Squashed 'third_party/GSL/' content from commit 0cebbd7
Change-Id: Iffb2e32f2f45297ac6d3e82168cd9df4ac5acc2f
git-subtree-dir: third_party/GSL
git-subtree-split: 0cebbd77bfc21acbf1cc05983ad626539eeeb8e0
diff --git a/include/gsl/multi_span b/include/gsl/multi_span
new file mode 100644
index 0000000..9c0c27b
--- /dev/null
+++ b/include/gsl/multi_span
@@ -0,0 +1,2242 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// 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.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef GSL_MULTI_SPAN_H
+#define GSL_MULTI_SPAN_H
+
+#include <gsl/gsl_assert> // for Expects
+#include <gsl/gsl_byte> // for byte
+#include <gsl/gsl_util> // for narrow_cast
+
+#include <algorithm> // for transform, lexicographical_compare
+#include <array> // for array
+#include <cassert>
+#include <cstddef> // for ptrdiff_t, size_t, nullptr_t
+#include <cstdint> // for PTRDIFF_MAX
+#include <functional> // for divides, multiplies, minus, negate, plus
+#include <initializer_list> // for initializer_list
+#include <iterator> // for iterator, random_access_iterator_tag
+#include <limits> // for numeric_limits
+#include <new>
+#include <numeric>
+#include <stdexcept>
+#include <string> // for basic_string
+#include <type_traits> // for enable_if_t, remove_cv_t, is_same, is_co...
+#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
+#pragma warning(disable : 4702) // unreachable code
+
+#if _MSC_VER < 1910
+#pragma push_macro("constexpr")
+#define constexpr /*constexpr*/
+
+#endif // _MSC_VER < 1910
+#endif // _MSC_VER
+
+// GCC 7 does not like the signed unsigned missmatch (size_t ptrdiff_t)
+// While there is a conversion from signed to unsigned, it happens at
+// compiletime, so the compiler wouldn't have to warn indiscriminently, but
+// could check if the source value actually doesn't fit into the target type
+// and only warn in those cases.
+#if __GNUC__ > 6
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsign-conversion"
+#endif
+
+#ifdef GSL_THROW_ON_CONTRACT_VIOLATION
+#define GSL_NOEXCEPT /*noexcept*/
+#else
+#define GSL_NOEXCEPT noexcept
+#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 <std::size_t Rank>
+class multi_span_index final
+{
+ static_assert(Rank > 0, "Rank must be greater than 0!");
+
+ template <std::size_t OtherRank>
+ friend class multi_span_index;
+
+public:
+ static const std::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 multi_span_index() GSL_NOEXCEPT {}
+
+ constexpr multi_span_index(const value_type (&values)[Rank]) GSL_NOEXCEPT
+ {
+ std::copy(values, values + Rank, elems);
+ }
+
+ template <typename... Ts, typename = std::enable_if_t<(sizeof...(Ts) == Rank) &&
+ details::are_integral<Ts...>::value>>
+ constexpr multi_span_index(Ts... ds) GSL_NOEXCEPT : elems{narrow_cast<value_type>(ds)...}
+ {
+ }
+
+ constexpr multi_span_index(const multi_span_index& other) GSL_NOEXCEPT = default;
+
+ constexpr multi_span_index& operator=(const multi_span_index& rhs) GSL_NOEXCEPT = default;
+
+ // Preconditions: component_idx < rank
+ constexpr reference operator[](std::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[](std::size_t component_idx) const GSL_NOEXCEPT
+ {
+ Expects(component_idx < Rank); // Component index must be less than rank
+ return elems[component_idx];
+ }
+
+ constexpr bool operator==(const multi_span_index& rhs) const GSL_NOEXCEPT
+ {
+ return std::equal(elems, elems + rank, rhs.elems);
+ }
+
+ constexpr bool operator!=(const multi_span_index& rhs) const GSL_NOEXCEPT { return !(*this == rhs); }
+
+ constexpr multi_span_index operator+() const GSL_NOEXCEPT { return *this; }
+
+ constexpr multi_span_index operator-() const GSL_NOEXCEPT
+ {
+ multi_span_index ret = *this;
+ std::transform(ret, ret + rank, ret, std::negate<value_type>{});
+ return ret;
+ }
+
+ constexpr multi_span_index operator+(const multi_span_index& rhs) const GSL_NOEXCEPT
+ {
+ multi_span_index ret = *this;
+ ret += rhs;
+ return ret;
+ }
+
+ constexpr multi_span_index operator-(const multi_span_index& rhs) const GSL_NOEXCEPT
+ {
+ multi_span_index ret = *this;
+ ret -= rhs;
+ return ret;
+ }
+
+ constexpr multi_span_index& operator+=(const multi_span_index& rhs) GSL_NOEXCEPT
+ {
+ std::transform(elems, elems + rank, rhs.elems, elems, std::plus<value_type>{});
+ return *this;
+ }
+
+ constexpr multi_span_index& operator-=(const multi_span_index& rhs) GSL_NOEXCEPT
+ {
+ std::transform(elems, elems + rank, rhs.elems, elems, std::minus<value_type>{});
+ return *this;
+ }
+
+ constexpr multi_span_index operator*(value_type v) const GSL_NOEXCEPT
+ {
+ multi_span_index ret = *this;
+ ret *= v;
+ return ret;
+ }
+
+ constexpr multi_span_index operator/(value_type v) const GSL_NOEXCEPT
+ {
+ multi_span_index ret = *this;
+ ret /= v;
+ return ret;
+ }
+
+ friend constexpr multi_span_index operator*(value_type v, const multi_span_index& rhs) GSL_NOEXCEPT
