
using const_reference = std::add_const_t<reference>;
using size_type = value_type;
using difference_type = value_type;
using index_type = index<rank>;
using const_index_type = std::add_const_t<index_type>;
using iterator = bounds_iterator<const_index_type>;
using const_iterator = bounds_iterator<const_index_type>;
static const value_type dynamic_rank = rank;
static const value_type static_size = dynamic_range;
using sliced_type = std::conditional_t<rank != 0, strided_bounds<rank - 1>, void>;
using mapping_type = generalized_mapping_tag;
constexpr strided_bounds(const strided_bounds&) noexcept = default;
constexpr strided_bounds& operator=(const strided_bounds&) noexcept = default;
constexpr strided_bounds(const value_type (&values)[rank], index_type strides)
: m_extents(values), m_strides(std::move(strides))
{
}
constexpr strided_bounds(const index_type& extents, const index_type& strides) noexcept
: m_extents(extents),
m_strides(strides)
{
}
constexpr index_type strides() const noexcept { return m_strides; }
constexpr size_type total_size() const noexcept
{
size_type ret = 0;
for (size_t i = 0; i < rank; ++i) {
ret += (m_extents[i] - 1) * m_strides[i];
}
return ret + 1;
}
constexpr size_type size() const noexcept
{
size_type ret = 1;
for (size_t i = 0; i < rank; ++i) {
ret *= m_extents[i];
}
return ret;
}
constexpr bool contains(const index_type& idx) const noexcept
{
for (size_t i = 0; i < rank; ++i) {
if (idx[i] < 0 || idx[i] >= m_extents[i]) return false;
}
return true;
}
constexpr size_type linearize(const index_type& idx) const noexcept
{
size_type ret = 0;
for (size_t i = 0; i < rank; i++) {
Expects(idx[i] < m_extents[i]); // index is out of bounds of the array
ret += idx[i] * m_strides[i];
}
return ret;
}
constexpr size_type stride() const noexcept { return m_strides[0]; }
template <bool Enabled = (rank > 1), typename Ret = std::enable_if_t<Enabled, sliced_type>>
constexpr sliced_type slice() const
{
return {details::shift_left(m_extents), details::shift_left(m_strides)};
}
template <size_t Dim = 0>
constexpr size_type extent() const noexcept
{
static_assert(Dim < Rank,
"dimension should be less than rank (dimension count starts from 0)");
return m_extents[Dim];
}
constexpr index_type index_bounds() const noexcept { return m_extents; }
constexpr const_iterator begin() const noexcept { return const_iterator{*this, index_type{}}; }
constexpr const_iterator end() const noexcept { return const_iterator{*this, index_bounds()}; }
private:
index_type m_extents;
index_type m_strides;
};
template <typename T>
struct is_bounds : std::integral_constant<bool, false>
{
};
template <std::ptrdiff_t... Ranges>
struct is_bounds<static_bounds<Ranges...>> : std::integral_constant<bool, true>
{
};
template <size_t Rank>
struct is_bounds<strided_bounds<Rank>> : std::integral_constant<bool, true>
{
};
template <typename IndexType>
class bounds_iterator : public std::iterator<std::random_access_iterator_tag, IndexType>
{
private:
using Base = std::iterator<std::random_access_iterator_tag, IndexType>;
public:
static const size_t rank = IndexType::rank;
using typename Base::reference;
using typename Base::pointer;
using typename Base::difference_type;
using typename Base::value_type;
using index_type = value_type;
using index_size_type = typename IndexType::value_type;
template <typename Bounds>
explicit bounds_iterator(const Bounds& bnd, value_type curr) noexcept
: boundary_(bnd.index_bounds()),
curr_(std::move(curr))
{
static_assert(is_bounds<Bounds>::value, "Bounds type must be provided");
}
constexpr reference operator*() const noexcept { return curr_; }
constexpr pointer operator->() const noexcept { return &curr_; }
constexpr bounds_iterator& operator++() noexcept
{
for (size_t i = rank; i-- > 0;) {
if (curr_[i] < boundary_[i] - 1) {
curr_[i]++;
return *this;
}
curr_[i] = 0;
}
// If we're here we've wrapped over - set to past-the-end.
curr_ = boundary_;
return *this;
}
constexpr bounds_iterator operator++(int) noexcept
{
auto ret = *this;
++(*this);
return ret;
}
constexpr bounds_iterator& operator--() noexcept
{
if (!less(curr_, boundary_)) {
// if at the past-the-end, set to last element
for (size_t i = 0; i < rank; ++i) {
curr_[i] = boundary_[i] - 1;
}
return *this;
}
for (size_t i = rank; i-- > 0;) {
if (curr_[i] >= 1) {
curr_[i]--;
return *this;
}
curr_[i] = boundary_[i] - 1;
}
// If we're here the preconditions were violated
// "pre: there exists s such that r == ++s"
Expects(false);
return *this;
}
constexpr bounds_iterator operator--(int) noexcept
{
auto ret = *this;
--(*this);
return ret;
}
constexpr bounds_iterator operator+(difference_type n) const noexcept
{
bounds_iterator ret{*this};
return ret += n;
}
constexpr bounds_iterator& operator+=(difference_type n) noexcept
{
auto linear_idx = linearize(curr_) + n;
std::remove_const_t<value_type> stride = 0;
stride[rank - 1] = 1;
for (size_t i = rank - 1; i-- > 0;) {
stride[i] = stride[i + 1] * boundary_[i + 1];
}
for (size_t i = 0; i < rank; ++i) {
curr_[i] = linear_idx / stride[i];
linear_idx = linear_idx % stride[i];
}
// index is out of bounds of the array
Expects(!less(curr_, index_type{}) && !less(boundary_, curr_));
return *this;
}
constexpr bounds_iterator operator-(difference_type n) const noexcept
{
bounds_iterator ret{*this};
return ret -= n;
}
constexpr bounds_iterator& operator-=(difference_type n) noexcept { return * this += -n; }
constexpr difference_type operator-(const bounds_iterator& rhs) const noexcept
{
return linearize(curr_) - linearize(rhs.curr_);
}
constexpr value_type operator[](difference_type n) const noexcept { return *(*this + n); }
constexpr bool operator==(const bounds_iterator& rhs) const noexcept
{
return curr_ == rhs.curr_;
}
constexpr bool operator!=(const bounds_iterator& rhs) const noexcept { return !(*this == rhs); }
constexpr bool operator<(const bounds_iterator& rhs) const noexcept
{
return less(curr_, rhs.curr_);
}
constexpr bool operator<=(const bounds_iterator& rhs) const noexcept { return !(rhs < *this); }
constexpr bool operator>(const bounds_iterator& rhs) const noexcept { return rhs < *this; }
constexpr bool operator>=(const bounds_iterator& rhs) const noexcept { return !(rhs > *this); }
void swap(bounds_iterator& rhs) noexcept
{
std::swap(boundary_, rhs.boundary_);
std::swap(curr_, rhs.curr_);
}
private:
constexpr bool less(index_type& one, index_type& other) const noexcept
{
for (size_t i = 0; i < rank; ++i) {
if (one[i] < other[i]) return true;
}
return false;
}
constexpr index_size_type linearize(const value_type& idx) const noexcept
{
// TODO: Smarter impl.
