[board] Declare three new Display-like traits

- ASCIIDisplay → format a type using ASCII only characters
- UnicodeDisplay → format a type using any Unicode characters
- FENDisplay → format a type for inclusion in a FEN string

board/src/display.rs

@@ -0,0 +1,15 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use std::fmt;
+
+pub(crate) trait ASCIIDisplay {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result;
+}
+
+pub(crate) trait UnicodeDisplay {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result;
+}
+
+pub(crate) trait FENDisplay {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result;
+}

board/src/lib.rs

@@ -1,6 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
 mod bitboard;
+mod display;
 mod moves;
 #[macro_use]
 pub mod piece;

board/src/piece.rs

@@ -1,6 +1,9 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{bitboard::BitBoard, Square};
+use crate::{
+    display::{ASCIIDisplay, FENDisplay, UnicodeDisplay},
+    Square,
+};
 use std::fmt;
 use std::slice::Iter;
 
@@ -56,7 +59,7 @@ impl Shape {
 
     fn _ascii_representation(&self) -> char {
         match self {
-            Shape::Pawn => 'p',
+            Shape::Pawn => 'P',
             Shape::Knight => 'N',
             Shape::Bishop => 'B',
             Shape::Rook => 'R',
@@ -168,22 +171,50 @@ impl Piece {
 
 impl fmt::Display for Piece {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let char = match (self.color, self.shape) {
+        UnicodeDisplay::fmt(self, f)
-            (Color::White, Shape::Pawn) => '♟',
+    }
-            (Color::White, Shape::Knight) => '♞',
+}
-            (Color::White, Shape::Bishop) => '♝',
-            (Color::White, Shape::Rook) => '♜',
-            (Color::White, Shape::Queen) => '♛',
-            (Color::White, Shape::King) => '♚',
-            (Color::Black, Shape::Pawn) => '♙',
-            (Color::Black, Shape::Knight) => '♘',
-            (Color::Black, Shape::Bishop) => '♗',
-            (Color::Black, Shape::Rook) => '♖',
-            (Color::Black, Shape::Queen) => '♕',
-            (Color::Black, Shape::King) => '♔',
-        };
 
-        write!(f, "{}", char)
+impl ASCIIDisplay for Piece {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", Into::<char>::into(self.shape()))
+    }
+}
+
+impl UnicodeDisplay for Piece {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "{}",
+            match (self.color, self.shape) {
+                (Color::White, Shape::Pawn) => '♟',
+                (Color::White, Shape::Knight) => '♞',
+                (Color::White, Shape::Bishop) => '♝',
+                (Color::White, Shape::Rook) => '♜',
+                (Color::White, Shape::Queen) => '♛',
+                (Color::White, Shape::King) => '♚',
+                (Color::Black, Shape::Pawn) => '♙',
+                (Color::Black, Shape::Knight) => '♘',
+                (Color::Black, Shape::Bishop) => '♗',
+                (Color::Black, Shape::Rook) => '♖',
+                (Color::Black, Shape::Queen) => '♕',
+                (Color::Black, Shape::King) => '♔',
+            }
+        )
+    }
+}
+
+impl FENDisplay for Piece {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let ascii = self.shape()._ascii_representation();
+        write!(
+            f,
+            "{}",
+            match self.color {
+                Color::White => ascii.to_ascii_uppercase(),
+                Color::Black => ascii.to_ascii_lowercase(),
+            }
+        )
     }
 }