+ {
+ return rhs * v;
+ }
+
+ constexpr multi_span_index& operator*=(value_type v) GSL_NOEXCEPT
+ {
+ std::transform(elems, elems + rank, elems,
+ [v](value_type x) { return std::multiplies<value_type>{}(x, v); });
+ return *this;
+ }
+
+ constexpr multi_span_index& operator/=(value_type v) GSL_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] = {};
+};
+
+#if !defined(_MSC_VER) || _MSC_VER >= 1910
+
+struct static_bounds_dynamic_range_t
+{
+ template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
+ constexpr operator T() const GSL_NOEXCEPT
+ {
+ return narrow_cast<T>(-1);
+ }
+};
+
+constexpr bool operator==(static_bounds_dynamic_range_t, static_bounds_dynamic_range_t) GSL_NOEXCEPT
+{
+ return true;
+}
+
+constexpr bool operator!=(static_bounds_dynamic_range_t, static_bounds_dynamic_range_t) GSL_NOEXCEPT
+{
+ return false;
+}
+
+template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
+constexpr bool operator==(static_bounds_dynamic_range_t, T other) GSL_NOEXCEPT
+{
+ return narrow_cast<T>(-1) == other;
+}
+
+template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
+constexpr bool operator==(T left, static_bounds_dynamic_range_t right) GSL_NOEXCEPT
+{
+ return right == left;
+}
+
+template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
+constexpr bool operator!=(static_bounds_dynamic_range_t, T other) GSL_NOEXCEPT
+{
+ return narrow_cast<T>(-1) != other;
+}
+
+template <typename T, typename = std::enable_if_t<std::is_integral<T>::value>>
+constexpr bool operator!=(T left, static_bounds_dynamic_range_t right) GSL_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 std::ptrdiff_t* const) {}
+ BoundsRanges() = default;
+
+ template <typename T, std::size_t Dim>
+ void serialize(T&) const
+ {
+ }
+
+ template <typename T, std::size_t Dim>
+ size_type linearize(const T&) const
+ {
+ return 0;
+ }
+
+ template <typename T, std::size_t Dim>
+ size_type contains(const T&) const
+ {
+ return -1;
+ }
+
+ size_type elementNum(std::size_t) const GSL_NOEXCEPT { return 0; }
+
+ size_type totalSize() const GSL_NOEXCEPT { return TotalSize; }
+
+ bool operator==(const BoundsRanges&) const GSL_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 std::size_t Depth = Base::Depth + 1;
+ static const std::size_t DynamicNum = Base::DynamicNum + 1;
+ static const size_type CurrentRange = dynamic_range;
+ static const size_type TotalSize = dynamic_range;
+
+ private:
+ size_type m_bound;
+
+ public:
+ 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, std::size_t Dim = 0>
+ void serialize(T& arr) const
+ {
+ arr[Dim] = elementNum();
+ this->Base::template serialize<T, Dim + 1>(arr);
+ }
+
+ template <typename T, std::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, std::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 GSL_NOEXCEPT { return m_bound; }
+
+ size_type elementNum() const GSL_NOEXCEPT { return totalSize() / this->Base::totalSize(); }
+
+ size_type elementNum(std::size_t dim) const GSL_NOEXCEPT
+ {
+ if (dim > 0)
+ return this->Base::elementNum(dim - 1);
+ else
+ return elementNum();
+ }
+
+ bool operator==(const BoundsRanges& rhs) const GSL_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 std::size_t Depth = Base::Depth + 1;
+ static const std::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 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, std::size_t Dim = 0>
+ void serialize(T& arr) const
+ {
+ arr[Dim] = elementNum();
+ this->Base::template serialize<T, Dim + 1>(arr);
+ }
+
+ template <typename T, std::size_t Dim = 0>
+ size_type linearize(const T& arr) const
+ {
+ Expects(arr[Dim] >= 0 && 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, std::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 GSL_NOEXCEPT { return CurrentRange * this->Base::totalSize(); }
+
+ size_type elementNum() const GSL_NOEXCEPT { return CurrentRange; }
+
+ size_type elementNum(std::size_t dim) const GSL_NOEXCEPT
+ {
+ if (dim > 0)
+ return this->Base::elementNum(dim - 1);
+ else
+ return elementNum();
+ }
+
+ bool operator==(const BoundsRanges& rhs) const GSL_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 <std::size_t N>
+ const TypeChain& getObj(std::true_type)
+ {
+ return obj_;
+ }
+
+ template <std::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 <std::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 <std::size_t Rank, bool Enabled = (Rank > 1),
+ typename Ret = std::enable_if_t<Enabled, multi_span_index<Rank - 1>>>
+ constexpr Ret shift_left(const multi_span_index<Rank>& other) GSL_NOEXCEPT
+ {
+ Ret ret{};
+ for (std::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 std::size_t rank = MyRanges::Depth;
+ static const std::size_t dynamic_rank = MyRanges::DynamicNum;
+ static const std::ptrdiff_t static_size = MyRanges::TotalSize;
+
+ using size_type = std::ptrdiff_t;