// Check if past-the-end
index_size_type multiplier = 1;
index_size_type res = 0;
if (!less(idx, boundary_)) {
res = 1;
for (size_t i = rank; i-- > 0;) {
res += (idx[i] - 1) * multiplier;
multiplier *= boundary_[i];
}
}
else
{
for (size_t i = rank; i-- > 0;) {
res += idx[i] * multiplier;
multiplier *= boundary_[i];
}
}
return res;
}
value_type boundary_;
std::remove_const_t<value_type> curr_;
};
template <typename IndexType>
bounds_iterator<IndexType> operator+(typename bounds_iterator<IndexType>::difference_type n,
const bounds_iterator<IndexType>& rhs) noexcept
{
return rhs + n;
}
namespace details
{
template <typename Bounds>
constexpr std::enable_if_t<
std::is_same<typename Bounds::mapping_type, generalized_mapping_tag>::value,
typename Bounds::index_type>
make_stride(const Bounds& bnd) noexcept
{
return bnd.strides();
}
// Make a stride vector from bounds, assuming contiguous memory.
template <typename Bounds>
constexpr std::enable_if_t<
std::is_same<typename Bounds::mapping_type, contiguous_mapping_tag>::value,
typename Bounds::index_type>
make_stride(const Bounds& bnd) noexcept
{
auto extents = bnd.index_bounds();
typename Bounds::size_type stride[Bounds::rank] = {};
stride[Bounds::rank - 1] = 1;
for (size_t i = 1; i < Bounds::rank; ++i) {
stride[Bounds::rank - i - 1] = stride[Bounds::rank - i] * extents[Bounds::rank - i];
}
return {stride};
}
template <typename BoundsSrc, typename BoundsDest>
void verifyBoundsReshape(const BoundsSrc& src, const BoundsDest& dest)
{
static_assert(is_bounds<BoundsSrc>::value && is_bounds<BoundsDest>::value,
"The src type and dest type must be bounds");
static_assert(std::is_same<typename BoundsSrc::mapping_type, contiguous_mapping_tag>::value,
"The source type must be a contiguous bounds");
static_assert(BoundsDest::static_size == dynamic_range ||
BoundsSrc::static_size == dynamic_range ||
BoundsDest::static_size == BoundsSrc::static_size,
"The source bounds must have same size as dest bounds");
Expects(src.size() == dest.size());
}
} // namespace details
template <typename Span>
class contiguous_span_iterator;
template <typename Span>
class general_span_iterator;
enum class byte : std::uint8_t
{
};
template <std::ptrdiff_t DimSize = dynamic_range>
struct dim
{
static const std::ptrdiff_t value = DimSize;
};
template <>
struct dim<dynamic_range>
{
static const std::ptrdiff_t value = dynamic_range;
const std::ptrdiff_t dvalue;
dim(std::ptrdiff_t size) : dvalue(size) {}
};
template <typename ValueType, std::ptrdiff_t FirstDimension = dynamic_range,
std::ptrdiff_t... RestDimensions>
class span;
template <typename ValueType, size_t Rank>
class strided_span;
namespace details
{
template <typename T, typename = std::true_type>
struct SpanTypeTraits
{
using value_type = T;
using size_type = size_t;
};
template <typename Traits>
struct SpanTypeTraits<Traits, typename std::is_reference<typename Traits::span_traits&>::type>
{
using value_type = typename Traits::span_traits::value_type;
using size_type = typename Traits::span_traits::size_type;
};
template <typename T, std::ptrdiff_t... Ranks>
struct SpanArrayTraits
{
using type = span<T, Ranks...>;
using value_type = T;
using bounds_type = static_bounds<Ranks...>;
using pointer = T*;
using reference = T&;
};
template <typename T, std::ptrdiff_t N, std::ptrdiff_t... Ranks>
struct SpanArrayTraits<T[N], Ranks...> : SpanArrayTraits<T, Ranks..., N>
{
};
template <typename BoundsType>
BoundsType newBoundsHelperImpl(std::ptrdiff_t totalSize, std::true_type) // dynamic size
{
Expects(totalSize >= 0 && totalSize <= PTRDIFF_MAX);
return BoundsType{totalSize};
}
template <typename BoundsType>
BoundsType newBoundsHelperImpl(std::ptrdiff_t totalSize, std::false_type) // static size
{
Expects(BoundsType::static_size <= totalSize);
return {};
}
template <typename BoundsType>
BoundsType newBoundsHelper(std::ptrdiff_t totalSize)
{
static_assert(BoundsType::dynamic_rank <= 1, "dynamic rank must less or equal to 1");
return newBoundsHelperImpl<BoundsType>(
totalSize, std::integral_constant<bool, BoundsType::dynamic_rank == 1>());
}
struct Sep
{
};
template <typename T, typename... Args>
T static_as_span_helper(Sep, Args... args)
{
return T{narrow_cast<typename T::size_type>(args)...};
}
template <typename T, typename Arg, typename... Args>
std::enable_if_t<
!std::is_same<Arg, dim<dynamic_range>>::value && !std::is_same<Arg, Sep>::value, T>
static_as_span_helper(Arg, Args... args)
{
return static_as_span_helper<T>(args...);
}
template <typename T, typename... Args>
T static_as_span_helper(dim<dynamic_range> val, Args... args)
{
return static_as_span_helper<T>(args..., val.dvalue);
}
template <typename... Dimensions>
struct static_as_span_static_bounds_helper
{
using type = static_bounds<(Dimensions::value)...>;
};
template <typename T>
struct is_span_oracle : std::false_type
{
};
template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
struct is_span_oracle<span<ValueType, FirstDimension, RestDimensions...>> : std::true_type
{
};
template <typename ValueType, std::ptrdiff_t Rank>
struct is_span_oracle<strided_span<ValueType, Rank>> : std::true_type
{
};
template <typename T>
struct is_span : is_span_oracle<std::remove_cv_t<T>>
{
};
}
template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
class span
{
// TODO do we still need this?
