/*
* Make a DFA-ish automaton from the NFA-like structure of the regex
*/
public TokenAutomaton ConstructAutomaton()
{
Dictionary<ISet<Node>, TokenAutomaton.Node> DFAStates =
new Dictionary<ISet<Node>, TokenAutomaton.Node>(new SetEqualityComparer<Node>());
TokenAutomaton.Node DFAStartState = new TokenAutomaton.Node();
// set of nodes accessible from NFA start state
ISet<Node> NFAStartStates = start.EpsilonMove();
DFAStates.Add(NFAStartStates, DFAStartState);
Stack<ISet<Node>> s = new Stack<ISet<Node>>();
s.Push(NFAStartStates);
while (s.Count != 0)
{
// pop a NFA state
ISet<Node> currentNFAStates = s.Pop();
// get the corresponding DFA state
TokenAutomaton.Node currentDFAState = DFAStates[currentNFAStates];
ISet<char> nextChars = new HashSet<char>();
// find which characters we can move with from currentNFAStates
foreach (Node n in currentNFAStates)
nextChars.UnionWith(n.transitions.Keys);
foreach (char c in nextChars)
{
// set of NFA states that can be reached from the current set with input c
ISet<Node> nextNFAStates = Node.Move(currentNFAStates, c);
if (nextNFAStates.Count != 0)
{
// include NFA states that can be reached with an epsilon transition
HashSet<Node> epsilonClosure = new HashSet<Node>();
epsilonClosure.UnionWith(nextNFAStates);
epsilonClosure.UnionWith(Node.EpsilonMove(nextNFAStates));
TokenAutomaton.Node nextDFAState;
if (!DFAStates.TryGetValue(epsilonClosure, out nextDFAState))
{
// no DFA state exists for this set of NFA states yet, so we create one
nextDFAState = new TokenAutomaton.Node();
// set accepted token types for the DFA state
foreach (Node n in epsilonClosure)
{
if (n.tokenType != null &&
(nextDFAState.acceptedTokenType == null ||
(n.tokenType.TokenPriority == TokenType.Priority.Keyword)))
{
nextDFAState.acceptedTokenType = n.tokenType;
}
}
DFAStates.Add(epsilonClosure, nextDFAState);
s.Push(epsilonClosure);
}
// create transition
currentDFAState.transitions.Add(c, nextDFAState);
}
}
}
return new TokenAutomaton(DFAStartState);
}
/*
* Make a DFA-ish automaton from the NFA-like structure of the regex
*/
public TokenAutomaton ConstructAutomaton()
{
Dictionary <ISet <Node>, TokenAutomaton.Node> DFAStates =
new Dictionary <ISet <Node>, TokenAutomaton.Node>(new SetEqualityComparer <Node>());
TokenAutomaton.Node DFAStartState = new TokenAutomaton.Node();
// set of nodes accessible from NFA start state
ISet <Node> NFAStartStates = start.EpsilonMove();
DFAStates.Add(NFAStartStates, DFAStartState);
Stack <ISet <Node> > s = new Stack <ISet <Node> >();
s.Push(NFAStartStates);
while (s.Count != 0)
{
// pop a NFA state
ISet <Node> currentNFAStates = s.Pop();
// get the corresponding DFA state
TokenAutomaton.Node currentDFAState = DFAStates[currentNFAStates];
ISet <char> nextChars = new HashSet <char>();
// find which characters we can move with from currentNFAStates
foreach (Node n in currentNFAStates)
{
nextChars.UnionWith(n.transitions.Keys);
}
foreach (char c in nextChars)
{
// set of NFA states that can be reached from the current set with input c
ISet <Node> nextNFAStates = Node.Move(currentNFAStates, c);
if (nextNFAStates.Count != 0)
{
// include NFA states that can be reached with an epsilon transition
HashSet <Node> epsilonClosure = new HashSet <Node>();
epsilonClosure.UnionWith(nextNFAStates);
epsilonClosure.UnionWith(Node.EpsilonMove(nextNFAStates));
TokenAutomaton.Node nextDFAState;
if (!DFAStates.TryGetValue(epsilonClosure, out nextDFAState))
{
// no DFA state exists for this set of NFA states yet, so we create one
nextDFAState = new TokenAutomaton.Node();
// set accepted token types for the DFA state
foreach (Node n in epsilonClosure)
{
if (n.tokenType != null &&
(nextDFAState.acceptedTokenType == null ||
(n.tokenType.TokenPriority == TokenType.Priority.Keyword)))
{
nextDFAState.acceptedTokenType = n.tokenType;
}
}
DFAStates.Add(epsilonClosure, nextDFAState);
s.Push(epsilonClosure);
}
// create transition
currentDFAState.transitions.Add(c, nextDFAState);
}
}
}
return(new TokenAutomaton(DFAStartState));
}
