public void SparqlOptimiserQueryFilterPlacement5()
{
// given
var query = new SparqlQuery {
QueryType = SparqlQueryType.Select
};
query.AddVariable(new SparqlVariable("s", true));
query.RootGraphPattern = new GraphPattern();
var subj = new VariablePattern("s");
var rdfType = new NodeMatchPattern(new UriNode(null, new Uri(RdfSpecsHelper.RdfType)));
var type = new VariablePattern("type");
var triplePattern = new TriplePattern(subj, rdfType, type);
query.RootGraphPattern.AddTriplePattern(triplePattern);
query.RootGraphPattern.AddFilter(new UnaryExpressionFilter(new InFunction(new VariableTerm("type"), new[]
{
new ConstantTerm(new UriNode(null, new Uri("http://example.com/Type1"))),
new ConstantTerm(new UriNode(null, new Uri("http://example.com/Type2"))),
new ConstantTerm(new UriNode(null, new Uri("http://example.com/Type3")))
})));
// when
var algebra = query.ToAlgebra();
// then
Assert.IsType <Select>(algebra);
Assert.IsType <Filter>(((Select)algebra).InnerAlgebra);
}
/// <summary>
/// Formats a Pattern Item in nicely formatted SPARQL syntax
/// </summary>
/// <param name="item">Pattern Item</param>
/// <param name="segment">Triple Pattern Segment</param>
/// <returns></returns>
public virtual String Format(PatternItem item, TripleSegment?segment)
{
if (item is VariablePattern)
{
return(item.ToString());
}
else if (item is NodeMatchPattern)
{
NodeMatchPattern match = (NodeMatchPattern)item;
return(this.Format(match.Node, segment));
}
else if (item is FixedBlankNodePattern)
{
if (segment != null)
{
if (segment == TripleSegment.Predicate)
{
throw new RdfOutputException("Cannot format a Fixed Blank Node Pattern Item as the Predicate of a Triple Pattern as Blank Nodes are not permitted as Predicates");
}
}
return(item.ToString());
}
else if (item is BlankNodePattern)
{
return(item.ToString());
}
else
{
throw new RdfOutputException("Unable to Format an unknown PatternItem implementation as a String");
}
}
/// <summary>
/// Used to extract the patterns that make up a <see cref="FullTextPattern">FullTextPattern</see>
/// </summary>
/// <param name="patterns">Triple Patterns</param>
/// <returns></returns>
internal static List <FullTextPattern> ExtractPatterns(IEnumerable <ITriplePattern> patterns)
{
//Do a first pass which simply looks to find any pf:textMatch properties
Dictionary <PatternItem, List <TriplePattern> > ftPatterns = new Dictionary <PatternItem, List <TriplePattern> >();
List <TriplePattern> ps = patterns.OfType <TriplePattern>().ToList();
if (ps.Count == 0)
{
return(new List <FullTextPattern>());
}
foreach (TriplePattern tp in ps)
{
NodeMatchPattern predItem = tp.Predicate as NodeMatchPattern;
if (predItem == null)
{
continue;
}
IUriNode predNode = predItem.Node as IUriNode;
if (predNode == null)
{
continue;
}
if (predNode.Uri.ToString().Equals(FullTextMatchPredicateUri))
{
ftPatterns.Add(tp.Subject, new List <TriplePattern>());
ftPatterns[tp.Subject].Add(tp);
}
}
//Remove any Patterns we found from the original patterns
foreach (List <TriplePattern> fps in ftPatterns.Values)
{
fps.ForEach(tp => ps.Remove(tp));
}
if (ftPatterns.Count == 0)
{
return(new List <FullTextPattern>());
}
//Now for each pf:textMatch property we found do a further search to see if we are using
//the (?match ?score) form or the {'text' threshold limit) form rather than the simple ?match form
foreach (PatternItem key in ftPatterns.Keys)
{
if (key.VariableName != null && key.VariableName.StartsWith("_:"))
{
ExtractRelatedPatterns(key, key, ps, ftPatterns);
}
PatternItem searchKey = ftPatterns[key].First().Object;
if (searchKey.VariableName != null && searchKey.VariableName.StartsWith("_:"))
{
ExtractRelatedPatterns(key, searchKey, ps, ftPatterns);
}
}
return((from key in ftPatterns.Keys
select new FullTextPattern(ftPatterns[key])).ToList());
}
/// <summary>
/// Creates a Triple Pattern
/// </summary>
/// <param name="subj">Subject</param>
/// <param name="path">Property Path</param>
/// <param name="obj">Object</param>
/// <returns></returns>
public ITriplePattern GetTriplePattern(PatternItem subj, ISparqlPath path, PatternItem obj)
{
if (path is Property)
{
NodeMatchPattern nodeMatch = new NodeMatchPattern(((Property)path).Predicate);
return(new TriplePattern(subj, nodeMatch, obj));
}
else
{
return(new PropertyPathPattern(subj, path, obj));
}
}
/// <summary>
/// Used to help extract the patterns that make up a property function pattern.
