Which algorithm do XML Schema validators use to decide if a string matches a regular expression?

Hi Folks,

It is my understanding that there are 3 flavors of regular expression parsers [1]:

1. Nondeterministic Finite Automaton (NFA)

2. Deterministic Finite Automaton (DFA)

3. Backtracking

Which flavor of regular expression parser does SAXON use?

Which flavor of regular expression parser does XERCES use?

Which flavor of regular expression parser does MSXML use?

What about the other XML Schema validators?

/Roger


[1] http://en.wikipedia.org/wiki/Regular_expression#Implementations_and_running_times