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refactor: simplify square usage without underlying #163

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Feb 22, 2025
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refactor: simplify square usage without underlying #163

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20fd59a
refactor: simplify square usage without underlying
Disservin Feb 22, 2025
57aac2a
simplify code
Disservin Feb 22, 2025
813d297
update lib
Disservin Feb 22, 2025
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2 changes: 1 addition & 1 deletion docs/pages/move.md
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ before checking for captures.
Incase you want to manually create a move you can do it like so.

```cpp
Move m = Move::make<Move::NORMAL>(Square::underlying::SQ_E2, Square::underlying::SQ_E4);
Move m = Move::make<Move::NORMAL>(Square::SQ_E2, Square::SQ_E4);
```

## Other formats
Expand Down
75 changes: 52 additions & 23 deletions include/chess.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,16 @@ constexpr char tolower(char c) { return (c >= 'A' && c <= 'Z') ? (c - 'A' + 'a')

namespace chess {

#define CHESS_DECLARE_RANK(N) \
static constexpr auto SQ_A##N = underlying::SQ_A##N; \
static constexpr auto SQ_B##N = underlying::SQ_B##N; \
static constexpr auto SQ_C##N = underlying::SQ_C##N; \
static constexpr auto SQ_D##N = underlying::SQ_D##N; \
static constexpr auto SQ_E##N = underlying::SQ_E##N; \
static constexpr auto SQ_F##N = underlying::SQ_F##N; \
static constexpr auto SQ_G##N = underlying::SQ_G##N; \
static constexpr auto SQ_H##N = underlying::SQ_H##N;

class File {
public:
enum class underlying : std::uint8_t { FILE_A, FILE_B, FILE_C, FILE_D, FILE_E, FILE_F, FILE_G, FILE_H, NO_FILE };
Expand Down Expand Up @@ -276,6 +286,24 @@ class Square {
};
// clang-format on

// when c++20
#if __cplusplus >= 202002L
using enum underlying;
#else

CHESS_DECLARE_RANK(1)
CHESS_DECLARE_RANK(2)
CHESS_DECLARE_RANK(3)
CHESS_DECLARE_RANK(4)
CHESS_DECLARE_RANK(5)
CHESS_DECLARE_RANK(6)
CHESS_DECLARE_RANK(7)
CHESS_DECLARE_RANK(8)

static constexpr auto NO_SQ = underlying::NO_SQ;

#endif

constexpr Square() : sq(underlying::NO_SQ) {}

constexpr Square(int sq) : sq(static_cast<underlying>(sq)) { assert(sq <= 64 && sq >= 0); }
Expand Down Expand Up @@ -470,7 +498,7 @@ class Square {
* @return
*/
[[nodiscard]] static constexpr Square castling_king_square(bool is_king_side, Color c) noexcept {
return Square(is_king_side ? Square::underlying::SQ_G1 : Square::underlying::SQ_C1).relative_square(c);
return Square(is_king_side ? Square::SQ_G1 : Square::SQ_C1).relative_square(c);
}

/**
Expand All @@ -480,7 +508,7 @@ class Square {
* @return
*/
[[nodiscard]] static constexpr Square castling_rook_square(bool is_king_side, Color c) noexcept {
return Square(is_king_side ? Square::underlying::SQ_F1 : Square::underlying::SQ_D1).relative_square(c);
return Square(is_king_side ? Square::SQ_F1 : Square::SQ_D1).relative_square(c);
}

/**
Expand Down Expand Up @@ -518,6 +546,8 @@ constexpr Square operator+(Square sq, Direction dir) {
return static_cast<Square>(sq.index() + static_cast<int8_t>(dir));
}

#undef CHESS_DECLARE_RANK

} // namespace chess

namespace chess {
Expand Down Expand Up @@ -1945,7 +1975,7 @@ class Board {

// Append information about the en passant square (if any)
// and the half-move clock and full move number to the FEN string
if (ep_sq_ == Square::underlying::NO_SQ)
if (ep_sq_ == Square::NO_SQ)
ss += " -";
else {
ss += ' ';
Expand Down Expand Up @@ -1998,8 +2028,8 @@ class Board {
hfm_++;
plies_++;

if (ep_sq_ != Square::underlying::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::NO_SQ;

if (capture) {
removePiece(captured, move.to());
Expand Down Expand Up @@ -2221,8 +2251,8 @@ class Board {
prev_states_.emplace_back(key_, cr_, ep_sq_, hfm_, Piece::NONE);

key_ ^= Zobrist::sideToMove();
if (ep_sq_ != Square::underlying::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::NO_SQ;

stm_ = ~stm_;

Expand Down Expand Up @@ -2543,7 +2573,7 @@ class Board {
}

U64 ep_hash = 0ULL;
if (ep_sq_ != Square::underlying::NO_SQ) ep_hash ^= Zobrist::enpassant(ep_sq_.file());
if (ep_sq_ != Square::NO_SQ) ep_hash ^= Zobrist::enpassant(ep_sq_.file());

