Ayende csv user data searcher 2

UserDataSearcher.cs

public class UserData
{
    public int Id { get; set; }
    public string Email { get; set; }
}

public class UserDataSearcher
{
    private readonly List<UserData> userDataList;

    private class UserDataComparer : IComparer<UserData>
    {
        public int Compare(UserData x, UserData y)
        {
            return StringComparer.InvariantCultureIgnoreCase.Compare(x.Email, y.Email);
        }
    }
    private static readonly UserDataComparer comparer = new UserDataComparer();


    public UserDataSearcher(IEnumerable<UserData> usersData)
    {
        userDataList = usersData.ToList();
        userDataList.Sort(comparer);
    }

    public IEnumerable<UserData> GetUsersByEmail(string email)
    {
        int pos = this.userDataList.BinarySearch(new UserData { Email = email }, comparer);
        if (pos < 0) yield break;
        yield return userDataList[pos];
        for (int i = pos + 1; i < userDataList.Count; i++)
        {
            var userData = userDataList[i];
            if (string.Equals(userData.Email, email, StringComparison.InvariantCultureIgnoreCase))
            {
                yield return userData;
            }
            else break;
        }
        for (int i = pos - 1; i >= 0; i--)
        {
            var userData = userDataList[i];
            if (string.Equals(userData.Email, email, StringComparison.InvariantCultureIgnoreCase))
            {
                yield return userData;
            }
            else break;
        }
    }
}