/**
* Generate a NFA from the given pattern using Thompson's Construction and
* add it to the current overall NFA.
*/
public void post2nfa(Pattern pattern)
{
var tree = pattern.AstNode as SpecParserParser.PatternContext;
var post_order = ComputePostOrder(tree);
var fragmentStack = new Stack <Fragment>();
var completeNfa = new Fragment();
foreach (var p in post_order)
{
var p_text = p.GetText();
var p_type = p.GetType();
// simple_basic, kleen_star_basic, and continued_basic are very special:
// add in ".*" between each item.
if (p as SpecParserParser.Simple_basicContext != null ||
p as SpecParserParser.Kleene_star_basicContext != null
)
{
var last = fragmentStack.Pop();
var first = true;
var c = p.GetChild(0);
bool not = (c.GetText() == "!");
for (var i = p.ChildCount - (not ? 3:2); i >= 0; --i)
{
// For Piggy, we're going to use a special edge
// to denote attribute or child node recognition
// because there is lookahead for the attribute
// or child node, not one symbol. In addition, once
// a child is found next, no attributes can occur.
var f = fragmentStack.Pop();
//System.Console.Error.WriteLine(f.ToString());
//System.Console.Error.WriteLine(nfa.ToString());
if (i > 0 && first)
{
var foobar = last.StartState.Owner.SuccessorEdges(last.StartState);
var cc = foobar.Count();
var ff = foobar.FirstOrDefault();
if (cc == 1 &&
(ff.IsCode ||
ff.IsText))
{
}
else
{
// Add in ".*"
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var s3 = new State(_nfa);
var e1 = new Edge(_nfa, s1, s2, Edge.EmptyAst);
var e2 = new Edge(_nfa, s2, s3, Edge.EmptyAst);
var e3 = new Edge(_nfa, s2, s2, Edge.EmptyAst, (int)Edge.EdgeModifiersEnum.Any);
var e4 = new Edge(_nfa, s3, last.StartState, Edge.EmptyAst);
last = new Fragment(s1, last.OutStates);
}
}
foreach (var o in f.OutStates)
{
var e5 = new Edge(_nfa, o, last.StartState, Edge.EmptyAst);
}
last = new Fragment(f.StartState, last.OutStates);
}
fragmentStack.Push(last);
}
else if (p as SpecParserParser.BasicContext != null)
{
}
else if (p as SpecParserParser.PatternContext != null)
{
}
else if (p as TerminalNodeImpl != null)
{
var t = p as TerminalNodeImpl;
var s = t.Symbol;
var s_type = s.Type;
if (s.Type == SpecParserParser.OPEN_PAREN ||
s.Type == SpecParserParser.OPEN_KLEENE_STAR_PAREN ||
s.Type == SpecParserParser.CLOSE_PAREN ||
s.Type == SpecParserParser.CLOSE_KLEENE_STAR_PAREN)
{
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var e = new Edge(_nfa, s1, s2, new List <IParseTree> {
t
});
var f = new Fragment(s1, s2);
fragmentStack.Push(f);
}
}
else if (p as SpecParserParser.Id_or_star_or_emptyContext != null)
{
var c = p.GetChild(0);
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var e = new Edge(_nfa, s1, s2, new List <IParseTree> {
c
});
var f = new Fragment(s1, s2);
fragmentStack.Push(f);
}
else if (p as SpecParserParser.MoreContext != null)
{
}
else if (p as SpecParserParser.TextContext != null)
{
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var e = new Edge(_nfa, s1, s2, new List <IParseTree> {
p
}, (int)Edge.EdgeModifiersEnum.Text);
var f = new Fragment(s1, s2);
fragmentStack.Push(f);
}
else if (p as SpecParserParser.CodeContext != null)
{
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var e = new Edge(_nfa, s1, s2, new List <IParseTree> {
p
}, (int)Edge.EdgeModifiersEnum.Code);
var f = new Fragment(s1, s2);
fragmentStack.Push(f);
}
else if (p as SpecParserParser.Group_rexpContext != null)
{
}
else if (p as SpecParserParser.Star_rexpContext != null)
{
var previous = fragmentStack.Pop();
{
// Add in ".*" before "previous"
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var s3 = new State(_nfa);
var e1 = new Edge(_nfa, s1, s2, Edge.EmptyAst);
var e2 = new Edge(_nfa, s2, s3, Edge.EmptyAst);
var e3 = new Edge(_nfa, s2, s2, Edge.EmptyAst, (int)Edge.EdgeModifiersEnum.Any);
var e4 = new Edge(_nfa, s3, previous.StartState, Edge.EmptyAst);
previous = new Fragment(s1, previous.OutStates);
}
{
// Add in state s1 before previous.
