[board, explorer, moves] Make Board::active_color private

Make the struct attribute private, and export two new methods. A getter, active_color(),
and a setter, set_active_color().

Update all references to the attribute to use the methods.

board/src/board.rs

@@ -14,7 +14,7 @@ pub type FullMoveClock = u32;
 
 #[derive(Clone, Debug, Default, Eq, PartialEq)]
 pub struct Board {
-    pub active_color: Color,
+    active_color: Color,
     pieces: PieceSet,
     pub castling_rights: castle::Rights,
     pub en_passant_target: Option<Square>,
@@ -58,6 +58,19 @@ impl Board {
 }
 
 impl Board {
+    #[must_use]
+    pub fn active_color(&self) -> Color {
+        self.active_color
+    }
+
+    pub fn set_active_color(&mut self, color: Color) {
+        if color == self.active_color {
+            return;
+        }
+
+        self.active_color = color;
+    }
+
     #[must_use]
     pub fn get_piece(&self, square: Square) -> Option<Piece> {
         self.pieces.get(square)

board/src/castle.rs

@@ -78,13 +78,13 @@ impl Board {
     }
 
     pub(crate) fn castling_king(&self, square: Square) -> Option<Piece> {
-        let active_color = self.active_color;
+        let active_color = self.active_color();
         self.get_piece(square)
             .filter(|piece| piece.color == active_color && piece.is_king())
     }
 
     pub(crate) fn castling_rook(&self, square: Square) -> Option<Piece> {
-        let active_color = self.active_color;
+        let active_color = self.active_color();
         self.get_piece(square)
             .filter(|piece| piece.color == active_color && piece.is_rook())
     }

board/src/check.rs

@@ -7,7 +7,7 @@ use chessfriend_core::{Color, Piece};
 impl Board {
     #[must_use]
     pub fn active_color_is_in_check(&self) -> bool {
-        self.unwrapped_color_is_in_check(self.active_color)
+        self.unwrapped_color_is_in_check(self.active_color())
     }
 
     #[must_use]

board/src/fen.rs

@@ -113,7 +113,7 @@ impl ToFenStr for Board {
             }
         }
 
-        write!(fen_string, " {}", self.active_color.to_fen_str()?)
+        write!(fen_string, " {}", self.active_color().to_fen_str()?)
             .map_err(ToFenStrError::FmtError)?;
 
         let castling = [
@@ -224,7 +224,7 @@ impl FromFenStr for Board {
                 .next()
                 .ok_or(FromFenStrError::MissingField(Field::PlayerToMove))?,
         )?;
-        board.active_color = active_color;
+        board.set_active_color(active_color);
 
         let castling_rights = fields
             .next()

board/src/macros.rs

@@ -13,7 +13,7 @@ macro_rules! test_board {
                 chessfriend_core::Square::$square,
                 $crate::PlacePieceStrategy::default());
             )*
-            board.active_color = chessfriend_core::Color::$to_move;
+            board.set_active_color(chessfriend_core::Color::$to_move);
             board.en_passant_target = Some(chessfriend_core::Square::$en_passant);
 
             println!("{}", board.display());

board/src/sight.rs

@@ -32,7 +32,7 @@ impl Board {
     }
 
     pub fn active_sight(&self) -> BitBoard {
-        self.friendly_sight(self.active_color)
+        self.friendly_sight(self.active_color())
     }
 
     /// A [`BitBoard`] of all squares the given color can see.
@@ -45,7 +45,7 @@ impl Board {
     }
 
     pub fn active_color_opposing_sight(&self) -> BitBoard {
-        self.opposing_sight(self.active_color)
+        self.opposing_sight(self.active_color())
     }
 
     /// A [`BitBoard`] of all squares visible by colors that oppose the given color.