1 files changed, 57 insertions, 0 deletions
diff --git a/2024_rust/src/lib.rs b/2024_rust/src/lib.rs
index f1a6a68..1bf0a7a 100644
--- a/2024_rust/src/lib.rs
+++ b/2024_rust/src/lib.rs
@@ -1,3 +1,51 @@
+pub mod direction {
+    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+    pub enum Direction {
+        Up,
+        Right,
+        Down,
+        Left,
+    }
+    use Direction::*;
+
+    impl Direction {
+        pub fn iter_all() -> impl Iterator<Item = Self> {
+            [Up, Right, Down, Left].into_iter()
+        }
+
+        pub fn to_offset(&self) -> (isize, isize) {
+            match self {
+                Up => (-1, 0),
+                Right => (0, 1),
+                Down => (1, 0),
+                Left => (0, -1),
+            }
+        }
+
+        pub fn rotate(&self) -> Self {
+            match self {
+                Up => Right,
+                Right => Down,
+                Down => Left,
+                Left => Up,
+            }
+        }
+
+        pub fn around(&self) -> impl Iterator<Item = Self> + use<'_> {
+            Self::iter_all().filter(|&x| x != self.opposite())
+        }
+
+        pub fn opposite(&self) -> Self {
+            match self {
+                Up => Down,
+                Right => Left,
+                Down => Up,
+                Left => Right,
+            }
+        }
+    }
+}
+
 pub mod matrix {
     pub type Pos = (usize, usize);
     pub type PosDelta = (isize, isize);
@@ -29,6 +77,15 @@ pub mod matrix {
             self.dots[x][y] = dot;
         }
 
+        pub fn in_bounds(&self, (x, y): PosDelta) -> Option<Pos> {
+            if x >= 0 && y >= 0 && x < self.limit.0 as isize && y < self.limit.1 as isize {
+                Some((x as usize, y as usize))
+            } else {
+                None
+            }
+        }
+
+        // todo use in_bounds
         pub fn pos_move(&self, (x, y): Pos, (dx, dy): PosDelta) -> Option<Pos> {
             let x2 = x as isize + dx;
             if x2 < 0 || x2 >= self.limit.0 as isize {