Move 'FromFen' for 'ChessBoard' into 'fen' module

src/board/chess_board/mod.rs

@@ -1,7 +1,4 @@
-use crate::{
+use crate::movegen;
-    fen::{FenError, FromFen},
-    movegen,
-};
 
 use super::{Bitboard, CastleRights, Color, File, Move, Piece, Rank, Square};
 
@@ -403,94 +400,10 @@ impl Default for ChessBoard {
     }
 }
 
-/// Return a [ChessBoard] from the given FEN string.
-impl FromFen for ChessBoard {
-    type Err = FenError;
-
-    fn from_fen(s: &str) -> Result<Self, Self::Err> {
-        let mut split = s.split_ascii_whitespace();
-
-        let piece_placement = split.next().ok_or(FenError::InvalidFen)?;
-        let side_to_move = split.next().ok_or(FenError::InvalidFen)?;
-        let castling_rights = split.next().ok_or(FenError::InvalidFen)?;
-        let en_passant_square = split.next().ok_or(FenError::InvalidFen)?;
-        let half_move_clock = split.next().ok_or(FenError::InvalidFen)?;
-        let full_move_counter = split.next().ok_or(FenError::InvalidFen)?;
-
-        let mut builder = ChessBoardBuilder::new();
-
-        let castle_rights = <[CastleRights; 2]>::from_fen(castling_rights)?;
-        for color in Color::iter() {
-            builder.with_castle_rights(castle_rights[color.index()], color);
-        }
-
-        let side = Color::from_fen(side_to_move)?;
-        builder.with_current_player(side);
-
-        if let Some(square) = Option::<Square>::from_fen(en_passant_square)? {
-            builder.with_en_passant(square);
-        };
-
-        let half_move_clock = half_move_clock
-            .parse::<u8>()
-            .map_err(|_| FenError::InvalidFen)?;
-        builder.with_half_move_clock(half_move_clock);
-
-        let full_move_counter = full_move_counter
-            .parse::<u32>()
-            .map_err(|_| FenError::InvalidFen)?;
-        builder.with_total_plies(
-            (full_move_counter - 1) * 2 + if side == Color::White { 0 } else { 1 },
-        );
-
-        {
-            let mut rank: usize = 8;
-            for rank_str in piece_placement.split('/') {
-                rank -= 1;
-                let mut file: usize = 0;
-                for c in rank_str.chars() {
-                    let color = if c.is_uppercase() {
-                        Color::White
-                    } else {
-                        Color::Black
-                    };
-                    let piece = match c {
-                        digit @ '1'..='8' => {
-                            // Unwrap is fine since this arm is only matched by digits
-                            file += digit.to_digit(10).unwrap() as usize;
-                            continue;
-                        }
-                        _ => Piece::from_fen(&c.to_string())?,
-                    };
-
-                    // Only need to worry about underflow since those are `usize` values.
-                    if file >= 8 || rank >= 8 {
-                        return Err(FenError::InvalidFen);
-                    };
-
-                    let square = Square::new(File::from_index(file), Rank::from_index(rank));
-
-                    builder[square] = Some((piece, color));
-                    file += 1;
-                }
-                // We haven't read exactly 8 files.
-                if file != 8 {
-                    return Err(FenError::InvalidFen);
-                }
-            }
-            // We haven't read exactly 8 ranks
-            if rank != 0 {
-                return Err(FenError::InvalidFen);
-            }
-        };
-
-        Ok(builder.try_into()?)
-    }
-}
-
 #[cfg(test)]
 mod test {
     use crate::board::MoveBuilder;
+    use crate::fen::FromFen;
 
     use super::*;
 

src/fen.rs

@@ -1,4 +1,6 @@
-use crate::board::{CastleRights, Color, File, InvalidError, Piece, Rank, Square};
+use crate::board::{
+    CastleRights, ChessBoard, ChessBoardBuilder, Color, File, InvalidError, Piece, Rank, Square,
+};
 
 /// A trait to mark items that can be converted from a FEN input.
 pub trait FromFen: Sized {
@@ -115,3 +117,88 @@ impl FromFen for Piece {
         Ok(res)
     }
 }
+
+/// Return a [ChessBoard] from the given FEN string.
+impl FromFen for ChessBoard {
+    type Err = FenError;
+
+    fn from_fen(s: &str) -> Result<Self, Self::Err> {
+        let mut split = s.split_ascii_whitespace();
+
+        let piece_placement = split.next().ok_or(FenError::InvalidFen)?;
+        let side_to_move = split.next().ok_or(FenError::InvalidFen)?;
+        let castling_rights = split.next().ok_or(FenError::InvalidFen)?;
+        let en_passant_square = split.next().ok_or(FenError::InvalidFen)?;
+        let half_move_clock = split.next().ok_or(FenError::InvalidFen)?;
+        let full_move_counter = split.next().ok_or(FenError::InvalidFen)?;
+
+        let mut builder = ChessBoardBuilder::new();
+
+        let castle_rights = <[CastleRights; 2]>::from_fen(castling_rights)?;
+        for color in Color::iter() {
+            builder.with_castle_rights(castle_rights[color.index()], color);
+        }
+
+        let side = Color::from_fen(side_to_move)?;
+        builder.with_current_player(side);
+
+        if let Some(square) = Option::<Square>::from_fen(en_passant_square)? {
+            builder.with_en_passant(square);
+        };
+
+        let half_move_clock = half_move_clock
+            .parse::<u8>()
+            .map_err(|_| FenError::InvalidFen)?;
+        builder.with_half_move_clock(half_move_clock);
+
+        let full_move_counter = full_move_counter
+            .parse::<u32>()
+            .map_err(|_| FenError::InvalidFen)?;
+        builder.with_total_plies(
+            (full_move_counter - 1) * 2 + if side == Color::White { 0 } else { 1 },
+        );
+
+        {
+            let mut rank: usize = 8;
+            for rank_str in piece_placement.split('/') {
+                rank -= 1;
+                let mut file: usize = 0;
+                for c in rank_str.chars() {
+                    let color = if c.is_uppercase() {
+                        Color::White
+                    } else {
+                        Color::Black
+                    };
+                    let piece = match c {
+                        digit @ '1'..='8' => {
+                            // Unwrap is fine since this arm is only matched by digits
+                            file += digit.to_digit(10).unwrap() as usize;
+                            continue;
+                        }
+                        _ => Piece::from_fen(&c.to_string())?,
+                    };
+
+                    // Only need to worry about underflow since those are `usize` values.
+                    if file >= 8 || rank >= 8 {
+                        return Err(FenError::InvalidFen);
+                    };
+
+                    let square = Square::new(File::from_index(file), Rank::from_index(rank));
+
+                    builder[square] = Some((piece, color));
+                    file += 1;
+                }
+                // We haven't read exactly 8 files.
+                if file != 8 {
+                    return Err(FenError::InvalidFen);
+                }
+            }
+            // We haven't read exactly 8 ranks
+            if rank != 0 {
+                return Err(FenError::InvalidFen);
+            }
+        };
+
+        Ok(builder.try_into()?)
+    }
+}