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Add doc comments & tests. Some refactoring #28

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Oct 13, 2023
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Add doc comments & tests. Some refactoring #28

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78968f1
Add comments and tests to improve coverage
na2hiro Sep 14, 2023
92a53fc
Some refactoring and optimization
na2hiro Sep 14, 2023
2ed61bc
Apply cargo fmt
sugyan Oct 11, 2023
1a96943
Merge pull request #1 from sugyan/pull/28
na2hiro Oct 13, 2023
10f783c
Fix grammar issues in comment
na2hiro Oct 13, 2023
5776c78
Remove resolved TODO comment
na2hiro Oct 13, 2023
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87 changes: 43 additions & 44 deletions src/movegen.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -43,50 +43,49 @@ impl Position {
/// Generate moves to evade check, optimized using AttackInfo.
fn generate_evasions(&self, av: &mut ArrayVec<Move, MAX_LEGAL_MOVES>) {
let c = self.side_to_move();
if let Some(king) = self.king_position(c) {
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Unwrapped king_position() as this method should be called during evading

let mut checkers_attacks = Bitboard::empty();
let mut checkers_count = 0;
for ch in self.checkers() {
if let Some(p) = self.piece_at(ch) {
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Unwrapped piece_at(ch) as checkers() should only return positions where pieces exist

let pk = p.piece_kind();
// 龍が斜め位置から王手している場合のみ、他の駒の裏に逃がれることができる可能性がある
if pk == PieceKind::ProRook
&& ch.file() != king.file()
&& ch.rank() != king.rank()
{
checkers_attacks |= ATTACK_TABLE.hi.attack(ch, &self.occupied_bitboard());
} else {
checkers_attacks |= ATTACK_TABLE.pseudo_attack(pk, ch, c.flip());
}
}
checkers_count += 1;
}
for to in ATTACK_TABLE.ou.attack(king, c) & !self.player_bitboard(c) & !checkers_attacks
let king = self.king_position(c).unwrap();
let mut checkers_attacks = Bitboard::empty();
let mut checkers_count = 0;
for ch in self.checkers() {
let pk = self.piece_at(ch).unwrap().piece_kind();
// 龍が斜め位置から王手している場合のみ、他の駒の裏に逃がれることができる可能性がある
if pk == PieceKind::ProRook
&& ch.file() != king.file()
&& ch.rank() != king.rank()
{
av.push(Move::Normal {
from: king,
to,
promote: false,
});
}
// 両王手の場合は玉が逃げるしかない
if checkers_count > 1 {
return;
}
if let Some(ch) = self.checkers().into_iter().next() {
let target_drop = BETWEEN_TABLE[ch.array_index()][king.array_index()];
let target_move = target_drop | self.checkers();
self.generate_for_fu(av, &target_move);
self.generate_for_ky(av, &target_move);
self.generate_for_ke(av, &target_move);
self.generate_for_gi(av, &target_move);
self.generate_for_ka(av, &target_move);
self.generate_for_hi(av, &target_move);
self.generate_for_ki(av, &target_move);
self.generate_for_um(av, &target_move);
self.generate_for_ry(av, &target_move);
self.generate_drop(av, &target_drop);
checkers_attacks |= ATTACK_TABLE.hi.attack(ch, &self.occupied_bitboard());
} else {
checkers_attacks |= ATTACK_TABLE.pseudo_attack(pk, ch, c.flip());
}
checkers_count += 1;
}
for to in ATTACK_TABLE.ou.attack(king, c) & !self.player_bitboard(c) & !checkers_attacks
{
av.push(Move::Normal {
from: king,
to,
promote: false,
});
}
// 両王手の場合は玉が逃げるしかない
if checkers_count > 1 {
return;
}
let ch = self.checkers().into_iter().next().unwrap();
let target_drop = BETWEEN_TABLE[ch.array_index()][king.array_index()];
let target_move = target_drop | self.checkers();
self.generate_for_fu(av, &target_move);
self.generate_for_ky(av, &target_move);
self.generate_for_ke(av, &target_move);
self.generate_for_gi(av, &target_move);
self.generate_for_ka(av, &target_move);
self.generate_for_hi(av, &target_move);
self.generate_for_ki(av, &target_move);
self.generate_for_um(av, &target_move);
self.generate_for_ry(av, &target_move);
if !target_drop.is_empty() {
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@na2hiro na2hiro Sep 14, 2023 •
edited
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I'm guessing generate_drop is somewhat costly/redundant in case target_drop is empty, which is fairly often like in case attacker is not 飛び駒.

