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#pragma once
#include "asl/meta.hpp"
#include "asl/annotations.hpp"
#include "asl/layout.hpp"
#include "asl/assert.hpp"
namespace asl
{
static constexpr int64_t dynamic_size = -1;
template<is_object T, int64_t kSize = dynamic_size>
class span
{
static constexpr bool is_dynamic(int64_t size)
{
return size < 0;
}
static constexpr bool kIsDynamic = is_dynamic(kSize);
using SizeType = select_t<kIsDynamic, int64_t, empty>;
T* m_data{};
ASL_NO_UNIQUE_ADDRESS SizeType m_size{};
public:
constexpr span() requires (kIsDynamic || kSize == 0) = default;
constexpr span(T* data, int64_t size)
requires kIsDynamic
: m_data{data}
, m_size{size}
{}
constexpr explicit span(T* data, int64_t size)
requires (!kIsDynamic)
: m_data{data}
{
ASL_ASSERT(size == kSize);
}
template<int64_t N>
constexpr span(T (&array)[N]) // NOLINT(*-explicit-conversions)
requires (kIsDynamic)
: m_data{array}
, m_size{N}
{}
template<int64_t N>
constexpr span(T (&array)[N]) // NOLINT(*-explicit-conversions)
requires (!kIsDynamic) && (N == kSize)
: m_data{array}
{}
template<is_object U, int64_t kOtherSize>
constexpr explicit(!kIsDynamic)
span(const span<U, kOtherSize>& other) // NOLINT(*-explicit-conversions)
requires (
(
kIsDynamic ||
is_dynamic(kOtherSize) ||
kOtherSize == kSize
) && convertible_from<T(&)[], U(&)[]>
)
: span{static_cast<U*>(other.data()), other.size()}
{
}
constexpr span(const span&) = default;
constexpr span(span&&) = default;
constexpr span& operator=(const span&) = default;
constexpr span& operator=(span&&) = default;
~span() = default;
constexpr int64_t size() const
{
if constexpr (kIsDynamic) { return m_size; }
else { return kSize; }
}
constexpr int64_t size_bytes() const { return size() * size_of<T>; }
constexpr bool is_empty() const { return size() == 0; }
constexpr T* data() const { return m_data; }
constexpr T* begin() const { return m_data; }
constexpr T* end() const { return m_data + size(); }
constexpr T& operator[](int64_t i) const
{
ASL_ASSERT(i >= 0 && i < size());
return m_data[i]; // NOLINT(*-pointer-arithmetic)
}
// @Todo first, last
// @Todo as_(mutable_)bytes
template<int64_t kOffset, int64_t kSubSize = dynamic_size>
constexpr auto subspan() const
requires (
kOffset >= 0 &&
(kIsDynamic || kOffset <= kSize) &&
(kIsDynamic || is_dynamic(kSubSize) || kSubSize <= kSize - kOffset)
)
{
ASL_ASSERT(kOffset <= size());
if constexpr (is_dynamic(kSubSize))
{
if constexpr (kIsDynamic)
{
return span<T>(data() + kOffset, size() - kOffset);
}
else
{
return span<T, kSize - kOffset>(data() + kOffset, size() - kOffset);
}
}
else
{
ASL_ASSERT(kSubSize <= size() - kOffset);
return span<T, kSubSize>(data() + kOffset, kSubSize);
}
}
constexpr span<T> subspan(int64_t offset, int64_t sub_size = dynamic_size) const
{
ASL_ASSERT(offset <= size());
if (is_dynamic(sub_size))
{
return span<T>{ data() + offset, size() - offset };
}
ASL_ASSERT(sub_size <= size() - offset);
return span<T>{ data() + offset, sub_size };
}
};
} // namespace asl
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