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

// Relax function from BGL

public class relax {
  public static bool
    go<Vertex,
       Edge,
       WeightMap,
       Distance,
       DistanceMap,
       PredecessorMap,
       Combine,
       Compare>
  (Edge e, WeightMap w, DistanceMap d, PredecessorMap pi, Combine combine, Compare compare)
  where Edge: GraphEdge<Vertex>,
        WeightMap: ReadablePropertyMap<Edge,Distance>,
	DistanceMap: ReadWritePropertyMap<Vertex,Distance>,
	PredecessorMap: ReadWritePropertyMap<Vertex,Vertex>,
	Combine: BinaryFunction<Distance>,
	Compare: StrictWeakOrdering<Distance> {
    Distance dnew = combine.op(((ReadWritePropertyMap<Vertex,Distance>)d)[e.source], ((ReadablePropertyMap<Edge,Distance>)w)[e]);
    if (compare.less(dnew, ((ReadWritePropertyMap<Vertex,Distance>)d)[e.target])) {
      ((ReadWritePropertyMap<Vertex,Distance>)d)[e.target] = dnew;
      ((ReadWritePropertyMap<Vertex,Vertex>)pi)[e.target] = e.source;
      return true;
    }
    return false;
  }
}