Add bitboard iteration
Introduce 'BitboardIterator', use it to implement 'IntoIterator' for 'Bitboard'.
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17
src/board/bitboard/iterator.rs
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17
src/board/bitboard/iterator.rs
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@ -0,0 +1,17 @@
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/// An [Iterator](std::iter::Iterator) of [Square](crate::board::Square) contained in a
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/// [Bitboard](crate::board::Bitboard).
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pub struct BitboardIterator(pub(crate) u64);
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impl Iterator for BitboardIterator {
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type Item = crate::board::Square;
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fn next(&mut self) -> Option<Self::Item> {
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if self.0 == 0 {
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None
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} else {
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let lsb = self.0.trailing_zeros() as usize;
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self.0 ^= 1 << lsb;
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Some(crate::board::Square::from_index(lsb))
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}
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}
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}
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@ -1,4 +1,6 @@
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use super::Square;
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mod iterator;
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use iterator::*;
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/// Use a 64-bit number to represent a chessboard. Each bit is mapped from to a specific square, so
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/// that index 0 -> A1, 1 -> A2, ..., 63 -> H8.
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@ -40,6 +42,16 @@ impl Default for Bitboard {
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}
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}
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/// Iterate over the [Square](crate::board::Square) values included in the board.
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impl IntoIterator for Bitboard {
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type IntoIter = BitboardIterator;
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type Item = Square;
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fn into_iter(self) -> Self::IntoIter {
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BitboardIterator(self.0)
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}
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}
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/// Treat bitboard as a set of squares, shift each square's index left by the amount given.
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impl std::ops::Shl<usize> for Bitboard {
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type Output = Bitboard;
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@ -155,6 +167,37 @@ mod test {
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use super::*;
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use crate::board::square::*;
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#[test]
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fn iter() {
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assert_eq!(Bitboard::EMPTY.into_iter().collect::<Vec<_>>(), Vec::new());
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assert_eq!(
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Bitboard::RANKS[0].into_iter().collect::<Vec<_>>(),
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vec![
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Square::A1,
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Square::B1,
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Square::C1,
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Square::D1,
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Square::E1,
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Square::F1,
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Square::G1,
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Square::H1,
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]
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);
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assert_eq!(
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Bitboard::FILES[0].into_iter().collect::<Vec<_>>(),
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vec![
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Square::A1,
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Square::A2,
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Square::A3,
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Square::A4,
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Square::A5,
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Square::A6,
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Square::A7,
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Square::A8,
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]
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);
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}
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#[test]
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fn left_shift() {
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assert_eq!(Bitboard::RANKS[0] << 1, Bitboard::RANKS[1]);
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