seer/src/board/direction.rs

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use super::{Bitboard, Rank, Square};
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/// A direction on the board. Either along the rook, bishop, or knight directions
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum Direction {
North,
West,
South,
East,
NorthWest,
SouthWest,
SouthEast,
NorthEast,
NorthNorthWest,
NorthWestWest,
SouthWestWest,
SouthSouthWest,
SouthSouthEast,
SouthEastEast,
NorthEastEast,
NorthNorthEast,
}
impl Direction {
/// Directions that a rook could use.
pub const ROOK_DIRECTIONS: [Self; 4] = [Self::North, Self::West, Self::South, Self::East];
/// Directions that a bishop could use.
pub const BISHOP_DIRECTIONS: [Self; 4] = [
Self::NorthWest,
Self::SouthWest,
Self::SouthEast,
Self::NorthEast,
];
/// Directions that a knight could use.
pub const KNIGHT_DIRECTIONS: [Self; 8] = [
Self::NorthNorthWest,
Self::NorthWestWest,
Self::SouthWestWest,
Self::SouthSouthWest,
Self::SouthSouthEast,
Self::SouthEastEast,
Self::NorthEastEast,
Self::NorthNorthEast,
];
/// Iterate over all directions a rook can take.
pub fn iter_rook() -> impl Iterator<Item = Direction> {
Self::ROOK_DIRECTIONS.iter().cloned()
}
/// Iterate over all directions a bishop can take.
pub fn iter_bishop() -> impl Iterator<Item = Direction> {
Self::BISHOP_DIRECTIONS.iter().cloned()
}
/// Iterate over all directions a queen or king can take.
pub fn iter_royalty() -> impl Iterator<Item = Direction> {
Self::iter_rook().chain(Self::iter_bishop())
}
/// Iterate over all directions a knight can take.
pub fn iter_knight() -> impl Iterator<Item = Direction> {
Self::KNIGHT_DIRECTIONS.iter().cloned()
}
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/// Move a [Square] along the given [Direction], unless it would wrap at the end of the board
pub fn move_square(self, square: Square) -> Option<Square> {
let res = self.move_board(square.into_bitboard());
res.into_iter().next()
}
/// Move every piece on a board along the given direction. Do not wrap around the board.
#[inline(always)]
pub fn move_board(self, board: Bitboard) -> Bitboard {
// No need to filter for A/H ranks thanks to wrapping
match self {
Self::North => (board - Rank::Eighth.into_bitboard()) << 1,
Self::West => board >> 8,
Self::South => (board - Rank::First.into_bitboard()) >> 1,
Self::East => board << 8,
Self::NorthWest => (board - Rank::Eighth.into_bitboard()) >> 7,
Self::SouthWest => (board - Rank::First.into_bitboard()) >> 9,
Self::SouthEast => (board - Rank::First.into_bitboard()) << 7,
Self::NorthEast => (board - Rank::Eighth.into_bitboard()) << 9,
Self::NorthNorthWest => {
(board - Rank::Eighth.into_bitboard() - Rank::Seventh.into_bitboard()) >> 6
}
Self::NorthWestWest => (board - Rank::Eighth.into_bitboard()) >> 15,
Self::SouthWestWest => (board - Rank::First.into_bitboard()) >> 17,
Self::SouthSouthWest => {
(board - Rank::First.into_bitboard() - Rank::Second.into_bitboard()) >> 10
}
Self::SouthSouthEast => {
(board - Rank::First.into_bitboard() - Rank::Second.into_bitboard()) << 6
}
Self::SouthEastEast => (board - Rank::First.into_bitboard()) << 15,
Self::NorthEastEast => (board - Rank::Eighth.into_bitboard()) << 17,
Self::NorthNorthEast => {
(board - Rank::Eighth.into_bitboard() - Rank::Seventh.into_bitboard()) << 10
}
}
}
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/// Slide a board along the given [Direction], i.e: return all successive applications of
/// [Direction::move_square] until no new squares can be reached.
/// It does not make sense to use this method with knight-only directions, and it will panic in
/// debug-mode if it happens.
#[inline(always)]
pub fn slide_square(self, square: Square) -> Bitboard {
self.slide_board(square.into_bitboard())
}
/// Slide a board along the given [Direction], i.e: return all successive applications of
/// [Direction::move_board] until no new squares can be reached.
/// It does not make sense to use this method with knight-only directions, and it will panic in
/// debug-mode if it happens.
#[inline(always)]
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pub fn slide_board(self, board: Bitboard) -> Bitboard {
self.slide_board_with_blockers(board, Bitboard::EMPTY)
}
/// Slide a board along the given [Direction], i.e: return all successive applications of
/// [Direction::move_board] until no new squares can be reached.
