README
- ::apply_moveBoard::apply_move
- ::emptyBoard::empty
- ::find_kingBoard::find_king
- ::getBoard::get
- ::in_checkBoard::in_check
- ::initialBoard::initial
- ::is_attackedBoard::is_attacked
- ::is_checkmateBoard::is_checkmate
- ::is_stalemateBoard::is_stalemate
- ::kings_facingBoard::kings_facing
- ::legal_movesBoard::legal_moves
- ::move_from_chineseBoard::move_from_chinese
- ::move_from_iccsBoard::move_from_iccs
- ::move_to_chineseBoard::move_to_chinese
- ::move_to_iccsBoard::move_to_iccs
- ::of_squaresBoard::of_squares
- ::piece_countBoard::piece_count
- ::positions_ofBoard::positions_of
- ::positions_of_sideBoard::positions_of_side
- ::pseudo_movesBoard::pseudo_moves
- ::pseudo_moves_fromBoard::pseudo_moves_from
- ::render_boardBoard::render_board
- ::resultBoard::result
- ::sideBoard::side
- ::to_fenBoard::to_fen
- ::with_pieceBoard::with_piece
- ::with_sideBoard::with_side
- ::withoutBoard::without
T
FenError
T
GameResult
T
Kind
- ::newMove::new
T
NotationError
- ::blackPiece::black
- ::redPiece::red
- ::in_palacePos::in_palace
- ::indexPos::index
- ::is_validPos::is_valid
- ::newPos::new
- ::own_halfPos::own_half
- ::is_redSide::is_red
- ::opponentSide::opponent
V
char_to_piece_kind
V
parse_fen
V
perft

xiangqi

中国象棋规则引擎：完整的走法生成、将死/困毙判定、中文纵线记谱与 FEN 支持 / A Xiangqi (Chinese Chess) rules engine in pure MoonBit

xiangqi

chinese-chess

board-game

game-engine

rules

Download zip

Author

wbgxiaosu

Version

0.1.0

License

Apache-2.0

Repository

github.com/wbgxiaosu/xiangqi

Last updated

5 hours ago

Downloads

#wbgxiaosu/xiangqi

中国象棋规则引擎 / A Xiangqi (Chinese Chess) rules engine in pure MoonBit.

完整走法生成（蹩马腿、塞象眼、炮架、过河兵、九宫约束）
将军 / 将死 / 困毙判定，含将帅照面（飞将）规则
中文纵线记谱（炮二平五、前车进一）与 ICCS 坐标双向转换
XiangqiFEN 解析与生成
Perft 验证：44 / 1920 / 79666，与公开参考值一致

let board = @xiangqi.Board::initial()
let mv = board.move_from_chinese("炮二平五").unwrap()  // h2e2
let next = board.apply_move(mv)

Run moon run cmd/main for a terminal demo. License: Apache-2.0.

Board

source

pub struct Board {
  squares : Array[Piece?]
  side_to_move : Side
  move_number : Int
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

The 9x10 Xiangqi board plus game state metadata.

Squares are stored row-major with rank 0 (Red's back rank) first, so squares[pos.index()] is the piece at pos (or None if empty).

Board::apply_move

source

fn Board::apply_move(self : Board, mv : Move) -> Board

Apply a move and return the resulting board. The receiver is left untouched. This function trusts that the move is pseudo-legal; use legal_moves / move_from_* for validated play.

Board::empty

source

fn Board::empty() -> Board

An empty board with Red to move. Combine with with, without and with_side to construct custom test positions.

Board::find_king

source

fn Board::find_king(self : Board, side : Side) -> Pos?

Locate the king of side. Kings are always on the board in legal Xiangqi positions; returns None only for malformed boards.

Board::get

source

fn Board::get(self : Board, pos : Pos) -> Piece?

The piece at pos, or None when the square is empty.

Board::in_check

source

fn Board::in_check(self : Board, side : Side) -> Bool

Is the king of side in check (including the flying-general rule)?

Board::initial

source

fn Board::initial() -> Board

The classic starting position. Red is at the bottom (ranks 0-4), Black at the top (ranks 5-9). Red moves first.

Board::is_attacked

source

fn Board::is_attacked(self : Board, target : Pos, attacker : Side) -> Bool

Is target attacked by any piece of attacker? Includes rook, cannon (with screen), horse (with leg check) and pawn attacks. The flying-general rule is checked separately by kings_facing.

Board::is_checkmate

source

fn Board::is_checkmate(self : Board) -> Bool

True when the side to move is checkmated (in check with no legal response). Use Board::result for the complete outcome.

