Implemented self_capture and ko rules

kifu/kifu-core/Cargo.lock

@@ -49,6 +49,7 @@ name = "kifu-core"
 version = "0.1.0"
 dependencies = [
  "grid",
+ "thiserror",
  "tokio",
 ]
 
@@ -209,6 +210,37 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "syn"
+version = "2.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79d9531f94112cfc3e4c8f5f02cb2b58f72c97b7efd85f70203cc6d8efda5927"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "978c9a314bd8dc99be594bc3c175faaa9794be04a5a5e153caba6915336cebac"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9456a42c5b0d803c8cd86e73dd7cc9edd429499f37a3550d286d5e86720569f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.12",
+]
+
 [[package]]
 name = "tokio"
 version = "1.26.0"
@@ -237,7 +269,7 @@ checksum = "d266c00fde287f55d3f1c3e96c500c362a2b8c695076ec180f27918820bc6df8"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 1.0.109",
 ]
 
 [[package]]

kifu/kifu-core/Cargo.toml

@@ -8,3 +8,4 @@ edition = "2021"
 [dependencies]
 tokio       = { version = "1.26", features = [ "full" ] }
 grid        = { version = "0.9" }
+thiserror   = { version = "1" }

kifu/kifu-core/src/board.rs

@@ -1,13 +1,6 @@
-use crate::{Color, Size};
+use crate::{BoardError, Color, Size};
-use grid::Grid;
 use std::collections::HashSet;
 
-#[derive(Clone, Debug, PartialEq)]
-pub enum Error {
-    InvalidPosition,
-    SelfCapture,
-}
-
 #[derive(Clone, Debug)]
 pub struct Board {
     pub size: Size,
@@ -16,15 +9,15 @@ pub struct Board {
 
 impl std::fmt::Display for Board {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-        print!("   ");
+        write!(f, "   ")?;
         // for c in 'A'..'U' {
         for c in 0..19 {
-            print!("{:2}", c);
+            write!(f, "{:2}", c)?;
         }
-        println!("");
+        writeln!(f, "")?;
 
         for row in 0..self.size.height {
-            print!(" {:2}", row);
+            write!(f, " {:2}", row)?;
             for column in 0..self.size.width {
                 match self.stone(&Coordinate { column, row }) {
                     None => write!(f, " .")?,
@@ -38,6 +31,26 @@ impl std::fmt::Display for Board {
     }
 }
 
+impl PartialEq for Board {
+    fn eq(&self, other: &Self) -> bool {
+        if self.size != other.size {
+            return false;
+        }
+
+        for group in self.groups.iter() {
+            if !other.groups.contains(&group) {
+                return false;
+            }
+        }
+        for group in other.groups.iter() {
+            if !self.groups.contains(&group) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+
 impl Board {
     pub fn new() -> Self {
         Self {
@@ -49,12 +62,12 @@ impl Board {
         }
     }
 
-    pub fn from_coordinates(coordinates: impl Iterator<Item = (Coordinate, Color)>) -> Self {
+    pub fn from_coordinates(
-        let mut s = Self::new();
+        mut coordinates: impl Iterator<Item = (Coordinate, Color)>,
-        for (coordinate, color) in coordinates {
+    ) -> Result<Self, BoardError> {
-            s.place_stone(coordinate, color);
+        coordinates.try_fold(Self::new(), |board, (coordinate, color)| {
-        }
+            board.place_stone(coordinate, color)
-        s
+        })
     }
 }
 
@@ -65,13 +78,11 @@ pub struct Coordinate {
 }
 
 impl Board {
-    pub fn place_stone(&mut self, coordinate: Coordinate, color: Color) -> Result<(), Error> {
+    pub fn place_stone(mut self, coordinate: Coordinate, color: Color) -> Result<Self, BoardError> {
         if let Some(_) = self.stone(&coordinate) {
-            return Err(Error::InvalidPosition);
+            return Err(BoardError::InvalidPosition);
         }
 
-        let old_groups = self.groups.clone();
-
         let mut friendly_group = self
             .adjacencies(&coordinate)
             .into_iter()
@@ -99,11 +110,10 @@ impl Board {
         }
 
         if self.liberties(&friendly_group) == 0 {
-            self.groups = old_groups;
+            return Err(BoardError::SelfCapture);
-            return Err(Error::SelfCapture);
         }
 
-        Ok(())
+        Ok(self)
     }
 
     pub fn stone(&self, coordinate: &Coordinate) -> Option<Color> {
@@ -268,7 +278,8 @@ mod test {
                 (Coordinate { column: 18, row: 1 }, Color::White),
             ]
             .into_iter(),
-        );
+        )
+        .unwrap();
         test(board);
     }
 
