vendor/github.com/hashicorp/terraform/terraform/transform.go

   1 package terraform
   2
   3 import (
   4         "log"
   5
   6         "github.com/hashicorp/terraform/dag"
   7 )
   8
   9 // GraphTransformer is the interface that transformers implement. This
  10 // interface is only for transforms that need entire graph visibility.
  11 type GraphTransformer interface {
  12         Transform(*Graph) error
  13 }
  14
  15 // GraphVertexTransformer is an interface that transforms a single
  16 // Vertex within with graph. This is a specialization of GraphTransformer
  17 // that makes it easy to do vertex replacement.
  18 //
  19 // The GraphTransformer that runs through the GraphVertexTransformers is
  20 // VertexTransformer.
  21 type GraphVertexTransformer interface {
  22         Transform(dag.Vertex) (dag.Vertex, error)
  23 }
  24
  25 // GraphTransformIf is a helper function that conditionally returns a
  26 // GraphTransformer given. This is useful for calling inline a sequence
  27 // of transforms without having to split it up into multiple append() calls.
  28 func GraphTransformIf(f func() bool, then GraphTransformer) GraphTransformer {
  29         if f() {
  30                 return then
  31         }
  32
  33         return nil
  34 }
  35
  36 type graphTransformerMulti struct {
  37         Transforms []GraphTransformer
  38 }
  39
  40 func (t *graphTransformerMulti) Transform(g *Graph) error {
  41         var lastStepStr string
  42         for _, t := range t.Transforms {
  43                 log.Printf("[TRACE] (graphTransformerMulti) Executing graph transform %T", t)
  44                 if err := t.Transform(g); err != nil {
  45                         return err
  46                 }
  47                 if thisStepStr := g.StringWithNodeTypes(); thisStepStr != lastStepStr {
  48                         log.Printf("[TRACE] (graphTransformerMulti) Completed graph transform %T with new graph:\n%s------", t, thisStepStr)
  49                         lastStepStr = thisStepStr
  50                 } else {
  51                         log.Printf("[TRACE] (graphTransformerMulti) Completed graph transform %T (no changes)", t)
  52                 }
  53         }
  54
  55         return nil
  56 }
  57
  58 // GraphTransformMulti combines multiple graph transformers into a single
  59 // GraphTransformer that runs all the individual graph transformers.
  60 func GraphTransformMulti(ts ...GraphTransformer) GraphTransformer {
  61         return &graphTransformerMulti{Transforms: ts}
  62 }