1 files changed, 38 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/terraform/terraform/transform_root.go b/vendor/github.com/hashicorp/terraform/terraform/transform_root.go
new file mode 100644
index 00000000..aee053d1
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/terraform/transform_root.go
@@ -0,0 +1,38 @@
+package terraform
+
+import "github.com/hashicorp/terraform/dag"
+
+const rootNodeName = "root"
+
+// RootTransformer is a GraphTransformer that adds a root to the graph.
+type RootTransformer struct{}
+
+func (t *RootTransformer) Transform(g *Graph) 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
+}
+
+type graphNodeRoot struct{}
+
+func (n graphNodeRoot) Name() string {
+	return rootNodeName
+}