public static NFA CreateAutomaton(string a)
{
var result = new NFA();
var start = 0;
var next = 1;
result.AddState(start, false);
for (int i = 0; i < a.Length; ++i)
{
if (a[i] == '*')
{
result.AddTransition(next - 1, next - 1, NFA.Any);
}
else
{
result.AddState(next, false);
result.AddTransition(next - 1, next, (a[i] != '?' ? CharRange.SingleChar(a[i]) : NFA.Any));
++next;
}
}
result.AddState(next, true);
result.AddTransition(next - 1, next, NFA.Epsilon);
return(result);
}
public void AddExpression(string name, string regex)
{
using (var stream = new StringReader(InfixToPostfix.Convert(regex)))
{
while (stream.Peek() != -1)
{
var c = (char) stream.Read();
switch (c)
{
case '.': _stack.Concatenate(); break;
case '|': _stack.Unite(); break;
case '*': _stack.Iterate(); break;
case '+': _stack.AtLeast(); break;
case '?': _stack.Maybe(); break;
default:
var a = new NFA<char>();
a.AddTransition(a.Start, new State(), c == '\\' ? Escape((char) stream.Read()) : c);
_stack.Push(a);
break;
}
}
var top = _stack.Peek();
top.LastAdded.Final = true;
top.SetName(top.LastAdded, name);
}
}
public void AddExpression(string name, string regex)
{
using (var stream = new StringReader(InfixToPostfix.Convert(regex)))
{
while (stream.Peek() != -1)
{
var c = (char)stream.Read();
switch (c)
{
case '.': _stack.Concatenate(); break;
case '|': _stack.Unite(); break;
case '*': _stack.Iterate(); break;
case '+': _stack.AtLeast(); break;
case '?': _stack.Maybe(); break;
default:
var a = new NFA <char>();
a.AddTransition(a.Start, new State(), c == '\\' ? Escape((char)stream.Read()) : c);
_stack.Push(a);
break;
}
}
var top = _stack.Peek();
top.LastAdded.Final = true;
top.SetName(top.LastAdded, name);
}
}
public void NFATests()
{
var a = new NFA<char>();
// "a" automaton
a.AddTransition(a.Start, new State { Final = true }, 'a');
a.Initial();
a.Trigger('a');
Assert.That(a.Current.Contains(a.LastAdded), Is.True);
a.Initial();
Assert.That(() => a.Trigger('b'), Throws.TypeOf<StateNotFoundException>());
// "abcd" automaton
a = new NFA<char>();
a.AddTransition(a.Start, new State(), 'a');
a.AddTransition(a.LastAdded, new State(), 'b');
a.AddTransition(a.LastAdded, new State(), 'c');
a.AddTransition(a.LastAdded, new State { Final = true }, 'd');
a.Initial();
foreach (char c in "abcd") {
Assert.That(a.Current.Contains(a.LastAdded), Is.False);
a.Trigger(c);
}
Assert.That(a.Current.Contains(a.LastAdded), Is.True);
Assert.That(() => a.Trigger('b'), Throws.TypeOf<StateNotFoundException>());
}
public override NFA ToNFA()
{
var start = new State();
var accept = new State();
var nfa = new NFA(start, accept);
nfa.AddTransition(start, accept, Sym);
return(nfa);
}
public override StateRange AddTo <T>(NFA <T> nfa, CodePointEquivalenceClasses equivalenceClasses)
{
var startState = nfa.AddState();
var endState = nfa.AddState();
foreach (var equivalenceClass in equivalenceClasses.GetClasses(CodePoints))
{
nfa.AddTransition(startState, equivalenceClass, endState);
}
return(new StateRange(startState, endState));
}
public override NFA ToNFA()
{
var leftNfa = Left.ToNFA();
var rightNfa = Right.ToNFA();
var nfa = new NFA(leftNfa.Start, rightNfa.Accept);
foreach (var transition in leftNfa.Transitions)
{
nfa.AddTransition(transition.Source, transition.Target, transition.Label);
}
foreach (var transition in rightNfa.Transitions)
{
nfa.AddTransition(transition.Source, transition.Target, transition.Label);
}
nfa.AddTransition(leftNfa.Accept, rightNfa.Start, null);
return(nfa);
}
public override StateRange AddTo <T>(NFA <T> nfa, CodePointEquivalenceClasses equivalenceClasses)
{
var startState = nfa.AddState();
var endState = startState;
foreach (var codePoint in Value.GetCodePoints())
{
var lastState = endState;
endState = nfa.AddState();
nfa.AddTransition(lastState, equivalenceClasses.GetClass(codePoint), endState);
}
return(new StateRange(startState, endState));
}
public override StateRange AddTo <T>(NFA <T> nfa, CodePointEquivalenceClasses equivalenceClasses)
{
// Create a separate NFA
var tempNFA = new NFA <State?>(equivalenceClasses.Count);
var states = Expression.AddTo(tempNFA, equivalenceClasses);
tempNFA.SetStart(states.Start);
tempNFA.SetFinal(states.End);
// Convert to a DFA
var dfa = tempNFA.ToDFA(stateData => null).Item2;
dfa = dfa.Minimize().Item2;
dfa.MakeComplete(); // Can only do complement on complete DFA
// Now add the complement to this nfa
var startState = nfa.AddState();
var endState = nfa.AddState();
foreach (var dfaState in dfa.States)
{
var nfaState = GetMatchingState(nfa, dfa, dfaState);
if (dfa.IsStart(dfaState))
{
nfa.AddEpsilonTransition(startState, nfaState);
}
if (!dfa.IsFinal(dfaState))
{
nfa.AddEpsilonTransition(nfaState, endState);
}
// Copy transitions
foreach (var input in nfa.Inputs)
{
var toDFAState = dfa.GetTransition(dfaState, input);
if (toDFAState != null)
{
var toNFAState = GetMatchingState(nfa, dfa, toDFAState.Value);
nfa.AddTransition(nfaState, input, toNFAState);
}
}
}
return(new StateRange(startState, endState));
}
public void AddExpression(string name, string regex)
{
var stream = new StringReader(InfixToPostfix.Convert(regex));
while (stream.Peek() != -1)
{
var c = (char) stream.Read();
NFA<char> a;
switch (c)
{
case '.':
_stack.Concatenate();
break;
case '|':
_stack.Unite();
break;
case '*':
_stack.Iterate();
break;
case '+':
_stack.AtLeast();
break;
case '?':
_stack.Maybe();
break;
case '\\':
char n = (char) stream.Read();
a = new NFA<char>();
a.AddTransition(a.Start, new State(), Escape(n));
_stack.Push(a);
break;
default:
a = new NFA<char>();
a.AddTransition(a.Start, new State(), c);
_stack.Push(a);
break;
}
}
var automaton = _stack.Peek();
automaton.LastAdded.Final = true;
automaton.SetName(automaton.LastAdded, name);
}