Improve common types

src/common/transformation.rs

@@ -0,0 +1,42 @@
+use crate::prelude::*;
+
+#[derive(Clone, Copy, Debug)]
+pub struct Transformation {
+    rot: Direction,
+    pos: Position,
+}
+
+impl Transformation {
+    pub fn new(rot: Direction, pos: Position) -> Self {
+        Self { rot, pos }
+    }
+
+    pub fn transform_position(&self, pos: Position) -> Position {
+        (match self.rot {
+            Direction::Up => pos,
+            Direction::Right => Position::new(-pos.y, pos.x),
+            Direction::Down => Position::new(-pos.x, -pos.y),
+            Direction::Left => Position::new(pos.y, -pos.x),
+        }) + self.pos
+    }
+
+    pub fn rot(&self) -> Direction {
+        self.rot
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::prelude::*;
+
+    #[test]
+    fn position() {
+        let p = Position::new(3, 5);
+
+        let t = Transformation::new(Direction::Up, Position::new(-3, -5));
+        assert_eq!(t.transform_position(p), Position::new(0, 0));
+
+        let t = Transformation::new(Direction::Down, Position::new(-3, -5));
+        assert_eq!(t.transform_position(p), Position::new(-6, -10));
+    }
+}