enum-with-transition.java

public enum ParserState {

    INITIAL {
        @Override
        public ParserState nextState(ParseWindow window) {
            String line = window.getFocusLine();
            if (matchesFromFilePattern(line)) {
                logTransition(line, INITIAL, FROM_FILE);
                return FROM_FILE;
            } else {
                logTransition(line, INITIAL, HEADER);
                return HEADER;
            }
        }
    }
    
    // ... other states
    
    public abstract ParserState nextState(ParseWindow window);
    
    // ... other methods
}

enum.java

public enum ParserState {

    INITIAL,
    HEADER,
    FROM_FILE,
    TO_FILE,
    HUNK_START,
    FROM_LINE,
    TO_LINE,
    NEUTRAL_LINE,
    END;
    
}

states.txt

      HEADER: Modified: trunk/test.txt                              
      HEADER: ===================================================================
   FROM_FILE: --- /trunk/test.txt	2013-10-23 19:41:56 UTC (rev 46)  
     TO_FILE: +++ /trunk/test.txt	2013-10-23 19:44:39 UTC (rev 47)  
  HUNK_START: @@ -1,4 +1,3 @@                                                    
NEUTRAL_LINE: test1                                                              
   FROM_LINE: -test1                                                             
     TO_LINE: +test234                                                           
NEUTRAL_LINE:                                                                    
   FROM_LINE: -test1                                                             
NEUTRAL_LINE: \ No newline at end of file                                        
  HUNK_START: @@ -5,9 +6,10 @@                                                   
   FROM_LINE: -test1                                                             
   FROM_LINE: -test1                                                             
     TO_LINE: +asdasd
     TO_LINE: +asdasd                               

transitions.txt

      INITIAL ->       HEADER: Modified: trunk/test.txt                              
       HEADER ->       HEADER: ===================================================================
       HEADER ->    FROM_FILE: --- /trunk/test.txt	2013-10-23 19:41:56 UTC (rev 46)  
    FROM_FILE ->      TO_FILE: +++ /trunk/test.txt	2013-10-23 19:44:39 UTC (rev 47)  
      TO_FILE ->   HUNK_START: @@ -1,4 +1,3 @@                                                    
   HUNK_START -> NEUTRAL_LINE: test1                                                              
 NEUTRAL_LINE ->    FROM_LINE: -test1                                                             
    FROM_LINE ->      TO_LINE: +test234                                                           
      TO_LINE -> NEUTRAL_LINE:                                                                    
 NEUTRAL_LINE ->    FROM_LINE: -test1                                                             
    FROM_LINE -> NEUTRAL_LINE: \ No newline at end of file                                        
 NEUTRAL_LINE ->   HUNK_START: @@ -5,9 +6,10 @@                                                   
   HUNK_START ->    FROM_LINE: -test1                                                             
    FROM_LINE ->    FROM_LINE: -test1                                                             
    FROM_LINE ->      TO_LINE: +asdasd
      TO_LINE ->      TO_LINE: +asdasd                                                            

unified-diff.txt

Modified: trunk/test.txt                              
===================================================================
--- /trunk/test.txt	2013-10-23 19:41:56 UTC (rev 46)  
+++ /trunk/test.txt	2013-10-23 19:44:39 UTC (rev 47)  
@@ -1,4 +1,3 @@                                                    
test1                                                              
-test1                                                             
+test234                                                           
                                                                    
-test1                                                             
\ No newline at end of file                                        
@@ -5,9 +6,10 @@                                                   
-test1                                                             
-test1                                                             
+asdasd
+asdasd