DAJ Examples

Managing a collection of CD's.

• The .cd file :

                {
                  parser lookahead=2;
                }
  
                import java.util.*;
  
                DiscCollection = CDList EOF. 
                CD = "("*s*l "CDTitle."<title> Title "by" <artist> Artist ["genre" <genre> Genre
                      ] "released" <year>Year "songs"<songs>List(Song)")" ".".
                Title = Ident. 
                Artist : Band | Singer | MultiArtist common Name.
                MultiArtist = "MultiArtis".
                Band = "band" List(Musicians).
                Name = Ident. 
                Musicians = Person ["known as"NickName]. 
                NickName = Ident. 
                Person = "Name"First ["Middle" Second] "Last" Last. 
                First = Ident. 
                Second = Ident. 
                Last = Ident. 
                Singer = Person.
                Genre : Pop | Rock | Jazz | Classical | Alternative | Soundtrack | Live.
                Pop = "Pop".
                Rock = "Rock".
                Jazz = "Jazz".
                Classical = "Classical".
                Alternative  = "Alternative".
                Soundtrack = "Soundtrack".
                Live= .
                Year = Integer.
                Song = ["track"TrackNo] Title ["duration"Time].
                TrackNo = Integer. 
                Time = Minutes ":" Seconds. 
                Minutes = Integer. 
                Seconds = <dd> Double. 
  
  
                CDList ~ "(" CD {CD}  ")".
                List(X) ~ "(" X {","X} ")".
  
            

• A sampe .trv file for the above class dictionary:

              aspect ToAll {
              declare strategy: eachCD: "from DiscCollection to *";
  
              declare traversal:
                void listAll(): eachCD(CDPrinter);
                }
  
            

• And a sample Visitor.

            class CDPrinter {
              void before (Minutes minutes){
                System.out.print("\t"+ minutes.integer.intValue());
              }
  
              void after (Minutes minutes){
                System.out.print(":");
              }
  
              void before (TrackNo tNo) {
                System.out.print(tNo.integer.intValue());
              }
  
              void before (Title title){
                System.out.print("\t"+title.ident+"\t");
              }
  
              void before (Seconds seconds){
                System.out.println(seconds.dd.toString());
              }
  
              void before (Song song){
                System.out.print("\t ->");
              }
              void before(CD cd) {
                System.out.println("---- Begin CD ------");
              }
  
              void after(CD cd) {
                System.out.println("---- End CD ------");
              }
            }
  
            

• Sample main.

            import java.io.File;
  
            class Main {
              public static void main(String[] args) {
                System.out.println(" **** START **** ");
                try {
                  DiscCollection cdcollection = DiscCollection.parse(new File(args[0]));
                  cdcollection.listAll();
                } catch (Exception e) {
                  System.err.println(e);
                }
                System.out.println(" **** END **** ");
              }
            }