1 files changed, 48 insertions, 0 deletions
diff --git a/CLI/rust/src/game_of_life/simulation.rs b/CLI/rust/src/game_of_life/simulation.rs
new file mode 100644
index 0000000..bac44a0
--- /dev/null
+++ b/CLI/rust/src/game_of_life/simulation.rs
@@ -0,0 +1,48 @@
+/// Implement memeory safe indexing (circular indexing)
+///
+/// When the index is out of bound (being negative or out of bound), the index
+/// will try to fetch the item from the other end of the vector as if it's a
+/// cylinder or circular array
+fn circular_index(mut idx: isize, length: isize) -> usize {
+    while idx.is_negative() {
+        idx += length;
+    }
+    (idx % length) as usize
+}
+
+#[cfg(test)]
+mod circular_index {
+    use super::*;
+
+    #[test]
+    fn negative_index() {
+        assert_eq!(circular_index(-1, 3), 2);
+        assert_eq!(circular_index(-2, 3), 1);
+        assert_eq!(circular_index(-3, 3), 0);
+        assert_eq!(circular_index(-4, 3), 2);
+        assert_eq!(circular_index(-5, 3), 1);
+        assert_eq!(circular_index(-6, 3), 0);
+        assert_eq!(circular_index(-7, 3), 2);
+        assert_eq!(circular_index(-8, 3), 1);
+        assert_eq!(circular_index(-9, 3), 0);
+    }
+
+    #[test]
+    fn positve_index() {
+        assert_eq!(circular_index(0, 3), 0);
+        assert_eq!(circular_index(1, 3), 1);
+        assert_eq!(circular_index(2, 3), 2);
+        assert_eq!(circular_index(3, 3), 0);
+        assert_eq!(circular_index(4, 3), 1);
+        assert_eq!(circular_index(5, 3), 2);
+        assert_eq!(circular_index(6, 3), 0);
+        assert_eq!(circular_index(7, 3), 1);
+        assert_eq!(circular_index(8, 3), 2);
+    }
+}
+
+/// Circular Plane used in Universe traversing
+pub(crate) mod plane;
+
+/// Universe object used for simulation
+pub(crate) mod universe;