[board] Add an option to display a board with ASCII characters

board/src/display.rs

@@ -5,9 +5,17 @@ use chessfriend_bitboard::BitBoard;
 use chessfriend_core::{File, Rank, Square};
 use std::fmt;
 
+#[derive(Default)]
+pub enum PieceDisplayStyle {
+    #[default]
+    Unicode,
+    ASCII,
+}
+
 #[must_use]
 pub struct DiagramFormatter<'a> {
     board: &'a Board,
+    piece_style: PieceDisplayStyle,
     marked_squares: BitBoard,
     highlighted_squares: BitBoard,
 }
@@ -16,6 +24,7 @@ impl<'a> DiagramFormatter<'a> {
     pub fn new(board: &'a Board) -> Self {
         Self {
             board,
+            piece_style: PieceDisplayStyle::default(),
             marked_squares: BitBoard::default(),
             highlighted_squares: BitBoard::default(),
         }
@@ -48,7 +57,11 @@ impl fmt::Display for DiagramFormatter<'_> {
                 }
 
                 if let Some(piece) = self.board.get_piece(square) {
-                    write!(f, "{piece}")?;
+                    let ch = match self.piece_style {
+                        PieceDisplayStyle::Unicode => piece.to_unicode(),
+                        PieceDisplayStyle::ASCII => piece.to_ascii(),
+                    };
+                    write!(f, "{ch}")?;
                 } else {
                     let ch = if self.marked_squares.contains(square) {
                         '*'

core/src/pieces.rs

@@ -63,7 +63,7 @@ impl Piece {
     }
 
     #[must_use]
-    fn to_unicode(self) -> char {
+    pub fn to_unicode(self) -> char {
         match (self.color, self.shape) {
             (Color::Black, Shape::Pawn) => '♟',
             (Color::Black, Shape::Knight) => '♞',