seer/src/board/castle_rights.rs

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2022-07-18 13:27:03 +02:00
/// Current castle rights for a player.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum CastleRights {
/// No castling allowed.
NoSide,
/// King-side castling only.
KingSide,
/// Queen-side castling only.
QueenSide,
/// Either side allowed.
BothSides,
}
impl CastleRights {
/// Convert from a castle rights index into a [CastleRights] type.
#[inline(always)]
pub fn from_index(index: usize) -> Self {
assert!(index < 4);
// SAFETY: we know the value is in-bounds
unsafe { Self::from_index_unchecked(index) }
}
/// Convert from a castle rights index into a [CastleRights] type, no bounds checking.
///
/// # Safety
///
/// This should only be called with values that can be output by [CastleRights::index()].
#[inline(always)]
pub unsafe fn from_index_unchecked(index: usize) -> Self {
std::mem::transmute(index as u8)
}
/// Return the index of a given [CastleRights].
#[inline(always)]
pub fn index(self) -> usize {
self as usize
}
/// Can the player castle king-side.
#[inline(always)]
pub fn has_king_side(self) -> bool {
(self.index() & 1) != 0
}
/// Can the player castle king-side.
#[inline(always)]
pub fn has_queen_side(self) -> bool {
(self.index() & 2) != 0
}
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}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn from_index() {
assert_eq!(CastleRights::from_index(0), CastleRights::NoSide);
assert_eq!(CastleRights::from_index(1), CastleRights::KingSide);
assert_eq!(CastleRights::from_index(2), CastleRights::QueenSide);
assert_eq!(CastleRights::from_index(3), CastleRights::BothSides);
}
#[test]
fn index() {
assert_eq!(CastleRights::NoSide.index(), 0);
assert_eq!(CastleRights::KingSide.index(), 1);
assert_eq!(CastleRights::QueenSide.index(), 2);
assert_eq!(CastleRights::BothSides.index(), 3);
}
#[test]
fn has_kingside() {
assert!(!CastleRights::NoSide.has_king_side());
assert!(!CastleRights::QueenSide.has_king_side());
assert!(CastleRights::KingSide.has_king_side());
assert!(CastleRights::BothSides.has_king_side());
}
#[test]
fn has_queenside() {
assert!(!CastleRights::NoSide.has_queen_side());
assert!(!CastleRights::KingSide.has_queen_side());
assert!(CastleRights::QueenSide.has_queen_side());
assert!(CastleRights::BothSides.has_queen_side());
}
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}