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Merge pull request #1239 from stevvooe/refactor-reference-grammar

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reference: refactor grammar and regular expressions
This commit is contained in:
Stephen Day 2015-12-07 10:31:43 -08:00
commit 7a584f21b8
3 changed files with 115 additions and 36 deletions
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20
reference/reference.go
View file

@ -4,22 +4,16 @@
// Grammar
//
// reference := repository [ ":" tag ] [ "@" digest ]
// name := [hostname '/'] component ['/' component]*
// hostname := hostcomponent ['.' hostcomponent]* [':' port-number]
// hostcomponent := /([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])/
// port-number := /[0-9]+/
// component := alpha-numeric [separator alpha-numeric]*
// alpha-numeric := /[a-z0-9]+/
// separator := /[_.]|__|[-]*/
//
// // repository.go
// repository := hostname ['/' component]+
// hostname := hostcomponent [':' port-number]
// component := subcomponent [separator subcomponent]*
// subcomponent := alpha-numeric ['-'* alpha-numeric]*
// hostcomponent := [hostpart '.']* hostpart
// alpha-numeric := /[a-z0-9]+/
// separator := /([_.]|__)/
// port-number := /[0-9]+/
// hostpart := /([a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])/
//
// // tag.go
// tag := /[\w][\w.-]{0,127}/
//
// // from the digest package
// digest := digest-algorithm ":" digest-hex
// digest-algorithm := digest-algorithm-component [ digest-algorithm-separator digest-algorithm-component ]
// digest-algorithm-separator := /[+.-_]/

