108 lines
2.8 KiB
Go
108 lines
2.8 KiB
Go
package terraform
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import (
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"fmt"
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"github.com/hashicorp/terraform/dag"
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)
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// GraphNodeFlatGraph must be implemented by nodes that have subgraphs
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// that they want flattened into the graph.
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type GraphNodeFlatGraph interface {
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FlattenGraph() *Graph
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}
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// GraphNodeFlattenable must be implemented by all nodes that can be
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// flattened. If a FlattenGraph returns any nodes that can't be flattened,
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// it will be an error.
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//
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// If Flatten returns nil for the Vertex along with a nil error, it will
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// removed from the graph.
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type GraphNodeFlattenable interface {
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Flatten(path []string) (dag.Vertex, error)
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}
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// FlattenTransformer is a transformer that goes through the graph, finds
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// subgraphs that can be flattened, and flattens them into this graph,
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// removing the prior subgraph node.
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type FlattenTransformer struct{}
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func (t *FlattenTransformer) Transform(g *Graph) error {
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for _, v := range g.Vertices() {
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fn, ok := v.(GraphNodeFlatGraph)
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if !ok {
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continue
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}
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// If we don't want to be flattened, don't do it
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subgraph := fn.FlattenGraph()
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if subgraph == nil {
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continue
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}
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// Get all the things that depend on this node. We'll re-connect
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// dependents later. We have to copy these here since the UpEdges
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// value will be deleted after the Remove below.
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dependents := make([]dag.Vertex, 0, 5)
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for _, v := range g.UpEdges(v).List() {
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dependents = append(dependents, v)
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}
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// Remove the old node
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g.Remove(v)
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// Go through the subgraph and flatten all the nodes
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for _, sv := range subgraph.Vertices() {
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// If the vertex already has a subpath then we assume it has
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// already been flattened. Ignore it.
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if _, ok := sv.(GraphNodeSubPath); ok {
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continue
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}
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fn, ok := sv.(GraphNodeFlattenable)
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if !ok {
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return fmt.Errorf(
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"unflattenable node: %s %T",
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dag.VertexName(sv), sv)
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}
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v, err := fn.Flatten(subgraph.Path)
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if err != nil {
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return fmt.Errorf(
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"error flattening %s (%T): %s",
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dag.VertexName(sv), sv, err)
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}
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if v == nil {
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subgraph.Remove(v)
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} else {
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subgraph.Replace(sv, v)
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}
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}
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// Now that we've handled any changes to the graph that are
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// needed, we can add them all to our graph along with their edges.
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for _, sv := range subgraph.Vertices() {
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g.Add(sv)
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}
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for _, se := range subgraph.Edges() {
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g.Connect(se)
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}
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// Connect the dependencies for all the new nodes that we added.
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// This will properly connect variables to their sources, for example.
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for _, sv := range subgraph.Vertices() {
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g.ConnectDependent(sv)
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}
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// Re-connect all the things that dependend on the graph
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// we just flattened. This should connect them back into the
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// correct nodes if their DependentOn() is setup correctly.
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for _, v := range dependents {
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g.ConnectDependent(v)
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}
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}
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return nil
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}
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