monorepo/kifu/core/src/board.rs

633 lines
21 KiB
Rust

use crate::{BoardError, Color, Size};
use std::collections::HashSet;
#[derive(Clone, Debug, Default)]
pub struct Goban {
pub size: Size,
pub groups: Vec<Group>,
}
impl std::fmt::Display for Goban {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
write!(f, " ")?;
// for c in 'A'..'U' {
for c in 0..19 {
write!(f, "{:2}", c)?;
}
writeln!(f)?;
for row in 0..self.size.height {
write!(f, " {:2}", row)?;
for column in 0..self.size.width {
match self.stone(&Coordinate { column, row }) {
None => write!(f, " .")?,
Some(Color::Black) => write!(f, " X")?,
Some(Color::White) => write!(f, " O")?,
}
}
writeln!(f)?;
}
Ok(())
}
}
impl PartialEq for Goban {
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;
}
}
true
}
}
impl Goban {
pub fn new() -> Self {
Self {
size: Size {
width: 19,
height: 19,
},
groups: Vec::new(),
}
}
pub fn from_coordinates(
mut coordinates: impl Iterator<Item = (Coordinate, Color)>,
) -> Result<Self, BoardError> {
coordinates.try_fold(Self::new(), |board, (coordinate, color)| {
board.place_stone(coordinate, color)
})
}
}
#[derive(Clone, Copy, Debug, PartialEq, Hash, Eq)]
pub struct Coordinate {
pub column: u8,
pub row: u8,
}
impl Goban {
pub fn place_stone(mut self, coordinate: Coordinate, color: Color) -> Result<Self, BoardError> {
if self.stone(&coordinate).is_some() {
return Err(BoardError::InvalidPosition);
}
let mut friendly_group = self
.adjacencies(&coordinate)
.into_iter()
.filter(|c| self.stone(c) == Some(color))
.filter_map(|c| self.group(&c).map(|g| g.coordinates.clone()))
.fold(HashSet::new(), |acc, set| {
acc.union(&set).cloned().collect()
});
friendly_group.insert(coordinate);
self.groups
.retain(|g| g.coordinates.is_disjoint(&friendly_group));
let friendly_group = Group {
color,
coordinates: friendly_group,
};
self.groups.push(friendly_group.clone());
let adjacent_groups = self.adjacent_groups(&friendly_group);
for group in adjacent_groups {
if self.liberties(&group) == 0 {
self.remove_group(&group);
}
}
if self.liberties(&friendly_group) == 0 {
return Err(BoardError::SelfCapture);
}
Ok(self)
}
pub fn stone(&self, coordinate: &Coordinate) -> Option<Color> {
self.groups
.iter()
.find(|g| g.contains(coordinate))
.map(|g| g.color)
}
pub fn group(&self, coordinate: &Coordinate) -> Option<&Group> {
self.groups
.iter()
.find(|g| g.coordinates.contains(coordinate))
}
pub fn remove_group(&mut self, group: &Group) {
self.groups.retain(|g| g != group);
}
pub fn adjacent_groups(&self, group: &Group) -> Vec<Group> {
let adjacent_spaces = self.group_halo(group).into_iter();
let mut grps: Vec<Group> = Vec::new();
adjacent_spaces.for_each(|coord| match self.group(&coord) {
None => {}
Some(adj) => {
if group.color == adj.color {
return;
}
if grps.iter().any(|g| g.coordinates.contains(&coord)) {
return;
}
grps.push(adj.clone());
}
});
grps
}
pub fn group_halo(&self, group: &Group) -> HashSet<Coordinate> {
group
.coordinates
.iter()
.flat_map(|c| self.adjacencies(c))
.collect::<HashSet<Coordinate>>()
}
pub fn liberties(&self, group: &Group) -> usize {
self.group_halo(group)
.into_iter()
.filter(|c| self.stone(c).is_none())
.count()
}
pub fn adjacencies(&self, coordinate: &Coordinate) -> Vec<Coordinate> {
let mut v = Vec::new();
if coordinate.column > 0 {
v.push(Coordinate {
column: coordinate.column - 1,
row: coordinate.row,
});
}
if coordinate.row > 0 {
v.push(Coordinate {
column: coordinate.column,
row: coordinate.row - 1,
});
}
v.push(Coordinate {
column: coordinate.column + 1,
row: coordinate.row,
});
v.push(Coordinate {
column: coordinate.column,
row: coordinate.row + 1,
});
v.into_iter().filter(|c| self.within_board(c)).collect()
}
pub fn within_board(&self, coordinate: &Coordinate) -> bool {
coordinate.column < self.size.width && coordinate.row < self.size.height
}
}
#[derive(Clone, Debug, PartialEq)]
pub struct Group {
color: Color,
coordinates: HashSet<Coordinate>,
}
impl Group {
fn contains(&self, coordinate: &Coordinate) -> bool {
self.coordinates.contains(coordinate)
}
}
#[cfg(test)]
mod test {
use super::*;
/* Two players (Black and White) take turns and Black plays first
* Stones are placed on the line intersections and not moved.
