Full-text query generator

fulltext.cs

public class FullTextUtils
{
	static HashSet<string> StopWords { get; set; }

	static FullTextUtils() //static constructor. init stopwords
	{
		try
		{
			using (var cn = DBUtils.GetNewOpenConnection())
			{
				StopWords = new HashSet<string>(cn.Query<string>("select distinct stopword from sys.fulltext_system_stopwords"), StringComparer.CurrentCultureIgnoreCase);
			}
		}
		catch
		{
			StopWords = new HashSet<string>(StringComparer.CurrentCultureIgnoreCase);
		}
	}

	public static string ToFtsQuery(string query)
	{
		if (string.IsNullOrEmpty(query)) return "\"\"";

		query = query.Trim();

		//if the whole query is in quotes - leave it like this, exact term.
		if (query.StartsWith("\"") && query.EndsWith("\"")) return query;

		string ftsQuery = "";


		//split query into separate words using white-space unless they are enclosed within "quotes"
		//enclose each of them into quotes, add an "NEAR" in between
		var terms = Split(query, ' ', '"').ToArray();
		if (terms == null || !terms.Any()) return "\"\"";

		terms = terms
			.Select(t => Regex.Replace(t, @"[^\w]", ""))
			.Where(t => !String.IsNullOrEmpty(t) && !StopWords.Contains(t)).ToArray();

		if (!terms.Any())
			return "\"\"";

		ftsQuery = terms.Aggregate((x, y) => x + " NEAR " + y);

		return ftsQuery;
	}

	//splits string by separator EXCEPT for the separator found between quotation marks
	private static List<String> Split(string myString, char separator, char escapeCharacter)
	{
		int nbEscapeCharactoers = myString.Count(c => c == escapeCharacter);
		if (nbEscapeCharactoers % 2 != 0) // uneven number of escape characters
		{
			int lastIndex = myString.LastIndexOf("" + escapeCharacter, StringComparison.Ordinal);
			myString = myString.Remove(lastIndex, 1); // remove the last escape character
		}
		var result = myString.Split(escapeCharacter)
								.Select((element, index) => index % 2 == 0  // If even index
														? element.Split(new[] { separator }, StringSplitOptions.RemoveEmptyEntries)  // Split the item
														: new string[] { element })  // Keep the entire item
								.SelectMany(element => element).ToList();
		return result;
	}
}