Parsing tnsnames.ora using regex...

Question

I am attempting to pull some information from my tnsnames file using regex. I started with the following pattern:

MYSCHEMA *? = *?[\W\w\S\s]*\(HOST *?= *?(?<host>\w+\s?)\)\s?\(PORT *?= *?(?<port>\d+)\s?\)[\W\w\S\s]*\(SERVICE_NAME *?= *?(?<servicename>\w+)\s?\)

which worked fine when MYSCHEMA was the only schema in the file, but when there are other schemas listed after MYSCHEMA it matches all the way to the last schema.

I have since created a new pattern:

MYSCHEMA *=\s*\(DESCRIPTION =\s*\(ADDRESS *= *\(PROTOCOL *= *TCP\)\(HOST *= *(?<host>\w+)\)\(PORT *= *(?<port>\d+)\)\)\s*\(CONNECT_DATA *=\s*(?<serverdedicated>\(SERVER *= *DEDICATED\))\s*\(SERVICE_NAME *= *(?<servicename>[\w\.]+) *\)\s*\)\s*\)

This pattern matches MYSCHEMA only, but I had to add every element that appeared in MYSCHEMA entry, and it won't match MYOTHERSCHEMA if it does not contain all the same elements.

Ideally, I'd like a pattern that matches MYSCHEMA entry only, and captures HOST, PORT and SERVICE NAME, and optionally (SERVER = DEDICATED) (which I didn't have in the first pattern) to named groups.

Below is the sample tnsnames that I've been using for testing:

SOMESCHEMA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = REMOTEHOST)(PORT = 1234))
    )
    (CONNECT_DATA = (SERVICE_NAME = REMOTE)
    )
  )

MYSCHEMA =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = MYHOST)(PORT = 1234))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = MYSERVICE.LOCAL )
    )
  )

MYOTHERSCHEMA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = MYHOST)(PORT = 1234))
    )
    (CONNECT_DATA = 
      (SERVICE_NAME = MYSERVICE.REMOTE)
    )

  )

SOMEOTHERSCHEMA = 
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = LOCALHOST)(PORT = 1234))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = LOCAL)
    )
  )

Answer 1

This should do it, using balanced groups. And modify the switch/case for your needs.

class TnsRegex
{
    public void Test()
    {
        Regex reTns = new Regex(_pattern, RegexOptions.Singleline | RegexOptions.IgnorePatternWhitespace);
        MatchCollection matchCollection = reTns.Matches(_text);

        foreach (Match match in matchCollection)
        {
            foreach (Capture capture in match.Groups["Settings"].Captures)
            {
                string[] setting = capture.Value.Split(new[] { '=' }, StringSplitOptions.RemoveEmptyEntries);
                string key = setting[0].Trim();
                string val = setting[1].Trim();
                if (val.Contains("(")) continue;
                switch (key)
                {
                    case "HOST":
                        break;
                    case "PORT":
                        break;
                    case "SERVICE_NAME":
                        break;
                    case "SERVER":
                        break;
                }
                Console.WriteLine(key + ":" + val);
            }
        }
    }
    string _pattern = @"
        MYSCHEMA\s+=\s+\(
        [^\(\)]*
        (
                    (
                                (?<Open>\()
                                [^\(\)]*
                    )+
                    (
                                (?<Settings-Open>\))
                                [^\(\)]*
                    )+
        )*
        (?(Open)(?!))
    \)";

    string _text = @"
    MYSCHEMA =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = MYHOST)(PORT = 1234))
        (CONNECT_DATA =
          (SERVER = DEDICATED)
          (SERVICE_NAME = MYSERVICE.LOCAL )
        )
      )

    SOMESCHEMA =
      (DESCRIPTION =
        (ADDRESS_LIST =
          (ADDRESS = (PROTOCOL = TCP)(HOST = REMOTEHOST)(PORT = 1234))
        )
        (CONNECT_DATA = (SERVICE_NAME = REMOTE)
        )
      )
    ";
}

Answer 2

Well, since I haven't found a compelling answer to this issue (no offense @Mikael Svenson), I have just stuck with the second pattern listed in my question. It is sufficient for the time being, as the tnsnames.ora file always follows that exact pattern within our organization. Should the tnsnames.ora file format change, I will most likely adopt a parser.