draconisplusplus/include/rfl/Variant.hpp

#ifndef RFL_VARIANT_HPP_
#define RFL_VARIANT_HPP_

#include <variant>

namespace rfl {

  template <class... AlternativeTypes>
  struct Variant {
    /// The type of the underlying variant.
    using VariantType = std::variant<AlternativeTypes...>;

    Variant(const VariantType& _variant) : variant_(_variant) {}

    Variant(VariantType&& _variant) noexcept : variant_(std::move(_variant)) {}

    Variant(const Variant<AlternativeTypes...>& _variant) = default;

    Variant(Variant<AlternativeTypes...>&& _variant) noexcept = default;

    template <
        class T,
        typename std::enable_if<std::is_convertible_v<T, VariantType>, bool>::
            type = true>
    Variant(const T& _t) : variant_(_t) {}

    template <
        class T,
        typename std::enable_if<std::is_convertible_v<T, VariantType>, bool>::
            type = true>
    Variant(T&& _t) noexcept : variant_(std::forward<T>(_t)) {}

    ~Variant() = default;

    /// Assigns the underlying object.
    Variant<AlternativeTypes...>& operator=(const VariantType& _variant) {
      variant_ = _variant;
      return *this;
    }

    /// Assigns the underlying object.
    Variant<AlternativeTypes...>& operator=(VariantType&& _variant) {
      variant_ = std::move(_variant);
      return *this;
    }

    /// Assigns the underlying object.
    template <
        class T,
        typename std::enable_if<std::is_convertible_v<T, VariantType>, bool>::
            type = true>
    Variant<AlternativeTypes...>& operator=(T&& _variant) {
      variant_ = std::forward<T>(_variant);
      return *this;
    }

    /// Assigns the underlying object.
    template <
        class T,
        typename std::enable_if<std::is_convertible_v<T, VariantType>, bool>::
            type = true>
    Variant<AlternativeTypes...>& operator=(const T& _variant) {
      variant_ = _variant;
      return *this;
    }

    /// Assigns the underlying object.
    Variant<AlternativeTypes...>& operator=(
        const Variant<AlternativeTypes...>& _other
    ) = default;

    /// Assigns the underlying object.
    Variant<AlternativeTypes...>& operator=(
        Variant<AlternativeTypes...>&& _other
    ) = default;

    /// Returns the underlying variant.
    VariantType& variant() { return variant_; }

    /// Returns the underlying variant.
    const VariantType& variant() const { return variant_; }

    /// The underlying variant - a Variant is a thin wrapper
    /// around a variant that is mainly used for parsing.
    VariantType variant_;
  };

} // namespace rfl

#endif