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almost parity with std::span
This commit is contained in:
Jordan Maples [MSFT]
parent
a49ff1b8df
commit
377b2db537
107
include/gsl/span
107
include/gsl/span
@ -111,8 +111,7 @@ namespace details
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template <std::size_t From, std::size_t To>
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struct is_allowed_extent_conversion
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: public std::integral_constant<bool, From == To || From == gsl::dynamic_extent ||
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To == gsl::dynamic_extent>
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: public std::integral_constant<bool, From == To || To == gsl::dynamic_extent>
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{
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};
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@ -301,7 +300,9 @@ namespace details
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if (n < 0) Expects(current_ - begin_ >= -n);
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}
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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constexpr pointer _Unwrapped() const noexcept
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{ // after seeking *this to a high water mark, or using one of the
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// _Verify_xxx functions above, unwrap this span_iterator to a raw
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@ -316,7 +317,9 @@ namespace details
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#else
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static constexpr bool _Unwrap_when_unverified = false;
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#endif
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// clang-format off
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GSL_SUPPRESS(con.3) // NO-FORMAT: attribute // TODO: false positive
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// clang-format on
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constexpr void _Seek_to(const pointer p) noexcept
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{ // adjust the position of *this to previously verified location p
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// after _Unwrapped
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@ -392,7 +395,9 @@ public:
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using value_type = std::remove_cv_t<ElementType>;
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using size_type = std::size_t;
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using pointer = element_type*;
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using const_pointer = const element_type*;
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using reference = element_type&;
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using const_reference = const element_type&;
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using difference_type = std::ptrdiff_t;
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using iterator = details::span_iterator<ElementType>;
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@ -410,38 +415,48 @@ public:
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// [span.cons], span constructors, copy, assignment, and destructor
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template <bool Dependent = false,
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// "Dependent" is needed to make "std::enable_if_t<Dependent || Extent == 0 || Extent == dynamic_extent>" SFINAE,
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// since "std::enable_if_t<Extent == 0 || Extent == dynamic_extent>" is ill-formed when Extent is greater than 0.
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// "Dependent" is needed to make "std::enable_if_t<Dependent || Extent == 0 || Extent
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// == dynamic_extent>" SFINAE, since "std::enable_if_t<Extent == 0 || Extent ==
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// dynamic_extent>" is ill-formed when Extent is greater than 0.
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class = std::enable_if_t<(Dependent || Extent == 0 || Extent == dynamic_extent)>>
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constexpr span() noexcept : storage_(nullptr, details::extent_type<0>())
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{}
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constexpr span(pointer ptr, size_type count) noexcept : storage_(ptr, count) {}
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constexpr span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
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{
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if (Extent != dynamic_extent) Expects(count == Extent);
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}
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constexpr span(pointer firstElem, pointer lastElem) noexcept
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: storage_(firstElem, static_cast<std::size_t>(std::distance(firstElem, lastElem)))
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{}
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{
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if (Extent != dynamic_extent) { Expects(lastElem - firstElem == Extent); }
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}
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template <std::size_t N>
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constexpr span(element_type (&arr)[N]) noexcept
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: storage_(KnownNotNull{std::addressof(arr[0])}, details::extent_type<N>())
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{}
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template <std::size_t N, class = std::enable_if_t<(N > 0)>>
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constexpr span(std::array<std::remove_const_t<element_type>, N>& arr) noexcept
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template <std::size_t N, std::size_t Ext = Extent,
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std::enable_if_t<(N == Ext || Ext == dynamic_extent), int> = 0>
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constexpr span(std::array<value_type, N>& arr) noexcept
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: storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
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{}
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constexpr span(std::array<std::remove_const_t<element_type>, 0>&) noexcept
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template <std::size_t N, std::size_t Ext = Extent,
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std::enable_if_t<((N == Ext || Ext == dynamic_extent) &&
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std::is_convertible<const value_type*, element_type*>::value),
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int> = 0>
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constexpr span(const std::array<value_type, N>& arr) noexcept
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: storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
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{}
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constexpr span(std::array<value_type, 0>&) noexcept
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: storage_(static_cast<pointer>(nullptr), details::extent_type<0>())
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{}
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template <std::size_t N, class = std::enable_if_t<(N > 0)>>
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constexpr span(const std::array<std::remove_const_t<element_type>, N>& arr) noexcept
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: storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
