// TSRJ 2008 - Advanced
// Lecture 3: Data Definitions - Part 2


// Class Diagram 
// -------------
//
// A diagram that specifies the name of a Class and its fields. 
// Think of Class Diagrams as a way of representing the 
// text (comments) part of the data definition in Scheme.
// This representation can be used for Scheme as well, but is very 
// useful in class based languages like Java, where the actual data definition
// is quite verbose.
//
//  To represent a plane trip 
//
//    +-----------------+
//    |   Flight        |
//    |-----------------|
//    |String  departure|
//    |String  arrival  |
//    |int     cost     |
//    |int     seat     |
//    +-----------------+

class Flight {
  String departure; 
  String arrival; 
  int    cost; 
  int    seat; 

  //Constructor
  Flight(String departure, String arrival, int cost, int seat){
    this.departure = departure; 
    this.arrival   = arrival; 
    this.cost      = cost; 
    this.seat      = seat; 
  }
}


// Notice, that you have to define the constructor yourselves - ProfessorJ 
// Begginer Language does not do it for you.

// To create an instance of your class you need to use the keyword 
// 'new' before you call your class' constructor. Instances of classes 
// are called 'objects'. To call a constructor you need to provide the 
// name of the constructor, 'Flight', and the arguments to the constructor 
// in a comma separated list inside parens, ("Logan", "JFK", 80, 21). 
// To name an object so that you can refer to it later you need to provide 
// the class name and then the name you want to use, i.e. 'Flight ltojfk' 
// followed by an equal sign '='. 
// You can think of this as saying that the name ltojfk can be used to refer 
// only to objects created by the class Flight and I want it to refer to the 
// instance that has "Logan" as the departure airport, "JFK" as the arriving 
// airport, it costs $80 and is assigned seat number 21. 

//  To represent a song in an album 
//
//    +-----------------+
//    |   Song          |
//    |-----------------|
//    |String  title    |
//    |String  artist   |
//    |String  album    |
//    |String  genre    |
//    +-----------------+


class Song {
  String title; 
  String artist; 
  String album; 
  String genre; 

  //Constructor

  Song(String title, String artist, String album, String genre){
    this.title  = title; 
    this.artist = artist; 
    this.album  = album; 
    this.genre  = genre; 
  }

}


//  To represent a recording of a show using Tivo.
//
//    +-----------------+
//    |   Show          |
//    |-----------------|
//    |String  title    |
//    |int     channel  |
//    |int     time     |
//    |int     duration |
//    +-----------------+

class Show {
  String title; 
  int channel; 
  int time; 
  int duration; 

  //Constructor
  Show(String title, int channel, int time, int duration){
    this.title    = title; 
    this.channel  = channel; 
    this.time     = time; 
    this.duration = duration; 
  }
}




// Look at the data definition for Song in Java. Specifically look at the field
// with the name 'time' inside the class Song. We are using an int to represent 
// time. int is a Java primitive type-of-data for integers, But that is not how 
// humans think of time. 

// Examples 
// --------
// 20:00  (8:00 PM) 
// 20:30  (8:30 PM)  
// 21:20  (8:20 PM)  
// 7:20   (7:20 AM)  
//
//  
//    +-----------------+
//    |   Time          |
//    |-----------------|
//    |int     hours    |
//    |int     minutes  |
//    +-----------------+
//

class Time {
  int hours; 
  int minutes; 

 Time (int hours, int minutes){ 
  this.hours = hours; 
  this.minutes = minutes; 
 } 
} 


// We can use our new data definition for Time inside Show as follows 
//
//  To represent a recording of a show using Tivo. (Attempt 2) 
//
//    +-----------------+
//    |   Show2         |
//    |-----------------|
//    |String  title    |        
//    |int     channel  |        +-----------------+
//    |Time    time     |------->|   Time          |  
//    |int     duration |        |-----------------|
//    +-----------------+        |int     hours    |
//                               |int     minutes  |
//                               +-----------------+

class Show2 {                     
  String title; 
  int channel; 
  Time time; 
  int duration; 

  //Constructor

  Show2(String title, int channel, Time time, int duration){
    this.title    = title; 
    this.channel  = channel; 
    this.time     = time; 
    this.duration = duration; 
  }
}
 

class Examples { 
  Examples() {}

  Flight ltojfk = new Flight("Logan", "JFK", 80, 21); 

  Song pib = 
    new Song("Paint it Black", "The Rolling Stones", "The Aftermath", "Rock"); 

  Show mwc = new Show("Married With Children", 25, 2100, 1); 

  Time t1 = new Time(22,15); 

  Show2 mwc2 = new Show2("Married With Children", 25, new Time(21,0), 1); 
} 


// Note how class names start with a capital letter (e.g. Show, Time etc.). 
// Also how the arrows in the our class diagrams correspond to the arrows
// that we draw in data definitions in Scheme when one define-struct refers 
// to another define-struct. 
//
// Notice how the Java code we have been writing to represent our class diagrams 
// is boilerplate code, i.e. a task that a program could do.  

// So back to scheme ... 

/*
;; A ClassDef is (make-cd String [Listof FieldDef])
;; interpretation: (make-cd c (list f1 f2)) creates a class definition with 
;;                 c as the class name 
;;                 f1 and f2 as the fields inside c
;;
;; A FieldDef is (make-fd String String)
;; interpretation: (make-fd t n) creates a field definition with 
;;                 t as the type of data that the field can hold
;;                 n as the name for the field 
(define-struct fd (type name))
(define-struct cd (name fields))

;; Examples: 
;; --------
(define show-cd (make-cd "Show" (list (make-fd "String" "title")
                                      (make-fd "int" "channel")
                                      (make-fd "Time" "time")
                                      (make-fd "int" "duration"))))

;; Challenge: Write a Scheme program that consumes a ClassDef and produces
;; a String that represents a Java constructor for the class defined by this
;; class definition.
*/