/// <summary>
/// Builds the triples required to access a given member and accociates its value with a variable.
/// </summary>
/// <param name="memberExpression">The member to be accessed.</param>
/// <returns>The object variable associated with the member value.</returns>
protected SparqlVariable BuildMemberAccessOptional(MemberExpression memberExpression)
{
var optionalBuilder = new GraphPatternBuilder(GraphPatternType.Optional);
var so = BuildMemberAccess(memberExpression, optionalBuilder);
Child(optionalBuilder);
return(so);
}
public override void OnBeforeFromClauseVisited(Expression expression)
{
SparqlVariable s = null;
SparqlVariable o = null;
if (expression is MemberExpression)
{
QuerySourceReferenceExpression sourceExpression = expression.TryGetQuerySourceReference();
s = VariableGenerator.TryGetSubjectVariable(sourceExpression) ?? VariableGenerator.TryGetObjectVariable(sourceExpression);
o = VariableGenerator.CreateObjectVariable(expression);
// The from clause is parsed first when handling a query. This allows us to detect if the
// query source is a subquery and proceed with implementing it _before_ hanlding its results.
MemberExpression memberExpression = expression as MemberExpression;
if (s.IsGlobal())
{
Type type = memberExpression.Member.DeclaringType;
if (type.IsSubclassOf(typeof(Resource)))
{
WhereResourceOfType(s, type);
}
}
// If the query model has a numeric result operator, we make all the following
// expressions optional in order to also allow to count zero occurences.
if (QueryModel.HasNumericResultOperator())
{
GraphPatternBuilder optionalBuilder = new GraphPatternBuilder(GraphPatternType.Optional);
Child(optionalBuilder);
PatternBuilder = optionalBuilder;
}
}
else
{
s = VariableGenerator.TryGetSubjectVariable(expression);
o = VariableGenerator.TryGetObjectVariable(expression);
}
if (s != null && o != null)
{
// Set the variable name of the query source reference as subject of the current query.
SetSubjectVariable(s, true);
SetObjectVariable(o, true);
}
}
public IGraphPatternBuilder Child(ISparqlQueryGenerator generator)
{
generator.BindSelectVariables();
var subQuery = generator.QueryBuilder.BuildQuery();
var childBuilder = new GraphPatternBuilder();
childBuilder.Where(new SubQueryPattern(subQuery));
// Note: This sets the enclosing pattern builder as the current pattern
// builder in order to build subsequent FILTERs on the selected variables
// into the enclosing block, rather than the parent query. This is because
// for OpenLink Virtuoso the FILTERs need to be inside the enclosing group
// of the subquery..
generator.PatternBuilder = childBuilder;
return(PatternBuilder.Child(childBuilder));
}
/// <summary>
/// Converts a <see cref="GraphDiffReport">diff</see> to an equivalent <see cref="ModifyCommand">SPARQL Update INSERT/DELETE command</see>.
/// </summary>
/// <param name="diff">The <see cref="GraphDiffReport">diff</see> to convert.</param>
/// <param name="graphUri">Optional <see cref="Uri">URI</see> of the affected graph.</param>
/// <param name="prefixes">Optional <see cref="INamespaceMapper">mapper</see> used to resolve prefixes.</param>
/// <returns>A <see cref="ModifyCommand">SPARQL Update INSERT/DELETE command</see> that represents the <see cref="GraphDiffReport">diff</see>.</returns>
public static ModifyCommand AsUpdate(this GraphDiffReport diff, Uri graphUri = null, INamespaceMapper prefixes = null)
{
var delete = new GraphPatternBuilder();
var insert = new GraphPatternBuilder();
var where = new GraphPatternBuilder();
// Removed ground triples are added as is to both delete and where clauses
foreach (var t in diff.RemovedTriples)
{
delete.AddTriplePattern(t);
where.AddTriplePattern(t);
}
foreach (var g in diff.RemovedMSGs)
{
// Blank nodes in removed non-ground triples are converted to variables and added to both delete and where clauses
foreach (var t in g.Triples)
{
delete.AddVariablePattern(t);
where.AddVariablePattern(t);
}
// An ISBLANK filter is added for each blank node in removed non-ground triples
foreach (var n in g.BlankNodes())
{
where.AddBlankNodeFilter(n);
}
}
// Added triples (ground or not) are added as is to the insert clause
foreach (var t in diff.AllAddedTriples())
{
insert.AddTriplePattern(t);
}
return(new ModifyCommand(
delete.BuildGraphPattern(prefixes),
insert.BuildGraphPattern(prefixes),
where.BuildGraphPattern(prefixes),
graphUri));
}
/// <summary>
/// Converts a <see cref="GraphDiffReport">diff</see> to an equivalent <see cref="ModifyCommand">SPARQL Update query</see>
/// </summary>
/// <param name="diff">The <see cref="GraphDiffReport">diff</see> to convert</param>
/// <returns>A <see cref="ModifyCommand">SPARQL Update query</see> that represents the <see cref="GraphDiffReport">diff</see></returns>
internal static ModifyCommand AsUpdate(this GraphDiffReport diff)
{
var delete = new GraphPatternBuilder();
var insert = new GraphPatternBuilder();
var where = new GraphPatternBuilder();
// Groud removed triples are added as is to both delete and where clauses
foreach (var t in diff.RemovedTriples)
{
delete.AddTriplePattern(t);
where.AddTriplePattern(t);
}
foreach (var g in diff.RemovedMSGs)
{
// Blank nodes in non-ground removed triples are converted to variables and added to both delete and where clauses
foreach (var t in g.Triples)
{
delete.AddVariablePattern(t);
where.AddVariablePattern(t);
}
// An ISBLANK filter is added for each blank node in non-ground removed triples
foreach (var n in g.BlankNodes())
{
where.AddBlankNodeFilter(n);
}
}
// Added triples (ground or not) are added as is to the insert clause
foreach (var t in diff.AllAddedTriples())
{
insert.AddTriplePattern(t);
}
return(new ModifyCommand(
delete.BuildGraphPattern(),
insert.BuildGraphPattern(),
where.BuildGraphPattern()));
}
public IGraphPatternBuilder Child(GraphPatternBuilder patternBuilder)
{
return(PatternBuilder.Child(patternBuilder));
}
public void Union(GraphPatternBuilder firstBuilder, params GraphPatternBuilder[] otherBuilders)
{
PatternBuilder.Union(firstBuilder, otherBuilders);
}
private static GraphPattern BuildGraphPattern(this GraphPatternBuilder builder)
{
var buildGraphPattern = typeof(GraphPatternBuilder).GetMethod(nameof(BuildGraphPattern), BindingFlags.Instance | BindingFlags.NonPublic);
return(buildGraphPattern.Invoke(builder, new[] { null as INamespaceMapper }) as GraphPattern);
}
