public override InputConfig Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
InputBackendType backendType = GetInputBackendType(ref reader);
return(backendType switch
{
InputBackendType.WindowKeyboard => (InputConfig)JsonSerializer.Deserialize(ref reader, typeof(StandardKeyboardInputConfig), options),
InputBackendType.GamepadSDL2 => (InputConfig)JsonSerializer.Deserialize(ref reader, typeof(StandardControllerInputConfig), options),
_ => throw new InvalidOperationException($"Unknown backend type {backendType}"),
});
private static InputBackendType GetInputBackendType(ref Utf8JsonReader reader)
{
// Temporary reader to get the backend type
Utf8JsonReader tempReader = reader;
InputBackendType result = InputBackendType.Invalid;
while (tempReader.Read())
{
// NOTE: We scan all properties ignoring the depth entirely on purpose.
// The reason behind this is that we cannot track in a reliable way the depth of the object because Utf8JsonReader never emit the first TokenType == StartObject if the json start with an object.
// As such, this code will try to parse very field named "backend" to the correct enum.
if (tempReader.TokenType == JsonTokenType.PropertyName)
{
string propertyName = tempReader.GetString();
if (propertyName.Equals("backend"))
{
tempReader.Read();
if (tempReader.TokenType == JsonTokenType.String)
{
string backendTypeRaw = tempReader.GetString();
if (!Enum.TryParse(backendTypeRaw, out result))
{
result = InputBackendType.Invalid;
}
else
{
break;
}
}
}
}
}
return(result);
}
