/// <summary>
/// Counts the results
/// </summary>
/// <param name="context">Evaluation Context</param>
/// <param name="bindingIDs">Binding IDs over which the Aggregate applies</param>
/// <returns></returns>
public override INode Apply(SparqlEvaluationContext context, IEnumerable <int> bindingIDs)
{
int c;
List <INode> values = new List <INode>();
if (this._varname != null)
{
//Ensure the COUNTed variable is in the Variables of the Results
if (!context.Binder.Variables.Contains(this._varname))
{
throw new RdfQueryException("Cannot use the Variable " + this._expr.ToString() + " in a COUNT Aggregate since the Variable does not occur in a Graph Pattern");
}
//Just Count the number of results where the variable is bound
VariableExpressionTerm varExpr = (VariableExpressionTerm)this._expr;
foreach (int id in bindingIDs)
{
INode temp = varExpr.Value(context, id);
if (temp != null)
{
values.Add(temp);
}
}
c = values.Distinct().Count();
}
else
{
//Count the distinct non-null results
foreach (int id in bindingIDs)
{
try
{
INode temp = this._expr.Value(context, id);
if (temp != null)
{
values.Add(temp);
}
}
catch
{
//Ignore errors
}
}
c = values.Distinct().Count();
}
LiteralNode count = new LiteralNode(null, c.ToString(), new Uri(XmlSpecsHelper.XmlSchemaDataTypeInteger));
return(count);
}
/// <summary>
/// Creates a new MEDIAN Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
/// <param name="distinct">Whether a DISTINCT modifier applies</param>
public MedianAggregate(VariableExpressionTerm expr, bool distinct)
: base(expr, distinct)
{
this._varname = expr.ToString().Substring(1);
}
/// <summary>
/// Creates a new NMIN Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
public NumericMinAggregate(VariableExpressionTerm expr)
: this(expr, false)
{
}
/// <summary>
/// Creates a new MEDIAN Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
public MedianAggregate(VariableExpressionTerm expr)
: this(expr, false)
{
}
/// <summary>
/// Creates a new MODE Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
public ModeAggregate(VariableExpressionTerm expr)
: base(expr, false)
{
}
/// <summary>
/// Creates a new Bound Filter
/// </summary>
/// <param name="varTerm">Variable Expression</param>
public BoundFilter(VariableExpressionTerm varTerm)
: base(varTerm)
{
}
/// <summary>
/// Creates a new AVG Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
public AverageAggregate(VariableExpressionTerm expr)
: this(expr, false)
{
}
/// <summary>
/// Creates a new COUNT(DISTINCT ?x) Aggregate
/// </summary>
/// <param name="expr">Variable Expression</param>
public CountDistinctAggregate(VariableExpressionTerm expr)
: base(expr)
{
this._varname = expr.ToString().Substring(1);
}
/// <summary>
/// Creates a new Bound() function expression
/// </summary>
/// <param name="varExpr">Variable Expression</param>
public BoundFunction(VariableExpressionTerm varExpr)
: base(varExpr) { }
