Multiple vcards in single file or string not properly separated

[keyboarder]

The call to VCardHelper.SplitCards() not only failed for my initial test with multiple vcards in one file, but looking at the regex call, it is completely ineffective. Not only does it look like Regex.Split() is misunderstood, but the regular expression itself --using default options-- will not match any vcard. First of all, the Split function expects a pattern to match delimiters, not the full expression. Next, the default interpretation of the period (.) operator is all characters except \n. So immediately the pattern should fail to match any vcard with line breaks. But even if it did match line breaks, the * is by default greedy and will continue to match every character until the very last "END:VCARD", so it would still not separate multiple vcards.

I have already crafted a valid regex and can submit a change, but I'm completely new to contributing on github and also want to get feedback, since I would be surprised if absolutely nobody has tried importing a multi-vcard file or string.

[binodnp]

Hi Keyboarder, thank you for your feedback. If you want to submit a pull request, it is simple and you may not even need to have git installed. Something like this:

• fork this repository
• make changes in your fork by directly editing the file in GitHub
• find the button in your fork which says "Submit Pull Request"
• done

[antonio-cervo]

Same error I replaced with my own function.

[DigitalSorceress]

It seems that the regex in
Regex.Split(contents, "((BEGIN:VCARD)(.*)(END:VCARD))");

at least in modern .NET / C#, is being "greedy"

I am unsure if this is a case where default interpretation of regex from non-greedy to greedy is the culprit or not, but I was in a hurry so I just did a hard Split and returned the removed END:VCARD before returning

My solution is not elegant, but my regex-fu is rusty...

in the file: Helpers\vCardHelpters.cs

public static string[] SplitCards(string contents)
{
    // this regex is likely an old style because it doesn't work in .NET 8
    // I can see it was written with the idea that it would match the first END:VCARD and split on it
    // but it ended up greedily sucking up all entries
    // I'm not quire sure how to limit regex to be nongreedy
    // so I just went with a more basic split
    //return Regex.Split(contents, "((BEGIN:VCARD)(.*)(END:VCARD))");
    string[] results = contents.Split("END:VCARD", StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries);
    List<string> cleanResults = new List<string>();

    foreach (string result in results)
    {
        cleanResults.Add(result + Environment.NewLine + "END:VCARD");
    }

    return cleanResults.ToArray();
}

[DigitalSorceress]

Ok, so I dusted off said 'regex-fu" I commented it a bunch just to explain why but the actual code is a one liner replacement

public static string[] SplitCards(string contents)
{
    // replaces eturn Regex.Split(contents, "((BEGIN:VCARD)(.*)(END:VCARD))");
    // which was failing likelly due to a change in regex behavior 
    // could have used return Regex.Split(contents, "(BEGIN:VCARD.*?END:VCARD)", RegexOptions.Singleline);
    // except that returns empty retults - Regex.Match is much better

    return new Regex("(BEGIN: VCARD.*? END : VCARD)", RegexOptions.Singleline | RegexOptions.IgnorePatternWhitespace).Matches(testString).Select(x => x.Value).ToArray();
}