header_view.hxx

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#pragma once
 
#include <concepts>
#include <cstdint>
#include <cstring>
 
namespace vbvx {
 
template <typename _Tp>
concept WireHeader = std::is_trivially_copyable_v<_Tp> &&
                     std::is_standard_layout_v<_Tp> && (alignof(_Tp) == 1);

template <WireHeader H> class HeaderView {
  using header_t = H;
 
public:
  constexpr HeaderView() noexcept = default;
  constexpr explicit HeaderView(const header_t* p) noexcept : p_{p} {}
 
  constexpr explicit HeaderView(const uint8_t* p) noexcept
      : p_{reinterpret_cast<const header_t*>(p)} {}
 
  constexpr explicit operator bool() const noexcept { return p_ != nullptr; }
  constexpr auto get() const noexcept -> const header_t* { return p_; }
 
  constexpr auto operator->() const noexcept -> const header_t* { return p_; }
  constexpr auto operator*() const noexcept -> const header_t& { return *p_; }
 
  constexpr auto copy() const noexcept -> header_t {
    header_t out{};
    if (p_) {
      std::memcpy(&out, p_, sizeof(header_t));
    }
    return out;
  }
 
private:
  const header_t* p_{};
};
 
} // namespace vbvx