/// </summary>
/// <param name="key">Key.</param>
/// <param name="subj">Subject.</param>
/// <param name="ps">Patterns.</param>
/// <param name="funcInfo">Function Information.</param>
/// <param name="argList">Argument List to add discovered arguments to.</param>
static void ExtractRelatedPatterns(PatternItem key, PatternItem subj, List <IMatchTriplePattern> ps, Dictionary <PatternItem, PropertyFunctionInfo> funcInfo, List <PatternItem> argList)
{
bool recurse = true, any = false, argSeen = false;
PatternItem nextSubj = subj;
while (recurse)
{
any = false;
foreach (IMatchTriplePattern tp in ps.ToList())
{
if (tp.Subject.VariableName == nextSubj.VariableName)
{
NodeMatchPattern predItem = tp.Predicate as NodeMatchPattern;
if (predItem == null)
{
continue;
}
IUriNode predNode = predItem.Node as IUriNode;
if (predNode == null)
{
continue;
}
if (!argSeen && predNode.Uri.AbsoluteUri.Equals(RdfSpecsHelper.RdfListFirst))
{
funcInfo[key].Patterns.Add(tp);
argList.Add(tp.Object);
ps.Remove(tp);
any = true;
argSeen = true;
}
else if (argSeen && predNode.Uri.AbsoluteUri.Equals(RdfSpecsHelper.RdfListRest))
{
funcInfo[key].Patterns.Add(tp);
ps.Remove(tp);
recurse = tp.Object.VariableName != null;
nextSubj = tp.Object;
any = true;
argSeen = false;
}
}
}
if (!any)
{
recurse = false;
}
if (nextSubj == null)
{
throw new RdfQueryException("Failed to find expected rdf:rest property");
}
}
}
/// <summary>
/// Used to help extract the patterns that make up a <see cref="FullTextPattern">FullTextPattern</see>
/// </summary>
/// <param name="key">Key</param>
/// <param name="subj">Subject</param>
/// <param name="ps">Patterns</param>
/// <param name="ftPatterns">Discovered Full Text Patterns</param>
internal static void ExtractRelatedPatterns(PatternItem key, PatternItem subj, List <TriplePattern> ps, Dictionary <PatternItem, List <TriplePattern> > ftPatterns)
{
bool recurse = true;
PatternItem nextSubj = null;
foreach (TriplePattern tp in ps)
{
if (tp.Subject.VariableName == subj.VariableName)
{
NodeMatchPattern predItem = tp.Predicate as NodeMatchPattern;
if (predItem == null)
{
continue;
}
IUriNode predNode = predItem.Node as IUriNode;
if (predNode == null)
{
continue;
}
if (predNode.Uri.ToString().Equals(RdfSpecsHelper.RdfListFirst))
{
ftPatterns[key].Add(tp);
}
else if (predNode.Uri.ToString().Equals(RdfSpecsHelper.RdfListRest))
{
ftPatterns[key].Add(tp);
recurse = tp.Object.VariableName != null;
nextSubj = tp.Object;
}
}
}
ftPatterns[key].ForEach(tp => ps.Remove(tp));
if (nextSubj == null)
{
throw new RdfQueryException("Failed to find expected rdf:rest property");
}
if (recurse)
{
ExtractRelatedPatterns(key, nextSubj, ps, ftPatterns);
}
}
private ISparqlAlgebra GetAlgebraUntransformed(ISparqlPath path, INode start, INode end)
{
PatternItem x, y;
if (start == null)
{
x = new VariablePattern("?x");
}
else
{
x = new NodeMatchPattern(start);
}
if (end == null)
{
y = new VariablePattern("?y");
}
else
{
y = new NodeMatchPattern(end);
}
return(new Bgp(new PropertyPathPattern(x, path, y)));
}
private ISparqlAlgebra GetAlgebra(ISparqlPath path, INode start, INode end)
{
PatternItem x, y;
if (start == null)
{
x = new VariablePattern("?x");
