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#ifndef array_view_hh_INCLUDED
#define array_view_hh_INCLUDED
#include <initializer_list>
#include <iterator>
namespace Kakoune
{
// An ArrayView provides a typed, non owning view of a memory
// range with an interface similar to std::vector.
template<typename T>
class ArrayView
{
public:
using size_t = std::size_t;
constexpr ArrayView()
: m_pointer(nullptr), m_size(0) {}
constexpr ArrayView(T& oneval)
: m_pointer(&oneval), m_size(1) {}
constexpr ArrayView(T* pointer, size_t size)
: m_pointer(pointer), m_size(size) {}
constexpr ArrayView(T* begin, T* end)
: m_pointer(begin), m_size(end - begin) {}
template<typename It>
requires std::contiguous_iterator<It> and std::is_same_v<std::iter_value_t<It>, T>
constexpr ArrayView(It begin, It end)
: m_pointer(&*begin), m_size(end - begin) {}
template<size_t N>
constexpr ArrayView(T(&array)[N]) : m_pointer(array), m_size(N) {}
template<typename Container>
requires (sizeof(decltype(*std::declval<Container>().data())) == sizeof(T))
constexpr ArrayView(Container&& c)
: m_pointer(c.data()), m_size(c.size()) {}
constexpr ArrayView(const std::initializer_list<T>& v)
: m_pointer(v.begin()), m_size(v.size()) {}
constexpr T* pointer() const { return m_pointer; }
constexpr size_t size() const { return m_size; }
[[gnu::always_inline]]
constexpr T& operator[](size_t n) const { return *(m_pointer + n); }
constexpr T* begin() const { return m_pointer; }
constexpr T* end() const { return m_pointer+m_size; }
using reverse_iterator = std::reverse_iterator<T*>;
constexpr reverse_iterator rbegin() const { return reverse_iterator(m_pointer+m_size); }
constexpr reverse_iterator rend() const { return reverse_iterator(m_pointer); }
constexpr T& front() const { return *m_pointer; }
constexpr T& back() const { return *(m_pointer + m_size - 1); }
constexpr bool empty() const { return m_size == 0; }
constexpr ArrayView subrange(size_t first, size_t count = -1) const
{
auto min = [](size_t a, size_t b) { return a < b ? a : b; };
return ArrayView(m_pointer + min(first, m_size),
min(count, m_size - min(first, m_size)));
}
private:
T* m_pointer;
size_t m_size;
};
template<typename It>
requires std::contiguous_iterator<It>
ArrayView(It begin, It end) -> ArrayView<std::iter_value_t<It>>;
template<typename T>
using ConstArrayView = ArrayView<const T>;
template<typename T>
bool operator==(ArrayView<T> lhs, ArrayView<T> rhs)
{
if (lhs.size() != rhs.size())
return false;
for (int i = 0; i < lhs.size(); ++i)
{
if (lhs[i] != rhs[i])
return false;
}
return true;
}
}
#endif // array_view_hh_INCLUDED
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