* A stone with no liberties is removed from the board.
* A group of stones of the same color share liberties.
* A stone at the edge of the board has only three liberties.
* A stone at the corner of the board has only two liberties.
* A stone may not be placed in a suicidal position.
* A stone placed in a suicidal position is legal if it captures other stones first.
*/
fn with_example_board(test: impl FnOnce(Goban)) {
let board = Goban::from_coordinates(
vec![
(Coordinate { column: 3, row: 3 }, Color::White),
(Coordinate { column: 3, row: 4 }, Color::White),
/* */
(Coordinate { column: 8, row: 3 }, Color::Black),
(Coordinate { column: 9, row: 3 }, Color::Black),
(Coordinate { column: 9, row: 4 }, Color::Black),
/* */
(Coordinate { column: 15, row: 3 }, Color::White),
(Coordinate { column: 15, row: 4 }, Color::White),
(Coordinate { column: 15, row: 5 }, Color::White),
(Coordinate { column: 14, row: 4 }, Color::White),
/* */
(Coordinate { column: 3, row: 8 }, Color::White),
(Coordinate { column: 3, row: 9 }, Color::White),
(Coordinate { column: 4, row: 9 }, Color::White),
(Coordinate { column: 3, row: 10 }, Color::Black),
/* */
(Coordinate { column: 0, row: 0 }, Color::White),
(Coordinate { column: 1, row: 0 }, Color::White),
(Coordinate { column: 0, row: 1 }, Color::White),
/* */
(Coordinate { column: 9, row: 9 }, Color::White),
(Coordinate { column: 8, row: 9 }, Color::Black),
(Coordinate { column: 9, row: 8 }, Color::Black),
(Coordinate { column: 9, row: 10 }, Color::Black),
/* */
(Coordinate { column: 0, row: 17 }, Color::White),
(Coordinate { column: 1, row: 18 }, Color::White),
(Coordinate { column: 0, row: 18 }, Color::White),
(Coordinate { column: 0, row: 16 }, Color::Black),
(Coordinate { column: 1, row: 17 }, Color::Black),
/* */
(Coordinate { column: 4, row: 17 }, Color::Black),
(Coordinate { column: 5, row: 17 }, Color::Black),
(Coordinate { column: 6, row: 17 }, Color::Black),
(Coordinate { column: 4, row: 18 }, Color::Black),
(Coordinate { column: 6, row: 18 }, Color::Black),
(Coordinate { column: 3, row: 17 }, Color::White),
(Coordinate { column: 3, row: 18 }, Color::White),
(Coordinate { column: 4, row: 16 }, Color::White),
(Coordinate { column: 5, row: 16 }, Color::White),
(Coordinate { column: 6, row: 16 }, Color::White),
(Coordinate { column: 7, row: 17 }, Color::White),
(Coordinate { column: 7, row: 18 }, Color::White),
/* */
(Coordinate { column: 17, row: 0 }, Color::White),
(Coordinate { column: 17, row: 1 }, Color::White),
(Coordinate { column: 18, row: 1 }, Color::White),
]
.into_iter(),
)
.unwrap();
test(board);
}
#[test]
fn it_gets_adjacencies_for_coordinate() {
let board = Goban::new();
for column in 0..19 {
for row in 0..19 {
for coordinate in board.adjacencies(&Coordinate { column, row }) {
assert!(
board.within_board(&coordinate),
"{} {}: {:?}",
column,
row,
coordinate
);
}
}
}
}
#[test]
fn it_counts_individual_liberties() {
let board = Goban::from_coordinates(
vec![
(Coordinate { column: 3, row: 3 }, Color::White),
(Coordinate { column: 0, row: 3 }, Color::White),
(Coordinate { column: 0, row: 0 }, Color::White),
(Coordinate { column: 18, row: 9 }, Color::Black),
(
Coordinate {
column: 18,
row: 18,
},
Color::Black,
),
]
.into_iter(),
)
.unwrap();
assert!(board.group(&Coordinate { column: 18, row: 3 }).is_none());
assert_eq!(
board
.group(&Coordinate { column: 3, row: 3 })
.map(|g| board.liberties(&g)),
Some(4)
);
assert_eq!(
board
.group(&Coordinate { column: 0, row: 3 })
.map(|g| board.liberties(&g)),
Some(3)
);
assert_eq!(
board
.group(&Coordinate { column: 0, row: 0 })
.map(|g| board.liberties(&g)),
Some(2)
);
assert_eq!(
board
.group(&Coordinate { column: 18, row: 9 })
.map(|g| board.liberties(&g)),
Some(3)
);
assert_eq!(
board
.group(&Coordinate {
column: 18,
row: 18
})
.map(|g| board.liberties(&g)),
Some(2)
);
}
#[test]
fn stones_share_liberties() {
with_example_board(|board: Goban| {
let test_cases = vec![
(
board.clone(),
