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love the span

v1
Brett 2024-02-11 14:05:53 -05:00
parent 7ac20db077
commit 3b7d3d4d2a
1 changed files with 249 additions and 5 deletions
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252
include/blt/std/ranges.h
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@ -11,6 +11,7 @@
#include <blt/std/types.h>
#include <type_traits>
#include <iterator>
#include <memory>
#include <utility>
#include <limits>
@ -209,10 +210,65 @@ namespace blt
template<typename C, typename T>
itr_offset(C, T) -> itr_offset<typename C::iterator>;
inline constexpr std::size_t dynamic_extent = std::numeric_limits<std::size_t>::max();
template<typename T, std::size_t extend = dynamic_extent>
template<typename T, std::size_t extent = dynamic_extent>
class span;
// https://codereview.stackexchange.com/questions/217814/c17-span-implementation
namespace span_detail
{
// detect specializations of span
template<class T>
struct is_span : std::false_type
{
};
template<class T, std::size_t N>
struct is_span<span<T, N>> : std::true_type
{
};
template<class T>
inline constexpr bool is_span_v = is_span<T>::value;
// detect specializations of std::array
template<class T>
struct is_array : std::false_type
{
};
template<class T, std::size_t N>
struct is_array<std::array<T, N>> : std::true_type
{
};
template<class T>
inline constexpr bool is_array_v = is_array<T>::value;
// detect container
template<class C, class = void>
struct is_cont : std::false_type
{
};
template<class C>
struct is_cont<C,
std::void_t<
std::enable_if_t<!is_span_v<C>>,
std::enable_if_t<!is_array_v<C>>,
std::enable_if_t<!std::is_array_v<C>>,
decltype(data(std::declval<C>())),
decltype(size(std::declval<C>()))
>> : std::true_type
{
};
template<class C>
inline constexpr bool is_cont_v = is_cont<C>::value;
}
template<typename T, std::size_t extent>
class span
{
public:
@ -224,11 +280,199 @@ namespace blt
using const_pointer = const T*;
using reference = T&;
using const_reference = const T&;
using iterator = T*;
using const_iterator = const T*;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
private:
size_type size_;
pointer* data_;
public:
constexpr span() noexcept: size_(0), data_(nullptr)
{}
template<class It, std::enable_if_t<extent != dynamic_extent, bool> = true>
constexpr explicit span(It first, size_type count): size_(count), data_(&*first)
{}
template<class It, std::enable_if_t<extent == dynamic_extent, bool> = true>
constexpr span(It first, size_type count): size_(count), data_(&*first)
{}
template<class It, class End, std::enable_if_t<extent != dynamic_extent, bool> = true>
constexpr explicit span(It first, End last): size_(&*last - &*first), data_(&*first)
{}
template<class It, class End, std::enable_if_t<extent == dynamic_extent, bool> = true>
constexpr span(It first, End last): size_(&*last - &*first), data_(&*first)
{}
template<std::size_t N, std::enable_if_t<(N == dynamic_extent || N == extent) &&
(std::is_convertible_v<std::remove_pointer_t<decltype(
std::data(std::declval<T(&)[N]>()))>(*)[], T(*)[]>), bool> = true>
constexpr span(element_type (& arr)[N]) noexcept: size_{N}, data_{arr}
{}
template<class U, std::size_t N, std::enable_if_t<(N == dynamic_extent || N == extent) &&
(std::is_convertible_v<std::remove_pointer_t<decltype(
std::data(std::declval<T(&)[N]>()))>(*)[], T(*)[]>), bool> = true>
constexpr span(std::array<U, N>& arr) noexcept: size_(N), data_{arr.data()}
{}
template<class U, std::size_t N, std::enable_if_t<(N == dynamic_extent || N == extent) &&
(std::is_convertible_v<std::remove_pointer_t<decltype(
std::data(std::declval<T(&)[N]>()))>(*)[], T(*)[]>), bool> = true>
constexpr span(const std::array<U, N>& arr) noexcept: size_(N), data_{arr.data()}
