func chooseFormattingPatternForNumber()

in phonenumbers.go [1806:1836]

• 24 lines of code
• 8 McCabe index (conditional complexity)

func chooseFormattingPatternForNumber(
	availableFormats []*NumberFormat,
	nationalNumber string) *NumberFormat {

	for _, numFormat := range availableFormats {
		leadingDigitsPattern := numFormat.GetLeadingDigitsPattern()
		size := len(leadingDigitsPattern)

		patP := `^(?:` + numFormat.GetPattern() + `)$` // Strictly match
		m := regexFor(patP)

		if size == 0 {
			mat := m.FindString(nationalNumber)
			if m.MatchString(nationalNumber) && len(mat) == len(nationalNumber) {
				return numFormat
			} else {
				continue
			}
		}

		// We always use the last leading_digits_pattern, as it is the
		// most detailed.
		reg := regexFor(leadingDigitsPattern[size-1])

		inds := reg.FindStringIndex(nationalNumber)
		if len(inds) > 0 && inds[0] == 0 && m.MatchString(nationalNumber) { // inds[0] == 0 ensures strict match of leading digits
			return numFormat
		}
	}
	return nil
}