Get value in case-insensitive HashSet<string>

Question

I have case-insensitive HashSet<string>:

private HashSet<string> a = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);

I'm curious if I can now extract the string in the actual case. Pseudo code of what I need:

return a.Contains(word) ? a[word] : null;

(just a pseudo code, it won't work)

For example, I have string "TestXxX" in the HashSet. I need for the code which gets "testxxx" (or "tEsTXXx") as input and returns "TestXxX".

My current workaround is to use Dictionary<string,string> instead and put the same value for both key and value. This is obviously not elegant and consumes 2x memory as it actually needs.

Answer 1

You can override KeyedCollection

public class Keyed : KeyedCollection<string, string>
{
    public Keyed(IEqualityComparer<string> comparer) : base(comparer)
    {

    }

    protected override string GetKeyForItem(string item)
    {
        return item;
    }
}

Then use it:

var keyed = new Keyed(StringComparer.InvariantCultureIgnoreCase);
keyed.Add("TestXxX");

Console.WriteLine(keyed["tEsTXXx"]);