/// Take into account the `blockers` [Bitboard]: a combination of all pieces on the board which
/// cannot be slid over. The slide is over once a square that is part of `blockers` is reached.
/// It does not make sense to use this method with knight-only directions, and it will panic in
/// debug-mode if it happens.
#[inline(always)]
pub fn slide_board_with_blockers(self, mut board: Bitboard, blockers: Bitboard) -> Bitboard {
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debug_assert!(!Self::KNIGHT_DIRECTIONS.contains(&self));
let mut res = Default::default();
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while !board.is_empty() {
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board = self.move_board(board);
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res |= board;
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if !(board & blockers).is_empty() {
break;
}
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}
res
}
}
#[cfg(test)]
mod test {
use super::*;
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use crate::board::{File, Rank};
#[test]
fn north() {
assert_eq!(
Direction::North.move_board(Square::A1.into_bitboard()),
Square::A2.into_bitboard()
);
assert_eq!(
Direction::North.move_board(Square::A2.into_bitboard()),
Square::A3.into_bitboard()
);
assert_eq!(
Direction::North.move_board(Square::A7.into_bitboard()),
Square::A8.into_bitboard()
);
assert_eq!(
Direction::North.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY
);
}
#[test]
fn west() {
assert_eq!(
Direction::West.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::West.move_board(Square::B1.into_bitboard()),
Square::A1.into_bitboard()
);
assert_eq!(
Direction::West.move_board(Square::G1.into_bitboard()),
Square::F1.into_bitboard()
);
assert_eq!(
Direction::West.move_board(Square::H1.into_bitboard()),
Square::G1.into_bitboard()
);
}
#[test]
fn south() {
assert_eq!(
Direction::South.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::South.move_board(Square::A2.into_bitboard()),
Square::A1.into_bitboard()
);
assert_eq!(
Direction::South.move_board(Square::A7.into_bitboard()),
Square::A6.into_bitboard()
);
assert_eq!(
Direction::South.move_board(Square::A8.into_bitboard()),
Square::A7.into_bitboard()
);
}
#[test]
fn east() {
assert_eq!(
Direction::East.move_board(Square::A1.into_bitboard()),
Square::B1.into_bitboard()
);
assert_eq!(
Direction::East.move_board(Square::B1.into_bitboard()),
Square::C1.into_bitboard()
);
assert_eq!(
Direction::East.move_board(Square::G1.into_bitboard()),
Square::H1.into_bitboard()
);
assert_eq!(
Direction::East.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY
);
}
#[test]
fn north_west() {
assert_eq!(
Direction::NorthWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthWest.move_board(Square::B1.into_bitboard()),
Square::A2.into_bitboard()
);
assert_eq!(
Direction::NorthWest.move_board(Square::H1.into_bitboard()),
Square::G2.into_bitboard()
);
assert_eq!(
Direction::NorthWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthWest.move_board(Square::B8.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthWest.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY
);
}
#[test]
fn south_west() {
assert_eq!(
Direction::SouthWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthWest.move_board(Square::B1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthWest.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthWest.move_board(Square::B8.into_bitboard()),
Square::A7.into_bitboard()
);
assert_eq!(
Direction::SouthWest.move_board(Square::H8.into_bitboard()),
Square::G7.into_bitboard()
);
}
#[test]
fn south_east() {
assert_eq!(
Direction::SouthEast.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthEast.move_board(Square::B1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::SouthEast.move_board(Square::A8.into_bitboard()),
Square::B7.into_bitboard()
);
assert_eq!(
Direction::SouthEast.move_board(Square::B8.into_bitboard()),
Square::C7.into_bitboard()
);
assert_eq!(
Direction::SouthEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY
);
}
#[test]
fn north_east() {
assert_eq!(
Direction::NorthEast.move_board(Square::A1.into_bitboard()),
Square::B2.into_bitboard()
);
assert_eq!(
Direction::NorthEast.move_board(Square::B1.into_bitboard()),
Square::C2.into_bitboard()
);
assert_eq!(
Direction::NorthEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthEast.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthEast.move_board(Square::B8.into_bitboard()),
Bitboard::EMPTY
);
assert_eq!(
Direction::NorthEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY
);
}
#[test]
fn north_north_west() {
assert_eq!(
Direction::NorthNorthWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::B2.into_bitboard()),
Square::A4.into_bitboard()
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::H1.into_bitboard()),
Square::G3.into_bitboard()
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::G2.into_bitboard()),
Square::F4.into_bitboard()
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::B7.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthWest.move_board(Square::G7.into_bitboard()),
Bitboard::EMPTY,
);
}
#[test]
fn north_west_west() {
assert_eq!(
Direction::NorthWestWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::B2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::H1.into_bitboard()),
