question: private boolean attemptToExtractIdd ( ) { Pattern internationalPrefix = regexCache . getPatternForRegex ( "\\" + PhoneNumberUtil . PLUS_SIGN + "|" + currentMetadata . getInternationalPrefix ( ) ) ; Matcher iddMatcher = internationalPrefix . matcher ( accruedInputWithoutFormatting ) ; if ( iddMatcher . lookingAt ( ) ) { isCompleteNumber = true ; int startOfCountryCallingCode = iddMatcher . end ( ) ; nationalNumber . setLength ( 0 ) ; nationalNumber . append ( accruedInputWithoutFormatting . substring ( startOfCountryCallingCode ) ) ; prefixBeforeNationalNumber . setLength ( 0 ) ; prefixBeforeNationalNumber . append ( accruedInputWithoutFormatting . substring ( 0 , startOfCountryCallingCode ) ) ; if ( accruedInputWithoutFormatting . charAt ( 0 ) != PhoneNumberUtil . PLUS_SIGN ) { prefixBeforeNationalNumber . append ( SEPARATOR_BEFORE_NATIONAL_NUMBER ) ; } return true ; } return false ; }
target:  Extracts IDD and plus sign to prefixBeforeNationalNumber when they are available, and places the remaining input into nationalNumber.