// No need to exclude occupied bitboard: Existence of cells between attacker and king is given.
self.generate_drop(av, &target_drop);
}
}
fn generate_for_fu(&self, av: &mut ArrayVec<Move, MAX_LEGAL_MOVES>, target: &Bitboard) {
Expand Down Expand Up @@ -333,8 +332,8 @@ impl Position {
// 玉が相手の攻撃範囲内に動いてしまう指し手は除外
if self.piece_at(from) == Some(king)
&& !self
.attackers_to(c.flip(), m.to(), &self.occupied_bitboard())
.is_empty()
.attackers_to(c.flip(), m.to(), &self.occupied_bitboard())
.is_empty()
{
return false;
}
Expand Down
52 changes: 20 additions & 32 deletions src/position.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -73,25 +73,21 @@ impl Position {
match m {
Move::Normal { from, to, promote } => {
let piece = self.inner.piece_at(from).unwrap();
let p = if promote {
if let Some(p) = piece.promote() {
p
} else {
piece
}
let pk = piece.piece_kind();
let pk = if promote {
pk.promote().unwrap_or(pk)
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I did a few refactor with unwrap_or to improve readability. Hoping if this is not harmful for performance.

} else {
piece
pk
};
if self.checkable(p.piece_kind(), to) {
if self.checkable(pk, to) {
return true;
}
// 開き王手
let c = self.inner.side;
if self.pinned(c.flip()).contains(from) {
if let Some(sq) = self.king_position(c.flip()) {
return !(BETWEEN_TABLE[sq.array_index()][from.array_index()].contains(to)
|| BETWEEN_TABLE[sq.array_index()][to.array_index()].contains(from));
}
let c = self.inner.side.flip();
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When only flip side is used for multiple times, I rewrote to flipping it once than doing it in every occurrence.

if self.pinned(c).contains(from) {
let sq = self.king_position(c).unwrap();
return !(BETWEEN_TABLE[sq.array_index()][from.array_index()].contains(to)
|| BETWEEN_TABLE[sq.array_index()][to.array_index()].contains(from));
}
false
}
Expand All @@ -110,11 +106,7 @@ impl Position {
last_moved = Some(piece);
if let Some(p) = captured {
let pk = p.piece_kind();
let pk_unpromoted = if let Some(pk) = pk.unpromote() {
pk
} else {
pk
};
let pk_unpromoted = pk.unpromote().unwrap_or(pk);
// Update keys
keys.0 ^= ZOBRIST_TABLE.board(to, p);
keys.1 ^= ZOBRIST_TABLE.hand(
Expand Down Expand Up @@ -182,7 +174,7 @@ impl Position {
});
}
pub fn undo_move(&mut self, m: Move) {
let c = self.side_to_move();
let c = self.side_to_move().flip();
match m {
Move::Normal {
from,
Expand All @@ -193,13 +185,9 @@ impl Position {
let captured = self.captured();
if let Some(p_cap) = captured {
let pk = p_cap.piece_kind();
let pk_unpromoted = if let Some(pk) = pk.unpromote() {
pk
} else {
pk
};
let pk_unpromoted = pk.unpromote().unwrap_or(pk);
self.inner.xor_piece(to, p_cap);
let hand = self.inner.hand_of_a_player_mut(c.flip());
let hand = self.inner.hand_of_a_player_mut(c);
*hand = hand.removed(pk_unpromoted).unwrap();
}
self.inner.xor_piece(from, last_moved);
Expand All @@ -210,11 +198,11 @@ impl Position {
Move::Drop { to, piece } => {
self.inner.xor_piece(to, piece);
*self.inner.piece_at_mut(to) = None;
let hand = self.inner.hand_of_a_player_mut(c.flip());
let hand = self.inner.hand_of_a_player_mut(c);
*hand = hand.added(piece.piece_kind()).unwrap();
}
}
self.inner.side = c.flip();
self.inner.side = c;
self.inner.ply -= 1;
self.states.pop();
}
Expand Down Expand Up @@ -393,14 +381,14 @@ impl AttackInfo {
let ka = ATTACK_TABLE.ka.attack(sq, &occ);
let hi = ATTACK_TABLE.hi.attack(sq, &occ);
let ki = ATTACK_TABLE.ki.attack(sq, opp);
let ou = ATTACK_TABLE.ou.attack(sq, opp);
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Inspired by calculate_checkers(), omit one table lookup for OU.

let gi = ATTACK_TABLE.gi.attack(sq, opp);
Self {
checkers,
checkables: [
ATTACK_TABLE.fu.attack(sq, opp),
ATTACK_TABLE.ky.attack(sq, opp, &occ),
ATTACK_TABLE.ke.attack(sq, opp),
ATTACK_TABLE.gi.attack(sq, opp),
gi,
ki,
ka,
hi,
Expand All @@ -409,8 +397,8 @@ impl AttackInfo {
ki,
ki,
ki,
ka | ou,
hi | ou,
ka | ki,
hi | gi,
],
pinned,
}
Expand Down