draconisplusplus/include/rfl/visit.hpp

#ifndef RFL_VISIT_HPP_
#define RFL_VISIT_HPP_

#include <variant>

#include "Literal.hpp"
#include "TaggedUnion.hpp"
#include "internal/StringLiteral.hpp"
#include "internal/VisitTree.hpp"
#include "internal/VisitorWrapper.hpp"

namespace rfl {

  /// Implements the visitor pattern for Literals.
  template <class Visitor, internal::StringLiteral... _fields, class... Args>
  inline auto visit(
      const Visitor&            _visitor,
      const Literal<_fields...> _literal,
      const Args&... _args
  ) {
    constexpr int size = sizeof...(_fields);
    using WrapperType  = internal::VisitorWrapper<Visitor, _fields...>;
    const auto wrapper = WrapperType(&_visitor);
    return internal::VisitTree::visit<0, size, WrapperType>(
        wrapper, _literal.value(), _args...
    );
  }

  /// Implements the visitor pattern for TaggedUnions.
  template <
      class Visitor,
      internal::StringLiteral _discriminator,
      class... Args>
  inline auto visit(
      const Visitor&                              _visitor,
      const TaggedUnion<_discriminator, Args...>& _tagged_union
  ) {
    return std::visit(_visitor, _tagged_union.variant());
  }

} // namespace rfl

#endif // RFL_VISIT_HPP_