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Merge pull request #922 from JordanMaples/constexpr-string_span

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constexpr string_span
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Jordan Maples [MSFT] 2020-08-27 14:29:30 -07:00 committed by GitHub
commit d58e50c6f4
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1 changed files with 12 additions and 11 deletions
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23
include/gsl/string_span
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@ -81,7 +81,7 @@ using u32zstring = basic_zstring<char32_t, Extent>;
namespace details namespace details
{ {
template <class CharT> template <class CharT>
std::size_t string_length(const CharT* str, std::size_t n) constexpr std::size_t string_length(const CharT* str, std::size_t n)
{ {
if (str == nullptr || n == dynamic_extent) return 0; if (str == nullptr || n == dynamic_extent) return 0;
@ -103,7 +103,7 @@ namespace details
// Will fail-fast if sentinel cannot be found before max elements are examined. // Will fail-fast if sentinel cannot be found before max elements are examined.
// //
template <typename T, const T Sentinel> template <typename T, const T Sentinel>
span<T, dynamic_extent> ensure_sentinel(T* seq, constexpr span<T, dynamic_extent> ensure_sentinel(T* seq,
std::size_t max = static_cast<std::size_t>(-1)) std::size_t max = static_cast<std::size_t>(-1))
{ {
Ensures(seq != nullptr); Ensures(seq != nullptr);
@ -124,20 +124,20 @@ span<T, dynamic_extent> ensure_sentinel(T* seq,
// Will fail fast if a null-terminator cannot be found before the limit of size_type. // Will fail fast if a null-terminator cannot be found before the limit of size_type.
// //
template <typename CharT> template <typename CharT>
span<CharT, dynamic_extent> ensure_z(CharT* const& sz, constexpr span<CharT, dynamic_extent> ensure_z(CharT* const& sz,
std::size_t max = static_cast<std::size_t>(-1)) std::size_t max = static_cast<std::size_t>(-1))
{ {
return ensure_sentinel<CharT, CharT(0)>(sz, max); return ensure_sentinel<CharT, CharT(0)>(sz, max);
} }
template <typename CharT, std::size_t N> template <typename CharT, std::size_t N>
span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N]) constexpr span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N])
{ {
return ensure_z(&sz[0], N); return ensure_z(&sz[0], N);
} }
template <class Cont> template <class Cont>
span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_extent> constexpr span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_extent>
ensure_z(Cont& cont) ensure_z(Cont& cont)
{ {
return ensure_z(cont.data(), cont.size()); return ensure_z(cont.data(), cont.size());
@ -300,13 +300,13 @@ public:
constexpr reverse_iterator rend() const noexcept { return span_.rend(); } constexpr reverse_iterator rend() const noexcept { return span_.rend(); }
private: private:
static impl_type remove_z(pointer const& sz, std::size_t max) static constexpr impl_type remove_z(pointer const& sz, std::size_t max)
{ {
return impl_type(sz, details::string_length(sz, max)); return impl_type(sz, details::string_length(sz, max));
} }
template <std::size_t N> template <std::size_t N>
static impl_type remove_z(element_type (&sz)[N]) static constexpr impl_type remove_z(element_type (&sz)[N])
{ {
return remove_z(&sz[0], N); return remove_z(&sz[0], N);
} }
@ -343,7 +343,7 @@ using cu32string_span = basic_string_span<const char32_t, Extent>;
// //
template <typename CharT, std::size_t Extent> template <typename CharT, std::size_t Extent>
std::basic_string<typename std::remove_const<CharT>::type> constexpr std::basic_string<typename std::remove_const<CharT>::type>
to_string(basic_string_span<CharT, Extent> view) to_string(basic_string_span<CharT, Extent> view)
{ {
return {view.data(), narrow_cast<std::size_t>(view.length())}; return {view.data(), narrow_cast<std::size_t>(view.length())};
@ -351,13 +351,14 @@ to_string(basic_string_span<CharT, Extent> view)
template <typename CharT, typename Traits = typename std::char_traits<CharT>, template <typename CharT, typename Traits = typename std::char_traits<CharT>,
typename Allocator = std::allocator<CharT>, typename gCharT, std::size_t Extent> typename Allocator = std::allocator<CharT>, typename gCharT, std::size_t Extent>
std::basic_string<CharT, Traits, Allocator> to_basic_string(basic_string_span<gCharT, Extent> view) constexpr std::basic_string<CharT, Traits, Allocator>
to_basic_string(basic_string_span<gCharT, Extent> view)
{ {
return {view.data(), narrow_cast<std::size_t>(view.length())}; return {view.data(), narrow_cast<std::size_t>(view.length())};
} }
template <class ElementType, std::size_t Extent> template <class ElementType, std::size_t Extent>
basic_string_span<const byte, details::calculate_byte_size<ElementType, Extent>::value> constexpr basic_string_span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
as_bytes(basic_string_span<ElementType, Extent> s) noexcept as_bytes(basic_string_span<ElementType, Extent> s) noexcept
{ {
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
@ -366,7 +367,7 @@ as_bytes(basic_string_span<ElementType, Extent> s) noexcept
template <class ElementType, std::size_t Extent, template <class ElementType, std::size_t Extent,
class = std::enable_if_t<!std::is_const<ElementType>::value>> class = std::enable_if_t<!std::is_const<ElementType>::value>>
basic_string_span<byte, details::calculate_byte_size<ElementType, Extent>::value> constexpr basic_string_span<byte, details::calculate_byte_size<ElementType, Extent>::value>
as_writable_bytes(basic_string_span<ElementType, Extent> s) noexcept as_writable_bytes(basic_string_span<ElementType, Extent> s) noexcept
{ {
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute GSL_SUPPRESS(type.1) // NO-FORMAT: attribute