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