Add Plane (circular array) implementation w/testing

Refactor the code to use Plane struct instead of Vec<bool>

1 files changed, 184 insertions, 2 deletions

diff --git a/CLI/rust/src/game_of_life/universe.rs b/CLI/rust/src/game_of_life/universe.rs
index 83cb7d7..11912fd 100644
--- a/CLI/rust/src/game_of_life/universe.rs
+++ b/CLI/rust/src/game_of_life/universe.rs
@@ -1,9 +1,191 @@
 use crate::game_of_life::opts::Opts;
+use std::ops::{Index, IndexMut};
+
+/// 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);
+    }
+}
+
+/// Game of Life universe building blocks (a plane is a circular Vec)
+///
+/// This is used internally in the implementation of the Universe to allow
+/// more readable and safer traversing of the universe blocks
+#[derive(Debug, Clone, PartialEq)]
+pub(crate) struct Plane(pub Vec<bool>);
+
+impl Index<isize> for Plane {
+    type Output = bool;
+    fn index(&self, idx: isize) -> &bool {
+        let len = self.0.len() as isize;
+        &self.0[circular_index(idx, len)]
+    }
+}
+
+impl IndexMut<isize> for Plane {
+    fn index_mut(&mut self, idx: isize) -> &mut Self::Output {
+        let len = self.0.len() as isize;
+        &mut self.0[circular_index(idx, len)]
+    }
+}
+
+#[cfg(test)]
+mod plane {
+    use super::*;
+
+    mod index {
+        use super::*;
+
+        #[test]
+        fn get_element() {
+            let p = Plane(vec![false, false, true, false, false]);
+            assert_eq!(p[0], false);
+            assert_eq!(p[1], false);
+            assert_eq!(p[3], false);
+            assert_eq!(p[4], false);
+
+            assert_eq!(p[-3], true);
+            assert_eq!(p[2], true);
+            assert_eq!(p[7], true);
+        }
+    }
+
+    #[cfg(test)]
+    mod index_mut {
+        use super::*;
+
+        #[test]
+        fn set_negative_index_element() {
+            let mut p = Plane(vec![false, false, false, false, false]);
+            p[-3] = true;
+            assert_eq!(p, Plane(vec![false, false, true, false, false]));
+        }
+
+        #[test]
+        fn set_element() {
+            let mut p = Plane(vec![false, false, false, false, false]);
+            p[2] = true;
+            assert_eq!(p, Plane(vec![false, false, true, false, false]));
+        }
+
+        #[test]
+        fn set_out_of_bound_element() {
+            let mut p = Plane(vec![false, false, false, false, false]);
+            p[7] = true;
+            assert_eq!(p, Plane(vec![false, false, true, false, false]));
+        }
+    }
+}
+
 
 /// Game of Life universe struct for running simulations
 #[derive(Debug, Clone, PartialEq)]
 pub(crate) struct Universe {
     pub opts: Opts,
-    pub current: Vec<Vec<bool>>,
-    pub future: Vec<Vec<bool>>,
+    pub current: Vec<Plane>,
+    pub future: Vec<Plane>,
+}
+
+impl Index<isize> for Universe
+{
+    type Output = Plane;
+    fn index(&self, idx: isize) -> &Plane {
+        let len = self.current.len() as isize;
+        &self.current[circular_index(idx, len)]
+    }
+}
+
+#[cfg(test)]
+mod universe {
+    use super::*;
+
+    mod index {
+        use super::*;
+
+        #[test]
+        fn get_element() {
+            let opts = Opts {
+                seed: 1337,
+                input: None,
+                width: 13,
+                height: 13,
+                live_cell: 'L',
+                dead_cell: 'D',
+                delay: 13,
+            };
+            let u = Universe {
+                opts,
+                current: vec![
+                    Plane(vec![false; 5]),
+                    Plane(vec![false, false, true, false, false]),
+                    Plane(vec![false; 5]),
+                ],
+                future: vec![Plane(vec![])],
+            };
+
+            assert_eq!(u[-3][0], false);
+            assert_eq!(u[-3][1], false);
+            assert_eq!(u[-3][3], false);
+            assert_eq!(u[-3][4], false);
+            assert_eq!(u[0][0], false);
+            assert_eq!(u[0][1], false);
+            assert_eq!(u[0][3], false);
+            assert_eq!(u[0][4], false);
+            assert_eq!(u[2][0], false);
+            assert_eq!(u[2][1], false);
+            assert_eq!(u[2][3], false);
+            assert_eq!(u[2][4], false);
+            assert_eq!(u[5][0], false);
+            assert_eq!(u[5][1], false);
+            assert_eq!(u[5][3], false);
+            assert_eq!(u[5][4], false);
+
+            assert_eq!(u[-2][-3], true);
+            assert_eq!(u[-2][2], true);
+            assert_eq!(u[-2][7], true);
+            assert_eq!(u[1][-3], true);
+            assert_eq!(u[1][2], true);
+            assert_eq!(u[1][7], true);
+            assert_eq!(u[4][-3], true);
+            assert_eq!(u[4][2], true);
+            assert_eq!(u[4][7], true);
+        }
+    }
 }