castling: simplify castle updates
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b62dd1c076
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8b0f4c9255
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@ -1,19 +1,21 @@
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//! Castling flags.
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pub const CASTLING_WH_K: u8 = 0b00000001;
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pub const CASTLING_WH_Q: u8 = 0b00000010;
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pub const CASTLING_WH_MASK: u8 = 0b00000011;
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pub const CASTLING_BL_K: u8 = 0b00000100;
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pub const CASTLING_BL_Q: u8 = 0b00001000;
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pub const CASTLING_BL_MASK: u8 = 0b00001100;
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pub const CASTLING_K_MASK: u8 = 0b00000101;
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pub const CASTLING_Q_MASK: u8 = 0b00001010;
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pub const CASTLING_MASK: u8 = 0b00001111;
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pub type Castle = u8;
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pub const CASTLING_WH_K: Castle = 0b00000001;
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pub const CASTLING_WH_Q: Castle = 0b00000010;
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pub const CASTLING_WH_MASK: Castle = 0b00000011;
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pub const CASTLING_BL_K: Castle = 0b00000100;
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pub const CASTLING_BL_Q: Castle = 0b00001000;
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pub const CASTLING_BL_MASK: Castle = 0b00001100;
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pub const CASTLING_K_MASK: Castle = 0b00000101;
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pub const CASTLING_Q_MASK: Castle = 0b00001010;
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pub const CASTLING_MASK: Castle = 0b00001111;
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/// Castling sides parameters.
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///
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/// For both sides, the 3-uple contains files that should be empty
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/// and not attacked, an optional file that should be empty for
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/// queen-side, and the castling side-mask.
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pub const CASTLING_SIDES: [([i8; 2], Option<i8>, u8); 2] =
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pub const CASTLING_SIDES: [([i8; 2], Option<i8>, Castle); 2] =
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[([5i8, 6i8], None, CASTLING_K_MASK), ([3i8, 2i8], Some(1i8), CASTLING_Q_MASK)];
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134
src/movement.rs
134
src/movement.rs
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@ -6,9 +6,6 @@ use crate::board::*;
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use crate::castling::*;
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use crate::rules::GameState;
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const START_WH_K_POS: Square = E1;
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const START_BL_K_POS: Square = E8;
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/// A movement, with before/after positions and optional promotion.
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#[derive(Clone, PartialEq)]
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pub struct Move {
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@ -39,119 +36,50 @@ impl Move {
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/// Apply this move to `board` and `game_state`.
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pub fn apply_to(&self, board: &mut Board, game_state: &mut GameState) {
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// If a rook is taken, remove its castling option. Needs to be checked before we update
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// board. Note that we only check for a piece going to rook's initial position: it means
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// the rook either moved previously, or it has been taken.
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match self.source {
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A1 => { game_state.castling &= !CASTLING_WH_Q; }
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H1 => { game_state.castling &= !CASTLING_WH_K; }
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A8 => { game_state.castling &= !CASTLING_BL_Q; }
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H8 => { game_state.castling &= !CASTLING_BL_K; }
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_ => {}
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}
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// If a king moves, remove it from castling options.
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if self.source == E1 { game_state.castling &= !CASTLING_WH_MASK; }
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else if self.source == E8 { game_state.castling &= !CASTLING_BL_MASK; }
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// Same for rooks.
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if self.source == A1 || self.dest == A1 { game_state.castling &= !CASTLING_WH_Q; }
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else if self.source == H1 || self.dest == H1 { game_state.castling &= !CASTLING_WH_K; }
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else if self.source == A8 || self.dest == A8 { game_state.castling &= !CASTLING_BL_Q; }
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else if self.source == H8 || self.dest == H8 { game_state.castling &= !CASTLING_BL_K; }
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// Update board and game state.
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self.apply_to_board(board);
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game_state.color = opposite(game_state.color);
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// If the move is a castle, remove it from castling options.
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if let Some(castle) = self.get_castle() {
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match castle {
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CASTLING_WH_K | CASTLING_WH_Q => game_state.castling &= !CASTLING_WH_MASK,
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CASTLING_BL_K | CASTLING_BL_Q => game_state.castling &= !CASTLING_BL_MASK,
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_ => {}
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};
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}
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// Else, check if the king or a rook moved to update castling options.
