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

// Relax function from BGL

public class relax {
  public static
    <Vertex,
     Edge extends GraphEdge<Vertex>,
     WeightMap extends ReadablePropertyMap, //<Edge,Distance>,
     Distance,
     DistanceMap extends ReadWritePropertyMap, //<Vertex,Distance>,
     PredecessorMap extends ReadWritePropertyMap, //<Vertex,Vertex>,
     Combine extends BinaryFunction, //<Distance>,
     Compare extends StrictWeakOrdering> //<Distance>>
  boolean relax(Edge e, WeightMap w, DistanceMap d, PredecessorMap pi, Combine combine, Compare compare) {
    Distance dnew = (Distance)combine.op((Distance)d.get(e.source()), (Distance)w.get(e));
    if (compare.less(dnew, d.get(e.target()))) {
      d.set(e.target(), dnew);
      pi.set(e.target(), e.source());
      return true;
    }
    return false;
  }
}