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

   1 package terraform
   2
   3 import (
   4         "github.com/hashicorp/terraform/addrs"
   5         "github.com/hashicorp/terraform/dag"
   6         "github.com/hashicorp/terraform/tfdiags"
   7 )
   8
   9 // GraphWalker is an interface that can be implemented that when used
  10 // with Graph.Walk will invoke the given callbacks under certain events.
  11 type GraphWalker interface {
  12         EnterPath(addrs.ModuleInstance) EvalContext
  13         ExitPath(addrs.ModuleInstance)
  14         EnterVertex(dag.Vertex)
  15         ExitVertex(dag.Vertex, tfdiags.Diagnostics)
  16         EnterEvalTree(dag.Vertex, EvalNode) EvalNode
  17         ExitEvalTree(dag.Vertex, interface{}, error) tfdiags.Diagnostics
  18 }
  19
  20 // NullGraphWalker is a GraphWalker implementation that does nothing.
  21 // This can be embedded within other GraphWalker implementations for easily
  22 // implementing all the required functions.
  23 type NullGraphWalker struct{}
  24
  25 func (NullGraphWalker) EnterPath(addrs.ModuleInstance) EvalContext      { return new(MockEvalContext) }
  26 func (NullGraphWalker) ExitPath(addrs.ModuleInstance)                   {}
  27 func (NullGraphWalker) EnterVertex(dag.Vertex)                          {}
  28 func (NullGraphWalker) ExitVertex(dag.Vertex, tfdiags.Diagnostics)      {}
  29 func (NullGraphWalker) EnterEvalTree(v dag.Vertex, n EvalNode) EvalNode { return n }
  30 func (NullGraphWalker) ExitEvalTree(dag.Vertex, interface{}, error) tfdiags.Diagnostics {
  31         return nil
  32 }