improve player management

src/piece.rs

@@ -0,0 +1,29 @@
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub enum Piece {
+    Black,
+    White,
+}
+
+impl Piece {
+    pub const fn flip(&self) -> Self {
+        match self {
+            Piece::Black => Piece::White,
+            Piece::White => Piece::Black,
+        }
+    }
+
+    pub const fn text(&self) -> &'static str {
+        match self {
+            Piece::White => "■",
+            Piece::Black => "□",
+        }
+    }
+}
+
+impl std::ops::Not for Piece {
+    type Output = Piece;
+
+    fn not(self) -> Self::Output {
+        self.flip()
+    }
+}