Does FindIndex call pcre_exec twice?

[govcert-ch]

I have a question about FindIndex()(though I'm not sure if this project is still supported)... am I wrong, or does it call pcre_exec twice, first time via Matcher() - Reset() - Match() and then again via Match? I tried using the following replacement (Matchesinstead of Match), which seems to work, but I'm not sure if I miss something:

func (re *Regexp) FindIndex2(bytes []byte, flags int) []int {
	m := re.Matcher(bytes, flags)
	if m.Matches() {
		return []int{int(m.ovector[0]), int(m.ovector[1])}
	}
	return nil
}

However, I need the offset of all groups, not only the first one, plus additional information. Plus, I don't like changing other code, so I also tried this in my own code, which seems to work as well (but again, do I miss something?):

m := patt.Matcher(payload, 0)
if m.Matches() {
	grp := m.Group(0)
	off := len(payload) - cap(grp)

of curse this relies on the returned slice being part of the full subject array, which again is not perfect - but there is no official access to the offsets from outside the package.