Change Board state to HashMap

rs/src/board.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 #[derive(Clone)]
 enum Color {
     Black,
@@ -204,17 +206,22 @@ impl Piece {
 }
 
 pub struct Board {
-    state: [[Option<Piece>; File::ALL_VALUES.len()]; Rank::ALL_VALUES.len()],
+    state: HashMap<Position, Piece>,
 }
 
 impl Board {
-    pub fn get_at(&self, position: &Position) -> &Option<Piece> {
-        &self.state[position.rank.get_index() as usize]
-            [position.file.get_index() as usize]
+    pub fn get_at(&self, position: &Position) -> Option<&Piece> {
+        return self.state.get(position);
     }
-    fn set_at(&mut self, position: &Position, piece_or_empty: Option<Piece>) {
-        self.state[position.rank.get_index() as usize]
-            [position.file.get_index() as usize] = piece_or_empty;
+    pub fn set_at(
+        &mut self,
+        position: Position,
+        piece_or_empty: Option<Piece>,
+    ) {
+        match piece_or_empty {
+            Some(piece) => self.state.insert(position, piece),
+            None => self.state.remove(&position),
+        };
     }
     pub fn new() -> Board {
         let mut board = Board {
@@ -222,9 +229,12 @@ impl Board {
         };
         for piece_type in &[PieceType::Pawn] {
             for (piece, position) in piece_type.initial_setup() {
-                board.set_at(&position, Some(piece));
+                board.set_at(position, Some(piece));
             }
         }
         board
     }
+    pub fn iter(&self) -> impl Iterator<Item = (&Position, &Piece)> {
+        self.state.iter()
+    }
 }