ipldutil

type ContextCancelError struct{}

type TraversalBuilder struct {
	Root       ipld.Link
	Selector   ipld.Node
	Visitor    traversal.AdvVisitFn
	LinkSystem ipld.LinkSystem
	Chooser    traversal.LinkTargetNodePrototypeChooser
	Budget     *traversal.Budget
}

type Traverser interface {
	// IsComplete returns the completion state (boolean) and if so, the final
	// error result from IPLD.
	//
	// Note that CurrentRequest will block if the traverser is performing an
	// IPLD load.
	IsComplete() (bool, error)

	// CurrentRequest returns the parameters for the current block load waiting
	// to be fulfilled in order to advance further.
	//
	// Note that CurrentRequest will block if the traverser is performing an
	// IPLD load.
	CurrentRequest() (ipld.Link, ipld.LinkContext)

	// Advance advances the traversal successfully by supplying the given reader
	// as the result of the next IPLD load.
	Advance(reader io.Reader) error

	// Error errors the traversal by returning the given error as the result of
	// the next IPLD load.
	Error(err error)

	// Shutdown cancels the traversal
	Shutdown(ctx context.Context)

	// NBlocksTraversed returns the number of blocks successfully traversed
	NBlocksTraversed() int
}