Tutorial :Transform Search String into FullText Compatible Search String?


I'm working with the fulltext search engine of MSSQL 2008 which expects a search string like this:

("keyword1" AND "keyword2*" OR "keyword3")  

My users are entering things like this:

engine 2009  "san francisco"     hotel december xyz  stuff* "in miami"   1234  something or "something else"  

I'm trying to transform these into fulltext engine compatible strings like these:

("engine" AND "2009")  ("san francisco" AND "hotel" AND "december" AND "xyz")  ("stuff*" "in miami" "1234")  ("something" OR "something else")  

I have a really difficult time with this, tried doing it using counting quotation marks, spaces and inserting etc. but my code looks like horrible for-and-if vomit.

Can someone help?


Here you go:

class Program {      static void Main(string[] args) {          // setup some test expressions          List<string> searchExpressions = new List<string>(new string[] {               "engine 2009",               "\"san francisco\"     hotel december xyz",               "stuff* \"in miami\"   1234 ",               "something or \"something else\""          });            // display and parse each expression          foreach (string searchExpression in searchExpressions) {              Console.WriteLine(string.Concat(                  "User Input: ", searchExpression,                   "\r\n\tSql Expression: ", ParseSearchExpression(searchExpression),                   "\r\n"));          }            Console.ReadLine();        }    private static string ParseSearchExpression(string searchExpression) {      // replace all 'spacecharacters' that exists within quotes with character 0      string temp = Regex.Replace(searchExpression, @"""[^""]+""", (MatchEvaluator)delegate(Match m) {          return Regex.Replace(m.Value, @"[\s]", "\x00");      });        // split string on any spacecharacter (thus: quoted items will not be splitted)      string[] tokens = Regex.Split(temp, @"[""\s]+", RegexOptions.IgnoreCase | RegexOptions.ExplicitCapture);        // generate result      StringBuilder result = new StringBuilder();      string tokenLast = string.Empty;      foreach (string token in tokens) {          if (token.Length > 0) {              if ((token.Length > 0) && (!token.Equals("AND", StringComparison.OrdinalIgnoreCase))) {                  if (result.Length > 0) {                      result.Append(tokenLast.Equals("OR", StringComparison.OrdinalIgnoreCase) ? " OR " : " AND ");                  }                  result.Append("\"").Append(token.Replace("\"", "\"\"").Replace("\x00", " ")).Append("\"");              }              tokenLast = token;          }      }      if (result.Length > 0) {          result.Insert(0, "(").Append(")");      }        return result.ToString();  }  }  

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