template <typename ValueType2, std::ptrdiff_t FirstDimension2,
std::ptrdiff_t... RestDimensions2>
friend class span;
public:
using bounds_type = static_bounds<FirstDimension, RestDimensions...>;
static const size_t Rank = bounds_type::rank;
using size_type = typename bounds_type::size_type;
using index_type = typename bounds_type::index_type;
using value_type = ValueType;
using const_value_type = std::add_const_t<value_type>;
using pointer = std::add_pointer_t<value_type>;
using reference = std::add_lvalue_reference_t<value_type>;
using iterator = contiguous_span_iterator<span>;
using const_span = span<const_value_type, FirstDimension, RestDimensions...>;
using const_iterator = contiguous_span_iterator<const_span>;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using sliced_type =
std::conditional_t<Rank == 1, value_type, span<value_type, RestDimensions...>>;
private:
pointer data_;
bounds_type bounds_;
friend iterator;
friend const_iterator;
public:
// default constructor - same as constructing from nullptr_t
constexpr span() noexcept : span(nullptr, bounds_type{})
{
static_assert(bounds_type::dynamic_rank != 0 ||
(bounds_type::dynamic_rank == 0 && bounds_type::static_size == 0),
"Default construction of span<T> only possible "
"for dynamic or fixed, zero-length spans.");
}
// construct from nullptr - get an empty span
constexpr span(std::nullptr_t) noexcept : span(nullptr, bounds_type{})
{
static_assert(bounds_type::dynamic_rank != 0 ||
(bounds_type::dynamic_rank == 0 && bounds_type::static_size == 0),
"nullptr_t construction of span<T> only possible "
"for dynamic or fixed, zero-length spans.");
}
// construct from nullptr with size of 0 (helps with template function calls)
template <class IntType, typename = std::enable_if_t<std::is_integral<IntType>::value>>
constexpr span(std::nullptr_t, IntType size) noexcept : span(nullptr, bounds_type{})
{
static_assert(bounds_type::dynamic_rank != 0 ||
(bounds_type::dynamic_rank == 0 && bounds_type::static_size == 0),
"nullptr_t construction of span<T> only possible "
"for dynamic or fixed, zero-length spans.");
Expects(size == 0);
}
// construct from a single element
constexpr span(reference data) noexcept : span(&data, bounds_type{1})
{
static_assert(bounds_type::dynamic_rank > 0 || bounds_type::static_size == 0 ||
bounds_type::static_size == 1,
"Construction from a single element only possible "
"for dynamic or fixed spans of length 0 or 1.");
}
// prevent constructing from temporaries for single-elements
constexpr span(value_type&&) = delete;
// construct from pointer + length
constexpr span(pointer ptr, size_type size) noexcept : span(ptr, bounds_type{size}) {}
// construct from pointer + length - multidimensional
constexpr span(pointer data, bounds_type bounds) noexcept : data_(data),
bounds_(std::move(bounds))
{
Expects((bounds_.size() > 0 && data != nullptr) || bounds_.size() == 0);
}
// construct from begin,end pointer pair
template <typename Ptr,
typename = std::enable_if_t<std::is_convertible<Ptr, pointer>::value &&
details::LessThan<bounds_type::dynamic_rank, 2>::value>>
constexpr span(pointer begin, Ptr end)
: span(begin, details::newBoundsHelper<bounds_type>(static_cast<pointer>(end) - begin))
{
Expects(begin != nullptr && end != nullptr && begin <= static_cast<pointer>(end));
}
// construct from n-dimensions static array
template <typename T, size_t N, typename Helper = details::SpanArrayTraits<T, N>>
constexpr span(T (&arr)[N])
: span(reinterpret_cast<pointer>(arr), bounds_type{typename Helper::bounds_type{}})
{
static_assert(
std::is_convertible<typename Helper::value_type(*) [], value_type(*) []>::value,
"Cannot convert from source type to target span type.");
static_assert(std::is_convertible<typename Helper::bounds_type, bounds_type>::value,
"Cannot construct a span from an array with fewer elements.");
}
// construct from n-dimensions dynamic array (e.g. new int[m][4])
// (precedence will be lower than the 1-dimension pointer)
template <typename T, typename Helper = details::SpanArrayTraits<T, dynamic_range>>
constexpr span(T* const& data, size_type size)
: span(reinterpret_cast<pointer>(data), typename Helper::bounds_type{size})
{
static_assert(
std::is_convertible<typename Helper::value_type(*) [], value_type(*) []>::value,
"Cannot convert from source type to target span type.");
}
// construct from std::array
template <typename T, size_t N>
constexpr span(std::array<T, N>& arr) : span(arr.data(), bounds_type{static_bounds<N>{}})
{
static_assert(
std::is_convertible<T(*) [], typename std::remove_const_t<value_type>(*) []>::value,
"Cannot convert from source type to target span type.");
static_assert(std::is_convertible<static_bounds<N>, bounds_type>::value,
"You cannot construct a span from a std::array of smaller size.");
}
// construct from const std::array
template <typename T, size_t N>
constexpr span(const std::array<std::remove_const_t<value_type>, N>& arr)
: span(arr.data(), static_bounds<N>())
{
static_assert(std::is_convertible<T(*) [], std::remove_const_t<value_type>>::value,
"Cannot convert from source type to target span type.");
static_assert(std::is_convertible<static_bounds<N>, bounds_type>::value,
"You cannot construct a span from a std::array of smaller size.");
}
// prevent constructing from temporary std::array
template <typename T, size_t N>
constexpr span(std::array<T, N>&& arr) = delete;
// construct from containers
// future: could use contiguous_iterator_traits to identify only contiguous containers
// type-requirements: container must have .size(), operator[] which are value_type compatible
