add TaggedVariant

Author: jube

include/gf2/core/TaggedVariant.h

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: Zlib
+// Copyright (c) 2023 Julien Bernard
+#ifndef GF_TAGGED_VARIANT_H
+#define GF_TAGGED_VARIANT_H
+
+#include <variant>
+
+#include "TypeTraits.h"
+
+namespace gf {
+
+  template<typename Enum, typename ... Args>
+  class TaggedVariant {
+  public:
+    TaggedVariant() = default;
+
+    template<typename T, typename = PreventHiddenCopyMove<T, TaggedVariant>>
+    constexpr TaggedVariant(T&& data)
+    : m_data(std::forward<T>(data))
+    {
+    }
+
+    Enum type() const
+    {
+      return static_cast<Enum>(m_data.index());
+    }
+
+    template<typename T>
+    constexpr bool is() const
+    {
+      return std::holds_alternative<T>(m_data);
+    }
+
+    template<typename T>
+    constexpr T& get()
+    {
+      return std::get<T>(m_data);
+    }
+
+    template<typename T>
+    constexpr const T& get() const
+    {
+      return std::get<T>(m_data);
+    }
+
+    template<Enum E>
+    constexpr auto& from()
+    {
+      return std::get<static_cast<std::size_t>(E)>(m_data);
+    }
+
+    template<Enum E>
+    constexpr const auto& from() const
+    {
+      return std::get<static_cast<std::size_t>(E)>(m_data);
+    }
+
+    constexpr auto& raw()
+    {
+      return m_data;
+    }
+
+    constexpr const auto& raw() const
+    {
+      return m_data;
+    }
+
+  private:
+    std::variant<std::monostate, Args...> m_data;
+  };
+
+  namespace details {
+
+    template<typename Archive, typename Self>
+    Archive& handle_tagged_variant_serialization(Archive& ar, Self& self)
+    {
+      return ar | self.raw();
+    }
+
+  }
+
+  template<typename Archive, typename Enum, typename ... Args>
+  inline Archive& operator|(Archive& ar, TaggedVariant<Enum, Args...>& variant)
+  {
+    return details::handle_tagged_variant_serialization(ar, variant);
+  }
+
+  template<typename Archive, typename Enum, typename ... Args>
+  inline Archive& operator|(Archive& ar, const TaggedVariant<Enum, Args...>& variant)
+  {
+    return details::handle_tagged_variant_serialization(ar, variant);
+  }
+
+}
+
+#endif // GF_TAGGED_VARIANT_H

library/core/TaggedVariant.cc

@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: Zlib
+// Copyright (c) 2023 Julien Bernard
+
+#include <gf2/core/TaggedVariant.h>