reference: introduce remoteName variable

This pattern was used in two places, so adding an intermediate variable allows
documenting its purpose. The "remote-name" grammer (which is interchangably
used with "path") also seemed to be missing from the grammar, so adding it.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

reference/normalize.go

@@ -58,14 +58,14 @@ func ParseNormalizedNamed(s string) (Named, error) {
 		return nil, fmt.Errorf("invalid repository name (%s), cannot specify 64-byte hexadecimal strings", s)
 	}
 	domain, remainder := splitDockerDomain(s)
-	var remoteName string
+	var remote string
 	if tagSep := strings.IndexRune(remainder, ':'); tagSep > -1 {
-		remoteName = remainder[:tagSep]
+		remote = remainder[:tagSep]
 	} else {
-		remoteName = remainder
+		remote = remainder
 	}
-	if strings.ToLower(remoteName) != remoteName {
+	if strings.ToLower(remote) != remote {
-		return nil, fmt.Errorf("invalid reference format: repository name (%s) must be lowercase", remoteName)
+		return nil, fmt.Errorf("invalid reference format: repository name (%s) must be lowercase", remote)
 	}
 
 	ref, err := Parse(domain + "/" + remainder)
@@ -120,7 +120,7 @@ func ParseDockerRef(ref string) (Named, error) {
 	return TagNameOnly(named), nil
 }
 
-// splitDockerDomain splits a repository name to domain and remotename string.
+// splitDockerDomain splits a repository name to domain and remote-name.
 // If no valid domain is found, the default domain is used. Repository name
 // needs to be already validated before.
 func splitDockerDomain(name string) (domain, remainder string) {

reference/reference.go

@@ -4,13 +4,14 @@
 // Grammar
 //
 //	reference                       := name [ ":" tag ] [ "@" digest ]
-//	name                            := [domain '/'] path-component ['/' path-component]*
+//	name                            := [domain '/'] remote-name
 //	domain                          := host [':' port-number]
 //	host                            := domain-name | IPv4address | \[ IPv6address \]	; rfc3986 appendix-A
 //	domain-name                     := domain-component ['.' domain-component]*
 //	domain-component                := /([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])/
 //	port-number                     := /[0-9]+/
 //	path-component                  := alpha-numeric [separator alpha-numeric]*
+//	path (or "remote-name")         := path-component ['/' path-component]*
 //	alpha-numeric                   := /[a-z0-9]+/
 //	separator                       := /[_.]|__|[-]*/
 //

reference/regexp.go

@@ -101,7 +101,13 @@ var (
 	// character, with following parts able to be separated by a separator
 	// (one period, one or two underscore and multiple dashes).
 	pathComponent = alphanumeric + anyTimes(separator+alphanumeric)
-	namePat       = optional(domainAndPort+`/`) + pathComponent + anyTimes(`/`+pathComponent)
+
+	// remoteName matches the remote-name of a repository. It consists of one
+	// or more forward slash (/) delimited path-components:
+	//
+	//	pathComponent[[/pathComponent] ...] // e.g., "library/ubuntu"
+	remoteName = pathComponent + anyTimes(`/`+pathComponent)
+	namePat    = optional(domainAndPort+`/`) + remoteName
 
 	// NameRegexp is the format for the name component of references, including
 	// an optional domain and port, but without tag or digest suffix.
@@ -109,7 +115,7 @@ var (
 
 	// anchoredNameRegexp is used to parse a name value, capturing the
 	// domain and trailing components.
-	anchoredNameRegexp = regexp.MustCompile(anchored(optional(capture(domainAndPort), `/`), capture(pathComponent, anyTimes(`/`+pathComponent))))
+	anchoredNameRegexp = regexp.MustCompile(anchored(optional(capture(domainAndPort), `/`), capture(remoteName)))
 
 	referencePat = anchored(capture(namePat), optional(`:`, capture(tag)), optional(`@`, capture(digestPat)))