template <typename Cont, typename DataType = typename Cont::value_type,
typename = std::enable_if_t<
!details::is_span<Cont>::value &&
std::is_convertible<DataType (*)[], value_type (*)[]>::value &&
std::is_same<std::decay_t<decltype(std::declval<Cont>().size(),
*std::declval<Cont>().data())>,
DataType>::value>>
constexpr span(Cont& cont)
: span(static_cast<pointer>(cont.data()),
details::newBoundsHelper<bounds_type>(narrow_cast<size_type>(cont.size())))
{
}
// prevent constructing from temporary containers
template <typename Cont, typename DataType = typename Cont::value_type,
typename = std::enable_if_t<
!details::is_span<Cont>::value &&
std::is_convertible<DataType (*)[], value_type (*)[]>::value &&
std::is_same<std::decay_t<decltype(std::declval<Cont>().size(),
*std::declval<Cont>().data())>,
DataType>::value>>
explicit constexpr span(Cont&& cont) = delete;
// construct from a convertible span
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename OtherBounds = static_bounds<OtherDimensions...>,
typename = std::enable_if_t<std::is_convertible<OtherValueType, ValueType>::value &&
std::is_convertible<OtherBounds, bounds_type>::value>>
constexpr span(span<OtherValueType, OtherDimensions...> other) noexcept : data_(other.data_),
bounds_(other.bounds_)
{
}
// trivial copy and move
#ifndef GSL_MSVC_NO_SUPPORT_FOR_MOVE_CTOR_DEFAULT
constexpr span(span&&) = default;
#endif
constexpr span(const span&) = default;
// trivial assignment
#ifndef GSL_MSVC_NO_SUPPORT_FOR_MOVE_CTOR_DEFAULT
constexpr span& operator=(span&&) = default;
#endif
constexpr span& operator=(const span&) = default;
// first() - extract the first Count elements into a new span
template <std::ptrdiff_t Count>
constexpr span<ValueType, Count> first() const noexcept
{
static_assert(Count >= 0, "Count must be >= 0.");
static_assert(bounds_type::static_size == dynamic_range ||
Count <= bounds_type::static_size,
"Count is out of bounds.");
Expects(bounds_type::static_size != dynamic_range || Count <= this->size());
return {this->data(), Count};
}
// first() - extract the first count elements into a new span
constexpr span<ValueType, dynamic_range> first(size_type count) const noexcept
{
Expects(count >= 0 && count <= this->size());
return {this->data(), count};
}
// last() - extract the last Count elements into a new span
template <std::ptrdiff_t Count>
constexpr span<ValueType, Count> last() const noexcept
{
static_assert(Count >= 0, "Count must be >= 0.");
static_assert(bounds_type::static_size == dynamic_range ||
Count <= bounds_type::static_size,
"Count is out of bounds.");
Expects(bounds_type::static_size != dynamic_range || Count <= this->size());
return {this->data() + this->size() - Count, Count};
}
// last() - extract the last count elements into a new span
constexpr span<ValueType, dynamic_range> last(size_type count) const noexcept
{
Expects(count >= 0 && count <= this->size());
return {this->data() + this->size() - count, count};
}
// subspan() - create a subview of Count elements starting at Offset
template <std::ptrdiff_t Offset, std::ptrdiff_t Count>
constexpr span<ValueType, Count> subspan() const noexcept
{
static_assert(Count >= 0, "Count must be >= 0.");
static_assert(Offset >= 0, "Offset must be >= 0.");
static_assert(bounds_type::static_size == dynamic_range ||
((Offset <= bounds_type::static_size) &&
Count <= bounds_type::static_size - Offset),
"You must describe a sub-range within bounds of the span.");
Expects(bounds_type::static_size != dynamic_range ||
(Offset <= this->size() && Count <= this->size() - Offset));
return {this->data() + Offset, Count};
}
// subspan() - create a subview of count elements starting at offset
// supplying dynamic_range for count will consume all available elements from offset
constexpr span<ValueType, dynamic_range> subspan(size_type offset,
size_type count = dynamic_range) const noexcept
{
Expects((offset >= 0 && offset <= this->size()) &&
(count == dynamic_range || (count <= this->size() - offset)));
return {this->data() + offset, count == dynamic_range ? this->length() - offset : count};
}
// section - creates a non-contiguous, strided span from a contiguous one
constexpr strided_span<ValueType, Rank> section(index_type origin, index_type extents) const
noexcept
{
size_type size = this->bounds().total_size() - this->bounds().linearize(origin);
return {&this->operator[](origin), size,
strided_bounds<Rank>{extents, details::make_stride(bounds())}};
}
// length of the span in elements
constexpr size_type size() const noexcept { return bounds_.size(); }
// length of the span in elements
constexpr size_type length() const noexcept { return this->size(); }
// length of the span in bytes
constexpr size_type size_bytes() const noexcept { return sizeof(value_type) * this->size(); }
// length of the span in bytes
constexpr size_type length_bytes() const noexcept { return this->size_bytes(); }
constexpr bool empty() const noexcept { return this->size() == 0; }
static constexpr std::size_t rank() { return Rank; }
template <size_t Dim = 0>
constexpr size_type extent() const noexcept
{
static_assert(Dim < Rank,
"Dimension should be less than rank (dimension count starts from 0).");
return bounds_.template extent<Dim>();
}
template <typename IntType>
constexpr size_type extent(IntType dim) const noexcept
{
return bounds_.extent(dim);
}
constexpr bounds_type bounds() const noexcept { return bounds_; }
constexpr pointer data() const noexcept { return data_; }
template <typename FirstIndex>
constexpr reference operator()(FirstIndex index)
{
return this->operator[](narrow_cast<std::ptrdiff_t>(index));
}
