func checkCaptureIndex(L *LState, m *pm.MatchData, idx int) {
if idx <= 2 {
return
}
if idx >= m.CaptureLength() {
L.RaiseError("invalid capture index")
}
}
func capturedString(L *LState, m *pm.MatchData, str string, idx int) string {
checkCaptureIndex(L, m, idx)
if idx >= m.CaptureLength() && idx == 2 {
idx = 0
}
if m.IsPosCapture(idx) {
return fmt.Sprint(m.Capture(idx))
} else {
return str[m.Capture(idx):m.Capture(idx+1)]
}
}