private bool IsCompletedTermConsistentWithNextTerm(NonTerminalObject completedTerm, NonTerminalObject nextTerm,
out NonTerminalStack intersection)
{
intersection = null;
if (nextTerm == null)
{
return(false);
}
//the above case happens where the rule to be continued is already completed at the start column (next term = null).
//this can only happen in a single case: that rule was an epsilon rule.
if (completedTerm.NonTerminal != nextTerm.NonTerminal)
{
return(false);
}
if (nextTerm.Stack == null && completedTerm.Stack == null)
{
return(true);
}
var intersectAlgo = new StackGraphIntersect();
intersection = intersectAlgo.Execute(nextTerm.Stack, completedTerm.Stack);
return(intersection != null);
}
public NonTerminalStack GetPrefixListStackObjectOfGivenTop(string top)
{
if (top != Top && Top != Grammar.Epsilon)
{
throw new Exception(
string.Format("popping {0} from stack graph headed by {1}, should be headed by EPSILON", top, Top));
}
var newPrefixList = PrefixList;
if (Top == Grammar.Epsilon)
{
if (PrefixList != null)
{
newPrefixList = PrefixList.Where(x => x.Top == top).ToList();
}
}
if (PrefixList == null)
{
return(null);
}
if (newPrefixList.Count == 1)
{
return(newPrefixList.First());
}
var newStack = new NonTerminalStack(Grammar.Epsilon);
newStack.PrefixList = newPrefixList;
return(newStack);
}
public override NonTerminalStack Execute(NonTerminalStack arg1, NonTerminalStack arg2)
{
var stackToIntersect = arg1;
var otherStackToIntersect = arg2;
if (arg1 == null || arg2 == null)
{
return(null);
}
if (arg1.Top != arg2.Top)
{
if (arg1.Top != Grammar.Epsilon)
{
stackToIntersect = new NonTerminalStack(Grammar.Epsilon, arg1);
//stackToMerge.Weight = arg1.Weight;
}
if (arg2.Top != Grammar.Epsilon)
{
otherStackToIntersect = new NonTerminalStack(Grammar.Epsilon, arg2);
//otherStackToMerge.Weight = arg2.Weight;
}
}
InputNonTerminalStack v1 = new InputNonTerminalStack(stackToIntersect, 1);
InputNonTerminalStack v2 = new InputNonTerminalStack(otherStackToIntersect, 2);
return(InnerExecute(v1, v2));
}
protected void RecordSonDataOfInputGraphs(NonTerminalStack outputStack, int inputGraphNumber)
{
if (inputGraphNumber == 0)
{
SonsOfInputVertices[outputStack] = new SonDataFromInputGraphs(false, false);
}
else if (inputGraphNumber == 1)
{
if (!SonsOfInputVertices.ContainsKey(outputStack))
{
SonsOfInputVertices[outputStack] = new SonDataFromInputGraphs(true, false);
}
SonsOfInputVertices[outputStack].VertexFromGraph1HasSon = true;
}
else if (inputGraphNumber == 2)
{
if (!SonsOfInputVertices.ContainsKey(outputStack))
{
SonsOfInputVertices[outputStack] = new SonDataFromInputGraphs(false, true);
}
SonsOfInputVertices[outputStack].VertexFromGraph2HasSon = true;
}
else if (inputGraphNumber == 3)
{
SonsOfInputVertices[outputStack] = new SonDataFromInputGraphs(true, true);
}
}
//shallow copy.
public NonTerminalStack(NonTerminalStack otherStack)
{
if (otherStack == null) return;
Top = otherStack.Top;
//Weight = otherStack.Weight;
if (otherStack.PrefixList != null)
PrefixList = otherStack.PrefixList; //shallow copy.
//GetID();
}
//deep copy, used in intersect
// ReSharper disable once UnusedParameter.Local
public NonTerminalStack(NonTerminalStack otherStack, bool deepCopy)
{
if (otherStack == null) return;
Top = otherStack.Top;
//Weight = otherStack.Weight;
if (otherStack.PrefixList != null)
{
PrefixList = new List<NonTerminalStack>(otherStack.PrefixList.Count);
PrefixList = otherStack.PrefixList.Select(x => new NonTerminalStack(x, deepCopy)).ToList();
}
}
//StackEquality here is used to identify the exact same structure - used
//only in specific EqualityComparer (NonTerminalObjectStackComparer).