{}
template<class R, class RCV = std::remove_cv_t<std::remove_reference_t<R>>, std::enable_if_t<
extent != dynamic_extent && span_detail::is_cont_v<RCV> &&
std::is_convertible_v<std::remove_pointer_t<decltype(std::data(std::declval<R>()))>(*)[], T(*)[]>, bool> = true>
explicit constexpr span(R&& range): size_(std::size(range)), data_(std::data(range))
{}
template<class R, class RCV = std::remove_cv_t<std::remove_reference_t<R>>, std::enable_if_t<
extent == dynamic_extent && span_detail::is_cont_v<RCV> &&
std::is_convertible_v<std::remove_pointer_t<decltype(std::data(std::declval<R>()))>(*)[], T(*)[]>, bool> = true>
constexpr span(R&& range): size_(std::size(range)), data_(std::data(range))
{}
template<std::enable_if_t<extent != dynamic_extent && std::is_const_v<element_type>, bool> = true>
explicit constexpr span(std::initializer_list<value_type> il) noexcept: size_(il.size()), data_(&il.begin())
{}
template<std::enable_if_t<extent == dynamic_extent && std::is_const_v<element_type>, bool> = true>
explicit span(std::initializer_list<value_type> il) noexcept: size_(il.size()), data_(&il.begin())
{}
template<class U, std::size_t N, std::enable_if_t<
extent != dynamic_extent && N == dynamic_extent && std::is_convertible_v<U(*)[], T(*)[]>, bool> = true>
explicit constexpr span(const span<U, N>& source) noexcept: size_{source.size()}, data_{source.data()}
{}
template<class U, std::size_t N, std::enable_if_t<
!(extent != dynamic_extent && N == dynamic_extent) && std::is_convertible_v<U(*)[], T(*)[]>, bool> = true>
constexpr span(const span<U, N>& source) noexcept: size_{source.size()}, data_{source.data()}
{}
constexpr span(const span& other) noexcept = default;
constexpr iterator begin() const noexcept
{
return data();
}
constexpr iterator end() const noexcept
{
return data() + size();
}
constexpr const_iterator cbegin() const noexcept
{
return data();
}
constexpr const_iterator cend() const noexcept
{
return data() + size();
}
constexpr reverse_iterator rbegin() const noexcept
{
return reverse_iterator{end()};
}
constexpr reverse_iterator rend() const noexcept
{
return reverse_iterator{begin()};
}
constexpr const_reverse_iterator crbegin() const noexcept
{
return reverse_iterator{cend()};
}
constexpr const_reverse_iterator crend() const noexcept
{
return reverse_iterator{cbegin()};
}
friend constexpr iterator begin(span s) noexcept
{
return s.begin();
}
friend constexpr iterator end(span s) noexcept
{
return s.end();
}
[[nodiscard]] constexpr size_type size() const noexcept
{
return size_;
}
[[nodiscard]] constexpr size_type size_bytes() const noexcept
{
return size() * sizeof(T);
}
[[nodiscard]] constexpr bool empty() const noexcept
{
return size() == 0;
}
constexpr reference operator[](size_type idx) const
{
return *(data() + idx);
}
constexpr reference front() const
{
return *data();
}
constexpr reference back() const
{
return *(data() + (size() - 1));
}
constexpr pointer data() const noexcept
{
return data_;
}
constexpr span<T, dynamic_extent> first(size_type cnt) const
{
return {data(), cnt};
}
constexpr span<T, dynamic_extent> last(size_type cnt) const
{
return {data() + (size() - cnt), cnt};
}
constexpr span<T, dynamic_extent> subspan(size_type off, size_type cnt = dynamic_extent) const
{
return {data() + off, cnt == dynamic_extent ? size() - off : cnt};
}
};
template<class T, std::size_t N>
span(T (&)[N]) -> span<T, N>;
template<class T, std::size_t N>
span(std::array<T, N>&) -> span<T, N>;
template<class T, std::size_t N>
span(const std::array<T, N>&) -> span<const T, N>;
template<class Cont>
span(Cont&) -> span<typename Cont::value_type>;
template<class Cont>
span(const Cont&) -> span<const typename Cont::value_type>;
}
#endif //BLT_RANGES_H