YAPC::EU 2018 Glasgow Update!

Task/Conways-Game-of-Life/Java/conways-game-of-life-3.java

@@ -0,0 +1,92 @@
+import static java.util.List.of;
+
+class GameOfLife {
+
+   boolean[][] board = new boolean[3][3];
+
+   GameOfLife() {}
+
+   GameOfLife(String[] board) {
+      set((i, j, s) -> board[i].charAt(j * 2) == '■');
+   }
+
+   void set(Setter setter) {
+      for (int i = 0; i < board.length; i++) {
+         for (int j = 0; j < board[i].length; j++) {
+            board[i][j] = setter.set(i, j, board[i][j]);
+         }
+      }
+   }
+
+   void get(Getter getter) {
+      set((i, j, s) -> {
+         getter.get(i, j, s);
+         return s;
+      });
+   }
+
+   int countNeighbors(int i, int j) {
+      var counter = new Getter() {
+         int count;
+
+         @Override
+         public void get(int li, int lj, boolean state) {
+            if (distance(i, j, li, lj) == 1 && board[li][lj])
+               count++;
+         }
+      };
+      get(counter);
+      return counter.count;
+   }
+
+   int distance(int i, int j, int li, int lj) {
+      return Math.max(
+           Math.abs(i - li),
+           Math.abs(j - lj));
+   }
+
+   GameOfLife makeNextGeneration() {
+      var n = new GameOfLife();
+      n.set((i, j, s) -> {
+         var alive = board[i][j];
+         int c = countNeighbors(i, j);
+         if (alive) {
+            return c == 2 || c == 3;
+         } else {
+            return c == 3;
+         }
+      });
+      return n;
+   }
+
+   void print() {
+      get((i, j, s) -> {
+         if (j == 0)
+            System.out.println();
+         System.out.print(s ? "■ " : "□ ");
+      });
+   }
+
+   interface Setter {
+      boolean set(int i, int j, boolean state);
+   }
+
+   interface Getter {
+      void get(int i, int j, boolean state);
+   }
+
+   public static void main(String[] args) {
+      String[] board = {
+           "□ ■ □ ",
+           "□ ■ □ ",
+           "□ ■ □ ",
+      };
+      var gol = new GameOfLife(board);
+      for (var generation : of(0, 1, 2)) {
+         gol.print();
+         System.out.println("\n");
+         gol = gol.makeNextGeneration();
+      }
+   }
+
+}