using System;
  using edu.neu.ccs.demeterf;
  using Fields = edu.neu.ccs.demeterf.control.Fields;
  using System.IO;

  // shape.java
  public abstract class shape{
    public abstract double area();
    public shape add(shape s){ return new pair(s,this); }

      
    public static void Main(String[] a){
      shape s = 
          new circle(5)
          .add(new square(5))
          .add(new circle(2))
          .add(new rect(4,9));

       Console.WriteLine("          s == "+s);
       Console.WriteLine("   s.area() == "+s.area());
       Console.WriteLine("    area(s) == "+Area.area(s));
       Console.WriteLine("    area(s) == "+Count.count(s));
       Console.WriteLine("    c->s(s) == "+Circ2sqr.circ2sqr(s));
       Console.WriteLine("   scale(s) == "+Scale.scale(s));
       Console.WriteLine("depthScl(s) == "+DepthScl.scale(s));
       Console.WriteLine(" leftScl(s) == "+LeftScl.scale(s));
       
       shape[] ss = {s,Circ2sqr.circ2sqr(s),Scale.scale(s),
                     DepthScl.scale(s),LeftScl.scale(s)};
       string[] fs = {"shape.svg","circ2sqr.svg","scale.svg",
                      "depth.svg","left.svg"};
       for(int i = 0; i < fs.Length; i++){
           Console.WriteLine(" Do["+i+"]: "+fs[i]);
           try{
               StreamWriter o = new StreamWriter(new FileStream(fs[i],FileMode.Create));
               o.WriteLine(Display.display(ss[i]));
               o.Close();
           }catch(IOException e){
               Console.WriteLine("BAD: "+e);
           }
       }
    }
    public override string ToString()
     { return new Traversal(new Str()).traverse<string>(this); }
  }

  class circle : shape{
     int radius;
     public circle(int r){ radius = r; }
     public override double area(){ return Math.PI*radius*radius; }
  }
  class square : shape{
     int side;
     public square(int s){ side = s; }
     public override double area(){ return side*side; }
  }
  class pair : shape{
     shape left,
           right;
     public pair(shape l, shape r){ left = l; right = r; }
     public override double area(){ return left.area()+right.area(); }
     public class leftF : Fields.any{}
     public class rightF : Fields.any{}
  }

  class rect : shape{
     int width,
         height;
     public rect(int w, int h){ width = w; height = h; }
     public override double area(){ return width*height; }
  }

  // Area function class
  class Area : ID{
     double combine(circle c, int r){ return Math.PI*r*r; }
     double combine(square s, int d){ return d*d; }
     double combine(rect r, int w, int h){ return w*h; }
     double combine(pair p, double l, double r){ return l+r; }

     public static double area(shape s){
       return new Traversal(new Area()).traverse<double>(s);
     }
  }

  // Count function class
  class Count : ID{
     int combine(shape c){ return 1; }
     int combine(pair p, int l, int r){ return l+r; }

     public static int count(shape s){
       return new Traversal(new Count()).traverse<int>(s);
     }
  }

  // circle -> square  function class
  class Circ2sqr : Bc{
      shape combine(circle c, int r){ return new square(r+r); }

     public static shape circ2sqr(shape s){
        return new Traversal(new Circ2sqr()).traverse<shape>(s);
     }
  }


  class Str : ID{
     string combine(circle c, int r){ return "circle("+r+")"; }
     string combine(square s, int d){ return "square("+d+")"; }
     string combine(rect r, int w, int h)
      { return "rect("+w+", "+h+")"; }
     string combine(pair p, string l, string r)
      { return "pair("+l+", "+r+")"; }
  }

  // scale  function class
  class Scale : Bc{
     int combine(int i){ return i*2; }

     public static shape scale(shape s){
       return new Traversal(new Scale()).traverse<shape>(s);
     }
  }

  // DepthScl  function class
  class DepthScl : Bc{
     int update(pair p, Fields.any f, int d){ return d+1; }
     int combine(int i, int d){ return i*d; }

     public static shape scale(shape s){
         return new Traversal(new DepthScl()).traverse<shape>(s,1);
     }
  }


  // LeftScl function class
  class LeftScl : DepthScl{
     // Don't increase the depth for 'right' children
     int update(pair p, pair.rightF f, int d){ return d; }

     public static shape scale(shape s){
       return new Traversal(new LeftScl()).traverse<shape>(s,1);
     }
  }


  class Display : ID{
      static int y = 50;
      int update(pair p, pair.rightF f, int x){ return x+45; }
      string combine(pair p, string l, string r){ return l+r; }

      int combine(int i){ return 3*i; }
      string combine(circle c, int r, int x)
       { return svg.circle(x,y,r); }
      string combine(square s, int sd, int x)
       { return svg.rect(x,y,sd,sd); }
      string combine(rect r, int w, int h, int x)
       { return svg.rect(x,y,w,h); }

      public static string display(shape s){
          return svg.image(240, 100,
                           new Traversal(new Display())
                           .traverse<string>(s,40));
      }
  }

  class svg{
      public static string head(int w, int h){
          round = 0;
          return 
              "<!DOCTYPE svg PUBLIC '-//W3C//DTD SVG 1.1//EN'\n"+
              "'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'>"+
              "<svg xmlns='http://www.w3.org/2000/svg' version='1.1' "+
              "width='"+w+"' height='"+h+"'>"+
              "<rect x='1' y='1' width='"+(w-2)+"' height='"+(h-2)+"'"+
              " fill-opacity='0' stroke='black'/>\n";
      }
      public static string foot(){ return "</svg>\n"; }
      public static string end(){ return " fill='"+col()+"' fill-opacity='0.5' />\n"; }
      
      public static string[] colors = {"red","green","blue","orange","purple"};
      public static int round = 0;
      public static string col(){ return colors[round++]; }

      public static string circle(int x, int y, int r){
          return ("  <circle cx='"+x+"' cy='"+y+
                  "' r='"+r+"'"+svg.end());
      }
      public static string rect(int x, int y, int w, int h){
          return ("  <rect x='"+(x-w/2)+"' y='"+(y-h/2)+
                  "' width='"+w+"' height='"+h+"'"+svg.end());
      }
      public static string image(int w, int h, string bdy){
          return head(w,h)+bdy+foot();
      }
  }