@@ -307,7 +318,8 @@ mod test {
                 ),
             ]
             .into_iter(),
-        );
+        )
+        .unwrap();
         assert!(board.group(&Coordinate { column: 18, row: 3 }).is_none());
         assert_eq!(
             board
@@ -494,8 +506,7 @@ mod test {
 
     #[test]
     fn it_finds_adjacent_groups() {
-        with_example_board(|mut board| {
+        with_example_board(|board| {
-            println!("{}", board);
             let group = board
                 .group(&Coordinate { column: 0, row: 0 })
                 .cloned()
@@ -512,17 +523,23 @@ mod test {
 
     #[test]
     fn surrounding_a_group_removes_it() {
-        with_example_board(|mut board| {
+        with_example_board(|board| {
-            board.place_stone(Coordinate { column: 10, row: 9 }, Color::Black);
+            let board = board
+                .place_stone(Coordinate { column: 10, row: 9 }, Color::Black)
+                .unwrap();
             assert!(board.stone(&Coordinate { column: 9, row: 9 }).is_none());
 
-            board.place_stone(Coordinate { column: 2, row: 18 }, Color::Black);
+            let board = board
+                .place_stone(Coordinate { column: 2, row: 18 }, Color::Black)
+                .unwrap();
             assert!(board.stone(&Coordinate { column: 0, row: 18 }).is_none());
             assert!(board.stone(&Coordinate { column: 1, row: 18 }).is_none());
             assert!(board.stone(&Coordinate { column: 0, row: 17 }).is_none());
             assert!(board.group(&Coordinate { column: 0, row: 18 }).is_none());
 
-            board.place_stone(Coordinate { column: 5, row: 18 }, Color::White);
+            let board = board
+                .place_stone(Coordinate { column: 5, row: 18 }, Color::White)
+                .unwrap();
             assert!(board.stone(&Coordinate { column: 4, row: 17 }).is_none());
             assert!(board.stone(&Coordinate { column: 5, row: 17 }).is_none());
             assert!(board.stone(&Coordinate { column: 6, row: 17 }).is_none());
@@ -533,16 +550,84 @@ mod test {
 
     #[test]
     fn self_capture_is_forbidden() {
-        with_example_board(|mut board| {
+        with_example_board(|board| {
+            {
+                let board = board.clone();
                 let res = board.place_stone(Coordinate { column: 18, row: 0 }, Color::Black);
-            assert_eq!(res, Err(Error::SelfCapture));
+                assert_eq!(res, Err(BoardError::SelfCapture));
+            }
 
+            {
+                let board = board.clone();
                 let res = board.place_stone(Coordinate { column: 5, row: 18 }, Color::Black);
-            assert_eq!(res, Err(Error::SelfCapture));
+                assert_eq!(res, Err(BoardError::SelfCapture));
+            }
         });
     }
 
-    fn captures_preceed_self_capture() {
+    #[test]
-        assert!(false);
+    fn validate_group_comparisons() {
+        {
+            let b1 = Board::from_coordinates(
+                vec![(Coordinate { column: 7, row: 9 }, Color::White)].into_iter(),
+            )
+            .unwrap();
+            let b2 = Board::from_coordinates(
+                vec![(Coordinate { column: 7, row: 9 }, Color::White)].into_iter(),
+            )
+            .unwrap();
+
+            assert_eq!(b1, b2);
+        }
+
+        {
+            let b1 = Board::from_coordinates(
+                vec![
+                    (Coordinate { column: 7, row: 9 }, Color::White),
+                    (Coordinate { column: 8, row: 10 }, Color::White),
+                ]
+                .into_iter(),
+            )
+            .unwrap();
+            let b2 = Board::from_coordinates(
+                vec![
+                    (Coordinate { column: 8, row: 10 }, Color::White),
+                    (Coordinate { column: 7, row: 9 }, Color::White),
+                ]
+                .into_iter(),
+            )
+            .unwrap();
+
+            assert_eq!(b1, b2);
+        }
+    }
+
+    #[test]
+    fn two_boards_can_be_compared() {
+        let board = Board::from_coordinates(
+            vec![
+                (Coordinate { column: 7, row: 9 }, Color::White),
+                (Coordinate { column: 8, row: 8 }, Color::White),
+                (Coordinate { column: 8, row: 10 }, Color::White),
+                (Coordinate { column: 9, row: 9 }, Color::White),
+                (Coordinate { column: 10, row: 9 }, Color::Black),
+                (Coordinate { column: 9, row: 8 }, Color::Black),
+                (Coordinate { column: 9, row: 10 }, Color::Black),
+            ]
+            .into_iter(),
+        )
+        .unwrap();
+
+        let b1 = board
+            .clone()
+            .place_stone(Coordinate { column: 8, row: 9 }, Color::Black)
+            .unwrap();
+
+        let b2 = b1
+            .clone()
+            .place_stone(Coordinate { column: 9, row: 9 }, Color::White)
+            .unwrap();
+
+        assert_eq!(board, b2);
     }
 }

