/// <summary>
/// Adds a new path to the list of current incomplete paths.
/// </summary>
/// <param name="p">Path.</param>
public void AddPath(PotentialPath p)
{
if (!_incompletePaths.Contains(p))
{
_incompletePaths.Add(p);
}
}
/// <summary>
/// Creates a new Potential Path which is a copy of an existing Path
/// </summary>
/// <param name="p">Potentuak Path</param>
public PotentialPath(PotentialPath p)
{
this._start = p.Start;
this._current = p.Current;
this._complete = p.IsComplete;
this._deadend = p.IsDeadEnd;
this._partial = p.IsPartial;
this._length = p.Length;
}
/// <summary>
/// Creates a new Potential Path which is a copy of an existing Path
/// </summary>
/// <param name="p">Potentuak Path</param>
public PotentialPath(PotentialPath p)
{
this._start = p.Start;
this._current = p.Current;
this._complete = p.IsComplete;
this._deadend = p.IsDeadEnd;
this._partial = p.IsPartial;
this._length = p.Length;
}
/// <summary>
/// Adds a new path to the list of complete paths.
/// </summary>
/// <param name="p">Path.</param>
public void AddCompletePath(PotentialPath p)
{
if (p.IsComplete && !p.IsPartial)
{
if (!_completePaths.Contains(p))
{
_completePaths.Add(p);
}
}
}
/// <summary>
/// Checks whether the other object is an equivalent potential path
/// </summary>
/// <param name="obj">Object to test</param>
/// <returns></returns>
public override bool Equals(object obj)
{
if (obj is PotentialPath)
{
PotentialPath other = (PotentialPath)obj;
return(this._start.Equals(other.Start) && this._current.Equals(other.Current));
}
else
{
return(false);
}
}
/// <summary>
/// Evaluates the Path using the given Path Evaluation Context.
/// </summary>
/// <param name="context">Path Evaluation Context.</param>
public void Evaluate(PathEvaluationContext context)
{
IEnumerable <Triple> ts;
if (context.IsFirst)
{
// First thing firsts we'll set that the path is no longer at the first thing since we're the first thing!
context.IsFirst = false;
// We're the start of a Path
if (context.PathStart.VariableName != null)
{
// Path starts from a Variable
String var = context.PathStart.VariableName;
if (context.SparqlContext.InputMultiset.ContainsVariable(var))
{
// Path starts from a Variable for which we have existing values
IEnumerable <INode> values = (from s in context.SparqlContext.InputMultiset.Sets
where s.ContainsVariable(var)
select s[var]).Distinct();
foreach (INode n in values)
{
if (context.IsReversed)
{
// If the Path is currently reversed then we'll look at triples with the given Predicate-Object pair
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(_predicate, n);
}
else
{
// For normal forward paths we'll look at triples with the given Subject-Predicate pair
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(n, _predicate);
}
// Bind path as appropriate
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(n, t.Subject);
}
else
{
p = new PotentialPath(n, t.Object);
}
context.AddPath(p);
}
}
}
else
{
// Path starts from an as yet unbound Variable
ts = context.SparqlContext.Data.GetTriplesWithPredicate(_predicate);
// Bind paths as appropriate
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, t.Subject);
}
else
{
p = new PotentialPath(t.Subject, t.Object);
}
context.AddPath(p);
}
}
}
else
{
// Path starts from a fixed value
INode fixedSubj = ((NodeMatchPattern)context.PathStart).Node;
if (context.IsReversed)
{
// If the Path is currently reversed then we'll look at triples with the given Predicate-Object pair
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(_predicate, fixedSubj);
}
else
{
// For normal forward paths we'll look at triples with the given Subject-Predicate pair
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(fixedSubj, _predicate);
}
// Map each Triple as a Path
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, fixedSubj);
}
else
{
p = new PotentialPath(fixedSubj, t.Object);
}
context.AddPath(p);
}
}
}
else
{
