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