template <typename FirstIndex, typename... OtherIndices>
constexpr reference operator()(FirstIndex index, OtherIndices... indices)
{
index_type idx = {narrow_cast<std::ptrdiff_t>(index),
narrow_cast<std::ptrdiff_t>(indices...)};
return this->operator[](idx);
}
constexpr reference operator[](const index_type& idx) const noexcept
{
return data_[bounds_.linearize(idx)];
}
template <bool Enabled = (Rank > 1), typename Ret = std::enable_if_t<Enabled, sliced_type>>
constexpr Ret operator[](size_type idx) const noexcept
{
Expects(idx < bounds_.size()); // index is out of bounds of the array
const size_type ridx = idx * bounds_.stride();
// index is out of bounds of the underlying data
Expects(ridx < bounds_.total_size());
return Ret{data_ + ridx, bounds_.slice()};
}
constexpr iterator begin() const noexcept { return iterator{this, true}; }
constexpr iterator end() const noexcept { return iterator{this, false}; }
constexpr const_iterator cbegin() const noexcept
{
return const_iterator{reinterpret_cast<const const_span*>(this), true};
}
constexpr const_iterator cend() const noexcept
{
return const_iterator{reinterpret_cast<const const_span*>(this), false};
}
constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator{end()}; }
constexpr reverse_iterator rend() const noexcept { return reverse_iterator{begin()}; }
constexpr const_reverse_iterator crbegin() const noexcept
{
return const_reverse_iterator{cend()};
}
constexpr const_reverse_iterator crend() const noexcept
{
return const_reverse_iterator{cbegin()};
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator==(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return bounds_.size() == other.bounds_.size() &&
(data_ == other.data_ || std::equal(this->begin(), this->end(), other.begin()));
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator!=(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return !(*this == other);
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator<(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return std::lexicographical_compare(this->begin(), this->end(), other.begin(), other.end());
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator<=(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return !(other < *this);
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator>(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return (other < *this);
}
template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator>=(const span<OtherValueType, OtherDimensions...>& other) const noexcept
{
return !(*this < other);
}
};
//
// Free functions for manipulating spans
//
// reshape a span into a different dimensionality
// DimCount and Enabled here are workarounds for a bug in MSVC 2015
template <typename SpanType, typename... Dimensions2, size_t DimCount = sizeof...(Dimensions2),
bool Enabled = (DimCount > 0), typename = std::enable_if_t<Enabled>>
constexpr span<typename SpanType::value_type, Dimensions2::value...> as_span(SpanType s,
Dimensions2... dims)
{
static_assert(details::is_span<SpanType>::value,
"Variadic as_span() is for reshaping existing spans.");
using BoundsType =
typename span<typename SpanType::value_type, (Dimensions2::value)...>::bounds_type;
auto tobounds = details::static_as_span_helper<BoundsType>(dims..., details::Sep{});
details::verifyBoundsReshape(s.bounds(), tobounds);
return {s.data(), tobounds};
}
// convert a span<T> to a span<const byte>
template <typename U, std::ptrdiff_t... Dimensions>
span<const byte, dynamic_range> as_bytes(span<U, Dimensions...> s) noexcept
{
static_assert(std::is_trivial<std::decay_t<U>>::value,
"The value_type of span must be a trivial type.");
return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
}
// convert a span<T> to a span<byte> (a writeable byte span)
// this is not currently a portable function that can be relied upon to work
// on all implementations. It should be considered an experimental extension
// to the standard GSL interface.
template <typename U, std::ptrdiff_t... Dimensions>
span<byte> as_writeable_bytes(span<U, Dimensions...> s) noexcept
{
static_assert(std::is_trivial<std::decay_t<U>>::value,
"The value_type of span must be a trivial type.");
return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
}
// convert a span<const byte> to a span<const T>
// this is not currently a portable function that can be relied upon to work
// on all implementations. It should be considered an experimental extension
// to the standard GSL interface.
template <typename U, std::ptrdiff_t... Dimensions>
constexpr auto as_span(span<const byte, Dimensions...> s) noexcept
-> span<const U, static_cast<std::ptrdiff_t>(
span<const byte, Dimensions...>::bounds_type::static_size != dynamic_range
? (static_cast<size_t>(
span<const byte, Dimensions...>::bounds_type::static_size) /
sizeof(U))
: dynamic_range)>
{
using ConstByteSpan = span<const byte, Dimensions...>;
static_assert(
std::is_trivial<std::decay_t<U>>::value &&
(ConstByteSpan::bounds_type::static_size == dynamic_range ||
ConstByteSpan::bounds_type::static_size % narrow_cast<std::ptrdiff_t>(sizeof(U)) == 0),
"Target type must be a trivial type and its size must match the byte array size");
Expects((s.size_bytes() % sizeof(U)) == 0 && (s.size_bytes() / sizeof(U)) < PTRDIFF_MAX);
return {reinterpret_cast<const U*>(s.data()),
s.size_bytes() / narrow_cast<std::ptrdiff_t>(sizeof(U))};
}
// convert a span<byte> to a span<T>
// this is not currently a portable function that can be relied upon to work
// on all implementations. It should be considered an experimental extension
// to the standard GSL interface.