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else {
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let color = board.get_color_on(self.dest);
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if color == WHITE && game_state.castling & CASTLING_WH_MASK != 0 {
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match board.get_piece_on(self.dest) {
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KING => {
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if self.source == E1 {
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game_state.castling &= !CASTLING_WH_MASK;
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}
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}
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ROOK => {
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if self.source == A1 {
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game_state.castling &= !CASTLING_WH_Q;
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} else if self.source == H1 {
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game_state.castling &= !CASTLING_WH_K;
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}
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}
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_ => {}
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}
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} else if color == BLACK && game_state.castling & CASTLING_BL_MASK != 0 {
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match board.get_piece_on(self.dest) {
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KING => {
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if self.source == E8 {
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game_state.castling &= !CASTLING_BL_MASK;
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}
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}
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ROOK => {
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if self.source == A8 {
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game_state.castling &= !CASTLING_BL_Q;
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} else if self.source == H8 {
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game_state.castling &= !CASTLING_BL_K;
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}
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}
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_ => {}
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}
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}
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}
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}
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/// Apply the move into `board`.
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pub fn apply_to_board(&self, board: &mut Board) {
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if let Some(castle) = self.get_castle() {
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match castle {
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CASTLING_WH_K => {
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board.move_square(START_WH_K_POS, G1);
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board.move_square(H1, F1);
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let piece = board.get_piece_on(self.source);
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// If a king is castling, apply special move.
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if piece == KING {
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if let Some(castle) = self.get_castle() {
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match castle {
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CASTLING_WH_K => { board.move_square(E1, G1); board.move_square(H1, F1); }
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CASTLING_WH_Q => { board.move_square(E1, C1); board.move_square(A1, D1); }
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CASTLING_BL_K => { board.move_square(E8, G8); board.move_square(H8, F8); }
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CASTLING_BL_Q => { board.move_square(E8, C8); board.move_square(A8, D8); }
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_ => { panic!("Invalid castle.") }
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}
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CASTLING_WH_Q => {
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board.move_square(START_WH_K_POS, C1);
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board.move_square(A1, D1);
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}
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CASTLING_BL_K => {
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board.move_square(START_BL_K_POS, G8);
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board.move_square(H8, F8);
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}
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CASTLING_BL_Q => {
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board.move_square(START_BL_K_POS, C8);
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board.move_square(A8, D8);
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}
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_ => {}
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}
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} else {
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board.move_square(self.source, self.dest);
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if let Some(piece) = self.promotion {
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let color = board.get_color_on(self.dest);
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board.set_square(self.dest, color, piece);
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return
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}
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}
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board.move_square(self.source, self.dest);
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if let Some(piece) = self.promotion {
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let color = board.get_color_on(self.dest);
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board.set_square(self.dest, color, piece);
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}
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}
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/// Get the corresponding castling flag for this move.
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pub fn get_castle(&self) -> Option<u8> {
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if self.source == E1 {
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if self.dest == C1 {
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Some(CASTLING_WH_Q)
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} else if self.dest == G1 {
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Some(CASTLING_WH_K)
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} else {
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None
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}
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} else if self.source == E8 {
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if self.dest == C8 {
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Some(CASTLING_BL_Q)
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} else if self.dest == G8 {
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Some(CASTLING_BL_K)
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} else {
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None
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}
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} else {
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None
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pub fn get_castle(&self) -> Option<Castle> {
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match (self.source, self.dest) {
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(E1, C1) => Some(CASTLING_WH_Q),
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(E1, G1) => Some(CASTLING_WH_K),
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(E8, C8) => Some(CASTLING_BL_Q),
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(E8, G8) => Some(CASTLING_BL_K),
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_ => None,
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}
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}
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@ -54,11 +54,6 @@ impl fmt::Display for Node {
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let mut s = vec!();
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self.board.draw(&mut s);
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let board_drawing = String::from_utf8_lossy(&s).to_string();
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write!(
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f,
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"* Board:\n{}\n\
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* Game state:\n{}",
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board_drawing, self.game_state
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)
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write!(f, "* Board:\n{}\nGame state: {}", board_drawing, self.game_state)
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}
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}
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@ -43,11 +43,7 @@ impl std::fmt::Display for GameState {
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fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
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write!(
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f,
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"- color: {}\n\
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- castling: {:04b}\n\
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- en_passant: {}\n\
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- halfmove: {}\n\
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- fullmove: {}",
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"[color: {}, castling: {:04b}, en_passant: {}, halfmove: {}, fullmove: {}]",
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color_to_string(self.color), self.castling,
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fen::en_passant_to_string(self.en_passant),
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self.halfmove, self.fullmove
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