syft/internal/regex_helpers.go

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package internal
import "regexp"
// MatchNamedCaptureGroups takes a regular expression and string and returns all of the named capture group results in a map.
// This is only for the first match in the regex. Callers shouldn't be providing regexes with multiple capture groups with the same name.
func MatchNamedCaptureGroups(regEx *regexp.Regexp, content string) map[string]string {
// note: we are looking across all matches and stopping on the first non-empty match. Why? Take the following example:
// input: "cool something to match against" pattern: `((?P<name>match) (?P<version>against))?`. Since the pattern is
// encapsulated in an optional capture group, there will be results for each character, but the results will match
// on nothing. The only "true" match will be at the end ("match against").
allMatches := regEx.FindAllStringSubmatch(content, -1)
var results map[string]string
for _, match := range allMatches {
// fill a candidate results map with named capture group results, accepting empty values, but not groups with
// no names
for nameIdx, name := range regEx.SubexpNames() {
if nameIdx > len(match) || len(name) == 0 {
continue
}
if results == nil {
results = make(map[string]string)
}
results[name] = match[nameIdx]
}
// note: since we are looking for the first best potential match we should stop when we find the first one
// with non-empty results.
if !isEmptyMap(results) {
break
}
}
return results
}
func isEmptyMap(m map[string]string) bool {
if len(m) == 0 {
return true
}
for _, value := range m {
if value != "" {
return false
}
}
return true
}