//Equals is not implemented - the regular behavior of NonTerminalStack is ByReference.
public static bool StackEquality(NonTerminalStack x, NonTerminalStack y)
{
if (x.Top != y.Top) return false;
if (x.PrefixList != null && y.PrefixList != null)
{
if (x.PrefixList.Count != y.PrefixList.Count) return false;
for (var i = 0; i < x.PrefixList.Count; i++)
if (!StackEquality(x.PrefixList[i], y.PrefixList[i])) return false;
return true;
}
return x.PrefixList == null && y.PrefixList == null;
}
public void MapVertices(InputNonTerminalStack vertex1, NonTerminalStack target)
{
if (Mappings.ContainsKey(vertex1) && Mappings[vertex1].Contains(target))
{
return;
}
if (!Mappings.ContainsKey(vertex1))
{
Mappings[vertex1] = new List <NonTerminalStack>();
}
Mappings[vertex1].Add(target);
}
//shallow copy.
public NonTerminalStack(NonTerminalStack otherStack)
{
if (otherStack == null)
{
return;
}
Top = otherStack.Top;
//Weight = otherStack.Weight;
if (otherStack.PrefixList != null)
{
PrefixList = otherStack.PrefixList; //shallow copy.
}
//GetID();
}
protected override NonTerminalStack AddSubtree(InputNonTerminalStack inputStack, int inputGraphNumber)
{
if (Mappings.ContainsKey(inputStack))
{
if (inputGraphNumber == 1 &&
SonsOfInputVertices.ContainsKey(Mappings[inputStack].Last()) &&
!SonsOfInputVertices[Mappings[inputStack].Last()].VertexFromGraph2HasSon)
{
return(Mappings[inputStack].Last());
}
if (inputGraphNumber == 2 &&
SonsOfInputVertices.ContainsKey(Mappings[inputStack].Last()) &&
!SonsOfInputVertices[Mappings[inputStack].Last()].VertexFromGraph1HasSon)
{
return(Mappings[inputStack].Last());
}
}
var newStack = new NonTerminalStack(inputStack.Stack.Top);
if (inputStack.Stack.PrefixList != null)
{
foreach (var vertex in inputStack.Stack.PrefixList)
{
var vv = new InputNonTerminalStack(vertex, inputGraphNumber);
var subtree = AddSubtree(vv, inputGraphNumber);
if (newStack.PrefixList == null)
{
newStack.PrefixList = new List <NonTerminalStack>();
}
newStack.PrefixList.Add(subtree);
}
RecordSonDataOfInputGraphs(newStack, inputGraphNumber);
}
else
{
RecordSonDataOfInputGraphs(newStack, 0);
}
MapVertices(inputStack, newStack);
return(newStack);
}
// uncomment for debugging purposes (commented to maximize efficiency)
//public static int IDCounter;
//public int ID { get; set; }
//public int Weight { get; set; }
//private void GetID()
//{
// ID = IDCounter;
// IDCounter += 1;
//}
public NonTerminalStack(string term, NonTerminalStack prefixStack)
{
Top = term;
if (prefixStack != null)
{
PrefixList = new List <NonTerminalStack>();
if (prefixStack.Top == Grammar.Epsilon)
{
PrefixList = prefixStack.PrefixList;
}
else
{
PrefixList.Add(prefixStack);
}
}
//GetID();
}
// uncomment for debugging purposes (commented to maximize efficiency)
//public static int IDCounter;
//public int ID { get; set; }
//public int Weight { get; set; }
//private void GetID()
//{
// ID = IDCounter;
// IDCounter += 1;
//}
public NonTerminalStack(string term, NonTerminalStack prefixStack)
{
Top = term;
if (prefixStack != null)
{
PrefixList = new List<NonTerminalStack>();
if (prefixStack.Top == Grammar.Epsilon)
{
PrefixList = prefixStack.PrefixList;
}
else
{
PrefixList.Add(prefixStack);
}
}
//GetID();
}
public bool Equals(NonTerminalObject x, NonTerminalObject y)
{
var b = x.NonTerminal == y.NonTerminal;
if (!b)
{
return(false);
}
if (x.Stack == null && y.Stack == null)
{
return(true);
}
if (x.Stack != null && y.Stack != null)
{
return(NonTerminalStack.StackEquality(x.Stack, y.Stack));
}
return(false); //one of the stack is null and the other is not.
