Add 'Move'

This commit is contained in:
Bruno BELANYI 2022-07-25 19:12:51 +02:00
parent 80e3ace8fc
commit e7e5927902
2 changed files with 234 additions and 0 deletions

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@ -13,6 +13,9 @@ pub use direction::*;
pub mod file;
pub use file::*;
pub mod r#move;
pub use r#move::*;
pub mod piece;
pub use piece::*;

231
src/board/move.rs Normal file
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@ -0,0 +1,231 @@
use super::{Piece, Square};
type Bitset = u32;
/// A chess move, containing:
/// * Piece type.
/// * Starting square.
/// * Destination square.
/// * Optional capture type.
/// * Optional promotion type.
/// * Optional captured type.
/// * Whether the move was an en-passant capture.
/// * Whether the move was a double-step.
/// * Whether the move was a castling.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Move(Bitset);
/// A builder for [Move]. This is the prefered and only way of building a [Move].
pub struct MoveBuilder {
pub piece: Piece,
pub start: Square,
pub destination: Square,
pub capture: Option<Piece>,
pub promotion: Option<Piece>,
pub en_passant: bool,
pub double_step: bool,
pub castling: bool,
}
impl From<MoveBuilder> for Move {
#[inline(always)]
fn from(builder: MoveBuilder) -> Self {
Self::new(
builder.piece,
builder.start,
builder.destination,
builder.capture,
builder.promotion,
builder.en_passant,
builder.double_step,
builder.castling,
)
}
}
/// A [Move] is structured as a bitset with the following fields:
/// | Field | Size | Range of values | Note |
/// |-------------|------|-----------------|-------------------------------------------------|
/// | Piece | 3 | 0-6 | Can be interpreted as a [Piece] index |
/// | Start | 6 | 0-63 | Can be interpreted as a [Square] index |
/// | Destination | 6 | 0-63 | Can be interpreted as a [Square] index |
/// | Capture | 3 | 0-7 | Can be interpreted as a [Piece] index if not 7 |
/// | Promotion | 3 | 0-7 | Can be interpreted as a [Piece] index if not 7 |
/// | En-pasant | 1 | 0-1 | Boolean value |
/// | Double-step | 1 | 0-1 | Boolean value |
/// | Castling | 1 | 0-1 | Boolean value |
mod shift {
use super::Bitset;
pub const PIECE: usize = 0;
pub const PIECE_MASK: Bitset = 0b111;
pub const START: usize = 3;
pub const START_MASK: Bitset = 0b11_1111;
pub const DESTINATION: usize = 9;
pub const DESTINATION_MASK: Bitset = 0b11_1111;
pub const CAPTURE: usize = 15;
pub const CAPTURE_MASK: Bitset = 0b111;
pub const PROMOTION: usize = 18;
pub const PROMOTION_MASK: Bitset = 0b111;
pub const EN_PASSANT: usize = 21;
pub const EN_PASSANT_MASK: Bitset = 0b1;
pub const DOUBLE_STEP: usize = 22;
pub const DOUBLE_STEP_MASK: Bitset = 0b1;
pub const CASTLING: usize = 23;
pub const CASTLING_MASK: Bitset = 0b1;
}
impl Move {
/// Construct a new move.
#[inline(always)]
fn new(
piece: Piece,
start: Square,
destination: Square,
capture: Option<Piece>,
promotion: Option<Piece>,
en_passant: bool,
double_step: bool,
castling: bool,
) -> Self {
let mut value = 0;
value |= (piece.index() as Bitset) << shift::PIECE;
value |= (start.index() as Bitset) << shift::START;
value |= (destination.index() as Bitset) << shift::DESTINATION;
value |=
(capture.map(Piece::index).unwrap_or(Piece::NUM_VARIANTS) as Bitset) << shift::CAPTURE;
value |= (promotion.map(Piece::index).unwrap_or(Piece::NUM_VARIANTS) as Bitset)
<< shift::PROMOTION;
value |= (en_passant as Bitset) << shift::EN_PASSANT;
