draconisplusplus/include/rfl/internal/StringLiteral.hpp

#ifndef RFL_INTERNAL_STRINGLITERAL_HPP_
#define RFL_INTERNAL_STRINGLITERAL_HPP_

#include <algorithm>
#include <array>
#include <string>
#include <string_view>

namespace rfl {
  namespace internal {

    /// Normal strings cannot be used as template
    /// parameters, but this can. This is needed
    /// for the parameters names in the NamedTuples.
    template <size_t N>
    struct StringLiteral {
      constexpr StringLiteral(const auto... _chars) : arr_ {_chars..., '\0'} {}

      constexpr StringLiteral(const std::array<char, N> _arr) : arr_(_arr) {}

      constexpr StringLiteral(const char (&_str)[N]) {
        std::copy_n(_str, N, std::data(arr_));
      }

      /// Returns the value as a string.
      std::string str() const { return std::string(std::data(arr_), N - 1); }

      /// Returns the value as a string.
      constexpr std::string_view string_view() const {
        return std::string_view(std::data(arr_), N - 1);
      }

      std::array<char, N> arr_ {};
    };

    template <size_t N1, size_t N2>
    constexpr inline bool operator==(
        const StringLiteral<N1>& _first,
        const StringLiteral<N2>& _second
    ) {
      if constexpr (N1 != N2) {
        return false;
      }
      return _first.string_view() == _second.string_view();
    }

    template <size_t N1, size_t N2>
    constexpr inline bool operator!=(
        const StringLiteral<N1>& _first,
        const StringLiteral<N2>& _second
    ) {
      return !(_first == _second);
    }

  } // namespace internal
} // namespace rfl

#endif