1 files changed, 48 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/terraform/terraform/transform_expand.go b/vendor/github.com/hashicorp/terraform/terraform/transform_expand.go
new file mode 100644
index 00000000..982c098b
--- /dev/null
+++ b/vendor/github.com/hashicorp/terraform/terraform/transform_expand.go
@@ -0,0 +1,48 @@
+package terraform
+
+import (
+	"log"
+
+	"github.com/hashicorp/terraform/dag"
+)
+
+// GraphNodeExapndable is an interface that nodes can implement to
+// signal that they can be expanded. Expanded nodes turn into
+// GraphNodeSubgraph nodes within the graph.
+type GraphNodeExpandable interface {
+	Expand(GraphBuilder) (GraphNodeSubgraph, error)
+}
+
+// GraphNodeDynamicExpandable is an interface that nodes can implement
+// to signal that they can be expanded at eval-time (hence dynamic).
+// These nodes are given the eval context and are expected to return
+// a new subgraph.
+type GraphNodeDynamicExpandable interface {
+	DynamicExpand(EvalContext) (*Graph, error)
+}
+
+// GraphNodeSubgraph is an interface a node can implement if it has
+// a larger subgraph that should be walked.
+type GraphNodeSubgraph interface {
+	Subgraph() dag.Grapher
+}
+
+// ExpandTransform is a transformer that does a subgraph expansion
+// at graph transform time (vs. at eval time). The benefit of earlier
+// subgraph expansion is that errors with the graph build can be detected
+// at an earlier stage.
+type ExpandTransform struct {
+	Builder GraphBuilder
+}
+
+func (t *ExpandTransform) Transform(v dag.Vertex) (dag.Vertex, error) {
+	ev, ok := v.(GraphNodeExpandable)
+	if !ok {
+		// This isn't an expandable vertex, so just ignore it.
+		return v, nil
+	}
+
+	// Expand the subgraph!
+	log.Printf("[DEBUG] vertex %q: static expanding", dag.VertexName(ev))
+	return ev.Expand(t.Builder)
+}