forked from TrueCloudLab/distribution
Merge pull request #1239 from stevvooe/refactor-reference-grammar
reference: refactor grammar and regular expressions
This commit is contained in:
Stephen Day
commit
7a584f21b8
3 changed files with 115 additions and 36 deletions
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@ -4,22 +4,16 @@
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// Grammar
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//
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// reference := repository [ ":" tag ] [ "@" digest ]
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// name := [hostname '/'] component ['/' component]*
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// hostname := hostcomponent ['.' hostcomponent]* [':' port-number]
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// hostcomponent := /([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])/
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// port-number := /[0-9]+/
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// component := alpha-numeric [separator alpha-numeric]*
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// alpha-numeric := /[a-z0-9]+/
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// separator := /[_.]|__|[-]*/
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//
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// // repository.go
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// repository := hostname ['/' component]+
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// hostname := hostcomponent [':' port-number]
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// component := subcomponent [separator subcomponent]*
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// subcomponent := alpha-numeric ['-'* alpha-numeric]*
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// hostcomponent := [hostpart '.']* hostpart
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// alpha-numeric := /[a-z0-9]+/
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// separator := /([_.]|__)/
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// port-number := /[0-9]+/
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// hostpart := /([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])/
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//
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// // tag.go
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// tag := /[\w][\w.-]{0,127}/
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//
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// // from the digest package
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// digest := digest-algorithm ":" digest-hex
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// digest-algorithm := digest-algorithm-component [ digest-algorithm-separator digest-algorithm-component ]
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// digest-algorithm-separator := /[+.-_]/
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@ -3,47 +3,122 @@ package reference
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import "regexp"
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var (
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// nameSubComponentRegexp defines the part of the name which must be
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// begin and end with an alphanumeric character. These characters can
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// be separated by any number of dashes.
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nameSubComponentRegexp = regexp.MustCompile(`[a-z0-9]+(?:[-]+[a-z0-9]+)*`)
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// alphaNumericRegexp defines the alpha numeric atom, typically a
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// component of names. This only allows lower case characters and digits.
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alphaNumericRegexp = match(`[a-z0-9]+`)
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// nameComponentRegexp restricts registry path component names to
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// start with at least one letter or number, with following parts able to
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// be separated by one period, underscore or double underscore.
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nameComponentRegexp = regexp.MustCompile(nameSubComponentRegexp.String() + `(?:(?:[._]|__)` + nameSubComponentRegexp.String() + `)*`)
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// separatorRegexp defines the separators allowed to be embedded in name
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// components. This allow one period, one or two underscore and multiple
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// dashes.
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separatorRegexp = match(`(?:[._]|__|[-]*)`)
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nameRegexp = regexp.MustCompile(`(?:` + nameComponentRegexp.String() + `/)*` + nameComponentRegexp.String())
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// nameComponentRegexp restricts registry path component names to start
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// with at least one letter or number, with following parts able to be
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// separated by one period, one or two underscore and multiple dashes.
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nameComponentRegexp = expression(
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alphaNumericRegexp,
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optional(repeated(separatorRegexp, alphaNumericRegexp)))
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hostnameComponentRegexp = regexp.MustCompile(`(?:[a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])`)
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// hostnameComponentRegexp restricts the registry hostname component of a
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// repository name to start with a component as defined by hostnameRegexp
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// and followed by an optional port.
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hostnameComponentRegexp = match(`(?:[a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])`)
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// hostnameComponentRegexp restricts the registry hostname component of a repository name to
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// start with a component as defined by hostnameRegexp and followed by an optional port.
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hostnameRegexp = regexp.MustCompile(`(?:` + hostnameComponentRegexp.String() + `\.)*` + hostnameComponentRegexp.String() + `(?::[0-9]+)?`)
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// hostnameRegexp defines the structure of potential hostname components
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// that may be part of image names. This is purposely a subset of what is
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// allowed by DNS to ensure backwards compatibility with Docker image
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// names.
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hostnameRegexp = expression(
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hostnameComponentRegexp,
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optional(repeated(literal(`.`), hostnameComponentRegexp)),
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optional(literal(`:`), match(`[0-9]+`)))
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// TagRegexp matches valid tag names. From docker/docker:graph/tags.go.
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TagRegexp = regexp.MustCompile(`[\w][\w.-]{0,127}`)
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TagRegexp = match(`[\w][\w.-]{0,127}`)
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// anchoredTagRegexp matches valid tag names, anchored at the start and
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// end of the matched string.
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anchoredTagRegexp = regexp.MustCompile(`^` + TagRegexp.String() + `$`)
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anchoredTagRegexp = anchored(TagRegexp)
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// DigestRegexp matches valid digests.