template <typename U, std::ptrdiff_t... Dimensions>
constexpr auto as_span(span<byte, Dimensions...> s) noexcept -> span<
U, narrow_cast<std::ptrdiff_t>(
span<byte, Dimensions...>::bounds_type::static_size != dynamic_range
? static_cast<std::size_t>(span<byte, Dimensions...>::bounds_type::static_size) /
sizeof(U)
: dynamic_range)>
{
using ByteSpan = span<byte, Dimensions...>;
static_assert(
std::is_trivial<std::decay_t<U>>::value &&
(ByteSpan::bounds_type::static_size == dynamic_range ||
ByteSpan::bounds_type::static_size % static_cast<std::size_t>(sizeof(U)) == 0),
"Target type must be a trivial type and its size must match the byte array size");
Expects((s.bytes() % sizeof(U)) == 0);
return {reinterpret_cast<U*>(s.data()),
s.size_bytes() / narrow_cast<std::ptrdiff_t>(sizeof(U))};
}
template <typename T, std::ptrdiff_t... Dimensions>
constexpr auto as_span(T* const& ptr, dim<Dimensions>... args)
-> span<std::remove_all_extents_t<T>, Dimensions...>
{
return {reinterpret_cast<std::remove_all_extents_t<T>*>(ptr),
details::static_as_span_helper<static_bounds<Dimensions...>>(args..., details::Sep{})};
}
template <typename T>
constexpr auto as_span(T* arr, std::ptrdiff_t len) ->
typename details::SpanArrayTraits<T, dynamic_range>::type
{
return {reinterpret_cast<std::remove_all_extents_t<T>*>(arr), len};
}
template <typename T, size_t N>
constexpr auto as_span(T (&arr)[N]) -> typename details::SpanArrayTraits<T, N>::type
{
return {arr};
}
template <typename T, size_t N>
constexpr span<const T, N> as_span(const std::array<T, N>& arr)
{
return {arr};
}
template <typename T, size_t N>
constexpr span<const T, N> as_span(const std::array<T, N>&&) = delete;
template <typename T, size_t N>
constexpr span<T, N> as_span(std::array<T, N>& arr)
{
return {arr};
}
template <typename T>
constexpr span<T, dynamic_range> as_span(T* begin, T* end)
{
return {begin, end};
}
template <typename Cont>
constexpr auto as_span(Cont& arr) -> std::enable_if_t<
!details::is_span<std::decay_t<Cont>>::value,
span<std::remove_reference_t<decltype(arr.size(), *arr.data())>, dynamic_range>>
{
Expects(arr.size() < PTRDIFF_MAX);
return {arr.data(), narrow_cast<std::ptrdiff_t>(arr.size())};
}
template <typename Cont>
constexpr auto as_span(Cont&& arr) -> std::enable_if_t<
!details::is_span<std::decay_t<Cont>>::value,
span<std::remove_reference_t<decltype(arr.size(), *arr.data())>, dynamic_range>> = delete;
// from basic_string which doesn't have nonconst .data() member like other contiguous containers
template <typename CharT, typename Traits, typename Allocator>
constexpr auto as_span(std::basic_string<CharT, Traits, Allocator>& str)
-> span<CharT, dynamic_range>
{
Expects(str.size() < PTRDIFF_MAX);
return {&str[0], narrow_cast<std::ptrdiff_t>(str.size())};
}
// strided_span is an extension that is not strictly part of the GSL at this time.
// It is kept here while the multidimensional interface is still being defined.
template <typename ValueType, size_t Rank>
class strided_span
{
public:
using bounds_type = strided_bounds<Rank>;
using size_type = typename bounds_type::size_type;
using index_type = typename bounds_type::index_type;
using value_type = ValueType;
using const_value_type = std::add_const_t<value_type>;
using pointer = std::add_pointer_t<value_type>;
using reference = std::add_lvalue_reference_t<value_type>;
using iterator = general_span_iterator<strided_span>;
using const_strided_span = strided_span<const_value_type, Rank>;
using const_iterator = general_span_iterator<const_strided_span>;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using sliced_type =
std::conditional_t<Rank == 1, value_type, strided_span<value_type, Rank - 1>>;
private:
pointer data_;
bounds_type bounds_;
friend iterator;
friend const_iterator;
template <typename OtherValueType, size_t OtherRank>
friend class strided_span;
public:
// from raw data
constexpr strided_span(pointer ptr, size_type size, bounds_type bounds)
: data_(ptr), bounds_(std::move(bounds))
{
Expects((bounds_.size() > 0 && ptr != nullptr) || bounds_.size() == 0);
// Bounds cross data boundaries
Expects(this->bounds().total_size() <= size);
(void) size;
}
// from static array of size N
template <size_type N>
constexpr strided_span(value_type (&values)[N], bounds_type bounds)
: strided_span(values, N, std::move(bounds))
{
}
// from array view
template <typename OtherValueType, std::ptrdiff_t... Dimensions,
bool Enabled1 = (sizeof...(Dimensions) == Rank),
bool Enabled2 = std::is_convertible<OtherValueType*, ValueType*>::value,
typename Dummy = std::enable_if_t<Enabled1 && Enabled2>>
constexpr strided_span(span<OtherValueType, Dimensions...> av, bounds_type bounds)
: strided_span(av.data(), av.bounds().total_size(), std::move(bounds))
{
}
// convertible
template <typename OtherValueType, typename Dummy = std::enable_if_t<std::is_convertible<
OtherValueType (*)[], value_type (*)[]>::value>>
constexpr strided_span(const strided_span<OtherValueType, Rank>& other)
: data_(other.data_), bounds_(other.bounds_)
{
}
// convert from bytes
template <typename OtherValueType>
constexpr strided_span<
typename std::enable_if<std::is_same<value_type, const byte>::value, OtherValueType>::type,
Rank>
as_strided_span() const
{
static_assert((sizeof(OtherValueType) >= sizeof(value_type)) &&
(sizeof(OtherValueType) % sizeof(value_type) == 0),
"OtherValueType should have a size to contain a multiple of ValueTypes");
