public void Len(int idx)
{
var val = stack.get(idx);
if (new LuaValue(val).isString())
{
var s = new LuaValue(val).toString();
stack.push((long)s.Length);
}
else if (new LuaValue(val).isLuaTable())
{
var t = new LuaValue(val).toLuaTable();
stack.push((long)t.len());
}
else
{
throw new Exception("length error!");
}
}