public KthSet(KthSet prev)
{
Prev = prev;
LA = prev.LA + 1;
Alt = prev.Alt;
IsNongreedyExit = prev.IsNongreedyExit;
Set = prev.Set.Empty;
}
private KthSet NarrowDownToSet(KthSet kthSet, IPGTerminalSet set)
{
kthSet = kthSet.Clone(false);
var cases = kthSet.Cases;
for (int i = cases.Count - 1; i >= 0; i--)
{
cases[i].Set = cases[i].Set.Intersection(set);
if (cases[i].Set.IsEmptySet)
{
cases.RemoveAt(i);
}
}
kthSet.UpdateSet(false);
return(kthSet);
}
public KthSet Clone(bool updateSet)
{
KthSet copy = new KthSet(Prev)
{
LA = LA, Set = Set, Alt = Alt
};
for (int i = 0; i < Cases.Count; i++)
{
copy.Cases.Add(Cases[i].Clone());
}
if (updateSet)
{
copy.UpdateSet(Set.ContainsEOF);
}
return(copy);
}
private IPGTerminalSet ComputeSetForNextBranch(KthSet[] kthSets, List<KthSet> thisBranch, IPGTerminalSet covered)
{
int i;
IPGTerminalSet set = null;
for (i = 0; ; i++)
{
if (i == kthSets.Length)
return null; // done!
set = kthSets[i].Set.Subtract(covered);
if (!set.IsEmptySet) {
if (_currentRule.FullLLk ?? LLPG.FullLLk)
set = NarrowDownToOneCase(set, kthSets[i].Cases);
break;
}
}
thisBranch.Add(kthSets[i]);
for (i++; i < kthSets.Length; i++)
{
var next = set.Intersection(kthSets[i].Set);
if (!next.IsEmptySet) {
set = next;
if (_currentRule.FullLLk ?? LLPG.FullLLk)
set = NarrowDownToOneCase(set, kthSets[i].Cases);
thisBranch.Add(kthSets[i]);
}
}
return set;
}
private KthSet NarrowDownToSet(KthSet kthSet, IPGTerminalSet set)
{
kthSet = kthSet.Clone(false);
var cases = kthSet.Cases;
for (int i = cases.Count-1; i >= 0; i--)
{
cases[i].Set = cases[i].Set.Intersection(set);
if (cases[i].Set.IsEmptySet)
cases.RemoveAt(i);
}
kthSet.UpdateSet(kthSet.Set.ContainsEOF);
Debug.Assert(cases.Count > 0 || set.ContainsEOF);
return kthSet;
}
protected PredictionTree ComputePredictionTree(KthSet[] kthSets)
{
var children = InternalList<PredictionBranch>.Empty;
var thisBranch = new List<KthSet>();
int lookahead = kthSets[0].LA;
Debug.Assert(kthSets.All(p => p.LA == lookahead));
IPGTerminalSet covered = CGH.EmptySet;
for (;;)
{
thisBranch.Clear();
// e.g. given an Alts value of ('0' '0'..'7'+ | '0'..'9'+),
// ComputeSetForNextBranch finds the set '0' in the first
// iteration (recording both alts in 'thisBranch'), '1'..'9'
// on the second iteration, and finally null.
IPGTerminalSet set = ComputeSetForNextBranch(kthSets, thisBranch, covered);
if (set == null)
break;
if (thisBranch.Count == 1) {
var branch = thisBranch[0];
children.Add(new PredictionBranch(set, branch.Alt, covered));
} else {
Debug.Assert(thisBranch.Count > 1);
NarrowDownToSet(thisBranch, set);
PredictionTreeOrAlt sub;
if (thisBranch.Any(ks => ks.HasAnyAndPreds))
sub = ComputeAssertionTree(thisBranch);
else
sub = ComputeNestedPredictionTree(thisBranch);
children.Add(new PredictionBranch(set, sub, covered));
}
covered = covered.Union(set);
}
return new PredictionTree(lookahead, children, covered);
}
