public RDFAskQueryResult ApplyToFederation(RDFFederation federation)
{
if (federation != null) {
this.PatternGroupResultTables.Clear();
this.PatternResultTables.Clear();
RDFAskQueryResult askResult = new RDFAskQueryResult();
if (this.PatternGroups.Any()) {
//Iterate the pattern groups of the query
var fedPatternResultTables = new Dictionary<RDFPatternGroup, List<DataTable>>();
foreach (RDFPatternGroup patternGroup in this.PatternGroups) {
#region TrueFederations
foreach (RDFStore store in federation) {
//Step 1: Evaluate the patterns of the current pattern group on the current store
RDFQueryEngine.EvaluatePatterns(this, patternGroup, store);
//Step 2: Federate the patterns of the current pattern group on the current store
if (!fedPatternResultTables.ContainsKey(patternGroup)) {
fedPatternResultTables.Add(patternGroup, this.PatternResultTables[patternGroup]);
}
else {
fedPatternResultTables[patternGroup].ForEach(fprt =>
fprt.Merge(this.PatternResultTables[patternGroup].Single(prt => prt.TableName.Equals(fprt.TableName, StringComparison.Ordinal)), true, MissingSchemaAction.Add));
}
}
this.PatternResultTables[patternGroup] = fedPatternResultTables[patternGroup];
#endregion
//Step 3: Get the result table of the current pattern group
RDFQueryEngine.CombinePatterns(this, patternGroup);
//Step 4: Apply the filters of the current pattern group to its result table
RDFQueryEngine.ApplyFilters(this, patternGroup);
}
//Step 5: Get the result table of the query
DataTable queryResultTable = RDFQueryEngine.CombineTables(this.PatternGroupResultTables.Values.ToList(), false);
//Step 6: Transform the result into a boolean response
askResult.AskResult = (queryResultTable.Rows.Count > 0);
}
return askResult;
}
throw new RDFQueryException("Cannot execute ASK query because given \"federation\" parameter is null.");
}
