Factory for creating readers of the properties of the anonymous (and not only) types

ObjectPropertiesReadersFactory.cs

void Main()
{
	var generator = new ObjectPropertiesReadersFactory();
	var obj = new { @class = "css-class", @value = 2, items = new[] {1,2,3} };
	// var obj = new TestClass{ items = "123" };
	var reader = generator.GetReader(obj.GetType());
	var result = new Dictionary<string, object>();
	reader(result, obj);
	result.Dump();
	
}
public class TestClass{
	public string items {get;set;}
}
public class ObjectPropertiesReadersFactory
{
	/// <summary>
	/// Cache of type readers (lazy for thread-safe delegate creating)
	/// </summary>
	private static readonly ConcurrentDictionary<Type, Lazy<Action<IDictionary<string, object>, object>>> _objectReadersCache = new ConcurrentDictionary<Type, Lazy<Action<IDictionary<string, object>, object>>>();
	private static readonly Type[] _readerArgs = new []{ typeof(IDictionary<string, object>), typeof(object)};
	private static readonly MethodInfo _dictAddMethodInfo = typeof(IDictionary<string, object>).GetMethod("Add");

	public Action<IDictionary<string, object>, object> GetReader(Type type)
		=> _objectReadersCache.GetOrAdd(type, t => new Lazy<Action<IDictionary<string, object>, object>>(() => CreateReaderDelegate(t))).Value;

	private static Action<IDictionary<string, object>, object> CreateReaderDelegate(Type type)
	{
		
		var dm = new DynamicMethod($"TypeReader_{Guid.NewGuid():N}", null, _readerArgs, restrictedSkipVisibility: true);
		var il = dm.GetILGenerator();
		/* Example of generated IL:
		ldarg.1
		castclass AnonType
		stloc.0
		
		ldarg.0
		ldstr "ClassExample"
		ldloc.0
		callvirt instance string AnonType::get_ClassExample()
		callvirt instance void class [mscorlib]System.Collections.Generic.IDictionary`2<string, object>::Add(!0, !1)
		
		ldarg.0
		ldstr "ValueExample"
		ldloc.0
		callvirt instance int32 AnonType::get_ValueExample()
		box [mscorlib]System.Int32
		callvirt instance void class [mscorlib]System.Collections.Generic.IDictionary`2<string, object>::Add(!0, !1)
		
		ret
		*/
		il.DeclareLocal(type);
		il.Emit(OpCodes.Ldarg_1);
		il.Emit(OpCodes.Castclass, type);
		il.Emit(OpCodes.Stloc_0);


		// Indexed properties are not useful for grabbing
		var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance)
							.Where(prop => prop.GetIndexParameters().Length == 0 && prop.GetMethod != null);

		foreach (var p in properties)
		{
			il.Emit(OpCodes.Ldarg_0);
			il.Emit(OpCodes.Ldstr, p.Name);
			il.Emit(OpCodes.Ldloc_0);
			il.Emit(OpCodes.Callvirt, p.GetGetMethod());
			if(p.PropertyType.IsValueType)
				il.Emit(OpCodes.Box, p.PropertyType);
			il.Emit(OpCodes.Callvirt, _dictAddMethodInfo);
		}
		il.Emit(OpCodes.Ret);
		return (Action<IDictionary<string, object>, object>) dm.CreateDelegate(typeof(Action<IDictionary<string, object>, object>));
	}
}