value |= (double_step as Bitset) << shift::DOUBLE_STEP;
value |= (castling as Bitset) << shift::CASTLING;
Self(value)
}
/// Get the [Piece] that is being moved.
#[inline(always)]
pub fn piece(self) -> Piece {
let index = ((self.0 >> shift::PIECE) & shift::PIECE_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Piece::from_index_unchecked(index) }
}
/// Get the [Square] that this move starts from.
#[inline(always)]
pub fn start(self) -> Square {
let index = ((self.0 >> shift::START) & shift::START_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Square::from_index_unchecked(index) }
}
/// Get the [Square] that this move ends on.
#[inline(always)]
pub fn destination(self) -> Square {
let index = ((self.0 >> shift::DESTINATION) & shift::DESTINATION_MASK) as usize;
// SAFETY: we know the value is in-bounds
unsafe { Square::from_index_unchecked(index) }
}
/// Get the [Piece] that this move captures, or `None` if there are no captures.
#[inline(always)]
pub fn capture(self) -> Option<Piece> {
let index = ((self.0 >> shift::CAPTURE) & shift::CAPTURE_MASK) as usize;
if index < Piece::NUM_VARIANTS {
// SAFETY: we know the value is in-bounds
unsafe { Some(Piece::from_index_unchecked(index)) }
} else {
None
}
}
/// Get the [Piece] that this move promotes to, or `None` if there are no promotions.
#[inline(always)]
pub fn promotion(self) -> Option<Piece> {
let index = ((self.0 >> shift::PROMOTION) & shift::PROMOTION_MASK) as usize;
if index < Piece::NUM_VARIANTS {
// SAFETY: we know the value is in-bounds
unsafe { Some(Piece::from_index_unchecked(index)) }
} else {
None
}
}
/// Get the whether or not the move is an en-passant capture.
#[inline(always)]
pub fn is_en_passant(self) -> bool {
let index = (self.0 >> shift::EN_PASSANT) & shift::EN_PASSANT_MASK;
index != 0
}
/// Get the whether or not the move is a pawn double step.
#[inline(always)]
pub fn is_double_step(self) -> bool {
let index = (self.0 >> shift::DOUBLE_STEP) & shift::DOUBLE_STEP_MASK;
index != 0
}
/// Get the whether or not the move is a king castling.
#[inline(always)]
pub fn is_castling(self) -> bool {
let index = (self.0 >> shift::CASTLING) & shift::CASTLING_MASK;
index != 0
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn builder_simple() {
let chess_move: Move = MoveBuilder {
piece: Piece::Queen,
start: Square::A2,
destination: Square::A3,
capture: None,
promotion: None,
en_passant: false,
double_step: false,
castling: false,
}
.into();
assert_eq!(chess_move.piece(), Piece::Queen);
assert_eq!(chess_move.start(), Square::A2);
assert_eq!(chess_move.destination(), Square::A3);
assert_eq!(chess_move.capture(), None);
assert_eq!(chess_move.promotion(), None);
assert!(!chess_move.is_en_passant());
assert!(!chess_move.is_double_step());
assert!(!chess_move.is_castling());
}
#[test]
fn builder_all_fields() {
let chess_move: Move = MoveBuilder {
piece: Piece::Pawn,
start: Square::A7,
destination: Square::B8,
capture: Some(Piece::Queen),
promotion: Some(Piece::Knight),
en_passant: true,
double_step: true,
castling: true,
}
.into();
assert_eq!(chess_move.piece(), Piece::Pawn);
assert_eq!(chess_move.start(), Square::A7);
assert_eq!(chess_move.destination(), Square::B8);
assert_eq!(chess_move.capture(), Some(Piece::Queen));
assert_eq!(chess_move.promotion(), Some(Piece::Knight));
assert!(chess_move.is_en_passant());
assert!(chess_move.is_double_step());
assert!(chess_move.is_castling());
}
}