Coordinate { column: 0, row: 0 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 0, row: 0 },
Coordinate { column: 1, row: 0 },
Coordinate { column: 0, row: 1 },
]
.into_iter()
.collect(),
}),
Some(3),
),
(
board.clone(),
Coordinate { column: 1, row: 0 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 0, row: 0 },
Coordinate { column: 1, row: 0 },
Coordinate { column: 0, row: 1 },
]
.into_iter()
.collect(),
}),
Some(3),
),
(
board.clone(),
Coordinate { column: 9, row: 9 },
Some(Group {
color: Color::White,
coordinates: vec![Coordinate { column: 9, row: 9 }].into_iter().collect(),
}),
Some(1),
),
(
board.clone(),
Coordinate { column: 3, row: 4 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 3, row: 3 },
Coordinate { column: 3, row: 4 },
]
.into_iter()
.collect(),
}),
Some(6),
),
(
board.clone(),
Coordinate { column: 9, row: 3 },
Some(Group {
color: Color::Black,
coordinates: vec![
Coordinate { column: 8, row: 3 },
Coordinate { column: 9, row: 3 },
Coordinate { column: 9, row: 4 },
]
.into_iter()
.collect(),
}),
Some(7),
),
(
board.clone(),
Coordinate { column: 15, row: 4 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 15, row: 3 },
Coordinate { column: 15, row: 4 },
Coordinate { column: 15, row: 5 },
Coordinate { column: 14, row: 4 },
]
.into_iter()
.collect(),
}),
Some(8),
),
(
board.clone(),
Coordinate { column: 3, row: 9 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 3, row: 8 },
Coordinate { column: 3, row: 9 },
Coordinate { column: 4, row: 9 },
]
.into_iter()
.collect(),
}),
Some(6),
),
(
board.clone(),
Coordinate { column: 0, row: 18 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 0, row: 17 },
Coordinate { column: 0, row: 18 },
Coordinate { column: 1, row: 18 },
]
.into_iter()
.collect(),
}),
Some(1),
),
(
board.clone(),
Coordinate { column: 0, row: 17 },
Some(Group {
color: Color::White,
coordinates: vec![
Coordinate { column: 0, row: 17 },
Coordinate { column: 0, row: 18 },
Coordinate { column: 1, row: 18 },
]
.into_iter()
.collect(),
}),
Some(1),
),
];
println!("{}", board);
for (board, coordinate, group, liberties) in test_cases {
assert_eq!(board.group(&coordinate), group.as_ref());
assert_eq!(
board.group(&coordinate).map(|g| board.liberties(&g)),
liberties,
"{:?}",
coordinate
);
}
});
}
#[test]
fn it_finds_adjacent_groups() {
with_example_board(|board| {
let group = board
.group(&Coordinate { column: 0, row: 0 })
.cloned()
.unwrap();
assert_eq!(board.adjacent_groups(&group), Vec::new());
let group = board
.group(&Coordinate { column: 3, row: 10 })
.cloned()
.unwrap();
assert_eq!(board.adjacent_groups(&group).len(), 1);
});
}
#[test]
fn surrounding_a_group_removes_it() {
with_example_board(|board| {
let board = board
.place_stone(Coordinate { column: 10, row: 9 }, Color::Black)
.unwrap();
assert!(board.stone(&Coordinate { column: 9, row: 9 }).is_none());
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());
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());
assert!(board.stone(&Coordinate { column: 4, row: 18 }).is_none());
assert!(board.stone(&Coordinate { column: 6, row: 18 }).is_none());
});
}
#[test]
fn self_capture_is_forbidden() {
with_example_board(|board| {
{
let board = board.clone();
let res = board.place_stone(Coordinate { column: 18, row: 0 }, Color::Black);
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(BoardError::SelfCapture));
}
});
}
#[test]
fn validate_group_comparisons() {
{
let b1 = Goban::from_coordinates(
vec![(Coordinate { column: 7, row: 9 }, Color::White)].into_iter(),
)
.unwrap();
let b2 = Goban::from_coordinates(
vec![(Coordinate { column: 7, row: 9 }, Color::White)].into_iter(),
)
.unwrap();
assert_eq!(b1, b2);
}
{
let b1 = Goban::from_coordinates(
vec![
(Coordinate { column: 7, row: 9 }, Color::White),
(Coordinate { column: 8, row: 10 }, Color::White),
]
.into_iter(),
)
.unwrap();
let b2 = Goban::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 = Goban::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);
}
}