// We're not the start of a Path so we're continuing from a previous path
// This means all paths must continue from the Current position of an incomplete path
// If we are permitted to introduce new paths we can go ahead and do that here
if (context.PermitsNewPaths)
{
// Introduce new paths based on the predicate at this stage
ts = context.SparqlContext.Data.GetTriplesWithPredicate(_predicate);
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, t.Object);
p.Length = 0;
}
else
{
p = new PotentialPath(t.Subject, t.Subject);
p.Length = 0;
}
context.AddPath(p);
}
context.PermitsNewPaths = false;
}
// If there are no incomplete paths we abort
if (context.Paths.Count == 0)
{
return;
}
// For each incomplete path we attempt to extend the Path
HashSet <PotentialPath> incomplete = new HashSet <PotentialPath>();
foreach (PotentialPath p in context.Paths)
{
// Ignore dead-end paths
if (p.IsDeadEnd)
{
continue;
}
if (context.IsReversed)
{
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(_predicate, p.Current);
}
else
{
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(p.Current, _predicate);
}
// int c = 0;
foreach (Triple t in ts)
{
PotentialPath p2;;
if (context.IsReversed)
{
p2 = new PotentialPath(p.Start, t.Subject);
p2.Length = p.Length + 1;
}
else
{
p2 = new PotentialPath(p.Start, t.Object);
p2.Length = p.Length + 1;
}
incomplete.Add(p2);
}
}
// Add the newly found paths to the set of incomplete paths
foreach (PotentialPath p in incomplete)
{
context.AddPath(p);
}
}
// If we're the Last thing in the Path we can now mark any completed paths
if (context.IsLast)
{
bool objVar = (context.PathEnd.VariableName != null);
bool objVarBound = (objVar && context.SparqlContext.InputMultiset.ContainsVariable(context.PathEnd.VariableName));
foreach (PotentialPath p in context.Paths)
{
if (!p.IsDeadEnd && !p.IsComplete && !p.IsPartial)
{
if (objVar)
{
if (objVarBound)
{
// If the end of the Path is a previously bound variable then we do an accepts check
if (context.PathEnd.Accepts(context.SparqlContext, p.Current))
{
p.IsComplete = true;
context.AddCompletePath(p);
}
else
{
// We can mark this path as partial (I think) since it itself can't be completed
// but there's a possibility that it might lead to a completable path at a later point
p.IsPartial = true;
}
}
else
{
// If the end of the Path is an as yet unbound variable then any value is acceptable
p.IsComplete = true;
context.AddCompletePath(p);
}
}
else
{
if (context.PathEnd.Accepts(context.SparqlContext, p.Current))
{
// If the Path End accepts the current path end we can complete it
p.IsComplete = true;
context.AddCompletePath(p);
}
else
{
// We can mark this path as partial (I think) since it itself can't be completed
// but there's a possibility that it might lead to a completable path at a later point
p.IsPartial = true;
}
}
}
}
if (context.CanAbortEarly)
{
if (context.CompletePaths.Any(p => context.PathStart.Accepts(context.SparqlContext, p.Start) && context.PathEnd.Accepts(context.SparqlContext, p.Current)))
{
throw new RdfQueryPathFoundException();
}
}
}
}
/// <summary>
/// Adds a new path to the list of complete paths
/// </summary>
/// <param name="p">Path</param>
public void AddCompletePath(PotentialPath p)
{
if (p.IsComplete && !p.IsPartial)
{
if (!this._completePaths.Contains(p))
{
this._completePaths.Add(p);
}
}
}
/// <summary>
/// Adds a new path to the list of current incomplete paths
/// </summary>
/// <param name="p">Path</param>
public void AddPath(PotentialPath p)
{
if (!this._incompletePaths.Contains(p))
{
this._incompletePaths.Add(p);
}
}
/// <summary>
/// Evaluates the Path using the given Path Evaluation Context
/// </summary>
/// <param name="context">Path Evaluation Context</param>
public void Evaluate(PathEvaluationContext context)
{
IEnumerable<Triple> ts;
if (context.IsFirst)
{
//First thing firsts we'll set that the path is no longer at the first thing since we're the first thing!
