private void narrowDownPossibleFormats(String leadingDigits) {
int indexOfLeadingDigitsPattern = leadingDigits.length() - MIN_LEADING_DIGITS_LENGTH;
Iterator<NumberFormat> it = possibleFormats.iterator();
while (it.hasNext()) {
NumberFormat format = it.next();
if (format.leadingDigitsPatternSize() > indexOfLeadingDigitsPattern) {
Pattern leadingDigitsPattern =
regexCache.getPatternForRegex(
format.getLeadingDigitsPattern(indexOfLeadingDigitsPattern));
Matcher m = leadingDigitsPattern.matcher(leadingDigits);
if (!m.lookingAt()) {