[board, core] Update error types to use thiserror::Error

board/src/fen.rs

@@ -5,6 +5,7 @@ use chessfriend_core::{
     coordinates::ParseSquareError, piece, Color, File, Piece, PlacedPiece, Rank, Square,
 };
 use std::fmt::Write;
+use thiserror::Error;
 
 #[macro_export]
 macro_rules! fen {
@@ -13,18 +14,24 @@ macro_rules! fen {
     };
 }
 
-#[derive(Clone, Debug, Eq, PartialEq)]
+#[derive(Clone, Debug, Error, Eq, PartialEq)]
 pub enum ToFenStrError {
-    FmtError(std::fmt::Error),
+    #[error("{0}")]
+    FmtError(#[from] std::fmt::Error),
 }
 
-#[derive(Clone, Debug, Eq, PartialEq)]
+#[derive(Clone, Debug, Error, Eq, PartialEq)]
 pub enum FromFenStrError {
+    #[error("missing {0} field")]
     MissingField(Field),
+    #[error("missing piece placement")]
     MissingPlacement,
+    #[error("invalid value")]
     InvalidValue,
-    ParseIntError(std::num::ParseIntError),
-    ParseSquareError(ParseSquareError),
+    #[error("{0}")]
+    ParseIntError(#[from] std::num::ParseIntError),
+    #[error("{0}")]
+    ParseSquareError(#[from] ParseSquareError),
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -37,6 +44,19 @@ pub enum Field {
     FullMoveCounter,
 }
 
+impl std::fmt::Display for Field {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Field::Placements => write!(f, "Placements"),
+            Field::PlayerToMove => write!(f, "Player To Move"),
+            Field::CastlingRights => write!(f, "Castling Rights"),
+            Field::EnPassantSquare => write!(f, "En Passant Square"),
+            Field::HalfMoveClock => write!(f, "Half Move Clock"),
+            Field::FullMoveCounter => write!(f, "Full move Counter"),
+        }
+    }
+}
+
 pub trait ToFenStr {
     type Error;
 

board/src/lib.rs

@@ -10,6 +10,7 @@ mod board;
 mod piece_sets;
 
 pub use board::Board;
+pub use piece_sets::{PlacePieceError, PlacePieceStrategy};
 
 use castle::Castle;
 use en_passant::EnPassant;

board/src/piece_sets.rs

@@ -6,6 +6,7 @@ use self::mailbox::Mailbox;
 use chessfriend_bitboard::{BitBoard, IterationDirection};
 use chessfriend_core::{Color, Piece, Shape, Square};
 use std::ops::BitOr;
+use thiserror::Error;
 
 #[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
 pub enum PlacePieceStrategy {
@@ -14,9 +15,10 @@ pub enum PlacePieceStrategy {
     PreserveExisting,
 }
 
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Debug, Error, Eq, PartialEq)]
 pub enum PlacePieceError {
-    ExisitingPiece(PlacedPiece),
+    #[error("cannot place piece on {square} with existing {piece}")]
+    ExisitingPiece { piece: Piece, square: Square },
 }
 
 /// The internal data structure of a [Board] that efficiently manages the