}
public bool CheckForFinalLeaves(InputNonTerminalStack v1, InputNonTerminalStack v2, NonTerminalStack outputStack)
{
//both null prefix lists and identical tops = return stack1 / stack2. (the leaf).
if (v1.Stack.PrefixList == null && v2.Stack.PrefixList == null)
{
//if we already visited the output stack, if it has sons we cannot use it, we need to create new node.
if (SonsOfInputVertices.ContainsKey(outputStack))
{
if (SonsOfInputVertices[outputStack].VertexFromGraph1HasSon ||
SonsOfInputVertices[outputStack].VertexFromGraph2HasSon)
{
outputStack = new NonTerminalStack(v1.Stack.Top);
}
}
MapVertices(v1, outputStack);
MapVertices(v2, outputStack);
RecordSonDataOfInputGraphs(outputStack, 0);
return(true);
}
return(false);
}
protected override bool CheckForInternalLeaves(InputNonTerminalStack stack1, InputNonTerminalStack stack2,
NonTerminalStack outputStack, out NonTerminalStack res)
{
var retVal = false;
res = null;
if (stack1.Stack.IsInternalLeaf || stack2.Stack.IsInternalLeaf)
{
outputStack.IsInternalLeaf = true;
}
if (stack1.Stack.PrefixList == null && stack2.Stack.PrefixList != null)
{
RecordSonDataOfInputGraphs(outputStack, 2);
if (stack1.Stack.IsInternalLeaf)
{
throw new Exception("3: internal leaf, but prefix list is null; contradiction");
}
res = AddSubtree(stack2, 2);
res.IsInternalLeaf = true;
retVal = true;
}
if (stack2.Stack.PrefixList == null && stack1.Stack.PrefixList != null)
{
RecordSonDataOfInputGraphs(outputStack, 1);
if (stack2.Stack.IsInternalLeaf)
{
throw new Exception("4: internal leaf, but prefix list is null; contradiction");
}
res = AddSubtree(stack1, 1);
res.IsInternalLeaf = true;
retVal = true;
}
return(retVal);
}
protected override bool CheckForInternalLeaves(InputNonTerminalStack stack1, InputNonTerminalStack stack2,
NonTerminalStack outputStack, out NonTerminalStack res)
{
var retVal = false;
res = null;
if (stack1.Stack.IsInternalLeaf && stack2.Stack.IsInternalLeaf)
{
outputStack.IsInternalLeaf = true;
}
//one stack is leaf, the other is not => empty intersection.
if (stack1.Stack.PrefixList == null && stack2.Stack.PrefixList != null)
{
RecordSonDataOfInputGraphs(outputStack, 2);
if (stack1.Stack.IsInternalLeaf)
{
throw new Exception("1: internal leaf, but prefix list is null; contradiction");
}
res = stack2.Stack.IsInternalLeaf ? outputStack : null;
retVal = true;
}
else if (stack2.Stack.PrefixList == null && stack1.Stack.PrefixList != null)
{
RecordSonDataOfInputGraphs(outputStack, 1);
if (stack2.Stack.IsInternalLeaf)
{
throw new Exception("2:internal leaf, but prefix list is null; contradiction");
}
res = stack1.Stack.IsInternalLeaf ? outputStack : null;
retVal = true;
}
return(retVal);
}
protected override void TraverseRemainingList(bool moveNext, List <NonTerminalStack> .Enumerator iterator,
NonTerminalStack outputStack, int inputGraphNumber)
{
var bRecorded = false;
//map subtrees left after simulatenous traversal of the two lists ends (with the shorter list).
while (moveNext)
{
var current = iterator.Current;
InputNonTerminalStack vcurrent = new InputNonTerminalStack(current, inputGraphNumber);
var son = AddSubtree(vcurrent, inputGraphNumber);
if (outputStack.PrefixList == null)
{
outputStack.PrefixList = new List <NonTerminalStack>();
}
outputStack.PrefixList.Add(son);
if (!bRecorded)
{
RecordSonDataOfInputGraphs(outputStack, inputGraphNumber);
bRecorded = true;
}
moveNext = iterator.MoveNext();
}
}
private NonTerminalStack GetOrCreateOutputStack(InputNonTerminalStack v1, InputNonTerminalStack v2)
{
NonTerminalStack outputStack = null;
if (Mappings.ContainsKey(v1))
{
outputStack = Mappings[v1].Last();
}
if (Mappings.ContainsKey(v2))
{
if (outputStack != null)
{
throw new Exception("both vertices were already visited");
}
outputStack = Mappings[v2].Last();
}
if (outputStack == null)
{
outputStack = new NonTerminalStack(v1.Stack.Top);
}
return(outputStack);
}
//StackEquality here is used to identify the exact same structure - used
//only in specific EqualityComparer (NonTerminalObjectStackComparer).
