LicenseplateValidator 1.0.0

LicenseplateValidator

Fun little brain teaser turned into a small library

Main methods:

var lpv = new LicensePlateValidator(); // By default only knows about dutch license plate formats ("sidecodes")

lpv.IsValidPlate("AB-12-CD", "NL");  // Returns true
lpv.FormatPlate("AB12CD", "NL");     // Returns "AB-12-CD"
lpv.FindSideCode("AB12CD", "NL");    // Returns "XX-99-XX"

Most methods have a ignoreDashes argument; when true, dashes in the input are ignored. When false, dashes should be in the correct place.

target.IsValidPlate("AB12CD", "NL", ignoreDashes: false);    // Returns false
target.IsValidPlate("AB-12-CD", "NL", ignoreDashes: false);  // Returns true

target.IsValidPlate("AB12CD", "NL", ignoreDashes: true);     // Returns true
target.IsValidPlate("AB-12-CD", "NL", ignoreDashes: true);   // Returns true

Most methods will throw on errors; there are Try... methods that will not throw on common errors (unless documented).

Other countries / sidecodes:

The LicensePlateValidator supports other countries. All you need to do is pass in the allowed sidecodes. These are codes like XX-99-XX which describe where digits (9), letters (X), digit or letter (?) and dashes (-) should go in a plate. You can specify these, along with the country codes, in the constructor:

var lpv = new LicenseplateValidator(new Dictionary<string, string[]>(StringComparer.OrdinalIgnoreCase)
{
    { "XX", new[] { "XX-99-XX", "X9-9X-X9", "99-X-99X" } },
    { "YY", new[] { "99-XX-99", "XXX-999" } }
});

The above initializes a new LicenseplateValidator with two fictional countries ("XX" and "YY") with the sidecodes for each country. Note that because we use an overload of the dictionary that makes the key comparer case-insensitive you can pass "XX", "Xx", "xX" or "xx" as countrycode to all methods and this will work fine. If you don't want this behaviour then simply use the parameterless dictionary constructor or pass any other IDictionary<string, string[]> that implements the desired key comparison. Also note that you don't HAVE to stick with country codes like "NL", "XX" etc. You can use whatever key you like.

About actual validation

This project / library was born out of a little brainteaser that got a little out of hand. However; that doesn't mean in any way that this library is 100% correct. In fact, it doesn't even make any attempt to be correct. For example, ANY letter will be allowed where some sidecodes don't allow certain letters (like the letter C which isn't valid in Sidecode 1). Also some letters/digits are only allowed in certain places. All these minor details have not been added to this library. This is a quick'n'dirty fun little project that works fine for most purposes. If you want all the nitty gritty details supported or implemented then I suggest you look elsewhere (or make a pull request 😉). Methods like IsValid() therefore only return a 'minimal effort' result, an 'estimate' of whether a plate could be valid.

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