string s = "namespace A{class B{}}".FormatAsSourceCode();

public static class Extensions
{
  public static string FormatAsSourceCode(this string s)
  {
    int indent = 0;
    bool LineBreak = false;
    StringBuilder sb = new StringBuilder();
  
    try
    {
      foreach (char item in s)
      {
        switch (item)
        {
          case '{': sb.AppendLine(); sb.Append("".PadLeft(indent * 2) + '{'); sb.AppendLine(); indent++; LineBreak = true; break;
          case '}': indent--; sb.Append("".PadLeft(indent * 2) + '}'); sb.AppendLine(); LineBreak = true; break;
          case ';': sb.Append(';'); sb.AppendLine(); LineBreak = true; break;
  
          default: if (LineBreak) sb.Append("".PadLeft(indent * 2)); LineBreak = false; sb.Append(item); break;
        }
      }
      if (indent != 0) throw new Exception("");
    }
    catch (Exception ex)
    {
      sb.AppendLine("ERROR: No matching of opening and closing brackets.! " + ex.Message);
    }
    return sb.ToString();
  }
}