/**
* Merges pairs of rows by making them identical and marking them as equivalent. For each merged
* pair, also merges each pair of not yet merged images by the same generator, and so on
* recursively, until no more pairs need to be merged.
*
* @param Q a list of row pairs to merge.
* @param P the row equivalence classes (modified by this method).
* @return the number of individual merges performed.
*/
private int performIdentifications(final LinkedList Q, final IntPartition P) {
int count = 0;
while (Q.size() > 0) {
final IntPair pair = (IntPair) Q.removeFirst();
final int a = P.find(pair.getFirst());
final int b = P.find(pair.getSecond());
if (a == b) {
continue;
}
P.unite(a, b);
++count;
final int row_a[] = (int[]) this.table.get(a);
final int row_b[] = (int[]) this.table.get(b);
for (int g = 0; g < this.ngens; ++g) {
final int ag = row_a[g];
final int bg = row_b[g];
if (ag == 0) {
row_a[g] = bg;
} else if (bg == 0) {
row_b[g] = ag;
} else if (!P.areEquivalent(ag, bg)) {
Q.addLast(new IntPair(ag, bg));
}
}
this.table.set(b, row_a);
}
return count;
}
