public Move createUndoMove(WorkingMemory workingMemory) {
return new YChangeMove(queen, queen.getY());
}
public void doMove(WorkingMemory workingMemory) {
FactHandle queenHandle = workingMemory.getFactHandle(queen);
workingMemory.modifyRetract(queenHandle); // before changes are made
queen.setY(toY);
workingMemory.modifyInsert(queenHandle, queen); // after changes are made
}
public boolean isMoveDoable(WorkingMemory workingMemory) {
return queen.getY() != toY;
}