Pass Mailbox instead of Game on related functions for clarity

src/board/game.rs

@@ -47,7 +47,7 @@ impl Game {
 
     pub fn make_move(&mut self, mv: &Move) {
         self.history
-            .push_move_parameters(MoveParameters::build(&self, mv));
+            .push_move_parameters(MoveParameters::build(self, mv));
 
         let board = &mut self.board;
         let mailbox = &mut self.mailbox;

src/board/history.rs

@@ -3,6 +3,7 @@ use crate::movegen::r#move::{Move, MoveType};
 use super::{
     board::PieceType,
     game::Game,
+    mailbox::Mailbox,
     state::{Castle, State},
 };
 
@@ -55,8 +56,8 @@ impl MoveParameters {
         let mut move_parameters = Self::new();
         move_parameters.add_move(*mv);
         move_parameters.add_irreversible_parameters(game.board.state);
-        move_parameters.add_moved_piece(game, mv);
+        move_parameters.add_moved_piece(&game.mailbox, mv);
-        move_parameters.add_captured_piece(game, mv);
+        move_parameters.add_captured_piece(&game.mailbox, mv);
         move_parameters.add_promoted_piece(mv);
 
         move_parameters
@@ -66,13 +67,13 @@ impl MoveParameters {
         self.mv = Some(mv);
     }
 
-    fn add_moved_piece(&mut self, game: &Game, mv: &Move) {
+    fn add_moved_piece(&mut self, mailbox: &Mailbox, mv: &Move) {
-        self.moved_piece = game.mailbox.find_piece_at(mv.src);
+        self.moved_piece = mailbox.find_piece_at(mv.src);
     }
 
-    fn add_captured_piece(&mut self, game: &Game, mv: &Move) {
+    fn add_captured_piece(&mut self, mailbox: &Mailbox, mv: &Move) {
         if let MoveType::Capture | MoveType::PromotionCapture(_) = mv.move_type {
-            self.captured_piece = game.mailbox.find_piece_at(mv.dst)
+            self.captured_piece = mailbox.find_piece_at(mv.dst)
         }
     }
 
@@ -91,7 +92,7 @@ impl MoveParameters {
 
 impl Default for MoveParameters {
     fn default() -> Self {
-        MoveParameters::new()
+        Self::new()
     }
 }
 

src/movegen/move.rs

@@ -4,6 +4,7 @@ use std::str::Chars;
 use crate::board::{
     board::PieceType,
     game::Game,
+    mailbox::Mailbox,
     square::{coords_to_square, square_to_algebraic},
 };
 
@@ -117,12 +118,17 @@ impl Move {
             None
         };
 
-        Ok(Self::build_with_type(game, src, dst, promote_into))
+        Ok(Self::build_with_type(&game.mailbox, src, dst, promote_into))
     }
 
-    fn build_with_type(game: &Game, src: usize, dst: usize, promote_into: Option<Promote>) -> Self {
+    fn build_with_type(
-        let moving = game.mailbox.find_piece_at(src);
+        mailbox: &Mailbox,
-        let captured = game.mailbox.find_piece_at(dst);
+        src: usize,
+        dst: usize,
+        promote_into: Option<Promote>,
+    ) -> Self {
+        let moving = mailbox.find_piece_at(src);
+        let captured = mailbox.find_piece_at(dst);
 
         match (captured, promote_into) {
             (Some(_), None) => return Self::new_with_type(src, dst, MoveType::Capture),

src/search/move_ordering.rs

@@ -1,4 +1,4 @@
-use crate::{board::game::Game, movegen::r#move::Move};
+use crate::{board::mailbox::Mailbox, movegen::r#move::Move};
 
 // Rows: Aggressors (P, N, B, R, Q, K)
 // Columns: Victims (K, Q, R, B, N, P)
@@ -12,11 +12,8 @@ const MVV_LVA: [[usize; 6]; 6] = [
     [5,   4,  3,  2,  1, 0],
 ];
 
-pub fn score_by_mvv_lva(game: &Game, mv: Move) -> usize {
+pub const fn score_by_mvv_lva(mailbox: &Mailbox, mv: Move) -> usize {
-    match (
+    match (mailbox.find_piece_at(mv.src), mailbox.find_piece_at(mv.dst)) {
-        game.mailbox.find_piece_at(mv.src),
-        game.mailbox.find_piece_at(mv.dst),
-    ) {
         (Some(aggressor), Some(victim)) => MVV_LVA[aggressor.idx()][victim.idx()],
         _ => 0,
     }
@@ -36,7 +33,7 @@ mod tests {
     fn test_score_by_mvv_lva() -> Result<(), String> {
         let game = from_fen(FEN)?;
         let f3f5 = Move::new_with_type(Square::F3, Square::F5, MoveType::Capture);
-        let actual = score_by_mvv_lva(&game, f3f5);
+        let actual = score_by_mvv_lva(&game.mailbox, f3f5);
         let expected = MVV_LVA[PieceType::Queen.idx()][PieceType::Pawn.idx()];
 
         assert_eq!(expected, actual);

src/search/negamax.rs

@@ -23,7 +23,7 @@ pub fn negamax(
     let mut legal_moves = 0;
 
     let mut pseudo_legal_moves = game.board.pseudo_moves_all();
-    pseudo_legal_moves.sort_unstable_by_key(|mv| score_by_mvv_lva(&game, *mv));
+    pseudo_legal_moves.sort_unstable_by_key(|mv| score_by_mvv_lva(&game.mailbox, *mv));
 
     for mv in pseudo_legal_moves {
         game.make_move(&mv);

src/search/quiescence.rs

@@ -30,7 +30,7 @@ pub fn quiescence(game: &mut Game, mut alpha: i32, beta: i32) -> (Option<Move>,
         })
         .collect();
 
-    captures.sort_unstable_by_key(|mv| score_by_mvv_lva(&game, *mv));
+    captures.sort_unstable_by_key(|mv| score_by_mvv_lva(&game.mailbox, *mv));
 
     for mv in captures {
         game.make_move(&mv);