WIP

.drone.yml

@@ -6,7 +6,7 @@ name: abacus checks
 steps:
 - name: pre commit check
   commands:
-  - nix develop . --command pre-commit run --all
+  - nix develop . --command cargo vendor
 
 - name: flake check
   commands:

flake.nix

@@ -80,42 +80,44 @@
         rustc = my-rust;
       };
       inherit (pkgs) lib;
-      pre-commit =
-        let
-          # See https://github.com/cachix/pre-commit-hooks.nix/issues/126
-          rust-env = pkgs.buildEnv {
-            name = "rust-env";
-            buildInputs = [ pkgs.makeWrapper ];
-            paths = [ my-rust ];
-            pathsToLink = [ "/" "/bin" ];
-            postBuild = ''
-              for i in $out/bin/*; do
-                wrapProgram "$i" --prefix PATH : "$out/bin"
-              done
-            '';
-          };
-        in
-        pre-commit-hooks.lib.${system}.run {
-          src = self;
-
-          hooks = {
-            clippy = {
-              enable = true;
-              entry = lib.mkForce "${rust-env}/bin/cargo-clippy clippy";
-            };
-
-            nixpkgs-fmt = {
-              enable = true;
-            };
-
-            rustfmt = {
-              enable = true;
-              entry = lib.mkForce "${rust-env}/bin/cargo-fmt fmt -- --check --color always";
-            };
-          };
-        };
     in
     rec {
+      checks = {
+        pre-commit =
+          let
+            # See https://github.com/cachix/pre-commit-hooks.nix/issues/126
+            rust-env = pkgs.buildEnv {
+              name = "rust-env";
+              buildInputs = [ pkgs.makeWrapper ];
+              paths = [ my-rust ];
+              pathsToLink = [ "/" "/bin" ];
+              postBuild = ''
+                for i in $out/bin/*; do
+                  wrapProgram "$i" --prefix PATH : "$out/bin"
+                done
+              '';
+            };
+          in
+          pre-commit-hooks.lib.${system}.run {
+            src = self;
+
+            hooks = {
+              clippy = {
+                enable = true;
+                entry = lib.mkForce "${rust-env}/bin/cargo-clippy clippy";
+              };
+
+              nixpkgs-fmt = {
+                enable = true;
+              };
+
+              rustfmt = {
+                enable = true;
+                entry = lib.mkForce "${rust-env}/bin/cargo-fmt fmt -- --check --color always";
+              };
+            };
+          };
+      };
 
       devShells = {
         default = pkgs.mkShell {
@@ -129,7 +131,7 @@
             my-rust
           ];
 
-          inherit (pre-commit) shellHook;
+          inherit (checks.pre-commit) shellHook;
 
           RUST_SRC_PATH = "${my-rust}/lib/rustlib/src/rust/library";
         };

src/board/castle_rights.rs

@@ -1,4 +1,5 @@
-use super::{Bitboard, Color, File, Square};
+use super::{Bitboard, Color, File, FromFen, Square};
+use crate::error::Error;
 
 /// Current castle rights for a player.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -108,6 +109,39 @@ impl CastleRights {
     }
 }
 
+/// Convert the castling rights segment of a FEN string to an array of [CastleRights].
+impl FromFen for [CastleRights; 2] {
+    type Err = Error;
+
+    fn from_fen(s: &str) -> Result<Self, Self::Err> {
+        if s.len() > 4 {
+            return Err(Error::InvalidFen);
+        }
+
+        let mut res = [CastleRights::NoSide; 2];
+
+        if s == "-" {
+            return Ok(res);
+        }
+
+        for b in s.chars() {
+            let color = if b.is_uppercase() {
+                Color::White
+            } else {
+                Color::Black
+            };
+            let rights = &mut res[color.index()];
+            match b {
+                'k' | 'K' => *rights = rights.with_king_side(),
+                'q' | 'Q' => *rights = rights.with_queen_side(),
+                _ => return Err(Error::InvalidFen),
+            }
+        }
+
+        Ok(res)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

src/board/color.rs

@@ -1,4 +1,5 @@
-use super::{Direction, Rank};
+use super::{Direction, FromFen, Rank};
+use crate::error::Error;
 
 /// An enum representing the color of a player.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -106,6 +107,20 @@ impl Color {
     }
 }
 
+/// Convert a side to move segment of a FEN string to a [Color].
+impl FromFen for Color {
+    type Err = Error;
+
+    fn from_fen(s: &str) -> Result<Self, Self::Err> {
+        let res = match s {
+            "w" => Color::White,
+            "b" => Color::Black,
+            _ => return Err(Error::InvalidFen),
+        };
+        Ok(res)
+    }
+}
+
 impl std::ops::Not for Color {
     type Output = Color;
 

src/board/piece.rs

@@ -1,3 +1,6 @@
+use super::FromFen;
+use crate::error::Error;
+
 /// An enum representing the type of a piece.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Piece {
@@ -52,6 +55,23 @@ impl Piece {
     }
 }
 
+impl FromFen for Piece {
+    type Err = Error;
+
+    fn from_fen(s: &str) -> Result<Self, Self::Err> {
+        let res = match s {
+            "p" | "P" => Self::Pawn,
+            "n" | "N" => Self::Knight,
+            "b" | "B" => Self::Bishop,
+            "r" | "R" => Self::Rook,
+            "q" | "Q" => Self::Queen,
+            "k" | "K" => Self::King,
+            _ => return Err(Error::InvalidFen),
+        };
+        Ok(res)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

src/board/square.rs

@@ -1,5 +1,5 @@
-use super::{Bitboard, File, Rank};
-use crate::utils::static_assert;
+use super::{Bitboard, File, FromFen, Rank};
+use crate::{error::Error, utils::static_assert};
 
 /// Represent a square on a chessboard. Defined in the same order as the
 /// [Bitboard] squares.
@@ -107,6 +107,23 @@ impl Square {
     }
 }
 
+/// Convert an en-passant target square segment of a FEN string to an optional [Square].
+impl FromFen for Option<Square> {
+    type Err = Error;
+
+    fn from_fen(s: &str) -> Result<Self, Self::Err> {
+        let res = match s.as_bytes() {
+            [b'-'] => None,
+            [file @ b'a'..=b'h', rank @ b'1'..=b'8'] => Some(Square::new(
+                File::from_index((file - b'a') as usize),
+                Rank::from_index((rank - b'1') as usize),
+            )),
+            _ => return Err(Error::InvalidFen),
+        };
+        Ok(res)
+    }
+}
+
 /// Shift the square's index left by the amount given.
 impl std::ops::Shl<usize> for Square {
     type Output = Square;