PROBLEM ArtificialAnt

CODE <<
public struct Point { 
  public int x; public int y; 
  public Point(int x, int y) {
    this.x = x;
	this.y = y;
  }
};

class World {

private static string[] LosAltosTrail = new string[] {
" ###                                          ",
"   #                                  .###..  ",
"   #                                  #    #  ",
"   #                                  #    #  ",
"   ####.#####           .############..    .  ",
"            #           .                  #  ",
"            #           #                  .  ",
"            #           #                  .  ",
"            #           #                  #  ",
"            .           #                  .  ",
"            #           .                  .  ",
"            #           .                  #  ",
"            #           #                  .  ",
"            #           #            ...###.  ",
"            .       .#...            #        ",
"            .       .                .        ",
"            #       .                .        ",
"            #       #                .#...    ",
"            #       #                    #    ",
"            #       #                    .    ",
"            #       #                    .    ",
"            #       .                ...#.    ",
"            #       .                #        ",
" ..##..#####.       #                #        ",
" #                  #                #        ",
" #                  #                #        ",
" #                  #                #        ",
" #                  #                #        ",
" #                  #                #        ",
" #     .#####....##..                #        ",
" #     #                             #        ",
" .     #                             #        ",
" .####..                             #        ",
"                                   #.#        ",
"                                   #          ",
"                                   #          ",
"                                   #          ",
"                                   #          ",
"                                   #          ",
"                                   #          ",
"                                   #          ",
"                              ######          ",
"                              .               ",
"                              #               ",
"                              #               ",
"                              #               ",
"                              #               ",
"                              #               ",
"                              #               ",
"                            #..               ",
"                            #                 ",
"                            #                 ",
"                            #                 ",
"                            #                 ",
"                            #                 ",
"                      .######                 ",
"                      .                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       ",
"                      #                       "
};
  private char[][] world = LosAltosTrail.Select(l=>l.ToArray()).ToArray();
  public int TotalFood = LosAltosTrail.Select(l=>l.Where(c=>c=='#').Count()).Sum();
  public int Width { get { return 100; } }
  public int Height { get { return 100; } }
  
  public void Reset() {
    world = LosAltosTrail.Select(l=>l.ToArray()).ToArray();
  }
  
  public bool FoodAt(Point p) {
    if(p.x < 0 || p.y < 0) return false;
    if(world.Length <= p.y) return false;
	if(world[p.y].Length <= p.x) return false;
    return world[p.y][p.x] == '#';
  }
  public void RemoveFoodAt(Point p) {
    if(world.Length < p.y) return;
	if(world[p.y].Length < p.x) return;
    world[p.y][p.x] = ' ';
  }
}

enum Direction {West, East, North, South};

class AntState {
  public Point Position { get; set;} 
  public int MaxSteps { get; set;}
  public Direction Direction { get; set; }
  public World World { get; set; }
  public int Steps { get; set; }
  public int FoodEaten { get; set; }
 
  public AntState() {
    Steps = 0;	
	FoodEaten = 0;
  }
 
  public void TurnLeft() {
    Steps++;
    switch(Direction) {
	  case Direction.West: Direction = Direction.South; break;
	  case Direction.South: Direction = Direction.East; break;
	  case Direction.East: Direction = Direction.North; break;
	  case Direction.North: Direction = Direction.West; break;
	}
  }
  public void TurnRight() {
    Steps++;
    switch(Direction) {
	  case Direction.West: Direction = Direction.North; break;
	  case Direction.South: Direction = Direction.West; break;
	  case Direction.East: Direction = Direction.South; break;
	  case Direction.North: Direction = Direction.East; break;
	}
  }
  public void MoveForward() { 
    Position = NextPosition; 
	Steps++; 
	if(World.FoodAt(Position)) {
    	World.RemoveFoodAt(Position);
		FoodEaten++;
    }
  }
  public Point NextPosition { 
    get { 
	    int x, y;
        switch(Direction) {
    	  case Direction.West: 
		    x = (Position.x + World.Width - 1) % World.Width;
			y = Position.y;
			return new Point(x, y);
    	  case Direction.South: 
  		    x = Position.x;
			y = (Position.y + World.Height + 1) % World.Height;
			return new Point(x, y);
    	  case Direction.East:
  		    x = (Position.x + World.Width + 1) % World.Width;
			y = Position.y;
			return new Point(x, y);
    	  case Direction.North:
  		    x = Position.x;
			y = (Position.y + World.Height - 1) % World.Height;
			return new Point(x, y);
    	}
 		return new Point(-1,-1);
    } 
  }  
}

World CreateWorld() {   
  var w = new World();
  Console.WriteLine("Total food: "+w.TotalFood);
  return w;
}

World world;
>>
INIT <<
  world = CreateWorld();
>>

NONTERMINALS
  Ant<<World world, AntState state>>. 
  IfFoodAhead<<World world, AntState state>>.
  Prog2<<World world, AntState state>>.
  Prog3<<World world, AntState state>>.

TERMINALS
  Left. Right. Move.
 
RULES
  Ant<<World world, AntState state>> = 
    IfFoodAhead<<world, state>>
    | Prog2<<world, state>>
    | Prog3<<world, state>>
    | Left                                             SEM << state.TurnLeft(); >>
    | Right                                            SEM << state.TurnRight(); >>
    | Move                                             SEM << state.MoveForward(); >>
    .
    
  IfFoodAhead<<World world, AntState state>> =     
                                                   SEM <<
                                                      if(world.FoodAt(state.NextPosition)) {
                                                   >>
                                                   
    Ant<<world, state>>                            SEM << } else { >>
    Ant<<world, state>>                            SEM << } >> 
  .

  Prog2<<World world, AntState state>> = 
    Ant<<world, state>> Ant<<world, state>>
  .
  
  Prog3<<World world, AntState state>> =
    Ant<<world, state>> Ant<<world, state>> Ant<<world, state>>
  .


MAXIMIZE                                                   /* could also use the keyword MINIMIZE here */
  <<    
    world.Reset();
    var state = new AntState() {Position = new Point(0,0), MaxSteps=400, Direction=Direction.East, World = world};
    while(state.Steps < state.MaxSteps) {
      Ant(world, state);
    }
    return (double)state.FoodEaten;
  >>  
END ArtificialAnt.