Square::F2.into_bitboard()
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::G2.into_bitboard()),
Square::E3.into_bitboard()
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::B7.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthWestWest.move_board(Square::G7.into_bitboard()),
Square::E8.into_bitboard()
);
}
#[test]
fn south_west_west() {
assert_eq!(
Direction::SouthWestWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::B2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::G2.into_bitboard()),
Square::E1.into_bitboard()
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::B7.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::H8.into_bitboard()),
Square::F7.into_bitboard()
);
assert_eq!(
Direction::SouthWestWest.move_board(Square::G7.into_bitboard()),
Square::E6.into_bitboard()
);
}
#[test]
fn south_south_west() {
assert_eq!(
Direction::SouthSouthWest.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::B2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::G2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::B7.into_bitboard()),
Square::A5.into_bitboard()
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::H8.into_bitboard()),
Square::G6.into_bitboard()
);
assert_eq!(
Direction::SouthSouthWest.move_board(Square::G7.into_bitboard()),
Square::F5.into_bitboard()
);
}
#[test]
fn south_south_east() {
assert_eq!(
Direction::SouthSouthEast.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::B2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::G2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::A8.into_bitboard()),
Square::B6.into_bitboard()
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::B7.into_bitboard()),
Square::C5.into_bitboard()
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthSouthEast.move_board(Square::G7.into_bitboard()),
Square::H5.into_bitboard()
);
}
#[test]
fn south_east_east() {
assert_eq!(
Direction::SouthEastEast.move_board(Square::A1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::B2.into_bitboard()),
Square::D1.into_bitboard()
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::G2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::A8.into_bitboard()),
Square::C7.into_bitboard()
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::B7.into_bitboard()),
Square::D6.into_bitboard()
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::SouthEastEast.move_board(Square::G7.into_bitboard()),
Bitboard::EMPTY,
);
}
#[test]
fn north_east_east() {
assert_eq!(
Direction::NorthEastEast.move_board(Square::A1.into_bitboard()),
Square::C2.into_bitboard()
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::B2.into_bitboard()),
Square::D3.into_bitboard()
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::G2.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::B7.into_bitboard()),
Square::D8.into_bitboard()
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthEastEast.move_board(Square::G7.into_bitboard()),
Bitboard::EMPTY,
);
}
#[test]
fn north_north_east() {
assert_eq!(
Direction::NorthNorthEast.move_board(Square::A1.into_bitboard()),
Square::B3.into_bitboard()
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::B2.into_bitboard()),
Square::C4.into_bitboard()
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::H1.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::G2.into_bitboard()),
Square::H4.into_bitboard()
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::A8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::B7.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::H8.into_bitboard()),
Bitboard::EMPTY,
);
assert_eq!(
Direction::NorthNorthEast.move_board(Square::G7.into_bitboard()),
Bitboard::EMPTY,
);
}
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#[test]
fn slide() {
assert_eq!(
Direction::North.slide_square(Square::A1),
File::A.into_bitboard() - Square::A1
);
assert_eq!(
Direction::West.slide_square(Square::H1),
Rank::First.into_bitboard() - Square::H1
);
assert_eq!(
Direction::South.slide_square(Square::A8),
File::A.into_bitboard() - Square::A8
);
assert_eq!(
Direction::East.slide_square(Square::A1),
Rank::First.into_bitboard() - Square::A1
);
assert_eq!(
Direction::NorthWest.slide_square(Square::H1),
Bitboard::ANTI_DIAGONAL - Square::H1
);
assert_eq!(
Direction::SouthWest.slide_square(Square::H8),
Bitboard::DIAGONAL - Square::H8
);
assert_eq!(
Direction::SouthEast.slide_square(Square::A8),
Bitboard::ANTI_DIAGONAL - Square::A8
);
assert_eq!(
Direction::NorthEast.slide_square(Square::A1),
Bitboard::DIAGONAL - Square::A1
);
}
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#[test]
fn blocked_slides() {
assert_eq!(
Direction::North
.slide_board_with_blockers(Square::A1.into_bitboard(), Square::A2.into_bitboard()),
Square::A2.into_bitboard()
);
assert_eq!(
Direction::North
.slide_board_with_blockers(Square::A1.into_bitboard(), Square::A3.into_bitboard()),
Square::A2 | Square::A3
);
assert_eq!(
Direction::North
.slide_board_with_blockers(Square::A1.into_bitboard(), Square::A4.into_bitboard()),
Square::A2 | Square::A3 | Square::A4
);
// Ensure that the starting square being in `blockers` is not an issue
assert_eq!(
Direction::North
.slide_board_with_blockers(Square::A1.into_bitboard(), Square::A1.into_bitboard()),
File::A.into_bitboard() - Square::A1
);
}
}