+ using index_type = multi_span_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, std::size_t Rank>
+ struct BoundsRangeConvertible2;
+
+ template <std::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 <std::size_t Rank, typename SourceType, typename TargetType>
+ static auto helpBoundsRangeConvertible(SourceType, TargetType, ...) -> std::false_type;
+
+ template <typename SourceType, typename TargetType, std::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(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 sliced_type slice() const GSL_NOEXCEPT
+ {
+ return sliced_type{static_cast<const details::BoundsRanges<RestRanges...>&>(m_ranges)};
+ }
+
+ constexpr size_type stride() const GSL_NOEXCEPT { return rank > 1 ? slice().size() : 1; }
+
+ constexpr size_type size() const GSL_NOEXCEPT { return m_ranges.totalSize(); }
+
+ constexpr size_type total_size() const GSL_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 GSL_NOEXCEPT
+ {
+ return m_ranges.contains(idx) != -1;
+ }
+
+ constexpr size_type operator[](std::size_t idx) const GSL_NOEXCEPT
+ {
+ return m_ranges.elementNum(idx);
+ }
+
+ template <std::size_t Dim = 0>
+ constexpr size_type extent() const GSL_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 GSL_NOEXCEPT
+ {
+ static_assert(std::is_integral<IntType>::value,
+ "Dimension parameter must be supplied as an integral type.");
+ auto real_dim = narrow_cast<std::size_t>(dim);
+ Expects(real_dim < rank);
+
+ return m_ranges.elementNum(real_dim);
+ }
+
+ constexpr index_type index_bounds() const GSL_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 GSL_NOEXCEPT
+ {
+ return this->size() == rhs.size();
+ }
+
+ template <std::ptrdiff_t... Ranges>
+ constexpr bool operator!=(const static_bounds<Ranges...>& rhs) const GSL_NOEXCEPT
+ {
+ return !(*this == rhs);
+ }
+
+ constexpr const_iterator begin() const GSL_NOEXCEPT
+ {
+ return const_iterator(*this, index_type{});
+ }
+
+ constexpr const_iterator end() const GSL_NOEXCEPT
+ {
+ return const_iterator(*this, this->index_bounds());
+ }
+};
+
+template <std::size_t Rank>
+class strided_bounds
+{
+ template <std::size_t OtherRank>
+ friend class strided_bounds;
+
+public:
+ static const std::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 = multi_span_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&) GSL_NOEXCEPT = default;
+
+ constexpr strided_bounds& operator=(const strided_bounds&) GSL_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) GSL_NOEXCEPT
+ : m_extents(extents),
+ m_strides(strides)
+ {
+ }
+
+ constexpr index_type strides() const GSL_NOEXCEPT { return m_strides; }
+
+ constexpr size_type total_size() const GSL_NOEXCEPT
+ {
+ size_type ret = 0;
+ for (std::size_t i = 0; i < rank; ++i) {
+ ret += (m_extents[i] - 1) * m_strides[i];
+ }
+ return ret + 1;
+ }
+
+ constexpr size_type size() const GSL_NOEXCEPT
+ {
+ size_type ret = 1;
+ for (std::size_t i = 0; i < rank; ++i) {
+ ret *= m_extents[i];
+ }
+ return ret;
+ }
+
+ constexpr bool contains(const index_type& idx) const GSL_NOEXCEPT
+ {
+ for (std::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 GSL_NOEXCEPT
+ {
+ size_type ret = 0;
+ for (std::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 GSL_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 <std::size_t Dim = 0>
+ constexpr size_type extent() const GSL_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 GSL_NOEXCEPT { return m_extents; }
+ constexpr const_iterator begin() const GSL_NOEXCEPT
+ {
+ return const_iterator{*this, index_type{}};
+ }
+
+ constexpr const_iterator end() const GSL_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 <std::size_t Rank>
+struct is_bounds<strided_bounds<Rank>> : std::integral_constant<bool, true>
+{
+};
+
+template <typename IndexType>
+class bounds_iterator
+{
+public:
+ static const std::size_t rank = IndexType::rank;
+ using iterator_category = std::random_access_iterator_tag;
+ using value_type = IndexType;
+ using difference_type = std::ptrdiff_t;
+ using pointer = value_type*;
+ using reference = 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) GSL_NOEXCEPT
+ : boundary_(bnd.index_bounds()),
+ curr_(std::move(curr))
+ {
+ static_assert(is_bounds<Bounds>::value, "Bounds type must be provided");
+ }
+
+ constexpr reference operator*() const GSL_NOEXCEPT { return curr_; }
+
+ constexpr pointer operator->() const GSL_NOEXCEPT { return &curr_; }
+
+ constexpr bounds_iterator& operator++() GSL_NOEXCEPT
+ {
+ for (std::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) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ ++(*this);
+ return ret;
+ }
+
+ constexpr bounds_iterator& operator--() GSL_NOEXCEPT
+ {
+ if (!less(curr_, boundary_)) {
+ // if at the past-the-end, set to last element
+ for (std::size_t i = 0; i < rank; ++i) {
+ curr_[i] = boundary_[i] - 1;
+ }
+ return *this;
+ }