Board::is_stalemate

source

fn Board::is_stalemate(self : Board) -> Bool

True when the side to move is stalemated (no legal moves while not in check — 困毙, which loses in Xiangqi).

Board::kings_facing

source

fn Board::kings_facing(self : Board) -> Bool

The flying-general rule: the two kings face each other on the same file with no piece in between. Such a position is illegal for the side that just moved.

Board::legal_moves

source

fn Board::legal_moves(self : Board) -> Array[Move]

All fully legal moves for the side to move: pseudo-legal moves that leave the mover's own king safe (not in check, kings not facing).

Board::move_from_chinese

source

fn Board::move_from_chinese(self : Board, notation : String) -> Result[Move, NotationError]

Interpret a Chinese notation string against the current position. The implementation generates the notation of every legal move and selects the exact match, which guarantees round-trip consistency.

Board::move_from_iccs

source

fn Board::move_from_iccs(self : Board, iccs : String) -> Result[Move, NotationError]

Parse an ICCS coordinate string into a move, validating that it is legal in the current position.

Board::move_to_chinese

source

fn Board::move_to_chinese(self : Board, mv : Move) -> String

Render a move in Chinese file notation (中文纵线记谱法), e.g. 炮二平五, 马8进7, 前车进一. The board is required for disambiguation. Works for both the side to move and (for analysis tooling) the opposite side, as long as the moving piece belongs to board.side_to_move in the common case.

Board::move_to_iccs

source

fn Board::move_to_iccs(self : Board, mv : Move) -> String

Render a move in ICCS coordinate notation, e.g. h2e2. Files are a..i (a on Red's left), ranks 0..9 (0 is Red's back rank).

Board::of_squares

source

fn Board::of_squares(squares : Array[Piece?], side_to_move : Side, move_number : Int) -> Board

Build a board from a mutable square array.

Board::piece_count

source

fn Board::piece_count(self : Board) -> Int

Count all pieces currently on the board.

Board::positions_of

source

fn Board::positions_of(self : Board, side : Side, kind : Kind) -> Array[Pos]

Collect every position occupied by a piece of side and kind.

Board::positions_of_side

source

fn Board::positions_of_side(self : Board, side : Side) -> Array[Pos]

Collect every position occupied by a piece of side.

Board::pseudo_moves

source

fn Board::pseudo_moves(self : Board) -> Array[Move]

Generate all pseudo-legal moves for the side to move.

Board::pseudo_moves_from

source

fn Board::pseudo_moves_from(self : Board, from : Pos) -> Array[Move]

Generate all pseudo-legal moves for the piece at from. A pseudo-legal move follows the piece's movement pattern and does not land on a friendly piece; it may leave the mover's own king in check. Use legal_moves for fully validated moves.

Board::render_board

source

fn Board::render_board(self : Board) -> String

Full board rendering including river and side-to-move caption.

Board::result

source

fn Board::result(self : Board) -> GameResult

Evaluate the game status. In Xiangqi, a side with no legal moves loses whether or not it is in check (困毙 counts as a loss).

Board::side

source

fn Board::side(self : Board) -> Side

The side whose turn it is.

Board::to_fen

source

fn Board::to_fen(self : Board) -> String

Render a board as a FEN string in standard layout.

Board::with_piece

source

fn Board::with_piece(self : Board, pos : Pos, piece : Piece) -> Board

Place or replace a piece at pos (for constructing custom positions).

Board::with_side

source

fn Board::with_side(self : Board, side : Side) -> Board

Set the side to move (for constructing custom positions).

Board::without

source

fn Board::without(self : Board, pos : Pos) -> Board

Remove the piece at pos (for constructing custom positions).

FenError

source

pub enum FenError {
  BadFieldCount
  BadBoard(String)
  BadSide(String)
  BadMoveNumber(String)
} derive(Eq, Show, @moonbitlang/core/debug.Debug
Debug)

Errors produced while parsing a FEN string.

GameResult

source

pub(all) enum GameResult {
  Ongoing
  RedWins
  BlackWins
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Outcome of a position from the perspective of the game.

Kind

source

pub(all) enum Kind {
  King
  Advisor
  Elephant
  Horse
  Rook
  Cannon
  Pawn
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

The seven Xiangqi piece kinds.

Move

source

pub struct Move {
  from : Pos
  to : Pos
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

A move from from to to.

