public void Add(Fact fact, Atom matchingAtom)
{
if (!factTable.ContainsKey(fact.GetLongHashCode())) factTable.Add(fact.GetLongHashCode(), fact);
Fact resolved = Fact.Resolve(false, fact, matchingAtom);
for (int i=0; i<resolved.Members.Length; i++) {
object predicateValue = resolved.GetPredicateValue(i);
AddFactForPredicateValue(fact, i, predicateValue);
// if we are not strictly enforcing typing and if the predicate value is not a string, then also store it as a string
if ((!StrictTyping) && (!(predicateValue is string))) AddFactForPredicateValue(fact, i, predicateValue.ToString());
}
}
public void Remove(Fact fact)
{
factTable.Remove(fact.GetLongHashCode());
// if facttable is empty, then we re-initialize the predicate storage
if (factTable.Count == 0) InitializePredicateStorage();
}
private void AddFactForPredicateValue(Fact fact, int position, object predicateValue)
{
ArrayList matchingHashCodes = (ArrayList)predicateTables[position].Get(predicateValue);
if (matchingHashCodes == null) {
matchingHashCodes = new ArrayList();
predicateTables[position].Add(predicateValue, matchingHashCodes);
}
// we do not check for duplicates before adding as post processing filters duplicates anyway
matchingHashCodes.Add(fact.GetLongHashCode());
}
/// <summary>
/// Retracts (removes) a Fact from the FactBase.
/// </summary>
/// <param name="fact">The Fact to remove.</param>
/// <returns>True if the Fact has been retracted from the FactBase, otherwise False.</returns>
public bool Retract(Fact fact)
{
if (Exists(fact)) {
factList.Remove(fact.GetLongHashCode());
GetMatchingFactStorageTable(fact).Remove(fact);
// the fact existing and removed from the factbase, return true
if (!ModifiedFlag) ModifiedFlag = true;
return true;
}
return false;
}
/// <summary>
/// Checks if the FactBase contains a certain Fact.
/// </summary>
/// <param name="fact">The Fact to check.</param>
/// <returns>True if the Fact is already present in the FactBase, otherwise False.</returns>
public bool Exists(Fact fact)
{
return factList.ContainsKey(fact.GetLongHashCode());
}
///<remarks>As Facts labels are basically ignored (no retrieval nor any operation based
/// on it, the FactBase does not bother check if we have different facts with same labels.</remarks>
public bool Assert(Fact fact)
{
if (!fact.IsFact)
throw new BREException("Can not add non-facts to the fact base: "+fact.ToString());
if (!Exists(fact)) {
factList.Add(fact.GetLongHashCode(), fact);
// check if the new fact matches any of the registered atoms
// and if yes, then reference this fact in the list of matching ones
foreach(Atom atom in atomList.Values)
if (atom.Matches(fact))
GetMatchingFactStorageTable(atom).Add(fact, atom);
// the fact was new and added to the factbase, return true
if (!ModifiedFlag) ModifiedFlag = true;
return true;
}
else
// else return false
return false;
}
private void RemoveFactFromDataTable(Fact fact) {
DataTable table = GetDataTable(fact);
foreach(DataRow row in table.Select("hashcode='" + fact.GetLongHashCode().ToString() + "'"))
table.Rows.Remove(row);
}
private DataRow BuildDataRow(DataTable table, Fact fact, Atom atom) {
DataRow row = table.NewRow();
row["hashcode"] = fact.GetLongHashCode().ToString();
row["fact"] = fact;
if (atom != null) {
int i=0;
foreach(object predicateValue in Fact.Resolve(fact, atom).PredicateValues) {
row["predicate" + i] = (predicateValue is String)?predicateValue:predicateValue.GetHashCode().ToString();
i++;
}
}
return row;
}
