Refactoring If-Else to Table-Driven Approach

Table-DrivenApproach.cs

//If-Else Approach
public static class ParserFactory
{
   public static IFileParser Create(string filename)
   {
      var extension = Path.GetExtension(fileName);

      if (extension == ".json")
      {
          return new JsonParser();
      }
      else if (extension == ".xml")
      {
          return new XmlParser();
      }
      else if (extension == ".yaml")
      {
          return new YamlParser();
      }
      else
      {
          throw new NotSupportedException();
      }
   }
}

//Table-Driven Approach
public static class ParserFactory
{
   private static Dictionary<string, Func<Parser>> _parsers =
      new Dictionary<string, Func<Parser>>();

   static ParserFactory()
   {
      _parsers[".json"] = () => new JsonParser();
      _parsers[".xml"] = () => new XmlParser();
      _parsers[".yaml"] = () => new YamlParser();
   }

   public static IFileParser Create(string filename)
   {
      var extension = Path.GetExtension(fileName);

      _parsers.TryGetValue(extension, out Parser parser);

      if(parser == null)
         throw new NotSupportedExtension();

      return parser;
   }
}