}
else
{
x = new NodeMatchPattern(start);
}
if (end == null)
{
y = new VariablePattern("?y");
}
else
{
y = new NodeMatchPattern(end);
}
PathTransformContext context = new PathTransformContext(x, y);
return(path.ToAlgebra(context));
}
/// <summary>
/// Optimises the algebra so that all Node terms are virtualised
/// </summary>
/// <param name="algebra">Algebra</param>
/// <returns></returns>
public ISparqlAlgebra Optimise(ISparqlAlgebra algebra)
{
if (algebra is IAbstractJoin)
{
return(((IAbstractJoin)algebra).Transform(this));
}
else if (algebra is IUnaryOperator)
{
return(((IUnaryOperator)algebra).Transform(this));
}
else if (algebra is IBgp)
{
IBgp current = (IBgp)algebra;
if (current.PatternCount == 0)
{
return(current);
}
else
{
ISparqlAlgebra result = new Bgp();
List <ITriplePattern> patterns = new List <ITriplePattern>();
List <ITriplePattern> ps = new List <ITriplePattern>(current.TriplePatterns.ToList());
TNodeID nullID = this._provider.NullID;
for (int i = 0; i < current.PatternCount; i++)
{
if (ps[i] is FilterPattern || ps[i] is BindPattern)
{
//First ensure that if we've found any other Triple Patterns up to this point
//we dump this into a BGP and join with the result so far
if (patterns.Count > 0)
{
result = Join.CreateJoin(result, new Bgp(patterns));
patterns.Clear();
}
if (ps[i] is FilterPattern)
{
result = new Filter(result, ((FilterPattern)ps[i]).Filter);
}
else
{
BindPattern bind = (BindPattern)ps[i];
result = new Extend(result, bind.AssignExpression, bind.VariableName);
}
}
else
{
//Convert Terms in the Pattern into Virtual Nodes
TriplePattern tp = (TriplePattern)ps[i];
PatternItem subj, pred, obj;
if (tp.Subject is NodeMatchPattern)
{
TNodeID id = this._provider.GetID(((NodeMatchPattern)tp.Subject).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
subj = new NodeMatchPattern(this.CreateVirtualNode(id, ((NodeMatchPattern)tp.Subject).Node));
}
}
else
{
subj = tp.Subject;
}
if (tp.Predicate is NodeMatchPattern)
{
TNodeID id = this._provider.GetID(((NodeMatchPattern)tp.Predicate).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
pred = new NodeMatchPattern(this.CreateVirtualNode(id, ((NodeMatchPattern)tp.Predicate).Node));
}
}
else
{
pred = tp.Predicate;
}
if (tp.Object is NodeMatchPattern)
{
TNodeID id = this._provider.GetID(((NodeMatchPattern)tp.Object).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
obj = new NodeMatchPattern(this.CreateVirtualNode(id, ((NodeMatchPattern)tp.Object).Node));
}
}
else
{
obj = tp.Object;
}
patterns.Add(new TriplePattern(subj, pred, obj));
}
}
if (result is NullOperator)
{
return(result);
}
else if (patterns.Count == current.PatternCount)
{
//If count of remaining patterns same as original pattern count there was no optimisation
//to do so return as is
return(current);
}
else if (patterns.Count > 0)
{
//If any patterns left at end join as a BGP with result so far
result = Join.CreateJoin(result, new Bgp(patterns));
return(result);
}
else
{
return(result);
}
}
}
else if (algebra is ITerminalOperator)
{
return(algebra);
}
else
{
return(algebra);
}
}
/// <summary>
/// Used to extract the patterns that make up property functions.