+ for (std::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) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ --(*this);
+ return ret;
+ }
+
+ constexpr bounds_iterator operator+(difference_type n) const GSL_NOEXCEPT
+ {
+ bounds_iterator ret{*this};
+ return ret += n;
+ }
+
+ constexpr bounds_iterator& operator+=(difference_type n) GSL_NOEXCEPT
+ {
+ auto linear_idx = linearize(curr_) + n;
+ std::remove_const_t<value_type> stride = 0;
+ stride[rank - 1] = 1;
+ for (std::size_t i = rank - 1; i-- > 0;) {
+ stride[i] = stride[i + 1] * boundary_[i + 1];
+ }
+ for (std::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 GSL_NOEXCEPT
+ {
+ bounds_iterator ret{*this};
+ return ret -= n;
+ }
+
+ constexpr bounds_iterator& operator-=(difference_type n) GSL_NOEXCEPT { return *this += -n; }
+
+ constexpr difference_type operator-(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return linearize(curr_) - linearize(rhs.curr_);
+ }
+
+ constexpr value_type operator[](difference_type n) const GSL_NOEXCEPT { return *(*this + n); }
+
+ constexpr bool operator==(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return curr_ == rhs.curr_;
+ }
+
+ constexpr bool operator!=(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(*this == rhs);
+ }
+
+ constexpr bool operator<(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return less(curr_, rhs.curr_);
+ }
+
+ constexpr bool operator<=(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(rhs < *this);
+ }
+
+ constexpr bool operator>(const bounds_iterator& rhs) const GSL_NOEXCEPT { return rhs < *this; }
+
+ constexpr bool operator>=(const bounds_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(rhs > *this);
+ }
+
+ void swap(bounds_iterator& rhs) GSL_NOEXCEPT
+ {
+ std::swap(boundary_, rhs.boundary_);
+ std::swap(curr_, rhs.curr_);
+ }
+
+private:
+ constexpr bool less(index_type& one, index_type& other) const GSL_NOEXCEPT
+ {
+ for (std::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 GSL_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 (std::size_t i = rank; i-- > 0;) {
+ res += (idx[i] - 1) * multiplier;
+ multiplier *= boundary_[i];
+ }
+ }
+ else
+ {
+ for (std::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) GSL_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) GSL_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) GSL_NOEXCEPT
+ {
+ auto extents = bnd.index_bounds();
+ typename Bounds::size_type stride[Bounds::rank] = {};
+
+ stride[Bounds::rank - 1] = 1;
+ for (std::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;
+
+template <std::ptrdiff_t DimSize = dynamic_range>
+struct dim_t
+{
+ static const std::ptrdiff_t value = DimSize;
+};
+template <>
+struct dim_t<dynamic_range>
+{
+ static const std::ptrdiff_t value = dynamic_range;
+ const std::ptrdiff_t dvalue;
+ constexpr dim_t(std::ptrdiff_t size) GSL_NOEXCEPT : dvalue(size) {}
+};
+
+template <std::ptrdiff_t N, class = std::enable_if_t<(N >= 0)>>
+constexpr dim_t<N> dim() GSL_NOEXCEPT
+{
+ return dim_t<N>();
+}
+
+template <std::ptrdiff_t N = dynamic_range, class = std::enable_if_t<N == dynamic_range>>
+constexpr dim_t<N> dim(std::ptrdiff_t n) GSL_NOEXCEPT
+{
+ return dim_t<>(n);
+}
+
+template <typename ValueType, std::ptrdiff_t FirstDimension = dynamic_range,
+ std::ptrdiff_t... RestDimensions>
+class multi_span;
+template <typename ValueType, std::size_t Rank>
+class strided_span;
+
+namespace details
+{
+ template <typename T, typename = std::true_type>
+ struct SpanTypeTraits
+ {
+ using value_type = T;
+ using size_type = std::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 = multi_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_multi_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_t<dynamic_range>>::value && !std::is_same<Arg, Sep>::value, T>
+ static_as_multi_span_helper(Arg, Args... args)
+ {
+ return static_as_multi_span_helper<T>(args...);
+ }
+ template <typename T, typename... Args>
+ T static_as_multi_span_helper(dim_t<dynamic_range> val, Args... args)
+ {
+ return static_as_multi_span_helper<T>(args..., val.dvalue);
+ }
+
+ template <typename... Dimensions>
+ struct static_as_multi_span_static_bounds_helper
+ {
+ using type = static_bounds<(Dimensions::value)...>;
+ };
+
+ template <typename T>
+ struct is_multi_span_oracle : std::false_type
+ {
+ };
+
+ template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
+ struct is_multi_span_oracle<multi_span<ValueType, FirstDimension, RestDimensions...>>
+ : std::true_type
+ {
+ };
+
+ template <typename ValueType, std::ptrdiff_t Rank>
+ struct is_multi_span_oracle<strided_span<ValueType, Rank>> : std::true_type
+ {
+ };
+
+ template <typename T>
+ struct is_multi_span : is_multi_span_oracle<std::remove_cv_t<T>>
+ {
+ };
+}
+
+template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
+class multi_span
+{
+ // TODO do we still need this?