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{}
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constexpr span(const std::array<std::remove_const_t<element_type>, 0>&) noexcept
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constexpr span(const std::array<value_type, 0>&) noexcept
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: storage_(static_cast<pointer>(nullptr), details::extent_type<0>())
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{}
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@ -451,8 +466,8 @@ public:
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class = std::enable_if_t<
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!details::is_span<Container>::value && !details::is_std_array<Container>::value &&
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std::is_convertible<typename Container::pointer, pointer>::value &&
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std::is_convertible<typename Container::pointer,
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decltype(std::declval<Container>().data())>::value>>
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std::is_convertible<pointer, typename Container::pointer>::value &&
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std::is_convertible<decltype(std::declval<Container&>().data()), pointer>::value>>
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constexpr span(Container& cont) noexcept : span(cont.data(), cont.size())
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{}
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@ -460,10 +475,8 @@ public:
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class = std::enable_if_t<
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std::is_const<element_type>::value && !details::is_span<Container>::value &&
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std::is_convertible<typename Container::pointer, pointer>::value &&
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std::is_convertible<typename Container::pointer,
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decltype(std::declval<Container>().data())>::value>>
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constexpr span(const Container& cont) noexcept
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: span(cont.data(), cont.size())
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std::is_convertible<decltype(std::declval<Container&>().data()), pointer>::value>>
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constexpr span(const Container& cont) noexcept : span(cont.data(), cont.size())
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{}
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constexpr span(const span& other) noexcept = default;
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@ -489,16 +502,20 @@ public:
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}
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template <std::size_t Count>
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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constexpr span<element_type, Count> last() const noexcept
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// clang-format on
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constexpr span<element_type, Count> last() const noexcept
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{
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Expects(size() >= Count);
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return {data() + (size() - Count), Count};
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}
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template <std::size_t Offset, std::size_t Count = dynamic_extent>
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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constexpr auto subspan() const noexcept ->
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// clang-format on
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constexpr auto subspan() const noexcept ->
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typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type
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{
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Expects((size() >= Offset) && (Count == dynamic_extent || (Count <= size() - Offset)));
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@ -537,7 +554,9 @@ public:
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constexpr bool empty() const noexcept { return size() == 0; }
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// [span.elem], span element access
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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constexpr reference operator[](size_type idx) const noexcept
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{
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Expects(idx < size());
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@ -602,7 +621,9 @@ public:
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constexpr pointer _Unchecked_begin() const noexcept { return data(); }
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constexpr pointer _Unchecked_end() const noexcept
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{
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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return data() + size();
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}
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#endif // _MSC_VER
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@ -662,7 +683,9 @@ private:
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return tmp.subspan(offset, count);
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}
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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span<element_type, dynamic_extent> make_subspan(size_type offset, size_type count,
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subspan_selector<dynamic_extent>) const
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{
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@ -675,6 +698,20 @@ private:
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}
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};
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#if (defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L))
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// Deduction Guides
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template <class Type, std::size_t Extent>
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span(Type (&)[Extent])->span<Type, Extent>;
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template <class Type, std::size_t Size>
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span(std::array<Type, Size>&)->span<Type, Size>;
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template <class Type, std::size_t Size>
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span(const std::array<Type, Size>&)->span<const Type, Size>;
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#endif // ( defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L) )
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#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
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template <class ElementType, std::size_t Extent>
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constexpr const typename span<ElementType, Extent>::size_type span<ElementType, Extent>::extent;
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@ -742,16 +779,32 @@ template <class ElementType, std::size_t Extent>
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span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
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as_bytes(span<ElementType, Extent> s) noexcept
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{
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// clang-format off
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GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
