When reference.Parse returns a digest only ref?

[liubog2008]

I cannot see the test case in https://github.com/distribution/reference/blob/v0.6.0/reference_test.go#L14

It seems all are Named.

[milosgajdos]

Parse() returns Reference. Reference is an interface type whose underlying type may or may not have a digest based on the regexp match:

reference/reference.go

Lines 217 to 223 in ff14faf

	if matches[3] != "" {
	var err error
	ref.digest, err = digest.Parse(matches[3])
	if err != nil {
	return nil, err
	}
	}

The underlying type returned by Parse is reference

reference/reference.go

Line 356 in ff14faf

type reference struct {

The reference type implements Canonical interface so you will need to do a type assertion on it to check whether it implements Canonical interface which has a Digest method:

reference/reference.go

Line 142 in ff14faf

type Canonical interface {

[liubog2008]

If the ref implements the Canonical, it also implements the Named.

[liubog2008]

reference/reference.go

Lines 330 to 336 in ff14faf

	if ref.Name() == "" {
	// Allow digest only references
	if ref.digest != "" {
	return digestReference(ref.digest)
	}
	return nil
	}

It seems that Parse accepts a digest only ref, but I don't know what it looks like.