CPR.jl

# A datatype of storing Danish CPR numbers  and accommpanying function for converversion to/from strings

type CPR
	date::Date
	serialnumber::UInt16
end

Base.string(x::CPR) = string( dec(Integer(Dates.Day(x.date)),2), dec(Integer(Dates.Month(x.date)),2), dec(Integer(Dates.Year(x.date)) % 100), "-", dec(x.serialnumber, 4)) 

ismale(x::CPR) = x.serialnumber % 2 == 1

function convert(::Type{CPR}, x::ASCIIString) 
	matches = match(r"(\d{2})(\d{2})(\d{2})-?(\d{4})", x)
	seventh_digit = parse(UInt8,matches[4][1]) 
	year2 = parse(UInt8,matches[3])
	if seventh_digit <= 3 || (seventh_digit == 4 && year2 > 36) ||  (seventh_digit == 9 && year2 > 36)
		year_str = string("19", matches[3])
	elseif (seventh_digit == 4 && twodigit_year < 37) || (seventh_digit >= 5 && seventh_digit <= 8 && year2 < 37) || (seventh_digit == 9 && year2 < 37)
		year_str = string("20", matches[3])
	elseif (seventh_digit >= 5 && seventh_digit <= 8 && year2 >= 58)
		year_str = string("18", matches[3])
	else
		error("invalid seventh digit!")
	end

	CPR(Date(string(matches[1],matches[2],year_str), "ddmmyyyy"), parse(UInt16, matches[4]))
end