// Copyright 2003, Trustees of Indiana University
// Please see the license in the file ../LICENSE

public class dijkstra_visitor<
	      Graph,
	      QueueType extends MutableQueue<Vertex>,
	      WeightMap extends ReadablePropertyMap/*<Edge,Distance>*/,
	      PredecessorMap extends ReadWritePropertyMap/*<Vertex,Vertex>*/,
	      DistanceMap extends ReadWritePropertyMap/*<Vertex,Distance>*/,
	      DistanceCombine extends BinaryFunction/*<Distance>*/,
	      DistanceCompare extends StrictWeakOrdering/*<Distance>*/,
	      Vertex,
	      Edge extends GraphEdge<Vertex>,
	      Distance>
       implements Visitor<Graph, Vertex, Edge> {
  private WeightMap m_weight;
  private DistanceCompare m_compare;
  private DistanceCombine m_combine;
  private Distance m_zero;
  private DistanceMap m_distance;
  private PredecessorMap m_predecessor;
  private QueueType m_Q;

  public dijkstra_visitor(QueueType Q, WeightMap weight, PredecessorMap predecessor, DistanceMap distance, DistanceCombine combine, DistanceCompare compare, Distance zero) {
    m_Q = Q;
    m_weight = weight;
    m_predecessor = predecessor;
    m_distance = distance;
    m_combine = combine;
    m_compare = compare;
    m_zero = zero;
  }

  public void initialize_vertex(Vertex u, Graph g) {}
  public void discover_vertex(Vertex u, Graph g) {}
  public void examine_edge(Edge e, Graph g) {
    if (m_compare.less(m_weight.get(e), m_zero))
      {} // throw new negative_edge(); Requirement to catch all exceptions could make this painful to use
  }
  public void tree_edge(Edge e, Graph g) {
    relax.relax(e, m_weight, m_distance, m_predecessor, m_combine, m_compare);
  }
  public void non_tree_edge(Edge e, Graph g) {}
  public void gray_target(Edge e, Graph g) {
    boolean relaxed = relax.relax(e, m_weight, m_distance, m_predecessor, m_combine, m_compare);
    if (relaxed)
      m_Q.update(e.target());
  }
  public void black_target(Edge e, Graph g) {}
  public void finish_vertex(Vertex u, Graph g) {}
}