U64 stm_hash = 0ULL;
if (stm_ == Color::WHITE) stm_hash ^= Zobrist::sideToMove();
Expand Down Expand Up @@ -2654,7 +2684,7 @@ class Board {
const auto castling = params[2].has_value() ? *params[2] : "-";
const auto en_passant = params[3].has_value() ? *params[3] : "-";

const auto ep = en_passant == "-" ? Square::underlying::NO_SQ : Square(en_passant);
const auto ep = en_passant == "-" ? Square::NO_SQ : Square(en_passant);
const auto stm = (move_right == "w") ? Color::WHITE : Color::BLACK;

CastlingRights cr;
Expand Down Expand Up @@ -2823,7 +2853,7 @@ class Board {
// 14 => any black rook with castling rights, side will be deduced from the file
// 15 => black king and black is side to move
static std::uint8_t convertMeaning(const CastlingRights &cr, Color stm, Square ep, Square sq, Piece piece) {
if (piece.type() == PieceType::PAWN && ep != Square::underlying::NO_SQ) {
if (piece.type() == PieceType::PAWN && ep != Square::NO_SQ) {
if (Square(static_cast<int>(sq.index()) ^ 8) == ep) return 12;
}

Expand Down Expand Up @@ -2861,7 +2891,7 @@ class Board {
CastlingRights cr_ = {};
uint16_t plies_ = 0;
Color stm_ = Color::WHITE;
Square ep_sq_ = Square::underlying::NO_SQ;
Square ep_sq_ = Square::NO_SQ;
uint8_t hfm_ = 0;

bool chess960_ = false;
Expand Down Expand Up @@ -2942,7 +2972,7 @@ class Board {
plies_ = parseStringViewToInt(full_move).value_or(1);

plies_ = plies_ * 2 - 2;
ep_sq_ = en_passant == "-" ? Square::underlying::NO_SQ : Square(en_passant);
ep_sq_ = en_passant == "-" ? Square::NO_SQ : Square(en_passant);
stm_ = (move_right == "w") ? Color::WHITE : Color::BLACK;
key_ = 0ULL;
cr_.clear();
Expand Down Expand Up @@ -2978,8 +3008,7 @@ class Board {
static const auto find_rook = [](const Board &board, CastlingRights::Side side, Color color) {
const auto king_side = CastlingRights::Side::KING_SIDE;
const auto king_sq = board.kingSq(color);
const auto sq_corner = Square(side == king_side ? Square::underlying::SQ_H1 : Square::underlying::SQ_A1)
.relative_square(color);
const auto sq_corner = Square(side == king_side ? Square::SQ_H1 : Square::SQ_A1).relative_square(color);

const auto start = side == king_side ? king_sq + 1 : king_sq - 1;

Expand Down Expand Up @@ -3034,13 +3063,13 @@ class Board {
}

// check if ep square itself is valid
if (ep_sq_ != Square::underlying::NO_SQ && !((ep_sq_.rank() == Rank::RANK_3 && stm_ == Color::BLACK) ||
(ep_sq_.rank() == Rank::RANK_6 && stm_ == Color::WHITE))) {
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ && !((ep_sq_.rank() == Rank::RANK_3 && stm_ == Color::BLACK) ||
(ep_sq_.rank() == Rank::RANK_6 && stm_ == Color::WHITE))) {
ep_sq_ = Square::NO_SQ;
}

// check if ep square is valid, i.e. if there is a pawn that can capture it
if (ep_sq_ != Square::underlying::NO_SQ) {
if (ep_sq_ != Square::NO_SQ) {
bool valid;

if (stm_ == Color::WHITE) {
Expand All @@ -3050,7 +3079,7 @@ class Board {
}

if (!valid)
ep_sq_ = Square::underlying::NO_SQ;
ep_sq_ = Square::NO_SQ;
else
key_ ^= Zobrist::enpassant(ep_sq_.file());
}
Expand Down Expand Up @@ -3555,7 +3584,7 @@ inline void movegen::generatePawnMoves(const Board &board, Movelist &moves, Bitb

const Square ep = board.enpassantSq();

if (ep != Square::underlying::NO_SQ) {
if (ep != Square::NO_SQ) {
auto m = generateEPMove(board, checkmask, pin_d, pawns_lr, ep, c);

for (const auto &move : m) {
Expand Down Expand Up @@ -4735,7 +4764,7 @@ class uci {
}
}
// Handle moves with specific from square
else if (info.from != Square::underlying::NO_SQ) {
else if (info.from != Square::NO_SQ) {
if (move.from() != info.from) {
continue;
}
Expand Down Expand Up @@ -4775,9 +4804,9 @@ class uci {

PieceType promotion = PieceType::NONE;

Square from = Square::underlying::NO_SQ;
Square from = Square::NO_SQ;
// a valid move always has a to square
Square to = Square::underlying::NO_SQ;
Square to = Square::NO_SQ;

// a valid move always has a piece
PieceType piece = PieceType::NONE;
Expand Down
33 changes: 16 additions & 17 deletions src/board.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -227,7 +227,7 @@ class Board {

