public CellSet followStub(Cell cell, Cell blocked) {
if (!isStub(cell)) return null;
CellSet result = new CellSet();
if (isBoundary(cell.getEast())) result.add(cell.getEast());
else if (isBoundary(cell.getWest())) result.add(cell.getWest());
else if (isBoundary(cell.getNorth())) result.add(cell.getNorth());
else if (isBoundary(cell.getSouth())) result.add(cell.getSouth());
if (result.contains(blocked)) result.remove(blocked);
return result;
}
public CellSet followCrossOnLine(Cell cell, Cell blocked) {
CellSet result = new CellSet();
if (isHorizontalCrossOnLine(cell)) {
result.add(cell.getEast());
result.add(cell.getWest());
} else if (isVerticalCrossOnLine(cell)) {
result.add(cell.getNorth());
result.add(cell.getSouth());
}
if (result.contains(blocked)) result.remove(blocked);
return result;
}
public CellSet followIntersection(Cell cell, Cell blocked) {
if (!isIntersection(cell)) return null;
CellSet result = new CellSet();
Cell cN = cell.getNorth();
Cell cS = cell.getSouth();
Cell cE = cell.getEast();
Cell cW = cell.getWest();
if (hasEntryPoint(cN, 6)) result.add(cN);
if (hasEntryPoint(cS, 2)) result.add(cS);
if (hasEntryPoint(cE, 8)) result.add(cE);
if (hasEntryPoint(cW, 4)) result.add(cW);
if (result.contains(blocked)) result.remove(blocked);
return result;
}
public CellSet followLine(Cell cell, Cell blocked) {
CellSet nextCells = followLine(cell);
if (nextCells.contains(blocked)) nextCells.remove(blocked);
return nextCells;
}