//Equals is not implemented - the regular behavior of NonTerminalStack is ByReference.
public static bool StackEquality(NonTerminalStack x, NonTerminalStack y)
{
if (x.Top != y.Top)
{
return(false);
}
if (x.PrefixList != null && y.PrefixList != null)
{
if (x.PrefixList.Count != y.PrefixList.Count)
{
return(false);
}
for (var i = 0; i < x.PrefixList.Count; i++)
{
if (!StackEquality(x.PrefixList[i], y.PrefixList[i]))
{
return(false);
}
}
return(true);
}
return(x.PrefixList == null && y.PrefixList == null);
}
public static NonTerminalStack Intersect(NonTerminalStack stack1, NonTerminalStack stack2,
HashSet<NonTerminalStack> visited1, HashSet<NonTerminalStack> visited2,
Dictionary<NonTerminalStack, HashSet<NonTerminalStack>> mappings)
{
if (stack1 == null || stack2 == null) return null;
visited1.Add(stack1);
visited2.Add(stack2);
if (!stack1.Top.Equals(stack2.Top)) return null;
//both null prefix lists and identical tops = return stack1 / stack2. (the leaf).
if (stack1.PrefixList == null && stack2.PrefixList == null)
{
return new NonTerminalStack(stack1.Top);
}
//one stack is leaf, the other is not => empty intersection.
if (stack1.PrefixList == null || stack2.PrefixList == null) return null;
//SEFI - update the function to allow arbitrary nodes to be leaves.
//i.e. if TOP is leaf and the other top is leaf and one of the prefix lists is null, allow returning the leaf top as intersection.
var intersectedStack = new NonTerminalStack(stack1.Top);
var iterator1 = stack1.PrefixList.GetEnumerator();
var iterator2 = stack2.PrefixList.GetEnumerator();
var moveNext1 = iterator1.MoveNext();
var moveNext2 = iterator2.MoveNext();
//if MoveNext() passes the end of the list, it returns false
while (moveNext1 && moveNext2)
{
var current1 = iterator1.Current;
var current2 = iterator2.Current;
//if at least one of the sons was not visited, we neet to compare the sons.
if (!visited1.Contains(current1) || !visited2.Contains(current2))
{
var compare = string.CompareOrdinal(current1.Top, current2.Top);
if (compare > 0)
moveNext2 = iterator2.MoveNext();
else if (compare < 0)
moveNext1 = iterator1.MoveNext();
else //equal - call recursively.
{
var subtreesIntersection = Intersect(current1, current2, visited1, visited2, mappings);
if (subtreesIntersection != null)
{
if (intersectedStack.PrefixList == null)
intersectedStack.PrefixList = new List<NonTerminalStack>();
intersectedStack.PrefixList.Add(subtreesIntersection);
MapVertices(current1, current2, subtreesIntersection, mappings);
}
moveNext1 = iterator1.MoveNext();
moveNext2 = iterator2.MoveNext();
}
}
else //both sons were visited - we check if they are in the same equivalence set.
{
var visitedSequence = mappings[current1].Intersect(mappings[current2]);
if (visitedSequence.Any())
{
if (intersectedStack.PrefixList == null)
intersectedStack.PrefixList = new List<NonTerminalStack>();
intersectedStack.PrefixList.Add(visitedSequence.First());
}
moveNext1 = iterator1.MoveNext();
moveNext2 = iterator2.MoveNext();
}
}
//if there is no common son to both stacks, there is no intersection down the subtrees.
//reminder: if one of the prefixList of the compared stacks is null, we return earlier in this function.
if (intersectedStack.PrefixList == null) return null;
return intersectedStack;
}
protected abstract void TraverseRemainingList(bool moveNext, List <NonTerminalStack> .Enumerator iterator,
NonTerminalStack outputStack, int inputGraphNumber);
protected abstract bool CheckForInternalLeaves(InputNonTerminalStack stack1, InputNonTerminalStack stack2,
NonTerminalStack outputStack, out NonTerminalStack res);
public abstract NonTerminalStack Execute(NonTerminalStack stack1, NonTerminalStack stack2);
public static void MapVertices(NonTerminalStack vertex1, NonTerminalStack vertex2, NonTerminalStack target,
Dictionary<NonTerminalStack, HashSet<NonTerminalStack>> mappings)
{
if (mappings.ContainsKey(vertex1) && mappings.ContainsKey(vertex2))
{
throw new Exception("should not occur! visited vertices are compared elsewhere.");
}
if (!mappings.ContainsKey(vertex1))
mappings[vertex1] = new HashSet<NonTerminalStack>();
mappings[vertex1].Add(target);
if (!mappings.ContainsKey(vertex2))
mappings[vertex2] = new HashSet<NonTerminalStack>();
mappings[vertex2].Add(target);
}
public static List<NonTerminalStack> EnforceStrictOrdering(NonTerminalStack[] l)
{
var mergedSortedList = new List<NonTerminalStack>();
for (var i = 0; i < l.Length - 1; i++)
{
var currentStackObject = l[i];
var nextStackObject = l[i + 1];
if (currentStackObject.Top == nextStackObject.Top)
{
var mergedSon = Merge(currentStackObject, nextStackObject);
mergedSortedList.Add(mergedSon);
i++; //skip l[i+1] (nextStackObject) - it has been merged into mergedSon.
