public class MatchExpression

Overview

Match Expressions are built like "if" conditions in any common programming language. They work like queries in a database and can be used to search for Rooms or Users using custom criteria. These expressions are extremely easy to create and concatenate and they can be used for many different filtering operations within the SFS2X framework. This is a quick example:

             MatchExpression exp = new MatchExpression('rank', NumberMatch.GREATER_THAN, 5).and('country', StringMatch.EQUALS, 'Italy')
             

Expressions are made of three elements:

• Variable name
• Match operator
• Value

Additionally any number of expressions can be linked together with a logical AND / OR operator, just like in regular code. In the above example we have created an expression that will check for a rank value > 5 and a country value == "Italy". The search options are not just limited to User/Room Variables name. In fact the Matching engine provides two extra classes, RoomProperties and UserProperties, where you can access many specific attributes of the Room and User class. This is an example of matching specific Room properties and Variables:

             // Prepare match expression
             MatchExpression exp = new MatchExpression(RoomProperties.IS_GAME, BoolMatch.EQUALS, true).and
             					(RoomProperties.HAS_FREE_PLAYER_SLOTS, BoolMatch.EQUALS, true).and
             					("isGameStarted", BoolMatch.EQUALS, false);
             
             // Search Rooms
             List<Rooms> joinableRooms = sfsApi.findRooms(zone.getRoomListFromGroup("chess"), exp, 0);
             

Advanced features

the Match expression offer advanced capabilities of searching through nested data structures such as SFSObject and SFSArray. This is done via a very simple dot-syntax. Here's an example of how it works:

             MatchExpression exp = new MatchExpression("europe.italy.capital", StringMatch.EQUALS, "Rome")
             

The above example goes down deep into an SFSObject called europe, taking the italy object (another SFSObject) and finally reading its String field capital and matching it with another String. Here is one more examples using SFSObject and SFSArray:

             MatchExpression exp = new MatchExpression("europe.italy.majorCities.3.name", StringMatch.EQUALS, "Milan")
             

From the italy object we obtain a majorCities SFSArray and we grab the third item in it (the .3 expression means 'give me the element at index == 3'). The item is again an SFSObject whose name property we finally compare to a String. The power of Match Expression doesn't end here. You can run multiple passes of matching if you need complex searches to be performed. For example you can run a first match and obtain a list of filtered Rooms and then use it to apply another expression to further refine your search, and so on and so forth.

The power of Match Expression doesn't end here. You can run multiple passes of matching if you need complex searches to be performed. For example you can run a first match and obtain a list of filtered Rooms and then use it to apply another expression to further refine your search, and so on and so forth.

System..::..Object
  Sfs2X.Entities.Match..::..MatchExpression