public static bool IsNationalPrefixPresentIfRequired(PhoneNumber number, PhoneNumberUtil util)
{
// First, check how we deduced the country code. If it was written in international format, then
// the national prefix is not required.
if (number.CountryCodeSource != PhoneNumber.Types.CountryCodeSource.FROM_DEFAULT_COUNTRY)
{
return(true);
}
var phoneNumberRegion =
util.GetRegionCodeForCountryCode(number.CountryCode);
var metadata = util.GetMetadataForRegion(phoneNumberRegion);
if (metadata == null)
{
return(true);
}
// Check if a national prefix should be present when formatting this number.
var nationalNumber = util.GetNationalSignificantNumber(number);
var formatRule =
util.ChooseFormattingPatternForNumber(metadata.NumberFormatList, nationalNumber);
// To do this, we check that a national prefix formatting rule was present and that it wasn't
// just the first-group symbol ($1) with punctuation.
if (formatRule != null && formatRule.NationalPrefixFormattingRule.Length > 0)
{
if (formatRule.NationalPrefixOptionalWhenFormatting)
{
// The national-prefix is optional in these cases, so we don't need to check if it was
// present.
return(true);
}
// Remove the first-group symbol.
var candidateNationalPrefixRule = formatRule.NationalPrefixFormattingRule;
// We assume that the first-group symbol will never be _before_ the national prefix.
candidateNationalPrefixRule =
candidateNationalPrefixRule.Substring(0, candidateNationalPrefixRule.IndexOf("${1}", StringComparison.Ordinal));
candidateNationalPrefixRule =
PhoneNumberUtil.NormalizeDigitsOnly(candidateNationalPrefixRule);
if (candidateNationalPrefixRule.Length == 0)
{
// National Prefix not needed for this number.
return(true);
}
// Normalize the remainder.
var rawInputCopy = PhoneNumberUtil.NormalizeDigitsOnly(number.RawInput);
var rawInput = new StringBuilder(rawInputCopy);
// Check if we found a national prefix and/or carrier code at the start of the raw input, and
// return the result.
return(util.MaybeStripNationalPrefixAndCarrierCode(rawInput, metadata, null));
}
return(true);
}
