//^ [NotDelayed]
public TransposedGraph(IGraph <Node, OldEdgeInfo> /*!*/ orig, Converter <OldEdgeInfo, EdgeInfo> /*!*/ edgeinfomap)
{
Contract.Requires(orig != null); // Clousot Suggestion
Contract.Requires(edgeinfomap != null); // Clousot Suggestion
this.orig = orig;
this.edgeinfomap = edgeinfomap;
//^ base();
DepthFirst.Visitor <Node, OldEdgeInfo> v = new DepthFirst.Visitor <Node, OldEdgeInfo>(orig, this);
// Visit all edges to compute the transpose
v.VisitAll();
// debug
#if false
foreach (Node n in this.orig.Nodes)
{
DepthFirst.Info info = v.DepthFirstInfo(n);
Console.WriteLine("Depthfirst info: {0}: Start:{1}, Finish:{2}", n, info.StartTime, info.FinishTime);
}
#endif
}
public static List <List <Node> /*!*/> /*!*/ Compute <Node, EdgeInfo>(IGraph <Node, EdgeInfo> /*!*/ graph)
{
Contract.Requires(graph != null);// Clousot Suggestion
// Step 1: Call DFS(G) to compute finishing times f[u] for each vertex u
//
DepthFirst.Visitor <Node, EdgeInfo> /*!*/ dfs =
new DepthFirst.Visitor <Node, EdgeInfo>(graph);
dfs.VisitAll();
List <Node> nodesSortedByDecreasingFinishingTime =
new List <Node>(graph.Nodes);
// Sort in decreasing order of finish time
nodesSortedByDecreasingFinishingTime.Sort(
delegate(Node lhs, Node rhs)
{
return(dfs.DepthFirstInfo(rhs).FinishTime -
dfs.DepthFirstInfo(lhs).FinishTime);
}
);
// Step 2: Compute G^T
//
IGraph <Node, EdgeInfo> transposed = Transpose.Build <Node, EdgeInfo>(graph);
// Step 3: Call DFS(G^T), but in the main loop of DFS, consider the vertices
// in order of decreasing f[u] (as computed in Step 1)
//
bool startNewGroup = true;
List <List <Node> /*!*/> /*!*/ groups = new List <List <Node> /*!*/>();
DepthFirst.Visitor <Node, EdgeInfo> transposedDFS = new DepthFirst.Visitor <Node, EdgeInfo>(transposed,
delegate(Node n)
{
List <Node> group;
if (startNewGroup)
{
startNewGroup = false;
group = new List <Node>();
groups.Add(group);
}
else
{
group = groups[groups.Count - 1];
}
group.Add(n);
return(true);
});
foreach (Node n in nodesSortedByDecreasingFinishingTime)
{
// debug
#if false
Console.WriteLine("Node {0}, finish time {1}", n, dfs.DepthFirstInfo(n).FinishTime);
#endif
transposedDFS.VisitSubGraph(n);
startNewGroup = true;
}
return(groups);
}