+ template <typename ValueType2, std::ptrdiff_t FirstDimension2,
+ std::ptrdiff_t... RestDimensions2>
+ friend class multi_span;
+
+public:
+ using bounds_type = static_bounds<FirstDimension, RestDimensions...>;
+ static const std::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<multi_span>;
+ using const_span = multi_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, multi_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 multi_span() GSL_NOEXCEPT : multi_span(nullptr, bounds_type{})
+ {
+ static_assert(bounds_type::dynamic_rank != 0 ||
+ (bounds_type::dynamic_rank == 0 && bounds_type::static_size == 0),
+ "Default construction of multi_span<T> only possible "
+ "for dynamic or fixed, zero-length spans.");
+ }
+
+ // construct from nullptr - get an empty multi_span
+ constexpr multi_span(std::nullptr_t) GSL_NOEXCEPT : multi_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 multi_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 multi_span(std::nullptr_t, IntType size) GSL_NOEXCEPT
+ : multi_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 multi_span<T> only possible "
+ "for dynamic or fixed, zero-length spans.");
+ Expects(size == 0);
+ }
+
+ // construct from a single element
+ constexpr multi_span(reference data) GSL_NOEXCEPT : multi_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 multi_span(value_type&&) = delete;
+
+ // construct from pointer + length
+ constexpr multi_span(pointer ptr, size_type size) GSL_NOEXCEPT
+ : multi_span(ptr, bounds_type{size})
+ {
+ }
+
+ // construct from pointer + length - multidimensional
+ constexpr multi_span(pointer data, bounds_type bounds) GSL_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 multi_span(pointer begin, Ptr end)
+ : multi_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, std::size_t N, typename Helper = details::SpanArrayTraits<T, N>>
+ constexpr multi_span(T (&arr)[N])
+ : multi_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 multi_span type.");
+ static_assert(std::is_convertible<typename Helper::bounds_type, bounds_type>::value,
+ "Cannot construct a multi_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 multi_span(T* const& data, size_type size)
+ : multi_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 multi_span type.");
+ }
+
+ // construct from std::array
+ template <typename T, std::size_t N>
+ constexpr multi_span(std::array<T, N>& arr)
+ : multi_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 multi_span type.");
+ static_assert(std::is_convertible<static_bounds<N>, bounds_type>::value,
+ "You cannot construct a multi_span from a std::array of smaller size.");
+ }
+
+ // construct from const std::array
+ template <typename T, std::size_t N>
+ constexpr multi_span(const std::array<T, N>& arr)
+ : multi_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 multi_span type.");
+ static_assert(std::is_convertible<static_bounds<N>, bounds_type>::value,
+ "You cannot construct a multi_span from a std::array of smaller size.");
+ }
+
+ // prevent constructing from temporary std::array
+ template <typename T, std::size_t N>
+ constexpr multi_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_multi_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 multi_span(Cont& cont)
+ : multi_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_multi_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 multi_span(Cont&& cont) = delete;
+
+ // construct from a convertible multi_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 multi_span(multi_span<OtherValueType, OtherDimensions...> other) GSL_NOEXCEPT
+ : data_(other.data_),
+ bounds_(other.bounds_)
+ {
+ }
+
+ // trivial copy and move
+ constexpr multi_span(const multi_span&) = default;
+ constexpr multi_span(multi_span&&) = default;
+
+ // trivial assignment
+ constexpr multi_span& operator=(const multi_span&) = default;
+ constexpr multi_span& operator=(multi_span&&) = default;
+
+ // first() - extract the first Count elements into a new multi_span
+ template <std::ptrdiff_t Count>
+ constexpr multi_span<ValueType, Count> first() const GSL_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 multi_span
+ constexpr multi_span<ValueType, dynamic_range> first(size_type count) const GSL_NOEXCEPT
+ {
+ Expects(count >= 0 && count <= this->size());
+ return {this->data(), count};
+ }
+
+ // last() - extract the last Count elements into a new multi_span
+ template <std::ptrdiff_t Count>
+ constexpr multi_span<ValueType, Count> last() const GSL_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 multi_span
+ constexpr multi_span<ValueType, dynamic_range> last(size_type count) const GSL_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 multi_span<ValueType, Count> subspan() const GSL_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 multi_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 multi_span<ValueType, dynamic_range>
+ subspan(size_type offset, size_type count = dynamic_range) const GSL_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 multi_span from a contiguous one
+ constexpr strided_span<ValueType, Rank> section(index_type origin,
+ index_type extents) const GSL_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 multi_span in elements
+ constexpr size_type size() const GSL_NOEXCEPT { return bounds_.size(); }
+
