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zot/pkg/regexp/regexp.go

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package regexp
import "regexp"
//nolint:gochecknoglobals
var (
// alphaNumericRegexp defines the alpha numeric atom, typically a
// component of names. This only allows lower case characters and digits.
alphaNumericRegexp = match(`[a-z0-9]+`)
// separatorRegexp defines the separators allowed to be embedded in name
// components. This allow one period, one or two underscore and multiple
// dashes.
separatorRegexp = match(`(?:[._]|__|[-]*)`)
// 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)))
// 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 = expression(
nameComponentRegexp,
optional(repeated(literal(`/`), nameComponentRegexp)))
// FullNameRegexp is the format which matches the full string of the
// name component of reference.
FullNameRegexp = expression(match("^"), NameRegexp, match("$"))
)
// match compiles the string to a regular expression.
//
//nolint:gochecknoglobals
var match = regexp.MustCompile
// literal compiles s into a literal regular expression, escaping any regexp
// reserved characters.
func literal(s string) *regexp.Regexp {
regx := match(regexp.QuoteMeta(s))
if _, complete := regx.LiteralPrefix(); !complete {
panic("must be a literal")
}
return regx
}
// 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() + `)`)
}