Detect threefold repetition (#15)

* Refactor alpha-beta search a bit
* Zobrist hashing
* Add GameState::to_fen()
* Small performance improvements to Zobrist hashes
* v0.11

bump_version.sh

@@ -22,8 +22,7 @@ echo Updating package.json
 npm version --allow-same-version --commit-hooks false --git-tag-version false "$new_ver"
 
 echo Updating Cargo.toml
-cd src-tauri
-cargo bump "$new_ver"
+cargo set-version -p chusst-gen "$new_ver"
 
 echo Updating tauri.conf.json
-sed -E -i'' "s/\"version\": \"[0-9.]+\"/\"version\": \"$new_ver\"/" tauri.conf.json
+sed -E -i'' "s/\"version\": \"[0-9.]+\"/\"version\": \"$new_ver\"/" src-tauri/tauri.conf.json

chusst-gen/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "chusst-gen"
-version = "0.10.0"
+version = "0.11.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

chusst-gen/benches/search.rs

@@ -1,15 +1,16 @@
 use divan::Bencher;
 
-use chusst_gen::eval::{Game, SilentSearchFeedback};
+use chusst_gen::eval::{Game, GameHistory, SilentSearchFeedback};
 use chusst_gen::game::BitboardGame;
 
 #[divan::bench]
 fn search(bench: Bencher) {
     bench.bench_local(|| {
         let game = BitboardGame::new();
+        let history = GameHistory::new();
 
         let best_branch = game
-            .get_best_move_recursive(4, &mut (), &mut SilentSearchFeedback::default())
+            .get_best_move_recursive(4, &history, &mut (), &mut SilentSearchFeedback::default())
             .unwrap();
 
         best_branch.searched
@@ -123,9 +124,11 @@ fn game_benchmark() -> u64 {
     // use std::io::Write;
 
     let mut game = BitboardGame::new();
-    let get_best_move_helper = |game: &mut BitboardGame| {
+    let mut history = GameHistory::new();
+
+    let get_best_move_helper = |game: &mut BitboardGame, history: &mut GameHistory| {
         let best_branch = game
-            .get_best_move_recursive(3, &mut (), &mut SilentSearchFeedback::default())
+            .get_best_move_recursive(3, history, &mut (), &mut SilentSearchFeedback::default())
             .unwrap();
 
         (best_branch.searched, best_branch.moves.first().unwrap().mv)
@@ -147,14 +150,14 @@ fn game_benchmark() -> u64 {
         // print!("{}. ", turn);
         // std::io::stdout().flush().unwrap();
 
-        let (white_searched, white_move) = get_best_move_helper(&mut game);
+        let (white_searched, white_move) = get_best_move_helper(&mut game, &mut history);
         // let white_move_name = move_name(&game.board, &game.last_move, &game.player, &white_move);
         game.do_move(&white_move);
 
         // print!("{} ", white_move_name);
         // std::io::stdout().flush().unwrap();
 
-        let (black_searched, black_move) = get_best_move_helper(&mut game);
+        let (black_searched, black_move) = get_best_move_helper(&mut game, &mut history);
         // let black_move_name = move_name(&game.board, &game.last_move, &game.player, &black_move);
         game.do_move(&black_move);
 

chusst-gen/src/board.rs

@@ -555,6 +555,51 @@ pub trait Board:
 
         Some(board)
     }
+
+    fn to_fen(&self) -> String {
+        let mut fen = String::new();
+
+        for rank in (0..8).rev() {
+            let mut empty = 0;
+            for file in 0..8 {
+                let piece = self.at(&pos!(rank, file));
+                match piece {
+                    Some(Piece { piece, player }) => {
+                        if empty > 0 {
+                            fen.push_str(&empty.to_string());
+                            empty = 0;
+                        }
+                        let piece_char = match (player, piece) {
+                            (Player::White, PieceType::Pawn) => 'P',
+                            (Player::White, PieceType::Knight) => 'N',
+                            (Player::White, PieceType::Bishop) => 'B',
+                            (Player::White, PieceType::Rook) => 'R',
+                            (Player::White, PieceType::Queen) => 'Q',
+                            (Player::White, PieceType::King) => 'K',
+                            (Player::Black, PieceType::Pawn) => 'p',
+                            (Player::Black, PieceType::Knight) => 'n',
+                            (Player::Black, PieceType::Bishop) => 'b',
+                            (Player::Black, PieceType::Rook) => 'r',
+                            (Player::Black, PieceType::Queen) => 'q',
+                            (Player::Black, PieceType::King) => 'k',
+                        };
+                        fen.push(piece_char);
+                    }
+                    None => {
+                        empty += 1;
+                    }
+                }
+            }
+            if empty > 0 {
+                fen.push_str(&empty.to_string());
+            }
+            if rank > 0 {
+                fen.push('/');
+            }
+        }
+
+        fen
+    }
 }
 
 fn get_unicode_piece(piece: PieceType, player: Player) -> char {