+ // length of the multi_span in elements
+ constexpr size_type length() const GSL_NOEXCEPT { return this->size(); }
+
+ // length of the multi_span in bytes
+ constexpr size_type size_bytes() const GSL_NOEXCEPT
+ {
+ return narrow_cast<size_type>(sizeof(value_type)) * this->size();
+ }
+
+ // length of the multi_span in bytes
+ constexpr size_type length_bytes() const GSL_NOEXCEPT { return this->size_bytes(); }
+
+ constexpr bool empty() const GSL_NOEXCEPT { return this->size() == 0; }
+
+ static constexpr std::size_t rank() { return Rank; }
+
+ template <std::size_t Dim = 0>
+ constexpr size_type extent() const GSL_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 GSL_NOEXCEPT
+ {
+ return bounds_.extent(dim);
+ }
+
+ constexpr bounds_type bounds() const GSL_NOEXCEPT { return bounds_; }
+
+ constexpr pointer data() const GSL_NOEXCEPT { return data_; }
+
+ template <typename FirstIndex>
+ constexpr reference operator()(FirstIndex idx)
+ {
+ return this->operator[](narrow_cast<std::ptrdiff_t>(idx));
+ }
+
+ template <typename FirstIndex, typename... OtherIndices>
+ constexpr reference operator()(FirstIndex firstIndex, OtherIndices... indices)
+ {
+ index_type idx = {narrow_cast<std::ptrdiff_t>(firstIndex),
+ narrow_cast<std::ptrdiff_t>(indices)...};
+ return this->operator[](idx);
+ }
+
+ constexpr reference operator[](const index_type& idx) const GSL_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 GSL_NOEXCEPT
+ {
+ Expects(idx >= 0 && 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 GSL_NOEXCEPT { return iterator{this, true}; }
+
+ constexpr iterator end() const GSL_NOEXCEPT { return iterator{this, false}; }
+
+ constexpr const_iterator cbegin() const GSL_NOEXCEPT
+ {
+ return const_iterator{reinterpret_cast<const const_span*>(this), true};
+ }
+
+ constexpr const_iterator cend() const GSL_NOEXCEPT
+ {
+ return const_iterator{reinterpret_cast<const const_span*>(this), false};
+ }
+
+ constexpr reverse_iterator rbegin() const GSL_NOEXCEPT { return reverse_iterator{end()}; }
+
+ constexpr reverse_iterator rend() const GSL_NOEXCEPT { return reverse_iterator{begin()}; }
+
+ constexpr const_reverse_iterator crbegin() const GSL_NOEXCEPT
+ {
+ return const_reverse_iterator{cend()};
+ }
+
+ constexpr const_reverse_iterator crend() const GSL_NOEXCEPT
+ {
+ return const_reverse_iterator{cbegin()};
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
+ typename = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator==(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_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 = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator!=(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_NOEXCEPT
+ {
+ return !(*this == other);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
+ typename = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator<(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_NOEXCEPT
+ {
+ return std::lexicographical_compare(this->begin(), this->end(), other.begin(), other.end());
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
+ typename = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator<=(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_NOEXCEPT
+ {
+ return !(other < *this);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
+ typename = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator>(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_NOEXCEPT
+ {
+ return (other < *this);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t... OtherDimensions,
+ typename = std::enable_if_t<std::is_same<
+ std::remove_cv_t<value_type>, std::remove_cv_t<OtherValueType>>::value>>
+ constexpr bool
+ operator>=(const multi_span<OtherValueType, OtherDimensions...>& other) const GSL_NOEXCEPT
+ {
+ return !(*this < other);
+ }
+};
+
+//
+// Free functions for manipulating spans
+//
+
+// reshape a multi_span into a different dimensionality
+// DimCount and Enabled here are workarounds for a bug in MSVC 2015
+template <typename SpanType, typename... Dimensions2, std::size_t DimCount = sizeof...(Dimensions2),
+ bool Enabled = (DimCount > 0), typename = std::enable_if_t<Enabled>>
+constexpr auto as_multi_span(SpanType s, Dimensions2... dims)
+ -> multi_span<typename SpanType::value_type, Dimensions2::value...>
+{
+ static_assert(details::is_multi_span<SpanType>::value,
+ "Variadic as_multi_span() is for reshaping existing spans.");
+ using BoundsType =
+ typename multi_span<typename SpanType::value_type, (Dimensions2::value)...>::bounds_type;
+ auto tobounds = details::static_as_multi_span_helper<BoundsType>(dims..., details::Sep{});
+ details::verifyBoundsReshape(s.bounds(), tobounds);
+ return {s.data(), tobounds};
+}
+
+// convert a multi_span<T> to a multi_span<const byte>
+template <typename U, std::ptrdiff_t... Dimensions>
+multi_span<const byte, dynamic_range> as_bytes(multi_span<U, Dimensions...> s) GSL_NOEXCEPT
+{
+ static_assert(std::is_trivial<std::decay_t<U>>::value,
+ "The value_type of multi_span must be a trivial type.");
+ return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
+}
+
+// convert a multi_span<T> to a multi_span<byte> (a writeable byte multi_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>
+multi_span<byte> as_writeable_bytes(multi_span<U, Dimensions...> s) GSL_NOEXCEPT
+{
+ static_assert(std::is_trivial<std::decay_t<U>>::value,