/// </summary>
/// <param name="patterns">Triple Patterns.</param>
/// <param name="localFactories">Locally scoped factories.</param>
/// <returns></returns>
public static List <IPropertyFunctionPattern> ExtractPatterns(IEnumerable <ITriplePattern> patterns, IEnumerable <IPropertyFunctionFactory> localFactories)
{
// Do a first pass which simply looks to find any 'magic' properties
Dictionary <PatternItem, PropertyFunctionInfo> funcInfo = new Dictionary <PatternItem, PropertyFunctionInfo>();
List <IMatchTriplePattern> ps = patterns.OfType <IMatchTriplePattern>().ToList();
if (ps.Count == 0)
{
return(new List <IPropertyFunctionPattern>());
}
foreach (IMatchTriplePattern tp in ps)
{
NodeMatchPattern predItem = tp.Predicate as NodeMatchPattern;
if (predItem == null)
{
continue;
}
IUriNode predNode = predItem.Node as IUriNode;
if (predNode == null)
{
continue;
}
if (PropertyFunctionFactory.IsPropertyFunction(predNode.Uri, localFactories))
{
PropertyFunctionInfo info = new PropertyFunctionInfo(predNode.Uri);
info.Patterns.Add(tp);
funcInfo.Add(tp.Subject, info);
}
}
// Remove any Patterns we found from the original patterns
foreach (PropertyFunctionInfo info in funcInfo.Values)
{
info.Patterns.ForEach(tp => ps.Remove(tp));
}
if (funcInfo.Count == 0)
{
return(new List <IPropertyFunctionPattern>());
}
// Now for each 'magic' property we found do a further search to see if we are using
// the collection forms to provide extended arguments
foreach (PatternItem key in funcInfo.Keys)
{
if (key.VariableName != null && key.VariableName.StartsWith("_:"))
{
// If LHS is a blank node may be collection form
int count = funcInfo[key].Patterns.Count;
ExtractRelatedPatterns(key, key, ps, funcInfo, funcInfo[key].SubjectArgs);
if (funcInfo[key].Patterns.Count == count)
{
// If no further patterns found just single LHS argument
funcInfo[key].SubjectArgs.Add(key);
}
}
else
{
// Otherwise key is the only LHS argument
funcInfo[key].SubjectArgs.Add(key);
}
PatternItem searchKey = funcInfo[key].Patterns.First().Object;
if (searchKey.VariableName != null && searchKey.VariableName.StartsWith("_:"))
{
// If RHS is a blank node may be collection form
int count = funcInfo[key].Patterns.Count;
ExtractRelatedPatterns(key, searchKey, ps, funcInfo, funcInfo[key].ObjectArgs);
if (funcInfo[key].Patterns.Count == count)
{
// If no further patterns found just single RHS argument
funcInfo[key].ObjectArgs.Add(searchKey);
}
}
else
{
// Otherwise single RHS argument
funcInfo[key].ObjectArgs.Add(searchKey);
}
}
// Now try to create actual property functions
List <IPropertyFunctionPattern> propFunctions = new List <IPropertyFunctionPattern>();
foreach (PatternItem key in funcInfo.Keys)
{
IPropertyFunctionPattern propFunc;
if (PropertyFunctionFactory.TryCreatePropertyFunction(funcInfo[key], localFactories, out propFunc))
{
propFunctions.Add(propFunc);
}
}
return(propFunctions);
}
/// <summary>
/// Optimises the algebra so that all Node terms are virtualised.
/// </summary>
/// <param name="algebra">Algebra.</param>
/// <returns></returns>
public ISparqlAlgebra Optimise(ISparqlAlgebra algebra)
{
if (algebra is IAbstractJoin)
{
return(((IAbstractJoin)algebra).Transform(this));
}
else if (algebra is IUnaryOperator)
{
return(((IUnaryOperator)algebra).Transform(this));
}
else if (algebra is IBgp)
{
IBgp current = (IBgp)algebra;
if (current.PatternCount == 0)
{
return(current);
}
else
{
ISparqlAlgebra result = new Bgp();
List <ITriplePattern> patterns = new List <ITriplePattern>();
List <ITriplePattern> ps = new List <ITriplePattern>(current.TriplePatterns.ToList());
TNodeID nullID = _provider.NullID;
for (int i = 0; i < current.PatternCount; i++)
{
if (ps[i].PatternType == TriplePatternType.Filter || ps[i].PatternType == TriplePatternType.BindAssignment || ps[i].PatternType == TriplePatternType.LetAssignment)
{
// First ensure that if we've found any other Triple Patterns up to this point
// we dump this into a BGP and join with the result so far
if (patterns.Count > 0)
{
result = Join.CreateJoin(result, new Bgp(patterns));
patterns.Clear();
}
if (ps[i].PatternType == TriplePatternType.Filter)
{
result = new Filter(result, new UnaryExpressionFilter(Transform(((IFilterPattern)ps[i]).Filter.Expression)));
}
else
{
IAssignmentPattern bind = (IAssignmentPattern)ps[i];
result = new Extend(result, Transform(bind.AssignExpression), bind.VariableName);
