terraform/terraform/graph_walk.go

31 lines
1.1 KiB
Go

package terraform
import (
"github.com/hashicorp/terraform/dag"
)
// GraphWalker is an interface that can be implemented that when used
// with Graph.Walk will invoke the given callbacks under certain events.
type GraphWalker interface {
EnterGraph(*Graph) EvalContext
ExitGraph(*Graph)
EnterVertex(dag.Vertex)
ExitVertex(dag.Vertex, error)
EnterEvalTree(dag.Vertex, EvalNode) EvalNode
ExitEvalTree(dag.Vertex, interface{}, error) error
}
// NullGraphWalker is a GraphWalker implementation that does nothing.
// This can be embedded within other GraphWalker implementations for easily
// implementing all the required functions.
type NullGraphWalker struct{}
func (NullGraphWalker) EnterGraph(*Graph) EvalContext { return nil }
func (NullGraphWalker) ExitGraph(*Graph) {}
func (NullGraphWalker) EnterVertex(dag.Vertex) {}
func (NullGraphWalker) ExitVertex(dag.Vertex, error) {}
func (NullGraphWalker) EnterEvalTree(v dag.Vertex, n EvalNode) EvalNode { return n }
func (NullGraphWalker) ExitEvalTree(dag.Vertex, interface{}, error) error {
return nil
}