+ "The value_type of multi_span must be a trivial type.");
+ return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
+}
+
+// convert a multi_span<const byte> to a multi_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_multi_span(multi_span<const byte, Dimensions...> s) GSL_NOEXCEPT -> multi_span<
+ const U, static_cast<std::ptrdiff_t>(
+ multi_span<const byte, Dimensions...>::bounds_type::static_size != dynamic_range
+ ? (static_cast<std::size_t>(
+ multi_span<const byte, Dimensions...>::bounds_type::static_size) /
+ sizeof(U))
+ : dynamic_range)>
+{
+ using ConstByteSpan = multi_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() % narrow_cast<std::ptrdiff_t>(sizeof(U))) == 0 &&
+ (s.size_bytes() / narrow_cast<std::ptrdiff_t>(sizeof(U))) < PTRDIFF_MAX);
+ return {reinterpret_cast<const U*>(s.data()),
+ s.size_bytes() / narrow_cast<std::ptrdiff_t>(sizeof(U))};
+}
+
+// convert a multi_span<byte> to a multi_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_multi_span(multi_span<byte, Dimensions...> s) GSL_NOEXCEPT
+ -> multi_span<U, narrow_cast<std::ptrdiff_t>(
+ multi_span<byte, Dimensions...>::bounds_type::static_size != dynamic_range
+ ? static_cast<std::size_t>(
+ multi_span<byte, Dimensions...>::bounds_type::static_size) /
+ sizeof(U)
+ : dynamic_range)>
+{
+ using ByteSpan = multi_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 % 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);
+ 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_multi_span(T* const& ptr, dim_t<Dimensions>... args)
+ -> multi_span<std::remove_all_extents_t<T>, Dimensions...>
+{
+ return {reinterpret_cast<std::remove_all_extents_t<T>*>(ptr),
+ details::static_as_multi_span_helper<static_bounds<Dimensions...>>(args...,
+ details::Sep{})};
+}
+
+template <typename T>
+constexpr auto as_multi_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, std::size_t N>
+constexpr auto as_multi_span(T (&arr)[N]) -> typename details::SpanArrayTraits<T, N>::type
+{
+ return {arr};
+}
+
+template <typename T, std::size_t N>
+constexpr multi_span<const T, N> as_multi_span(const std::array<T, N>& arr)
+{
+ return {arr};
+}
+
+template <typename T, std::size_t N>
+constexpr multi_span<const T, N> as_multi_span(const std::array<T, N>&&) = delete;
+
+template <typename T, std::size_t N>
+constexpr multi_span<T, N> as_multi_span(std::array<T, N>& arr)
+{
+ return {arr};
+}
+
+template <typename T>
+constexpr multi_span<T, dynamic_range> as_multi_span(T* begin, T* end)
+{
+ return {begin, end};
+}
+
+template <typename Cont>
+constexpr auto as_multi_span(Cont& arr) -> std::enable_if_t<
+ !details::is_multi_span<std::decay_t<Cont>>::value,
+ multi_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_multi_span(Cont&& arr) -> std::enable_if_t<
+ !details::is_multi_span<std::decay_t<Cont>>::value,
+ multi_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_multi_span(std::basic_string<CharT, Traits, Allocator>& str)
+ -> multi_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, std::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, std::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 = std::enable_if_t<Enabled1 && Enabled2>>
+ constexpr strided_span(multi_span<OtherValueType, Dimensions...> av, bounds_type bounds)
+ : strided_span(av.data(), av.bounds().total_size(), std::move(bounds))
+ {
+ }
+
+ // convertible
+ template <typename OtherValueType, typename = 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 {const_cast<OtherValueType*>(reinterpret_cast<const 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 GSL_NOEXCEPT { return bounds_; }
+
+ template <std::size_t Dim = 0>
+ constexpr size_type extent() const GSL_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 GSL_NOEXCEPT { return bounds_.size(); }
+
+ constexpr pointer data() const GSL_NOEXCEPT { return data_; }
+
+ constexpr explicit operator bool() const GSL_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 = 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 GSL_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 = 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 GSL_NOEXCEPT
+ {
+ return !(*this == other);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t OtherRank,
+ typename = 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 GSL_NOEXCEPT
+ {
+ return std::lexicographical_compare(this->begin(), this->end(), other.begin(), other.end());
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t OtherRank,
+ typename = 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 GSL_NOEXCEPT
+ {
+ return !(other < *this);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t OtherRank,
+ typename = 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 GSL_NOEXCEPT
+ {
+ return (other < *this);
+ }
+
+ template <typename OtherValueType, std::ptrdiff_t OtherRank,
+ typename = 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 GSL_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 = std::enable_if_t<Enabled>>
+ static index_type resize_stride(const index_type& strides, std::ptrdiff_t, void* = nullptr)
+ {
+ // Only strided arrays with regular strides can be resized
+ Expects(strides[Rank - 1] == 1);
+
+ return strides;
+ }
+
+ template <bool Enabled = (Rank > 1), typename = 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 (std::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:
+ using iterator_category = std::random_access_iterator_tag;
+ using value_type = typename Span::value_type;
+ using difference_type = std::ptrdiff_t;
+ using pointer = value_type*;
+ using reference = value_type&;
+
+private:
+ template <typename ValueType, std::ptrdiff_t FirstDimension, std::ptrdiff_t... RestDimensions>
+ friend class multi_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 GSL_NOEXCEPT
+ {
+ validateThis();
+ return *data_;
+ }
+ pointer operator->() const GSL_NOEXCEPT
+ {
+ validateThis();
+ return data_;
+ }
+ contiguous_span_iterator& operator++() GSL_NOEXCEPT
+ {
+ ++data_;
+ return *this;
+ }
+ contiguous_span_iterator operator++(int) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ ++(*this);
+ return ret;
+ }
+ contiguous_span_iterator& operator--() GSL_NOEXCEPT
+ {
+ --data_;
+ return *this;
+ }
+ contiguous_span_iterator operator--(int) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ --(*this);
+ return ret;
+ }
+ contiguous_span_iterator operator+(difference_type n) const GSL_NOEXCEPT
+ {
+ contiguous_span_iterator ret{*this};
+ return ret += n;
+ }
+ contiguous_span_iterator& operator+=(difference_type n) GSL_NOEXCEPT
+ {
+ data_ += n;
+ return *this;
+ }
+ contiguous_span_iterator operator-(difference_type n) const GSL_NOEXCEPT
+ {
+ contiguous_span_iterator ret{*this};
+ return ret -= n;
+ }
+ contiguous_span_iterator& operator-=(difference_type n) GSL_NOEXCEPT { return *this += -n; }
+ difference_type operator-(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_validator == rhs.m_validator);
+ return data_ - rhs.data_;
+ }
+ reference operator[](difference_type n) const GSL_NOEXCEPT { return *(*this + n); }
+ bool operator==(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_validator == rhs.m_validator);
+ return data_ == rhs.data_;
+ }
+ bool operator!=(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(*this == rhs);
+ }
+ bool operator<(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_validator == rhs.m_validator);
+ return data_ < rhs.data_;
+ }
+ bool operator<=(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(rhs < *this);
+ }
+ bool operator>(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT { return rhs < *this; }
+ bool operator>=(const contiguous_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ return !(rhs > *this);
+ }
+ void swap(contiguous_span_iterator& rhs) GSL_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) GSL_NOEXCEPT
+{
+ return rhs + n;
+}
+
+template <typename Span>
+class general_span_iterator
+{
+public:
+ using iterator_category = std::random_access_iterator_tag;
+ using value_type = typename Span::value_type;
+ using difference_type = std::ptrdiff_t;
+ using pointer = value_type*;
+ using reference = value_type&;
+
+private:
+ template <typename ValueType, std::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*() GSL_NOEXCEPT { return (*m_container)[*m_itr]; }
+ pointer operator->() GSL_NOEXCEPT { return &(*m_container)[*m_itr]; }
+ general_span_iterator& operator++() GSL_NOEXCEPT
+ {
+ ++m_itr;
+ return *this;
+ }
+ general_span_iterator operator++(int) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ ++(*this);
+ return ret;
+ }
+ general_span_iterator& operator--() GSL_NOEXCEPT
+ {
+ --m_itr;
+ return *this;
+ }
+ general_span_iterator operator--(int) GSL_NOEXCEPT
+ {
+ auto ret = *this;
+ --(*this);
+ return ret;
+ }
+ general_span_iterator operator+(difference_type n) const GSL_NOEXCEPT
+ {
+ general_span_iterator ret{*this};
+ return ret += n;
+ }
+ general_span_iterator& operator+=(difference_type n) GSL_NOEXCEPT
+ {
+ m_itr += n;
+ return *this;
+ }
+ general_span_iterator operator-(difference_type n) const GSL_NOEXCEPT
+ {
+ general_span_iterator ret{*this};
+ return ret -= n;
+ }
+ general_span_iterator& operator-=(difference_type n) GSL_NOEXCEPT { return *this += -n; }
+ difference_type operator-(const general_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_container == rhs.m_container);
+ return m_itr - rhs.m_itr;
+ }
+ value_type operator[](difference_type n) const GSL_NOEXCEPT { return (*m_container)[m_itr[n]]; }
+
+ bool operator==(const general_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_container == rhs.m_container);
+ return m_itr == rhs.m_itr;
+ }
+ bool operator!=(const general_span_iterator& rhs) const GSL_NOEXCEPT { return !(*this == rhs); }
+ bool operator<(const general_span_iterator& rhs) const GSL_NOEXCEPT
+ {
+ Expects(m_container == rhs.m_container);
+ return m_itr < rhs.m_itr;
+ }
+ bool operator<=(const general_span_iterator& rhs) const GSL_NOEXCEPT { return !(rhs < *this); }
+ bool operator>(const general_span_iterator& rhs) const GSL_NOEXCEPT { return rhs < *this; }
+ bool operator>=(const general_span_iterator& rhs) const GSL_NOEXCEPT { return !(rhs > *this); }
+ void swap(general_span_iterator& rhs) GSL_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) GSL_NOEXCEPT
+{
+ return rhs + n;
+}
+
+} // namespace gsl
+
+#undef GSL_NOEXCEPT
+
+#ifdef _MSC_VER
+#if _MSC_VER < 1910
+
+#undef constexpr
+#pragma pop_macro("constexpr")
+#endif // _MSC_VER < 1910
+
+#pragma warning(pop)
+
+#endif // _MSC_VER
+
+#if __GNUC__ > 6
+#pragma GCC diagnostic pop
+#endif // __GNUC__ > 6
+
+#endif // GSL_MULTI_SPAN_H