packages.biu: yaml support enum

packages/biu/include/biu/yaml.hpp

@@ -34,6 +34,11 @@ namespace YAML
     static Node encode(const Set&);
     static bool decode(const Node& node, Set&);
   };
+  template <biu::Enumerable Enum> struct convert<Enum>
+  {
+    static Node encode(const Enum&);
+    static bool decode(const Node& node, Enum&);
+  };
   template <typename T> struct convert
   {
     static Node encode(const T&);

packages/biu/include/biu/yaml.tpp

@@ -5,6 +5,8 @@
 # include <biu/eigen.hpp>
 # include <boost/pfr.hpp>
 # include <boost/pfr/core_name.hpp>
+# include <nameof.hpp>
+# include <magic_enum.hpp>
 
 namespace YAML
 {
@@ -76,6 +78,16 @@ namespace YAML
     set = vec | ranges::to<Set>;
     return true;
   }
+  template <biu::Enumerable Enum> Node convert<Enum>::encode(const Enum& e)
+    { return convert<std::string_view>::encode(nameof::nameof_enum(e)); }
+  template <biu::Enumerable Enum> bool convert<Enum>::decode(const Node& node, Enum& e)
+  {
+    std::string name;
+    if (!convert<std::string>::decode(node, name)) return false;
+    auto optional_value = magic_enum::enum_cast<Enum>(name);
+    if (!optional_value) return false;
+    else { e = *optional_value; return true; }
+  }
   template <typename T> Node convert<T>::encode(const T& t)
   {
     YAML::Node node;

packages/biu/test/yaml.cpp

@@ -41,4 +41,9 @@ d: null
   auto e = node["c"].as<std::set<int>>();
   assert((e == std::set<int>{1, 2}));
   node["c"] = e;
+  std::string data2 = R"(
+a: AAA
+)";
+  enum class E { AAA, BBB, CCC };
+  auto f = YAML::Load(data2)["a"].as<E>();
 }