terraform: ExpandTransform

This commit is contained in:
Mitchell Hashimoto 2015-02-07 16:02:45 -08:00
parent 4d205ebcf6
commit e5fd7c9e84
2 changed files with 130 additions and 0 deletions

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package terraform
import (
"fmt"
"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) (*Graph, error)
}
// GraphNodeSubgraph is an interface a node can implement if it has
// a larger subgraph that should be walked.
type GraphNodeSubgraph interface {
Subgraph() *Graph
}
// 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!
g, err := ev.Expand(t.Builder)
if err != nil {
return nil, err
}
// Replace with our special node
return &graphNodeExpanded{
Graph: g,
OriginalName: dag.VertexName(v),
}, nil
}
type graphNodeExpanded struct {
Graph *Graph
OriginalName string
}
func (n *graphNodeExpanded) Name() string {
return fmt.Sprintf("%s (expanded)", n.OriginalName)
}
func (n *graphNodeExpanded) Subgraph() *Graph {
return n.Graph
}

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package terraform
import (
"strings"
"testing"
"github.com/hashicorp/terraform/dag"
)
func TestExpandTransform_impl(t *testing.T) {
var _ GraphVertexTransformer = new(ExpandTransform)
}
func TestExpandTransform(t *testing.T) {
var g Graph
g.Add(1)
g.Add(2)
g.Connect(dag.BasicEdge(1, 2))
tf := &ExpandTransform{}
out, err := tf.Transform(&testExpandable{
Result: &g,
})
if err != nil {
t.Fatalf("err: %s", err)
}
sn, ok := out.(GraphNodeSubgraph)
if !ok {
t.Fatalf("not subgraph: %#v", out)
}
actual := strings.TrimSpace(sn.Subgraph().String())
expected := strings.TrimSpace(testExpandTransformStr)
if actual != expected {
t.Fatalf("bad: %s", actual)
}
}
func TestExpandTransform_nonExpandable(t *testing.T) {
tf := &ExpandTransform{}
out, err := tf.Transform(42)
if err != nil {
t.Fatalf("err: %s", err)
}
if out != 42 {
t.Fatalf("bad: %#v", out)
}
}
type testExpandable struct {
// Inputs
Result *Graph
ResultError error
// Outputs
Builder GraphBuilder
}
func (n *testExpandable) Expand(b GraphBuilder) (*Graph, error) {
n.Builder = b
return n.Result, n.ResultError
}
const testExpandTransformStr = `
1
2
2
`