var s1 = new State(_nfa);
var e1 = new Edge(_nfa, s1, previous.StartState, Edge.EmptyAst);
// Add in back edges to s1.
foreach (var s in previous.OutStates)
{
var e2 = new Edge(_nfa, s, s1, Edge.EmptyAst);
}
var f = new Fragment(s1, s1);
fragmentStack.Push(f);
}
}
else if (p as SpecParserParser.Plus_rexpContext != null)
{
var previous = fragmentStack.Pop();
{
// Add in ".*" before "previous"
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var s3 = new State(_nfa);
var e1 = new Edge(_nfa, s1, s2, Edge.EmptyAst);
var e2 = new Edge(_nfa, s2, s3, Edge.EmptyAst);
var e3 = new Edge(_nfa, s2, s2, Edge.EmptyAst, (int)Edge.EdgeModifiersEnum.Any);
var e4 = new Edge(_nfa, s3, previous.StartState, Edge.EmptyAst);
previous = new Fragment(s1, previous.OutStates);
}
{
// Add state after previous outstates.
var s1 = new State(_nfa);
foreach (var s in previous.OutStates)
{
var e3 = new Edge(_nfa, s, s1, Edge.EmptyAst);
}
// Add edge from s1 back edge to previous.
var e4 = new Edge(_nfa, s1, previous.StartState, Edge.EmptyAst);
// Finish up with fragment.
var f = new Fragment(previous.StartState, s1);
fragmentStack.Push(f);
}
}
else if (p as SpecParserParser.AttrContext != null)
{
var c = p.GetChild(0);
if (c.GetText() == "!")
{
var c2 = p.GetChild(1);
var t = c2 as TerminalNodeImpl;
var s = t.Symbol;
var s_type = s.Type;
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var e = new Edge(_nfa, s1, s2, new List <IParseTree> {
t
}, (int)Edge.EdgeModifiersEnum.Not);
var f = new Fragment(s1, s2);
fragmentStack.Push(f);
}
else
{
var t = c as TerminalNodeImpl;
var s = t.Symbol;
var s_type = s.Type;
var s1 = new State(_nfa);
var s2 = new State(_nfa);
var s3 = new State(_nfa);
var s4 = new State(_nfa);
var e1 = new Edge(_nfa, s1, s2, new List <IParseTree> {
t
});
t = p.GetChild(1) as TerminalNodeImpl;
var e2 = new Edge(_nfa, s2, s3, new List <IParseTree> {
t
});
t = p.GetChild(2) as TerminalNodeImpl;
var e3 = new Edge(_nfa, s3, s4, new List <IParseTree> {
t
});
var f = new Fragment(s1, s4);
fragmentStack.Push(f);
}
}
else if (p as SpecParserParser.RexpContext != null)
{
for (var i = 2; i < p.ChildCount; i += 2)
{
var s = new State(_nfa);
var s2 = fragmentStack.Pop();
{
// Add in ".*"
var sa = new State(_nfa);
var sb = new State(_nfa);
var sc = new State(_nfa);
var ea = new Edge(_nfa, sa, sb, Edge.EmptyAst);
var eb = new Edge(_nfa, sb, sc, Edge.EmptyAst);
var e3 = new Edge(_nfa, sb, sb, Edge.EmptyAst, (int)Edge.EdgeModifiersEnum.Any);
var e4 = new Edge(_nfa, sc, s2.StartState, Edge.EmptyAst);
s2 = new Fragment(sa, s2.OutStates);
}
var s1 = fragmentStack.Pop();
{
// Add in ".*"
var sa = new State(_nfa);
var sb = new State(_nfa);
var sc = new State(_nfa);
var ea = new Edge(_nfa, sa, sb, Edge.EmptyAst);
var eb = new Edge(_nfa, sb, sc, Edge.EmptyAst);
var e3 = new Edge(_nfa, sb, sb, Edge.EmptyAst, (int)Edge.EdgeModifiersEnum.Any);
var e4 = new Edge(_nfa, sc, s1.StartState, Edge.EmptyAst);
s1 = new Fragment(sa, s1.OutStates);
}
var e1 = new Edge(_nfa, s, s1.StartState, Edge.EmptyAst);
var e2 = new Edge(_nfa, s, s2.StartState, Edge.EmptyAst);
var s3 = new State(_nfa);
foreach (var o in s1.OutStates)
{
var e3 = new Edge(_nfa, o, s3, Edge.EmptyAst);
}
foreach (var o in s2.OutStates)
{
var e3 = new Edge(_nfa, o, s3, Edge.EmptyAst);
}
var f = new Fragment(s, s3);
fragmentStack.Push(f);
}
}
}
completeNfa = fragmentStack.Pop();
if (fragmentStack.Count > 0)
{
throw new Exception("Fragment stack not empty.");
}
foreach (var s in completeNfa.OutStates)
{
_nfa.AddFinalState(s);
}
// Add in the NFA for this pattern into overall NFA.
var eek = new Edge(_nfa, _start_state, completeNfa.StartState, Edge.EmptyAst);
}
/* Apply powerset construction to the NFA to convert to a DFA.