Move::new

source

fn Move::new(from : Pos, to : Pos) -> Move

NotationError

source

pub enum NotationError {
  IllegalOrUnknown(String)
  BadIccs(String)
} derive(Eq, Show, @moonbitlang/core/debug.Debug
Debug)

Errors from coordinate parsing.

Piece

source

pub struct Piece {
  side : Side
  kind : Kind
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

A single piece on the board.

Piece::black

source

fn Piece::black(kind : Kind) -> Piece

Piece::red

source

fn Piece::red(kind : Kind) -> Piece

Constructors for the two sides.

Pos

source

pub struct Pos {
  file : Int
  rank : Int
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Board position. file is 0..8 (files a..i, a on Red's left), rank is 0..9 (rank 0 is Red's back rank, rank 9 is Black's).

Pos::in_palace

source

fn Pos::in_palace(self : Pos, side : Side) -> Bool

True when the position is inside the palace of side.

Pos::index

source

fn Pos::index(self : Pos) -> Int

Linear index into the 90-square board array.

Pos::is_valid

source

fn Pos::is_valid(self : Pos) -> Bool

True when the position lies on the 9x10 board.

Pos::new

source

fn Pos::new(file : Int, rank : Int) -> Pos

Pos::own_half

source

fn Pos::own_half(self : Pos, side : Side) -> Bool

True when the position is on side's own half of the river. The river lies between rank 4 and rank 5.

Side

source

pub(all) enum Side {
  Red
  Black
} derive(Eq, @moonbitlang/core/debug.Debug
Debug)

Side of a piece or the player to move. Red moves first and advances from rank 0 towards rank 9.

Side::is_red

source

fn Side::is_red(self : Side) -> Bool

Side::opponent

source

fn Side::opponent(self : Side) -> Side

The opposing side.

char_to_piece_kind

source

fn char_to_piece_kind(ch : Char) -> Kind?

Map a notation character to a piece kind (accepts simplified and traditional variants used by common software).

parse_fen

source

fn parse_fen(fen : String) -> Result[Board, FenError]

Parse a Xiangqi FEN string, e.g. "rnbakabnr/9/1c5c1/p1p1p1p1p/9/9/P1P1P1P1P/1C5C1/9/RNBAKABNR w - - 0 1".

Ranks are listed top-down: the first row is rank 9 (Black's back rank), the last row is rank 0 (Red's back rank). Letters are standard XiangqiFEN: k a b n r c p (case = side). The second field is w (Red) or b (Black); the last field, when present, is the full-move number.

perft

source

fn perft(board : Board, depth : Int) -> Int

Perft: count leaf nodes of the legal move tree to depth. Used to validate move generation against known reference counts.

Source Files

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xiangqi

#wbgxiaosu/xiangqi

#Board

#Board::apply_move

#Board::empty

#Board::find_king

#Board::get

#Board::in_check

#Board::initial

#Board::is_attacked

#Board::is_checkmate

#Board::is_stalemate

#Board::kings_facing

#Board::legal_moves

#Board::move_from_chinese

#Board::move_from_iccs

#Board::move_to_chinese

#Board::move_to_iccs

#Board::of_squares

#Board::piece_count

#Board::positions_of

#Board::positions_of_side

#Board::pseudo_moves

#Board::pseudo_moves_from

#Board::render_board

#Board::result

#Board::side

#Board::to_fen

#Board::with_piece

#Board::with_side

#Board::without

#FenError

#GameResult

#Kind

#Move

#Move::new

#NotationError

#Piece

#Piece::black

#Piece::red

#Pos

#Pos::in_palace

#Pos::index

#Pos::is_valid

#Pos::new

#Pos::own_half

#Side

#Side::is_red

#Side::opponent

#char_to_piece_kind

#parse_fen

#perft

Source Files

Board

Board::apply_move

Board::empty

Board::find_king

Board::get

Board::in_check

Board::initial

Board::is_attacked

Board::is_checkmate

Board::is_stalemate

Board::kings_facing

Board::legal_moves

Board::move_from_chinese

Board::move_from_iccs

Board::move_to_chinese

Board::move_to_iccs

Board::of_squares

Board::piece_count

Board::positions_of

Board::positions_of_side

Board::pseudo_moves

Board::pseudo_moves_from

Board::render_board

Board::result

Board::side

Board::to_fen

Board::with_piece

Board::with_side

Board::without

FenError

GameResult

Kind

Move

Move::new

NotationError

Piece

Piece::black

Piece::red

Pos

Pos::in_palace

Pos::index

Pos::is_valid

Pos::new

Pos::own_half

Side

Side::is_red

Side::opponent

char_to_piece_kind

parse_fen

perft