1 files changed, 156 insertions, 0 deletions
diff --git a/CLI/rust/src/game_of_life/simulation/universe.rs b/CLI/rust/src/game_of_life/simulation/universe.rs
index 782e611..a70fa11 100644
--- a/CLI/rust/src/game_of_life/simulation/universe.rs
+++ b/CLI/rust/src/game_of_life/simulation/universe.rs
@@ -72,3 +72,159 @@ mod index {
         assert_eq!(u[4][7], true);
     }
 }
+
+impl Universe {
+    /// Return the neighboring cells to the cell in index (Y,X) on a plane
+    ///
+    /// given a cell "C" in a universe of cells "." the immediate neighbors would be "x" as in
+    /// the following different examples
+    ///
+    ///     .....  |  .xxx.  |  .xCx.  |  xCx..  |  Cx..x  |  xx..x  |
+    ///     .xxx.  |  .xCx.  |  .xxx.  |  xxx..  |  xx..x  |  Cx..x  |
+    ///     .xCx.  |  .xxx.  |  .....  |  .....  |  .....  |  xx..x  |
+    ///     .xxx.  |  .....  |  .....  |  .....  |  .....  |  .....  |
+    ///     .....  |  .....  |  .xxx.  |  xxx..  |  xx..x  |  .....  |
+    ///
+    pub(crate) fn neighbors(self, y: isize, x: isize) -> Vec<bool> {
+        vec![
+            self[y - 1][x - 1],
+            self[y - 1][x],
+            self[y - 1][x + 1],
+            self[y][x - 1],
+            self[y][x + 1],
+            self[y + 1][x - 1],
+            self[y + 1][x],
+            self[y + 1][x + 1],
+        ]
+    }
+
+}
+
+#[cfg(test)]
+mod neighbors {
+    use super::*;
+
+    fn opts() -> Opts {
+        Opts {
+            seed: 1337,
+            input: None,
+            width: 13,
+            height: 13,
+            live_cell: 'L',
+            dead_cell: 'D',
+            delay: 13,
+        }
+    }
+
+    #[test]
+    fn center() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, false, false, false, false]),
+            ],
+        };
+        assert_eq!(u.neighbors(2,2), vec![true; 8]);
+    }
+
+    #[test]
+    fn top_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, true, true, true, false]),
+            ],
+        };
+        assert_eq!(u.neighbors(0,2), vec![true; 8]);
+    }
+
+    #[test]
+    fn bottom_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, true, true, true, false]),
+                Plane(vec![false, true, true, true, false]),
+            ],
+        };
+        assert_eq!(u.neighbors(4,2), vec![true; 8]);
+    }
+
+    #[test]
+    fn left_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![true, true, false, false, true]),
+                Plane(vec![true, true, false, false, true]),
+                Plane(vec![true, true, false, false, true]),
+                Plane(vec![false, false, false, false, false]),
+            ],
+        };
+        assert_eq!(u.neighbors(2,0), vec![true; 8]);
+    }
+
+    #[test]
+    fn right_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![true, false, false, true, true]),
+                Plane(vec![true, false, false, true, true]),
+                Plane(vec![true, false, false, true, true]),
+                Plane(vec![false, false, false, false, false]),
+            ],
+        };
+        assert_eq!(u.neighbors(2,4), vec![true; 8]);
+    }
+
+    #[test]
+    fn bottom_corner_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![true, false, false, true, true]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![true, false, false, true, true]),
+                Plane(vec![true, false, false, true, true]),
+            ],
+        };
+        assert_eq!(u.neighbors(4,4), vec![true; 8]);
+    }
+
+    #[test]
+    fn top_corner_edge() {
+        let u = Universe {
+            opts: opts(),
+            future: vec![Plane(vec![])],
+            current: vec![
+                Plane(vec![true, true, false, false, true]),
+                Plane(vec![true, true, false, false, true]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![false, false, false, false, false]),
+                Plane(vec![true, true, false, false, true]),
+            ],
+        };
+        assert_eq!(u.neighbors(0,0), vec![true; 8]);
+    }
+}