searchStep method

@override void searchStep(GridBFSState state)

Implementation

@override
void searchStep(GridBFSState state) {
  // If there is no open node, we are stuck.
  if (state.open.isEmpty) {
    state.status = Status.failure;
    return;
  }

  GridPoint point = state.open.removeFirst();
  point.set(state.grid, GridNode.closed);

  // We can return because the target node is reached.
  if (state.target.get(state.grid) == GridNode.closed) {
    state.status = Status.success;
    return;
  }

  for (var (i, j) in state.dirs) {
    GridPoint newPoint = GridPoint(point.x + i, point.y + j);
    if (state.isUntraversable(newPoint)) continue;
    GridNode newNode = newPoint.get(state.grid);
    if (newNode == GridNode.closed) continue;

    if (newNode != GridNode.open) {
      state.parents[newPoint] = point;
      state.open.add(newPoint);
      newPoint.set(state.grid, GridNode.open);
    }
  }
}