kifu/kifu-core/src/lib.rs

@@ -2,7 +2,7 @@ mod api;
 pub use api::{CoreApp, Request, Response};
 
 mod types;
-pub use types::{Color, Size};
+pub use types::{BoardError, Color, Size};
 pub mod ui;
 
 mod board;

kifu/kifu-core/src/types.rs

@@ -3,6 +3,17 @@ use crate::{
     board::{Board, Coordinate},
 };
 use std::time::Duration;
+use thiserror::Error;
+
+#[derive(Debug, PartialEq, Error)]
+pub enum BoardError {
+    #[error("Position is invalid")]
+    InvalidPosition,
+    #[error("Self-capture is forbidden")]
+    SelfCapture,
+    #[error("Ko")]
+    Ko,
+}
 
 #[derive(Clone, Copy, Debug, PartialEq, Hash, Eq)]
 pub enum Color {
@@ -80,6 +91,8 @@ pub struct Player {
 
 pub struct GameState {
     pub board: Board,
+    pub past_positions: Vec<Board>,
+
     pub conversation: Vec<String>,
     pub current_player: Color,
 
@@ -94,6 +107,7 @@ impl GameState {
     fn new() -> GameState {
         GameState {
             board: Board::new(),
+            past_positions: vec![],
             conversation: vec![],
             current_player: Color::Black,
             white_player: Player {
@@ -109,11 +123,79 @@ impl GameState {
         }
     }
 
-    fn place_stone(&mut self, coordinate: Coordinate) {
+    fn place_stone(&mut self, coordinate: Coordinate) -> Result<(), BoardError> {
-        self.board.place_stone(coordinate, self.current_player);
+        let board = self.board.clone();
+        let new_board = board.place_stone(coordinate, self.current_player)?;
+
+        println!("past positions: {}", self.past_positions.len());
+        if self.past_positions.contains(&new_board) {
+            return Err(BoardError::Ko);
+        }
+
+        self.past_positions.push(self.board.clone());
+        self.board = new_board;
         match self.current_player {
             Color::White => self.current_player = Color::Black,
             Color::Black => self.current_player = Color::White,
-        }
+        };
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn current_player_changes_after_move() {
+        let mut state = GameState::new();
+        assert_eq!(state.current_player, Color::Black);
+        state.place_stone(Coordinate { column: 9, row: 9 }).unwrap();
+        assert_eq!(state.current_player, Color::White);
+    }
+
+    #[test]
+    fn current_player_remains_the_same_after_self_capture() {
+        let mut state = GameState::new();
+        state.board = Board::from_coordinates(
+            vec![
+                (Coordinate { column: 17, row: 0 }, Color::White),
+                (Coordinate { column: 17, row: 1 }, Color::White),
+                (Coordinate { column: 18, row: 1 }, Color::White),
+            ]
+            .into_iter(),
+        )
+        .unwrap();
+        state.current_player = Color::Black;
+
+        assert_eq!(
+            state.place_stone(Coordinate { column: 18, row: 0 }),
+            Err(BoardError::SelfCapture)
+        );
+        assert_eq!(state.current_player, Color::Black);
+    }
+
+    #[test]
+    fn ko_rules_are_enforced() {
+        let mut state = GameState::new();
+        state.board = Board::from_coordinates(
+            vec![
+                (Coordinate { column: 7, row: 9 }, Color::White),
+                (Coordinate { column: 8, row: 8 }, Color::White),
+                (Coordinate { column: 8, row: 10 }, Color::White),
+                (Coordinate { column: 9, row: 9 }, Color::White),
+                (Coordinate { column: 10, row: 9 }, Color::Black),
+                (Coordinate { column: 9, row: 8 }, Color::Black),
+                (Coordinate { column: 9, row: 10 }, Color::Black),
+            ]
+            .into_iter(),
+        )
+        .unwrap();
+
+        state.place_stone(Coordinate { column: 8, row: 9 }).unwrap();
+        assert_eq!(
+            state.place_stone(Coordinate { column: 9, row: 9 }),
+            Err(BoardError::Ko)
+        );
     }
 }

kifu/kifu-gtk/Cargo.lock

@@ -667,6 +667,7 @@ name = "kifu-core"
 version = "0.1.0"
 dependencies = [
  "grid",
+ "thiserror",
  "tokio",
 ]