context.IsFirst = false;
//We're the start of a Path
if (context.PathStart.VariableName != null)
{
//Path starts from a Variable
String var = context.PathStart.VariableName;
if (context.SparqlContext.InputMultiset.ContainsVariable(var))
{
//Path starts from a Variable for which we have existing values
IEnumerable<INode> values = (from s in context.SparqlContext.InputMultiset.Sets
where s.ContainsVariable(var)
select s[var]).Distinct();
foreach (INode n in values)
{
if (context.IsReversed)
{
//If the Path is currently reversed then we'll look at triples with the given Predicate-Object pair
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(this._predicate, n);
}
else
{
//For normal forward paths we'll look at triples with the given Subject-Predicate pair
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(n, this._predicate);
}
//Bind path as appropriate
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(n, t.Subject);
}
else
{
p = new PotentialPath(n, t.Object);
}
context.AddPath(p);
}
}
}
else
{
//Path starts from an as yet unbound Variable
ts = context.SparqlContext.Data.GetTriplesWithPredicate(this._predicate);
//Bind paths as appropriate
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, t.Subject);
}
else
{
p = new PotentialPath(t.Subject, t.Object);
}
context.AddPath(p);
}
}
}
else
{
//Path starts from a fixed value
INode fixedSubj = ((NodeMatchPattern)context.PathStart).Node;
if (context.IsReversed)
{
//If the Path is currently reversed then we'll look at triples with the given Predicate-Object pair
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(this._predicate, fixedSubj);
}
else
{
//For normal forward paths we'll look at triples with the given Subject-Predicate pair
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(fixedSubj, this._predicate);
}
//Map each Triple as a Path
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, fixedSubj);
}
else
{
p = new PotentialPath(fixedSubj, t.Object);
}
context.AddPath(p);
}
}
}
else
{
//We're not the start of a Path so we're continuing from a previous path
//This means all paths must continue from the Current position of an incomplete path
//If we are permitted to introduce new paths we can go ahead and do that here
if (context.PermitsNewPaths)
{
//Introduce new paths based on the predicate at this stage
ts = context.SparqlContext.Data.GetTriplesWithPredicate(this._predicate);
foreach (Triple t in ts)
{
PotentialPath p;
if (context.IsReversed)
{
p = new PotentialPath(t.Object, t.Object);
p.Length = 0;
}
else
{
p = new PotentialPath(t.Subject, t.Subject);
p.Length = 0;
}
context.AddPath(p);
}
context.PermitsNewPaths = false;
}
//If there are no incomplete paths we abort
if (context.Paths.Count == 0) return;
//For each incomplete path we attempt to extend the Path
HashSet<PotentialPath> incomplete = new HashSet<PotentialPath>();
foreach (PotentialPath p in context.Paths)
{
//Ignore dead-end paths
if (p.IsDeadEnd) continue;
if (context.IsReversed)
{
ts = context.SparqlContext.Data.GetTriplesWithPredicateObject(this._predicate, p.Current);
}
else
{
ts = context.SparqlContext.Data.GetTriplesWithSubjectPredicate(p.Current, this._predicate);
}
//int c = 0;
foreach (Triple t in ts)
{
PotentialPath p2; ;
if (context.IsReversed)
{
p2 = new PotentialPath(p.Start, t.Subject);
p2.Length = p.Length + 1;
}
else
{
p2 = new PotentialPath(p.Start, t.Object);
p2.Length = p.Length + 1;
}
incomplete.Add(p2);
}
}
//Add the newly found paths to the set of incomplete paths
foreach (PotentialPath p in incomplete)
{
context.AddPath(p);
}
}
//If we're the Last thing in the Path we can now mark any completed paths
if (context.IsLast)
{
bool objVar = (context.PathEnd.VariableName != null);
bool objVarBound = (objVar && context.SparqlContext.InputMultiset.ContainsVariable(context.PathEnd.VariableName));
foreach (PotentialPath p in context.Paths)
{
if (!p.IsDeadEnd && !p.IsComplete && !p.IsPartial)
{
if (objVar)
{
if (objVarBound)
{
//If the end of the Path is a previously bound variable then we do an accepts check
if (context.PathEnd.Accepts(context.SparqlContext, p.Current))
{
p.IsComplete = true;
context.AddCompletePath(p);
}
else
{
//We can mark this path as partial (I think) since it itself can't be completed
//but there's a possibility that it might lead to a completable path at a later point
p.IsPartial = true;
}
}
else
{
//If the end of the Path is an as yet unbound variable then any value is acceptable
p.IsComplete = true;
context.AddCompletePath(p);
}
}
else
{
if (context.PathEnd.Accepts(context.SparqlContext, p.Current))
{
//If the Path End accepts the current path end we can complete it
p.IsComplete = true;
context.AddCompletePath(p);
}
else
{
//We can mark this path as partial (I think) since it itself can't be completed
//but there's a possibility that it might lead to a completable path at a later point
p.IsPartial = true;
}
}
}
}
if (context.CanAbortEarly)
{
if (context.CompletePaths.Any(p => context.PathStart.Accepts(context.SparqlContext, p.Start) && context.PathEnd.Accepts(context.SparqlContext, p.Current)))
{
throw new RdfQueryPathFoundException();
}
}
}
}
