func addRoot()

in astro/graph.go [31:53]


func addRoot(g *dag.AcyclicGraph) error {
	// If we already have a good root, we're done
	if _, err := g.Root(); err == nil {
		return nil
	}

	// Add a root
	var root graphNodeRoot
	g.Add(root)

	// Connect the root to all the edges that need it
	for _, v := range g.Vertices() {
		if v == root {
			continue
		}

		if g.UpEdges(v).Len() == 0 {
			g.Connect(dag.BasicEdge(root, v))
		}
	}

	return nil
}