private static INfa Character(RegexCharacter character)
{
var start = new NfaState();
var end = new NfaState();
var terminal = new CharacterTerminal(character.Value);
var transition = new TerminalNfaTransition(
terminal: terminal,
target: end);
start.AddTransistion(transition);
return new Nfa(start, end);
}
private static INfa Character(RegexCharacterClassCharacter character, bool negate)
{
var start = new NfaState();
var end = new NfaState();
ITerminal terminal = new CharacterTerminal(character.Value);
if (negate)
terminal = new NegationTerminal(terminal);
var transition = new TerminalNfaTransition(
terminal: terminal,
target: end);
start.AddTransistion(transition);
return new Nfa(start, end);
}
private static BaseLexerRule CreateNotDoubleQuoteLexerRule()
{
// ([^"]|(\\.))*
var start = new DfaState();
var escape = new DfaState();
var final = new DfaState(true);
var notDoubleQuoteTerminal = new NegationTerminal(
new CharacterTerminal('"'));
var escapeTerminal = new CharacterTerminal('\\');
var anyTerminal = new AnyTerminal();
var notDoubleQuoteEdge = new DfaTransition(notDoubleQuoteTerminal, final);
start.AddTransition(notDoubleQuoteEdge);
final.AddTransition(notDoubleQuoteEdge);
var escapeEdge = new DfaTransition(escapeTerminal, escape);
start.AddTransition(escapeEdge);
final.AddTransition(escapeEdge);
var anyEdge = new DfaTransition(anyTerminal, final);
escape.AddTransition(anyEdge);
return new DfaLexerRule(start, new TokenType(@"([^""]|(\\.))+"));
}
private static BaseLexerRule CreateMultiLineCommentLexerRule()
{
var pattern = @"\/[*]([*][^\/]|[^*])*[*][\/]";
var states = new DfaState[5];
for (int i = 0; i < states.Length; i++)
states[i] = new DfaState();
var slash = new CharacterTerminal('/');
var star = new CharacterTerminal('*');
var notStar = new NegationTerminal(star);
var notSlash = new NegationTerminal(slash);
var firstSlash = new DfaTransition(slash, states[1]);
var firstStar = new DfaTransition(star, states[2]);
var repeatNotStar = new DfaTransition(notStar, states[2]);
var lastStar = new DfaTransition(star, states[3]);
var goBackNotSlash = new DfaTransition(notSlash, states[2]);
var lastSlash = new DfaTransition(slash, states[4]);
states[0].AddTransition(firstSlash);
states[1].AddTransition(firstStar);
states[2].AddTransition(repeatNotStar);
states[2].AddTransition(lastStar);
states[3].AddTransition(goBackNotSlash);
states[3].AddTransition(lastSlash);
return new DfaLexerRule(states[0], pattern);
}
public void ShouldConvertComplexNfaToDfa()
{
var a = new CharacterTerminal('a');
var b = new CharacterTerminal('b');
var c = new CharacterTerminal('c');
var states = CreateStates(4);
states[0].AddTransistion(new TerminalNfaTransition(a, states[1]));
states[0].AddTransistion(new TerminalNfaTransition(c, states[3]));
states[1].AddTransistion(new NullNfaTransition(states[0]));
states[1].AddTransistion(new TerminalNfaTransition(b, states[2]));
states[2].AddTransistion(new TerminalNfaTransition(a, states[1]));
states[3].AddTransistion(new TerminalNfaTransition(c, states[2]));
states[3].AddTransistion(new NullNfaTransition(states[2]));
var dfa_0 = ConvertNfaToDfa(new Nfa(states[0], states[2]));
Assert.IsNotNull(dfa_0);
IDfaTransition transition_0_01 = null;
IDfaTransition transition_0_23 = null;
var count = 0;
foreach (var transition in dfa_0.Transitions)
{
var terminal = transition.Terminal;
if (terminal.IsMatch('a'))
transition_0_01 = transition;
else if (terminal.IsMatch('c'))
transition_0_23 = transition;
count++;
}
Assert.AreEqual(2, count);
var dfa_01 = transition_0_01.Target;
IDfaTransition transition_01_01 = null;
IDfaTransition transition_01_23 = null;
IDfaTransition transition_01_2 = null;
count = 0;
foreach (var transition in dfa_01.Transitions)
{
var terminal = transition.Terminal;
if (terminal.IsMatch('a'))
transition_01_01 = transition;
else if (terminal.IsMatch('b'))
transition_01_2 = transition;
else if (terminal.IsMatch('c'))
transition_01_23 = transition;
count++;
}
Assert.AreEqual(3, count);
var dfa_23 = transition_0_23.Target;
IDfaTransition transition_23_01 = null;
IDfaTransition transition_23_2 = null;
count = 0;
foreach (var transition in dfa_23.Transitions)
{
var terminal = transition.Terminal;
if (terminal.IsMatch('a'))
transition_23_01 = transition;
else if (terminal.IsMatch('c'))
transition_23_2 = transition;
count++;
}
Assert.AreEqual(2, count);
var dfa_2 = transition_23_2.Target;
IDfaTransition transition_2_01 = null;
count = 0;
foreach (var transition in dfa_2.Transitions)
{
var terminal = transition.Terminal;
if (terminal.IsMatch('a'))
transition_2_01 = transition;
count++;
}
Assert.AreEqual(1, count);
}
public void ShouldConvertSingleCharacterNfaToEquivalentDfa()
{
var a = new CharacterTerminal('a');
var states = CreateStates(2);
states[0].AddTransistion(new TerminalNfaTransition(a, states[1]));
var nfa = new Nfa(states[0], states[1]);
var dfa = ConvertNfaToDfa(nfa);
Assert.IsNotNull(dfa);
}