distribution/reference/regexp.go

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package reference
import "regexp"
var (
// alphaNumeric defines the alpha numeric atom, typically a
// component of names. This only allows lower case characters and digits.
alphaNumeric = `[a-z0-9]+`
// separator defines the separators allowed to be embedded in name
// components. This allow one period, one or two underscore and multiple
// dashes. Repeated dashes and underscores are intentionally treated
// differently. In order to support valid hostnames as name components,
// supporting repeated dash was added. Additionally double underscore is
// now allowed as a separator to loosen the restriction for previously
// supported names.
separator = `(?:[._]|__|[-]*)`
// nameComponent restricts registry path component names to start
// with at least one letter or number, with following parts able to be
// separated by one period, one or two underscore and multiple dashes.
nameComponent = expression(
alphaNumeric,
optional(repeated(separator, alphaNumeric)))
// domainComponent restricts the registry domain component of a
// repository name to start with a component as defined by DomainRegexp
// and followed by an optional port.
domainComponent = `(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])`
domain = expression(
domainComponent,
optional(repeated(literal(`.`), domainComponent)),
optional(literal(`:`), `[0-9]+`))
// DomainRegexp defines the structure of potential domain components
// that may be part of image names. This is purposely a subset of what is
// allowed by DNS to ensure backwards compatibility with Docker image
// names.
DomainRegexp = regexp.MustCompile(domain)
tag = `[\w][\w.-]{0,127}`
// TagRegexp matches valid tag names. From docker/docker:graph/tags.go.
TagRegexp = regexp.MustCompile(tag)
anchoredTag = anchored(tag)
// anchoredTagRegexp matches valid tag names, anchored at the start and
// end of the matched string.
anchoredTagRegexp = regexp.MustCompile(anchoredTag)
digestPat = `[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`
// DigestRegexp matches valid digests.
DigestRegexp = regexp.MustCompile(digestPat)
anchoredDigest = anchored(digestPat)
// anchoredDigestRegexp matches valid digests, anchored at the start and
// end of the matched string.
anchoredDigestRegexp = regexp.MustCompile(anchoredDigest)
namePat = expression(
optional(domain, literal(`/`)),
nameComponent,
optional(repeated(literal(`/`), nameComponent)))
// NameRegexp is the format for the name component of references. The
// regexp has capturing groups for the domain and name part omitting
// the separating forward slash from either.
NameRegexp = regexp.MustCompile(namePat)
anchoredName = anchored(
optional(capture(domain), literal(`/`)),
capture(nameComponent,
optional(repeated(literal(`/`), nameComponent))))
// anchoredNameRegexp is used to parse a name value, capturing the
// domain and trailing components.
anchoredNameRegexp = regexp.MustCompile(anchoredName)
referencePat = anchored(capture(namePat),
optional(literal(":"), capture(tag)),
optional(literal("@"), capture(digestPat)))
// ReferenceRegexp is the full supported format of a reference. The regexp
// is anchored and has capturing groups for name, tag, and digest
// components.
ReferenceRegexp = regexp.MustCompile(referencePat)
identifier = `([a-f0-9]{64})`
// IdentifierRegexp is the format for string identifier used as a
// content addressable identifier using sha256. These identifiers
// are like digests without the algorithm, since sha256 is used.
IdentifierRegexp = regexp.MustCompile(identifier)
shortIdentifier = `([a-f0-9]{6,64})`
// ShortIdentifierRegexp is the format used to represent a prefix
// of an identifier. A prefix may be used to match a sha256 identifier
// within a list of trusted identifiers.
ShortIdentifierRegexp = regexp.MustCompile(shortIdentifier)
anchoredIdentifier = anchored(identifier)
// anchoredIdentifierRegexp is used to check or match an
// identifier value, anchored at start and end of string.
anchoredIdentifierRegexp = regexp.MustCompile(anchoredIdentifier)
anchoredShortIdentifier = anchored(shortIdentifier)
// anchoredShortIdentifierRegexp is used to check if a value
// is a possible identifier prefix, anchored at start and end
// of string.
anchoredShortIdentifierRegexp = regexp.MustCompile(anchoredShortIdentifier)
)
// literal compiles s into a literal regular expression, escaping any regexp
// reserved characters.
func literal(s string) string {
re := regexp.MustCompile(regexp.QuoteMeta(s))
if _, complete := re.LiteralPrefix(); !complete {
panic("must be a literal")
}
return re.String()
}
// expression defines a full expression, where each regular expression must
// follow the previous.
func expression(res ...string) string {
var s string
for _, re := range res {
s += re
}
return s
}
// optional wraps the expression in a non-capturing group and makes the
// production optional.
func optional(res ...string) string {
return group(expression(res...)) + `?`
}
// repeated wraps the regexp in a non-capturing group to get one or more
// matches.
func repeated(res ...string) string {
return group(expression(res...)) + `+`
}
// group wraps the regexp in a non-capturing group.
func group(res ...string) string {
return `(?:` + expression(res...) + `)`
}
// capture wraps the expression in a capturing group.
func capture(res ...string) string {
return `(` + expression(res...) + `)`
}
// anchored anchors the regular expression by adding start and end delimiters.
func anchored(res ...string) string {
return `^` + expression(res...) + `$`
}