//also: assuming that both source lists are strictly ordered (each symbol appears only once),
//so the seqeunce of some identical symbols is at most of length 2.
}
else
mergedSortedList.Add(l[i]);
if (i == l.Length - 2)
{
//if we arrive at the one before last element without it being merged with the last element,
//add the last element (the loop above is from 0 to length-1).
mergedSortedList.Add(l[i + 1]);
}
}
return mergedSortedList;
}
public static NonTerminalStack Merge(NonTerminalStack arg1, NonTerminalStack arg2)
{
var stackToMerge = arg1;
var otherStackToMerge = arg2;
if (otherStackToMerge == null) return stackToMerge;
if (stackToMerge == null) return otherStackToMerge;
if (arg1.Top != arg2.Top)
{
if (arg1.Top != Grammar.Epsilon)
{
stackToMerge = new NonTerminalStack(Grammar.Epsilon, arg1);
//stackToMerge.Weight = arg1.Weight;
}
if (arg2.Top != Grammar.Epsilon)
{
otherStackToMerge = new NonTerminalStack(Grammar.Epsilon, arg2);
//otherStackToMerge.Weight = arg2.Weight;
}
}
var mergedStack = new NonTerminalStack(stackToMerge.Top);
//mergedStack.Weight = stackToMerge.Weight + otherStackToMerge.Weight;
if (stackToMerge.PrefixList == null && otherStackToMerge.PrefixList == null)
return mergedStack;
IEnumerable<NonTerminalStack> combinedList;
if (stackToMerge.PrefixList == null && otherStackToMerge.PrefixList != null)
combinedList = otherStackToMerge.PrefixList;
else if (stackToMerge.PrefixList != null && otherStackToMerge.PrefixList == null)
combinedList = stackToMerge.PrefixList;
else
combinedList = stackToMerge.PrefixList.Concat(otherStackToMerge.PrefixList);
var sortedList = combinedList.OrderBy(x => x.Top).ToArray();
var forcedList = EnforceStrictOrdering(sortedList);
//create a new merged stack without altering the original stacks.
mergedStack.PrefixList = forcedList;
return mergedStack;
}
public InputNonTerminalStack(NonTerminalStack s, int number)
{
Stack = s;
GraqphNumber = number;
}
private bool IsCompletedTermConsistentWithNextTerm(NonTerminalObject completedTerm, NonTerminalObject nextTerm,
out NonTerminalStack intersection)
{
intersection = null;
if (nextTerm == null) return false;
//the above case happens where the rule to be continued is already completed at the start column (next term = null).
//this can only happen in a single case: that rule was an epsilon rule.
if (completedTerm.NonTerminal != nextTerm.NonTerminal)
return false;
if (nextTerm.Stack == null && completedTerm.Stack == null) return true;
NonTerminalStack arg1 = null;
//deep copy the stacks in order not to alter the graphs of past stacks.
if (nextTerm.Stack != null)
arg1 = new NonTerminalStack(nextTerm.Stack, true);
NonTerminalStack arg2 = null;
if (completedTerm.Stack != null)
arg2 = new NonTerminalStack(completedTerm.Stack, true);
intersection = NonTerminalStack.Intersect(arg1, arg2, new HashSet<NonTerminalStack>(),
new HashSet<NonTerminalStack>(),
new Dictionary<NonTerminalStack, HashSet<NonTerminalStack>>());
return intersection != null;
}
public NonTerminalStack GetPrefixListStackObjectOfGivenTop(string top)
{
if (top != Top && Top != Grammar.Epsilon)
throw new Exception(
string.Format("popping {0} from stack graph headed by {1}, should be headed by EPSILON", top, Top));
var newPrefixList = PrefixList;
if (Top == Grammar.Epsilon)
{
if (PrefixList != null)
newPrefixList = PrefixList.Where(x => x.Top == top).ToList();
}
if (PrefixList == null)
return null;
if (newPrefixList.Count == 1)
return newPrefixList.First();
var newStack = new NonTerminalStack(Grammar.Epsilon);
newStack.PrefixList = newPrefixList;
return newStack;
}