}
}
else if (ps[i].PatternType == TriplePatternType.Match)
{
// Convert Terms in the Pattern into Virtual Nodes
IMatchTriplePattern tp = (IMatchTriplePattern)ps[i];
PatternItem subj, pred, obj;
if (tp.Subject is NodeMatchPattern)
{
TNodeID id = _provider.GetID(((NodeMatchPattern)tp.Subject).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
subj = new NodeMatchPattern(CreateVirtualNode(id, ((NodeMatchPattern)tp.Subject).Node));
}
}
else
{
subj = tp.Subject;
}
if (tp.Predicate is NodeMatchPattern)
{
TNodeID id = _provider.GetID(((NodeMatchPattern)tp.Predicate).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
pred = new NodeMatchPattern(CreateVirtualNode(id, ((NodeMatchPattern)tp.Predicate).Node));
}
}
else
{
pred = tp.Predicate;
}
if (tp.Object is NodeMatchPattern)
{
TNodeID id = _provider.GetID(((NodeMatchPattern)tp.Object).Node);
if (id == null || id.Equals(nullID))
{
result = new NullOperator(current.Variables);
break;
}
else
{
obj = new NodeMatchPattern(CreateVirtualNode(id, ((NodeMatchPattern)tp.Object).Node));
}
}
else
{
obj = tp.Object;
}
patterns.Add(new TriplePattern(subj, pred, obj));
}
else
{
// Can't optimize if other pattern types involved
return(current);
}
}
if (result is NullOperator)
{
return(result);
}
else if (patterns.Count > 0)
{
// If any patterns left at end join as a BGP with result so far
result = Join.CreateJoin(result, new Bgp(patterns));
return(result);
}
else
{
return(result);
}
}
}
else if (algebra is ITerminalOperator)
{
return(algebra);
}
else
{
return(algebra);
}
}
public ISparqlAlgebra Optimise(ISparqlAlgebra algebra)
{
try
{
if (algebra is Bgp)
{
var bgp = (Bgp)algebra;
if (bgp.TriplePatterns.OfType <FilterPattern>().Count() == 1)
{
var filter = bgp.TriplePatterns.OfType <FilterPattern>().Select(fp => fp.Filter).First();
string var;
INode term;
bool equals;
if (IsIdentityExpression(filter.Expression, out var, out term, out equals))
{
if (equals)
{
var triplePatterns = new List <ITriplePattern>();
foreach (var tp in bgp.TriplePatterns)
{
if (tp is FilterPattern)
{
continue;
}
if (tp is TriplePattern)
{
var triplePattern = (TriplePattern)tp;
if (triplePattern.Variables.Contains(var))
{
PatternItem subjPattern = triplePattern.Subject,
predPattern = triplePattern.Predicate,
objPattern = triplePattern.Object;
if (var.Equals(triplePattern.Subject.VariableName))
{
subjPattern = new NodeMatchPattern(term);
}
if (var.Equals(triplePattern.Predicate.VariableName))
{
predPattern = new NodeMatchPattern(term);
}
if (var.Equals(triplePattern.Object.VariableName))
{
objPattern = new NodeMatchPattern(term);
}
triplePatterns.Add(new TriplePattern(subjPattern, predPattern, objPattern));
}
else
{
triplePatterns.Add(triplePattern);
}
}
else
{
triplePatterns.Add(tp);
}
}
return(new Bgp(triplePatterns));
}
}
}
}
else if (algebra is IAbstractJoin)
{
return(((IAbstractJoin)algebra).Transform(this));
}
else if (algebra is IUnaryOperator)
{
return(((IUnaryOperator)algebra).Transform(this));
}
else
{
return(algebra);
}
}
catch
{
return(algebra);
}
return(algebra);
}
private bool OptimiseBgp(Bgp bgp, out ISparqlAlgebra optimisedAlgebra)
{
if (bgp.TriplePatterns.OfType <FilterPattern>().Count() == 1)
{
var filter = bgp.TriplePatterns.OfType <FilterPattern>().Select(fp => fp.Filter).First();
string var;
INode term;
bool equals;
if (IsIdentityExpression(filter.Expression, out var, out term, out @equals))
{
if (@equals)
{
var triplePatterns = new List <ITriplePattern>();
foreach (var tp in bgp.TriplePatterns)
{
if (tp is FilterPattern)
{
continue;
}
if (tp is TriplePattern)
{
var triplePattern = (TriplePattern)tp;
if (triplePattern.Variables.Contains(var))
{
PatternItem subjPattern = triplePattern.Subject,
predPattern = triplePattern.Predicate,
objPattern = triplePattern.Object;
if (var.Equals(triplePattern.Subject.VariableName))
{
subjPattern = new NodeMatchPattern(term);
}
if (var.Equals(triplePattern.Predicate.VariableName))
{
predPattern = new NodeMatchPattern(term);
}
if (var.Equals(triplePattern.Object.VariableName))
{
objPattern = new NodeMatchPattern(term);
}
triplePatterns.Add(new TriplePattern(subjPattern, predPattern, objPattern));
}
else
{
triplePatterns.Add(triplePattern);
}
}
else
{
triplePatterns.Add(tp);
}
}
{
optimisedAlgebra = new Bgp(triplePatterns);
return(true);
}
}
}
}
optimisedAlgebra = bgp;
return(false);
}