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DigestRegexp = regexp.MustCompile(`[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`)
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DigestRegexp = match(`[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`)
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// anchoredDigestRegexp matches valid digests, anchored at the start and
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// end of the matched string.
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anchoredDigestRegexp = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
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anchoredDigestRegexp = anchored(DigestRegexp)
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// NameRegexp is the format for the name component of references. The
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// regexp has capturing groups for the hostname and name part omitting
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// the seperating forward slash from either.
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NameRegexp = regexp.MustCompile(`(?:` + hostnameRegexp.String() + `/)?` + nameRegexp.String())
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NameRegexp = expression(
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optional(hostnameRegexp, literal(`/`)),
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nameComponentRegexp,
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optional(repeated(literal(`/`), nameComponentRegexp)))
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// ReferenceRegexp is the full supported format of a reference. The
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// regexp has capturing groups for name, tag, and digest components.
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ReferenceRegexp = regexp.MustCompile(`^((?:` + hostnameRegexp.String() + `/)?` + nameRegexp.String() + `)(?:[:](` + TagRegexp.String() + `))?(?:[@](` + DigestRegexp.String() + `))?$`)
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// anchoredNameRegexp is used to parse a name value, capturing the
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// hostname and trailing components.
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anchoredNameRegexp = anchored(
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optional(capture(hostnameRegexp), literal(`/`)),
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capture(nameComponentRegexp,
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optional(repeated(literal(`/`), nameComponentRegexp))))
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// anchoredNameRegexp is used to parse a name value, capturing hostname
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anchoredNameRegexp = regexp.MustCompile(`^(?:(` + hostnameRegexp.String() + `)/)?(` + nameRegexp.String() + `)$`)
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// ReferenceRegexp is the full supported format of a reference. The regexp
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// is anchored and has capturing groups for name, tag, and digest
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// components.
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ReferenceRegexp = anchored(capture(NameRegexp),
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optional(literal(":"), capture(TagRegexp)),
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optional(literal("@"), capture(DigestRegexp)))
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)
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// match compiles the string to a regular expression.
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var match = regexp.MustCompile
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// literal compiles s into a literal regular expression, escaping any regexp
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// reserved characters.
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func literal(s string) *regexp.Regexp {
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re := match(regexp.QuoteMeta(s))
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if _, complete := re.LiteralPrefix(); !complete {
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panic("must be a literal")
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}
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return re
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}
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// expression defines a full expression, where each regular expression must
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// follow the previous.
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func expression(res ...*regexp.Regexp) *regexp.Regexp {
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var s string
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for _, re := range res {
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s += re.String()
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}
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return match(s)
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}
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// optional wraps the expression in a non-capturing group and makes the
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// production optional.
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func optional(res ...*regexp.Regexp) *regexp.Regexp {
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return match(group(expression(res...)).String() + `?`)
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}
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// repeated wraps the regexp in a non-capturing group to get one or more
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// matches.
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func repeated(res ...*regexp.Regexp) *regexp.Regexp {
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return match(group(expression(res...)).String() + `+`)
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}
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// group wraps the regexp in a non-capturing group.
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func group(res ...*regexp.Regexp) *regexp.Regexp {
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return match(`(?:` + expression(res...).String() + `)`)
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}
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// capture wraps the expression in a capturing group.
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func capture(res ...*regexp.Regexp) *regexp.Regexp {
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return match(`(` + expression(res...).String() + `)`)
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}
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// anchored anchors the regular expression by adding start and end delimiters.
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func anchored(res ...*regexp.Regexp) *regexp.Regexp {
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return match(`^` + expression(res...).String() + `$`)
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}
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@ -119,6 +119,11 @@ func TestHostRegexp(t *testing.T) {
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}
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func TestFullNameRegexp(t *testing.T) {
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if anchoredNameRegexp.NumSubexp() != 2 {
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t.Fatalf("anchored name regexp should have two submatches: %v, %v != 2",
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anchoredNameRegexp, anchoredNameRegexp.NumSubexp())
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}
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testcases := []regexpMatch{
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{
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input: "",
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@ -401,6 +406,11 @@ func TestFullNameRegexp(t *testing.T) {
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}
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func TestReferenceRegexp(t *testing.T) {
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if ReferenceRegexp.NumSubexp() != 3 {
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t.Fatalf("anchored name regexp should have three submatches: %v, %v != 3",
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ReferenceRegexp, ReferenceRegexp.NumSubexp())
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}
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testcases := []regexpMatch{
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{
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input: "registry.com:8080/myapp:tag",
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