/// <summary>
/// Create a new partition
/// </summary>
/// <param name="symCard">The symbol alphabet cardinality</param>
internal Partition(int symCard, TaskState task)
{
this.myTask = task;
CharRange.Init(symCard);
PartitionElement.Reset();
elements.Add(PartitionElement.AllChars());
}
/// <summary>
/// Refine the current partition with respect
/// to the given range literal "lit".
/// </summary>
/// <param name="lit">The Range Literal</param>
internal void Refine(RangeLiteral lit)
{
int idx;
int max = elements.Count; // because this varies inside the loop
//
// For each of the *current* elements of the partition do:
//
for (idx = 0; idx < max; idx++)
{
PartitionElement elem = elements[idx];
RangeList intersection = lit.list.AND(elem.list);
//
// There are four cases here:
// (1) No intersection of lit and elem ... do nothing
// (2) Literal properly contains the partition element ...
// Add this element to the equivClasses list of this lit.
// Add this lit to the list of literals dependent on "elem".
// The intersection of other parts of the literal with other
// elements will be processed by other iterations of the loop.
// (3) Literal is properly contained in the partition element ...
// Split the element into two: a new element containing the
// intersection, and an updated "elem" with the intersection
// subtracted. All literals dependent on the old element are
// now dependent on the new element and (the new version of)
// this element. The literal cannot overlap with any other
// element, so the iteration can be terminated.
// (4) Literal partially overlaps the partition element ...
// Split the element as for case 2. Overlaps of the rest
// of the literal with other elements will be dealt with by
// other iterations of the loop.
//
if (!intersection.IsEmpty) // not empty intersection
{
// Test if elem is properly contained in lit
// If so, intersection == elem ...
if (intersection.EQU(elem.list))
{
elem.literals.Add(lit);
lit.equivClasses.Add(elem.ord);
}
else
{
PartitionElement newElem =
new PartitionElement(intersection.Ranges, false);
elements.Add(newElem);
lit.equivClasses.Add(newElem.ord);
newElem.literals.Add(lit);
//
// We are about to split elem.
// All literals that include elem
// must now also include newElem
//
foreach (RangeLiteral rngLit in elem.literals)
{
rngLit.equivClasses.Add(newElem.ord);
newElem.literals.Add(rngLit);
}
elem.list = elem.list.SUB(intersection);
//
// Test if lit is a subset of elem
// If so, intersection == lit and we can
// assert that no other loop iteration has
// a non-empty intersection with this lit.
//
if (intersection.EQU(lit.list))
{
return;
}
}
}
}
}