// Creates an NFA that matches a sequence of the two provided NFAs.
public static NFA Sequence(NFA first, NFA second)
{
first.exit.isFinalState = false;
second.exit.isFinalState = true;
first.exit.AddAnonymousEdge(second.entry);
return(new NFA(first.entry, second.exit, RegExType.Sequence));
}
public static NFA CharacterClass(char start, char end, bool included = true)
{
var charMap = new CharacterClass(start, end);
if (!included)
{
charMap = Ast.CharacterClass.Negate(charMap);
}
return(NFA.CharacterClass(charMap));
}
// Creates an NFA that matches either provided NFA.
public static NFA Alternation(NFA a, NFA b)
{
a.exit.isFinalState = false;
b.exit.isFinalState = false;
var entry = new NFAState(RegExType.Choice);
var exit = new NFAState(RegExType.Choice);
exit.isFinalState = true;
entry.AddAnonymousEdge(a.entry);
entry.AddAnonymousEdge(b.entry);
a.exit.AddAnonymousEdge(exit);
b.exit.AddAnonymousEdge(exit);
return(new NFA(entry, exit, RegExType.Choice));
}
public static NFA Sequence(params object[] rexps)
{
NFA exp = empty();
for (int i = 0; i < rexps.Length; i++)
{
var r = CastToNFA(rexps[i]);
if (r is NFA && exp is NFA)
{
exp = Sequence((NFA)exp, (NFA)r);
}
else
{
exp = Sequence(exp, r);
}
}
return(exp);
}
// Creates an NFA which matches one zero or one times of the given NFA.
public static NFA ZeroOrOne(NFA nfa)
{
nfa.entry.AddAnonymousEdge(nfa.exit);
return(nfa);
}
// Creates an NFA which matches at least one or more repetitions of the given NFA.
public static NFA OneOrMany(NFA nfa)
{
nfa.exit.AddAnonymousEdge(nfa.entry);
return(nfa);
}