/// <summary>
/// Build the NFSA from the abstract syntax tree.
/// There is an NfsaInstance for each start state.
/// Each rule starts with a new nfsa state, which
/// is the target of a new epsilon transition from
/// the real start state, nInst.Entry.
/// </summary>
/// <param name="ast"></param>
public void Build(AAST ast)
{
int index = 0;
DateTime time0 = DateTime.Now;
nfas = new NfsaInstance[ast.StartStateCount];
foreach (KeyValuePair<string, StartState> p in ast.startStates)
{
StartState s = p.Value;
string name = p.Key;
if (!s.IsAll)
{
NfsaInstance nInst = new NfsaInstance(s, this);
nfas[index++] = nInst;
nInst.key = name;
// for each pattern do ...
for (int i = 0; i < s.rules.Count; i++)
{
RuleDesc rule = s.rules[i];
RegExTree tree = rule.Tree;
// This test constructs the disjoint automata
// that test code points for predicate evaluation.
if (rule.isPredDummyRule)
{
NState entry = nInst.Entry;
nInst.MakePath(tree, entry, entry);
}
else
{
NState start = nInst.MkState();
NState endSt = nInst.MkState();
if (tree.op == RegOp.leftAnchor) // this is a left anchored pattern
{
nInst.AnchorState.AddEpsTrns(start);
tree = ((Unary)tree).kid;
}
else // this is not a left anchored pattern
nInst.Entry.AddEpsTrns(start);
//
// Now check for right anchors, and add states as necessary.
//
if (tree.op == RegOp.eof)
{
//
// <<EOF>> rules are always emitted outside
// of the usual subset construction framework.
// We ensure that we do not get spurious warnings.
//
rule.useCount = 1;
nInst.eofAction = rule.aSpan;
nInst.MakePath(tree, start, endSt);
nInst.MarkAccept(endSt, rule);
}
else if (tree.op == RegOp.rightAnchor)
{
tree = ((Unary)tree).kid;
nInst.MakePath(tree, start, endSt);
AddAnchorContext(nInst, endSt, rule);
}
else
{
nInst.MakePath(tree, start, endSt);
nInst.MarkAccept(endSt, rule);
}
}
}
}
}
if (task.Verbose)
{
Console.Write("GPLEX: NFSA built");
Console.Write((task.Errors ? ", errors detected" : " without error"));
Console.Write((task.Warnings ? "; warnings issued. " : ". "));
Console.WriteLine(TaskState.ElapsedTime(time0));
}
if (task.Summary)
WriteSummary(time0);
}
public NFSA(TaskState t) { task = t; }
