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GameBoard

GameBoard​

The GameBoard struct manages the chess board state using the shakmaty chess library. It maintains position history, move history, and handles all chess rule validation.

Responsibilities​

The GameBoard manages:

  • Position history - Complete history of board positions
  • Move history - All moves made in the game
  • Draw detection - 50-move rule, threefold repetition, stalemate, insufficient material
  • Move validation - Using shakmaty's legal move system
  • Coordinate conversion - Handling flipped board orientation

Key Fields​

pub struct GameBoard {
    pub move_history: Vec<Move>,              // History of all moves
    pub position_history: Vec<Chess>,         // History of board positions (last = current)
    pub consecutive_non_pawn_or_capture: i32, // Counter for 50-move rule
    pub taken_pieces: Vec<Piece>,             // Captured pieces (with color)
    pub is_flipped: bool,                     // Board orientation for display
}

Key Methods​

Position Access​

  • position_ref() -> &Chess - Gets a read-only reference to the last position in the history (panics if empty)
  • current_position() -> Option<&Chess> - Safe access to current position, returns None if history is empty

Move Execution​

  • execute_move(from: Square, to: Square, promotion: Option<Role>) -> Option<Move>

    • Validates move using shakmaty's legal move system
    • Tracks captured pieces
    • Updates position and move history
    • Returns executed Move if successful, None if illegal

  • execute_shakmaty_move(from: Square, to: Square) -> bool

    • Convenience method for moves without promotion
    • Returns true if move was executed

  • execute_standard_move(from: Square, to: Square, promotion: Option<Role>) -> Option<Move>

    • Executes moves from standard (non-flipped) coordinates
    • Used for bot and opponent moves which come in standard notation

  • execute_shakmaty_move_with_promotion(from: Square, to: Square, promotion: Option<Role>) -> bool

    • Executes move with explicit promotion piece

Move Information​

  • move_to_san(index: usize) -> String - Converts move to Standard Algebraic Notation

    • Uses shakmaty's SAN conversion
    • Examples: "e4", "Nf3", "O-O", "Qxd5+"

  • is_latest_move_promotion() -> bool - Checks if last move was a promotion

Piece Information​

  • get_role_at_square(square: &Square) -> Option<Role> - Gets piece type at square
  • get_piece_color_at_square(square: &Square) -> Option<Color> - Gets piece color at square
  • is_square_occupied(square: &Square) -> bool - Checks if square has a piece
  • get_authorized_positions(player_turn: Color, square: &Square) -> Vec<Square>
    • Returns all legal destination squares for a piece
    • Uses shakmaty's legal_moves() method
    • Filters moves by source square

Game End Detection​

  • is_checkmate() -> bool - Checks if current position is checkmate
  • is_draw() -> bool - Checks for draw conditions:
    • Stalemate
    • 50-move rule (consecutive_non_pawn_or_capture == 50)
    • Threefold repetition (is_draw_by_repetition())
    • Insufficient material
  • is_draw_by_repetition() -> bool - Checks if position repeated 3+ times
  • is_getting_checked(player_turn: Color) -> bool - Checks if player is in check

Taken Pieces​

  • white_taken_pieces() -> Vec<Role> - Returns captured white pieces
  • black_taken_pieces() -> Vec<Role> - Returns captured black pieces

Board Orientation​

  • flip_the_board() - Toggles board orientation (for perspective switching)
  • is_flipped: bool - Tracks current orientation

FEN Position​

  • fen_position() -> String
    • Generates FEN string for UCI engine communication
    • Uses shakmaty's FEN encoding
    • Automatically uses current board position

Utility​

  • reset() - Resets board to starting position
  • increment_consecutive_non_pawn_or_capture(role_from: Role, role_to: Option<Role>)
    • Updates 50-move rule counter
    • Resets on pawn moves or captures

Shakmaty Integration​

The GameBoard uses shakmaty's Chess type for position management:

  • Vec<Chess> - Position history, each element is a complete board state
  • Move - Move representation with promotion, castling, en passant support
  • Legal move validation - All moves are validated using chess.legal_moves()
  • SAN conversion - Uses San::from_move() for algebraic notation

This ensures all chess rules are correctly enforced by the shakmaty library.