* Note, the result of this method isn't strictly a DFA because
* edges in the automaton can be text or code, which function just like
* epsilon transitions--no input is consumed for the edge.
*/
public Automaton Optimize(Automaton nfa)
{
var dfa = new Automaton();
// For every state s, compute collection of states along epsilon edges
// to get an initial computation of dfa states.
foreach (var s in nfa.Vertices)
{
var c = ClosureTaker.GetClosure(new List <State> {
s
}, nfa);
_closure[s] = c;
}
// For every state set, compute sums and fix up state sets.
foreach (var p in _closure)
{
var key = p.Key;
var set = p.Value;
foreach (var s in set)
{
_closure[s].UnionWith(set);
}
}
// For every state in nfa using Tarjan walk,
// sum sets with common transitions.
var ordered_list = new TarjanNoBackEdges <State, Edge>(nfa).ToList();
ordered_list.Reverse();
var changed = true;
while (changed)
{
changed = false;
foreach (var s in ordered_list)
{
var closure = _closure[s];
var transitions = ClosureTaker.GatherTransitions(closure);
foreach (var transition_set in transitions)
{
var key = transition_set.Key;
var value = transition_set.Value;
var state_set = new SmartSet <State>();
// All states in value must have common set in dfa.
foreach (var e in value)
{
var c = e.To;
var cl = _closure[c];
state_set.UnionWith(cl);
}
foreach (var c in state_set)
{
if (!_closure[c].Equals(state_set))
{
_closure[c] = state_set;
changed = true;
}
}
}
}
}
var initialState = CreateInitialState(nfa, dfa);
foreach (var p in _closure)
{
var state_set = p.Value;
var new_dfa_state = FindHashSetState(dfa, state_set);
if (new_dfa_state == null)
{
var state = AddHashSetState(dfa, state_set);
{
var mark = false;
foreach (var s in state_set)
{
if (nfa.FinalStates.Contains(s))
{
mark = true;
}
}
if (mark && !dfa.FinalStates.Contains(state))
{
dfa.AddFinalState(state);
}
}
}
}
//System.Console.Error.WriteLine(dfa.ToString());
foreach (var p in _closure)
{
var k = p.Key;
var state_set = p.Value;
var dfa_state = FindHashSetState(dfa, state_set);
// System.Console.Error.WriteLine("State " + dfa_state.Id + ":"
// + state_set.Aggregate(
// "", // start with empty string to handle empty list case.
// (current, next) => current + ", " + next));
}
//System.Console.Error.WriteLine(dfa.ToString());
foreach (var from_dfa_state in dfa.Vertices)
{
var nfa_state_set = FindHashSet(from_dfa_state);
var transitions = ClosureTaker.GatherTransitions(nfa_state_set);
foreach (var transition_set in transitions)
{
// Note, transitions is a collection of edges for a given string.
// For the NFA, an edge has one Ast for the edge because it came from one pattern.
// But, for the DFA, there could be multiple edges for the same string,
// each from a different pattern! Compute the set of Asts for
// all edges.
var key = transition_set.Key;
var value = transition_set.Value;
var state_set = new HashSet <State>();
foreach (var e in value)
{
state_set.Add(e.To);
}
// Find in all previous states.
var new_state_set = _hash_sets.Where(hs => state_set.IsSubsetOf(hs.Key)).FirstOrDefault().Key;
if (new_state_set == null)
{
new_state_set = _closure[state_set.First()];
}
var to_dfa_state = FindHashSetState(dfa, new_state_set);
var mods = value.First().EdgeModifiers;
var asts = new List <IParseTree>();
foreach (var v in value)
{
foreach (var v2 in v.AstList)
{
asts.Add(v2);
}
}
var he = new Edge(dfa, from_dfa_state, to_dfa_state, asts, mods);
}
}
// Add in "any" fragment in order to match tree nodes that aren't in pattern.
//{
// State s3 = new State(dfa); s3.Commit();
// var e1 = new Edge(dfa, s3, s3, null, Edge.EmptyAst, (int)Edge.EdgeModifiers.Any); e1.Commit();
// var f = new Fragment(s3);
//}
return(dfa);
}