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// clang-format on
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return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
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}
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template <class ElementType, std::size_t Extent,
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class = std::enable_if_t<!std::is_const<ElementType>::value>>
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std::enable_if_t<!std::is_const<ElementType>::value, int> = 0>
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span<byte, details::calculate_byte_size<ElementType, Extent>::value>
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as_writable_bytes(span<ElementType, Extent> s) noexcept
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{
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// clang-format off
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GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
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// clang-format on
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return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
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}
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template <class ElementType, std::size_t Extent,
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std::enable_if_t<!std::is_const<ElementType>::value, int> = 0>
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[[deprecated(
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"use as_writable_bytes")]] span<byte, details::calculate_byte_size<ElementType, Extent>::value>
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as_writeable_bytes(span<ElementType, Extent> s) noexcept
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{
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// clang-format off
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GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
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// clang-format on
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return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
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}
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@ -759,8 +812,7 @@ as_writeable_bytes(span<ElementType, Extent> s) noexcept
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// make_span() - Utility functions for creating spans
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//
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template <class ElementType>
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constexpr span<ElementType> make_span(ElementType* ptr,
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typename span<ElementType>::size_type count)
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constexpr span<ElementType> make_span(ElementType* ptr, typename span<ElementType>::size_type count)
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{
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return span<ElementType>(ptr, count);
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}
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@ -812,8 +864,7 @@ constexpr ElementType& at(span<ElementType, Extent> s, index i)
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// [span.obs] Free observer functions
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template <class ElementType, std::size_t Extent>
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constexpr std::ptrdiff_t
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ssize(const span<ElementType, Extent>& s) noexcept
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constexpr std::ptrdiff_t ssize(const span<ElementType, Extent>& s) noexcept
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{
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return static_cast<std::ptrdiff_t>(s.size());
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}
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@ -1551,11 +1551,15 @@ TEST(span_test, from_array_constructor)
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// even when done dynamically
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{
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span<int> s = arr;
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/*
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// this now results in a compile-time error, rather than runtime.
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// There is no suitable conversion from dynamic span to fixed span.
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auto f = [&]() {
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const span<int, 2> s2 = s;
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static_cast<void>(s2);
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};
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EXPECT_DEATH(f(), deathstring);
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*/
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}
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// but doing so explicitly is ok
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@ -1570,12 +1574,19 @@ TEST(span_test, from_array_constructor)
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static_cast<void>(s1);
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}
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// ...or dynamically
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/*
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// this is not a legal operation in std::span, so we are no longer supporting it
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// conversion from span<int, 4> to span<int, dynamic_extent> via call to `first`
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// then convert from span<int, dynamic_extent> to span<int, 1>
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// The dynamic to fixed extents are not supported in the standard
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// to make this work, span<int, 1> would need to be span<int>.
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{
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// NB: implicit conversion to span<int,1> from span<int>
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span<int, 1> s1 = s4.first(1);
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static_cast<void>(s1);
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}
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*/
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// initialization or assignment to static span that requires size INCREASE is not ok.
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int arr2[2] = {1, 2};
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@ -1597,12 +1608,15 @@ TEST(span_test, from_array_constructor)
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EXPECT_DEATH(f(), deathstring);
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}
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/*
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// This no longer compiles. There is no suitable conversion from dynamic span to a fixed size span.
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// this should fail - we are trying to assign a small dynamic span to a fixed_size larger one
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span<int> av = arr2; auto f = [&]() {
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const span<int, 4> _s4 = av;
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static_cast<void>(_s4);
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};
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EXPECT_DEATH(f(), deathstring);
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*/
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}
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TEST(span_test, interop_with_std_regex)
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