auto d = narrow_cast<size_type>(sizeof(OtherValueType) / sizeof(value_type));
size_type size = this->bounds().total_size() / d;
return {(OtherValueType*) this->data(), size,
bounds_type{resize_extent(this->bounds().index_bounds(), d),
resize_stride(this->bounds().strides(), d)}};
}
constexpr strided_span section(index_type origin, index_type extents) const
{
size_type size = this->bounds().total_size() - this->bounds().linearize(origin);
return {&this->operator[](origin), size,
bounds_type{extents, details::make_stride(bounds())}};
}
constexpr reference operator[](const index_type& idx) const
{
return data_[bounds_.linearize(idx)];
}
template <bool Enabled = (Rank > 1), typename Ret = std::enable_if_t<Enabled, sliced_type>>
constexpr Ret operator[](size_type idx) const
{
Expects(idx < bounds_.size()); // index is out of bounds of the array
const size_type ridx = idx * bounds_.stride();
// index is out of bounds of the underlying data
Expects(ridx < bounds_.total_size());
return {data_ + ridx, bounds_.slice().total_size(), bounds_.slice()};
}
constexpr bounds_type bounds() const noexcept { return bounds_; }
template <size_t Dim = 0>
constexpr size_type extent() const noexcept
{
static_assert(Dim < Rank,
"dimension should be less than Rank (dimension count starts from 0)");
return bounds_.template extent<Dim>();
}
constexpr size_type size() const noexcept { return bounds_.size(); }
constexpr pointer data() const noexcept { return data_; }
constexpr explicit operator bool() const noexcept { return data_ != nullptr; }
constexpr iterator begin() const { return iterator{this, true}; }
constexpr iterator end() const { return iterator{this, false}; }
constexpr const_iterator cbegin() const
{
return const_iterator{reinterpret_cast<const const_strided_span*>(this), true};
}
constexpr const_iterator cend() const
{
return const_iterator{reinterpret_cast<const const_strided_span*>(this), false};
}
constexpr reverse_iterator rbegin() const { return reverse_iterator{end()}; }
constexpr reverse_iterator rend() const { return reverse_iterator{begin()}; }
constexpr const_reverse_iterator crbegin() const { return const_reverse_iterator{cend()}; }
constexpr const_reverse_iterator crend() const { return const_reverse_iterator{cbegin()}; }
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator==(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return bounds_.size() == other.bounds_.size() &&
(data_ == other.data_ || std::equal(this->begin(), this->end(), other.begin()));
}
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator!=(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return !(*this == other);
}
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator<(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return std::lexicographical_compare(this->begin(), this->end(), other.begin(), other.end());
}
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator<=(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return !(other < *this);
}
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator>(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return (other < *this);
}
template <typename OtherValueType, std::ptrdiff_t OtherRank,
typename Dummy = std::enable_if_t<std::is_same<
std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
constexpr bool operator>=(const strided_span<OtherValueType, OtherRank>& other) const noexcept
{
return !(*this < other);
}
private:
static index_type resize_extent(const index_type& extent, std::ptrdiff_t d)
{
// The last dimension of the array needs to contain a multiple of new type elements
Expects(extent[Rank - 1] >= d && (extent[Rank - 1] % d == 0));
index_type ret = extent;
ret[Rank - 1] /= d;
return ret;
}
template <bool Enabled = (Rank == 1), typename Dummy = std::enable_if_t<Enabled>>
static index_type resize_stride(const index_type& strides, std::ptrdiff_t, void* = 0)
{
// Only strided arrays with regular strides can be resized
Expects(strides[Rank - 1] == 1);
return strides;
}
template <bool Enabled = (Rank > 1), typename Dummy = std::enable_if_t<Enabled>>
static index_type resize_stride(const index_type& strides, std::ptrdiff_t d)
{
// Only strided arrays with regular strides can be resized
Expects(strides[Rank - 1] == 1);
// The strides must have contiguous chunks of
// memory that can contain a multiple of new type elements
Expects(strides[Rank - 2] >= d && (strides[Rank - 2] % d == 0));
for (size_t i = Rank - 1; i > 0; --i) {
// Only strided arrays with regular strides can be resized
Expects((strides[i - 1] >= strides[i]) && (strides[i - 1] % strides[i] == 0));
}
index_type ret = strides / d;
ret[Rank - 1] = 1;
return ret;
}
};
template <class Span>
class contiguous_span_iterator
: public std::iterator<std::random_access_iterator_tag, typename Span::value_type>
{
using Base = std::iterator<std::random_access_iterator_tag, typename Span::value_type>;
public:
using typename Base::reference;
using typename Base::pointer;
using typename Base::difference_type;
private:
template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
friend class span;
pointer data_;
const Span* m_validator;
void validateThis() const
{
// iterator is out of range of the array
Expects(data_ >= m_validator->data_ && data_ < m_validator->data_ + m_validator->size());
}
contiguous_span_iterator(const Span* container, bool isbegin)
: data_(isbegin ? container->data_ : container->data_ + container->size())
, m_validator(container)
{
}
public:
reference operator*() const noexcept