// Append information about the en passant square (if any)
// and the half-move clock and full move number to the FEN string
if (ep_sq_ == Square::underlying::NO_SQ)
if (ep_sq_ == Square::NO_SQ)
ss += " -";
else {
ss += ' ';
Expand Down Expand Up @@ -280,8 +280,8 @@ class Board {
hfm_++;
plies_++;

if (ep_sq_ != Square::underlying::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::NO_SQ;

if (capture) {
removePiece(captured, move.to());
Expand Down Expand Up @@ -503,8 +503,8 @@ class Board {
prev_states_.emplace_back(key_, cr_, ep_sq_, hfm_, Piece::NONE);

key_ ^= Zobrist::sideToMove();
if (ep_sq_ != Square::underlying::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ) key_ ^= Zobrist::enpassant(ep_sq_.file());
ep_sq_ = Square::NO_SQ;

stm_ = ~stm_;

Expand Down Expand Up @@ -825,7 +825,7 @@ class Board {
}

U64 ep_hash = 0ULL;
if (ep_sq_ != Square::underlying::NO_SQ) ep_hash ^= Zobrist::enpassant(ep_sq_.file());
if (ep_sq_ != Square::NO_SQ) ep_hash ^= Zobrist::enpassant(ep_sq_.file());

U64 stm_hash = 0ULL;
if (stm_ == Color::WHITE) stm_hash ^= Zobrist::sideToMove();
Expand Down Expand Up @@ -936,7 +936,7 @@ class Board {
const auto castling = params[2].has_value() ? *params[2] : "-";
const auto en_passant = params[3].has_value() ? *params[3] : "-";

const auto ep = en_passant == "-" ? Square::underlying::NO_SQ : Square(en_passant);
const auto ep = en_passant == "-" ? Square::NO_SQ : Square(en_passant);
const auto stm = (move_right == "w") ? Color::WHITE : Color::BLACK;

CastlingRights cr;
Expand Down Expand Up @@ -1105,7 +1105,7 @@ class Board {
// 14 => any black rook with castling rights, side will be deduced from the file
// 15 => black king and black is side to move
static std::uint8_t convertMeaning(const CastlingRights &cr, Color stm, Square ep, Square sq, Piece piece) {
if (piece.type() == PieceType::PAWN && ep != Square::underlying::NO_SQ) {
if (piece.type() == PieceType::PAWN && ep != Square::NO_SQ) {
if (Square(static_cast<int>(sq.index()) ^ 8) == ep) return 12;
}

Expand Down Expand Up @@ -1143,7 +1143,7 @@ class Board {
CastlingRights cr_ = {};
uint16_t plies_ = 0;
Color stm_ = Color::WHITE;
Square ep_sq_ = Square::underlying::NO_SQ;
Square ep_sq_ = Square::NO_SQ;
uint8_t hfm_ = 0;

bool chess960_ = false;
Expand Down Expand Up @@ -1224,7 +1224,7 @@ class Board {
plies_ = parseStringViewToInt(full_move).value_or(1);

plies_ = plies_ * 2 - 2;
ep_sq_ = en_passant == "-" ? Square::underlying::NO_SQ : Square(en_passant);
ep_sq_ = en_passant == "-" ? Square::NO_SQ : Square(en_passant);
stm_ = (move_right == "w") ? Color::WHITE : Color::BLACK;
key_ = 0ULL;
cr_.clear();
Expand Down Expand Up @@ -1260,8 +1260,7 @@ class Board {
static const auto find_rook = [](const Board &board, CastlingRights::Side side, Color color) {
const auto king_side = CastlingRights::Side::KING_SIDE;
const auto king_sq = board.kingSq(color);
const auto sq_corner = Square(side == king_side ? Square::underlying::SQ_H1 : Square::underlying::SQ_A1)
.relative_square(color);
const auto sq_corner = Square(side == king_side ? Square::SQ_H1 : Square::SQ_A1).relative_square(color);

const auto start = side == king_side ? king_sq + 1 : king_sq - 1;

Expand Down Expand Up @@ -1316,13 +1315,13 @@ class Board {
}

// check if ep square itself is valid
if (ep_sq_ != Square::underlying::NO_SQ && !((ep_sq_.rank() == Rank::RANK_3 && stm_ == Color::BLACK) ||
(ep_sq_.rank() == Rank::RANK_6 && stm_ == Color::WHITE))) {
ep_sq_ = Square::underlying::NO_SQ;
if (ep_sq_ != Square::NO_SQ && !((ep_sq_.rank() == Rank::RANK_3 && stm_ == Color::BLACK) ||
(ep_sq_.rank() == Rank::RANK_6 && stm_ == Color::WHITE))) {
ep_sq_ = Square::NO_SQ;
}

// check if ep square is valid, i.e. if there is a pawn that can capture it
if (ep_sq_ != Square::underlying::NO_SQ) {
if (ep_sq_ != Square::NO_SQ) {
bool valid;

if (stm_ == Color::WHITE) {
Expand All @@ -1332,7 +1331,7 @@ class Board {
}

if (!valid)
ep_sq_ = Square::underlying::NO_SQ;
ep_sq_ = Square::NO_SQ;
else
key_ ^= Zobrist::enpassant(ep_sq_.file());
}
Expand Down
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