Improvement potential for `Parse(...)`

[maettu-this]

• The method's description states InvalidOperationException as possible exception. However, Process() > OnProcess() may throw an UnhandledCharacterCodeException which is not documented, i.e. may get forgotten to be catched.
• The void/Exception semantic of the method makes usage potentially inefficient, as exceptions are involved on all mismatching chars. Consider int int.Parse(string s) vs. bool int.TryParse(string s, out int result). The latter indicates failure by the return value, but doesn't throw.