{
validateThis();
return *data_;
}
pointer operator->() const noexcept
{
validateThis();
return data_;
}
contiguous_span_iterator& operator++() noexcept
{
++data_;
return *this;
}
contiguous_span_iterator operator++(int) noexcept
{
auto ret = *this;
++(*this);
return ret;
}
contiguous_span_iterator& operator--() noexcept
{
--data_;
return *this;
}
contiguous_span_iterator operator--(int) noexcept
{
auto ret = *this;
--(*this);
return ret;
}
contiguous_span_iterator operator+(difference_type n) const noexcept
{
contiguous_span_iterator ret{*this};
return ret += n;
}
contiguous_span_iterator& operator+=(difference_type n) noexcept
{
data_ += n;
return *this;
}
contiguous_span_iterator operator-(difference_type n) const noexcept
{
contiguous_span_iterator ret{*this};
return ret -= n;
}
contiguous_span_iterator& operator-=(difference_type n) noexcept { return * this += -n; }
difference_type operator-(const contiguous_span_iterator& rhs) const noexcept
{
Expects(m_validator == rhs.m_validator);
return data_ - rhs.data_;
}
reference operator[](difference_type n) const noexcept { return *(*this + n); }
bool operator==(const contiguous_span_iterator& rhs) const noexcept
{
Expects(m_validator == rhs.m_validator);
return data_ == rhs.data_;
}
bool operator!=(const contiguous_span_iterator& rhs) const noexcept { return !(*this == rhs); }
bool operator<(const contiguous_span_iterator& rhs) const noexcept
{
Expects(m_validator == rhs.m_validator);
return data_ < rhs.data_;
}
bool operator<=(const contiguous_span_iterator& rhs) const noexcept { return !(rhs < *this); }
bool operator>(const contiguous_span_iterator& rhs) const noexcept { return rhs < *this; }
bool operator>=(const contiguous_span_iterator& rhs) const noexcept { return !(rhs > *this); }
void swap(contiguous_span_iterator& rhs) noexcept
{
std::swap(data_, rhs.data_);
std::swap(m_validator, rhs.m_validator);
}
};
template <typename Span>
contiguous_span_iterator<Span> operator+(typename contiguous_span_iterator<Span>::difference_type n,
const contiguous_span_iterator<Span>& rhs) noexcept
{
return rhs + n;
}
template <typename Span>
class general_span_iterator
: public std::iterator<std::random_access_iterator_tag, typename Span::value_type>
{
using Base = std::iterator<std::random_access_iterator_tag, typename Span::value_type>;
public:
using typename Base::reference;
using typename Base::pointer;
using typename Base::difference_type;
using typename Base::value_type;
private:
template <typename ValueType, size_t Rank>
friend class strided_span;
const Span* m_container;
typename Span::bounds_type::iterator m_itr;
general_span_iterator(const Span* container, bool isbegin)
: m_container(container)
, m_itr(isbegin ? m_container->bounds().begin() : m_container->bounds().end())
{
}
public:
reference operator*() noexcept { return (*m_container)[*m_itr]; }
pointer operator->() noexcept { return &(*m_container)[*m_itr]; }
general_span_iterator& operator++() noexcept
{
++m_itr;
return *this;
}
general_span_iterator operator++(int) noexcept
{
auto ret = *this;
++(*this);
return ret;
}
general_span_iterator& operator--() noexcept
{
--m_itr;
return *this;
}
general_span_iterator operator--(int) noexcept
{
auto ret = *this;
--(*this);
return ret;
}
general_span_iterator operator+(difference_type n) const noexcept
{
general_span_iterator ret{*this};
return ret += n;
}
general_span_iterator& operator+=(difference_type n) noexcept
{
m_itr += n;
return *this;
}
general_span_iterator operator-(difference_type n) const noexcept
{
general_span_iterator ret{*this};
return ret -= n;
}
general_span_iterator& operator-=(difference_type n) noexcept { return * this += -n; }
difference_type operator-(const general_span_iterator& rhs) const noexcept
{
Expects(m_container == rhs.m_container);
return m_itr - rhs.m_itr;
}
value_type operator[](difference_type n) const noexcept
{
return (*m_container)[m_itr[n]];
;
}
bool operator==(const general_span_iterator& rhs) const noexcept
{
Expects(m_container == rhs.m_container);
return m_itr == rhs.m_itr;
}
bool operator!=(const general_span_iterator& rhs) const noexcept { return !(*this == rhs); }
bool operator<(const general_span_iterator& rhs) const noexcept
{
Expects(m_container == rhs.m_container);
return m_itr < rhs.m_itr;
}
bool operator<=(const general_span_iterator& rhs) const noexcept { return !(rhs < *this); }
bool operator>(const general_span_iterator& rhs) const noexcept { return rhs < *this; }
bool operator>=(const general_span_iterator& rhs) const noexcept { return !(rhs > *this); }
void swap(general_span_iterator& rhs) noexcept
{
std::swap(m_itr, rhs.m_itr);
std::swap(m_container, rhs.m_container);
}
};
template <typename Span>
general_span_iterator<Span> operator+(typename general_span_iterator<Span>::difference_type n,
const general_span_iterator<Span>& rhs) noexcept
{
return rhs + n;
}
} // namespace gsl
#ifdef _MSC_VER
#undef constexpr
#pragma pop_macro("constexpr")
#if _MSC_VER <= 1800
#pragma warning(pop)
#ifndef GSL_THROW_ON_CONTRACT_VIOLATION
#undef noexcept
#pragma pop_macro("noexcept")
#endif // GSL_THROW_ON_CONTRACT_VIOLATION
#undef GSL_MSVC_HAS_VARIADIC_CTOR_BUG
#endif // _MSC_VER <= 1800
#endif // _MSC_VER
#if defined(GSL_THROW_ON_CONTRACT_VIOLATION)
#undef noexcept
#ifdef _MSC_VER
#pragma warning(pop)
#pragma pop_macro("noexcept")
#endif
#endif // GSL_THROW_ON_CONTRACT_VIOLATION
#endif // GSL_SPAN_H
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