diff options
Diffstat (limited to 'common/alspan.h')
| -rw-r--r-- | common/alspan.h | 43 |
1 files changed, 32 insertions, 11 deletions
diff --git a/common/alspan.h b/common/alspan.h index 4a0e0430..dcc5750b 100644 --- a/common/alspan.h +++ b/common/alspan.h @@ -51,27 +51,27 @@ namespace detail_ { template<typename T, size_t E> struct is_span_<span<T,E>> : std::true_type { }; template<typename T> - using is_span = is_span_<std::remove_cv_t<T>>; + constexpr bool is_span_v = is_span_<std::remove_cv_t<T>>::value; template<typename T> struct is_std_array_ : std::false_type { }; template<typename T, size_t N> struct is_std_array_<std::array<T,N>> : std::true_type { }; template<typename T> - using is_std_array = is_std_array_<std::remove_cv_t<T>>; + constexpr bool is_std_array_v = is_std_array_<std::remove_cv_t<T>>::value; template<typename T, typename = void> - struct has_size_and_data : std::false_type { }; + constexpr bool has_size_and_data = false; template<typename T> - struct has_size_and_data<T, + constexpr bool has_size_and_data<T, void_t<decltype(al::size(std::declval<T>())), decltype(al::data(std::declval<T>()))>> - : std::true_type { }; + = true; } // namespace detail_ -#define REQUIRES(...) bool rt_=true, std::enable_if_t<rt_ && (__VA_ARGS__),bool> = true +#define REQUIRES(...) std::enable_if_t<(__VA_ARGS__),bool> = true #define IS_VALID_CONTAINER(C) \ - !detail_::is_span<C>::value && !detail_::is_std_array<C>::value && \ - !std::is_array<C>::value && detail_::has_size_and_data<C>::value && \ + !detail_::is_span_v<C> && !detail_::is_std_array_v<C> && \ + !std::is_array<C>::value && detail_::has_size_and_data<C> && \ std::is_convertible<std::remove_pointer_t<decltype(al::data(std::declval<C&>()))>(*)[],element_type(*)[]>::value template<typename T, size_t E> @@ -94,13 +94,13 @@ public: static constexpr size_t extent{E}; - template<REQUIRES(extent==0)> + template<bool is0=(extent == 0), REQUIRES(is0)> constexpr span() noexcept { } constexpr span(pointer ptr, index_type /*count*/) : mData{ptr} { } constexpr span(pointer first, pointer /*last*/) : mData{first} { } constexpr span(element_type (&arr)[E]) noexcept : span{al::data(arr), al::size(arr)} { } constexpr span(std::array<value_type,E> &arr) noexcept : span{al::data(arr), al::size(arr)} { } - template<REQUIRES(std::is_const<element_type>::value)> + template<typename U=T, REQUIRES(std::is_const<U>::value)> constexpr span(const std::array<value_type,E> &arr) noexcept : span{al::data(arr), al::size(arr)} { } @@ -205,7 +205,7 @@ public: constexpr span(element_type (&arr)[N]) noexcept : span{al::data(arr), al::size(arr)} { } template<size_t N> constexpr span(std::array<value_type,N> &arr) noexcept : span{al::data(arr), al::size(arr)} { } - template<size_t N, REQUIRES(std::is_const<element_type>::value)> + template<size_t N, typename U=T, REQUIRES(std::is_const<U>::value)> constexpr span(const std::array<value_type,N> &arr) noexcept : span{al::data(arr), al::size(arr)} { } @@ -299,6 +299,27 @@ constexpr inline auto span<T,E>::subspan(size_t offset, size_t count) const span<element_type>{mData+offset, mData+offset+count}; } +/* Helpers to deal with the lack of user-defined deduction guides (C++17). */ +template<typename T, typename U> +constexpr auto as_span(T *ptr, U count_or_end) { return span<T>{ptr, count_or_end}; } +template<typename T, size_t N> +constexpr auto as_span(T (&arr)[N]) noexcept { return span<T,N>{al::data(arr), al::size(arr)}; } +template<typename T, size_t N> +constexpr auto as_span(std::array<T,N> &arr) noexcept +{ return span<T,N>{al::data(arr), al::size(arr)}; } +template<typename T, size_t N> +constexpr auto as_span(const std::array<T,N> &arr) noexcept +{ return span<std::add_const_t<T>,N>{al::data(arr), al::size(arr)}; } +template<typename U, REQUIRES(!detail_::is_span_v<U> && !detail_::is_std_array_v<U> + && !std::is_array<U>::value && detail_::has_size_and_data<U>)> +constexpr auto as_span(U &cont) +{ + using value_type = std::remove_pointer_t<decltype(al::data(std::declval<U&>()))>; + return span<value_type>{al::data(cont), al::size(cont)}; +} +template<typename T, size_t N> +constexpr auto as_span(span<T,N> span_) noexcept { return span_; } + #undef IS_VALID_CONTAINER #undef REQUIRES |