Confusing Reader.FindSubMatch

[IsSkyfalls]

Trying to match "" in "!!!!!".
Regex: !\[(.*?)]\((.+?)\)

Cursor is on 0th byte. block.FindSubMatch will advance 11 characters (length of match, line 558), which will place the cursor here: "!!!!!![abc] | (123)". The return value of block.FindSubMatchwill still be the expected {"","abc","123"}.

The current implementation is very confusing to me without reading any code. Would it be better if it matches only from the cursor, instead of anywhere in the line? Prepending ^ in the regex would do the trick, so maybe documenting this feature better?

goldmark/text/reader.go

Lines 539 to 561 in 829d874

	func findSubMatchReader(r Reader, reg *regexp.Regexp) [][]byte {
	oldline, oldseg := r.Position()
	match := reg.FindReaderSubmatchIndex(r)
	r.SetPosition(oldline, oldseg)
	if match == nil {
	return nil
	}
	runes := make([]rune, 0, match[1]-match[0])
	for i := 0; i < match[1]; {
	r, size, _ := readRuneReader(r)
	i += size
	runes = append(runes, r)
	}
	result := [][]byte{}
	for i := 0; i < len(match); i += 2 {
	result = append(result, []byte(string(runes[match[i]:match[i+1]])))
	}
	r.SetPosition(oldline, oldseg)
	r.Advance(match[1] - match[0])
	return result
	}