121
reference/regexp.go
View file

@ -3,47 +3,122 @@ package reference
import "regexp"
var (
// nameSubComponentRegexp defines the part of the name which must be
// begin and end with an alphanumeric character. These characters can
// be separated by any number of dashes.
nameSubComponentRegexp = regexp.MustCompile(`[a-z0-9]+(?:[-]+[a-z0-9]+)*`)
// alphaNumericRegexp defines the alpha numeric atom, typically a
// component of names. This only allows lower case characters and digits.
alphaNumericRegexp = match(`[a-z0-9]+`)
// nameComponentRegexp restricts registry path component names to
// start with at least one letter or number, with following parts able to
// be separated by one period, underscore or double underscore.
nameComponentRegexp = regexp.MustCompile(nameSubComponentRegexp.String() + `(?:(?:[._]|__)` + nameSubComponentRegexp.String() + `)*`)
// separatorRegexp defines the separators allowed to be embedded in name
// components. This allow one period, one or two underscore and multiple
// dashes.
separatorRegexp = match(`(?:[._]|__|[-]*)`)
nameRegexp = regexp.MustCompile(`(?:` + nameComponentRegexp.String() + `/)*` + nameComponentRegexp.String())
// nameComponentRegexp 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.
nameComponentRegexp = expression(
alphaNumericRegexp,
optional(repeated(separatorRegexp, alphaNumericRegexp)))
hostnameComponentRegexp = regexp.MustCompile(`(?:[a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])`)
// hostnameComponentRegexp restricts the registry hostname component of a
// repository name to start with a component as defined by hostnameRegexp
// and followed by an optional port.
hostnameComponentRegexp = match(`(?:[a-z0-9]|[a-z0-9][a-z0-9-]*[a-z0-9])`)
// hostnameComponentRegexp restricts the registry hostname component of a repository name to
// start with a component as defined by hostnameRegexp and followed by an optional port.
hostnameRegexp = regexp.MustCompile(`(?:` + hostnameComponentRegexp.String() + `\.)*` + hostnameComponentRegexp.String() + `(?::[0-9]+)?`)
// hostnameRegexp defines the structure of potential hostname 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.
hostnameRegexp = expression(
hostnameComponentRegexp,
optional(repeated(literal(`.`), hostnameComponentRegexp)),
optional(literal(`:`), match(`[0-9]+`)))
// TagRegexp matches valid tag names. From docker/docker:graph/tags.go.
TagRegexp = regexp.MustCompile(`[\w][\w.-]{0,127}`)
TagRegexp = match(`[\w][\w.-]{0,127}`)
// anchoredTagRegexp matches valid tag names, anchored at the start and
// end of the matched string.
anchoredTagRegexp = regexp.MustCompile(`^` + TagRegexp.String() + `$`)
anchoredTagRegexp = anchored(TagRegexp)
// DigestRegexp matches valid digests.
DigestRegexp = regexp.MustCompile(`[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`)
DigestRegexp = match(`[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`)
// anchoredDigestRegexp matches valid digests, anchored at the start and
// end of the matched string.
anchoredDigestRegexp = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
anchoredDigestRegexp = anchored(DigestRegexp)
// NameRegexp is the format for the name component of references. The
// regexp has capturing groups for the hostname and name part omitting
// the seperating forward slash from either.
NameRegexp = regexp.MustCompile(`(?:` + hostnameRegexp.String() + `/)?` + nameRegexp.String())
NameRegexp = expression(
optional(hostnameRegexp, literal(`/`)),
nameComponentRegexp,
optional(repeated(literal(`/`), nameComponentRegexp)))
// ReferenceRegexp is the full supported format of a reference. The
// regexp has capturing groups for name, tag, and digest components.
ReferenceRegexp = regexp.MustCompile(`^((?:` + hostnameRegexp.String() + `/)?` + nameRegexp.String() + `)(?:[:](` + TagRegexp.String() + `))?(?:[@](` + DigestRegexp.String() + `))?$`)
// anchoredNameRegexp is used to parse a name value, capturing the
// hostname and trailing components.
anchoredNameRegexp = anchored(
optional(capture(hostnameRegexp), literal(`/`)),
capture(nameComponentRegexp,
optional(repeated(literal(`/`), nameComponentRegexp))))
// anchoredNameRegexp is used to parse a name value, capturing hostname
anchoredNameRegexp = regexp.MustCompile(`^(?:(` + hostnameRegexp.String() + `)/)?(` + nameRegexp.String() + `)$`)
// ReferenceRegexp is the full supported format of a reference. The regexp
// is anchored and has capturing groups for name, tag, and digest
// components.
ReferenceRegexp = anchored(capture(NameRegexp),
optional(literal(":"), capture(TagRegexp)),
optional(literal("@"), capture(DigestRegexp)))
)
// match compiles the string to a regular expression.
var match = regexp.MustCompile
// literal compiles s into a literal regular expression, escaping any regexp
// reserved characters.
func literal(s string) *regexp.Regexp {
re := match(regexp.QuoteMeta(s))
if _, complete := re.LiteralPrefix(); !complete {
panic("must be a literal")
}
return re
}
// expression defines a full expression, where each regular expression must
// follow the previous.
func expression(res ...*regexp.Regexp) *regexp.Regexp {
var s string
for _, re := range res {
s += re.String()
}
return match(s)
}
// optional wraps the expression in a non-capturing group and makes the
// production optional.
func optional(res ...*regexp.Regexp) *regexp.Regexp {
return match(group(expression(res...)).String() + `?`)
}
// repeated wraps the regexp in a non-capturing group to get one or more
// matches.
func repeated(res ...*regexp.Regexp) *regexp.Regexp {
return match(group(expression(res...)).String() + `+`)
}
// group wraps the regexp in a non-capturing group.
func group(res ...*regexp.Regexp) *regexp.Regexp {
return match(`(?:` + expression(res...).String() + `)`)
}
// capture wraps the expression in a capturing group.
func capture(res ...*regexp.Regexp) *regexp.Regexp {
return match(`(` + expression(res...).String() + `)`)
}
// anchored anchors the regular expression by adding start and end delimiters.
func anchored(res ...*regexp.Regexp) *regexp.Regexp {
return match(`^` + expression(res...).String() + `$`)
}

10
reference/regexp_test.go
View file

@ -119,6 +119,11 @@ func TestHostRegexp(t *testing.T) {
}
func TestFullNameRegexp(t *testing.T) {
if anchoredNameRegexp.NumSubexp() != 2 {
t.Fatalf("anchored name regexp should have two submatches: %v, %v != 2",
anchoredNameRegexp, anchoredNameRegexp.NumSubexp())
}
testcases := []regexpMatch{
{
input: "",
@ -401,6 +406,11 @@ func TestFullNameRegexp(t *testing.T) {
}
func TestReferenceRegexp(t *testing.T) {
if ReferenceRegexp.NumSubexp() != 3 {
t.Fatalf("anchored name regexp should have three submatches: %v, %v != 3",
ReferenceRegexp, ReferenceRegexp.NumSubexp())
}
testcases := []regexpMatch{
{
input: "registry.com:8080/myapp:tag",