rules: use generic bitboard move generation
For bishops, knights, rooks and queens that is.
This commit is contained in:
parent
5efdd5407b
commit
ce62d3ab3a
30
res/scripts/gen_king_rays.py
Executable file
30
res/scripts/gen_king_rays.py
Executable file
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@ -0,0 +1,30 @@
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#!/usr/bin/env python3
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"""Pre-compute king ras bitboards for each square."""
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TEMPLATE = """\
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/// Pre-computed king rays.
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const KING_RAYS: [Bitboard; 64] = [
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{}
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];
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"""
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DIRS = [(1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)]
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def bit_pos(square):
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return 1 << square
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def get_rays():
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rays = []
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for f in range(8):
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for r in range(8):
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bitboard = 0
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for dir_f, dir_r in DIRS:
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ray_f = f + dir_f
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ray_r = r + dir_r
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if ray_f < 0 or ray_f > 7 or ray_r < 0 or ray_r > 7:
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continue
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bitboard |= bit_pos(ray_f * 8 + ray_r)
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rays.append(" 0b{:064b},".format(bitboard))
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return rays
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print(TEMPLATE.format("\n".join(get_rays())))
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@ -2,6 +2,7 @@
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"""Pre-compute knight ray bitboards for each square."""
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TEMPLATE = """\
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/// Pre-computed knight rays.
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const KNIGHT_RAYS: [Bitboard; 64] = [
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{}
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];
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79
src/board.rs
79
src/board.rs
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@ -99,6 +99,7 @@ pub const H5: Square = 60;
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pub const H6: Square = 61;
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pub const H7: Square = 62;
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pub const H8: Square = 63;
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pub const NUM_SQUARES: Square = 64;
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/// Get square from file and rank, both starting from 0.
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#[inline]
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@ -192,9 +193,8 @@ pub const fn after_on_file(file: i8, rank: i8) -> Bitboard {
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FILES[file as usize] & bits_after(file, rank)
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}
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/// Debug only: count positive bits of the bitboard.
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#[allow(dead_code)]
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pub(crate) fn count_bits(bitboard: Bitboard) -> u8 {
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/// Count positive bits of the bitboard.
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pub fn count_bits(bitboard: Bitboard) -> u8 {
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let mut bitboard = bitboard;
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let mut count = 0;
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while bitboard > 0 {
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@ -216,6 +216,75 @@ pub(crate) fn draw_bits(bitboard: Bitboard, f: &mut dyn std::io::Write) {
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}
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}
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// Generated by gen_king_rays.py.
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/// Pre-computed king rays.
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const KING_RAYS: [Bitboard; 64] = [
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0b00000000_00000000_00000000_00000000_00000000_00000000_00000011_00000010,
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0b00000000_00000000_00000000_00000000_00000000_00000000_00000111_00000101,
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0b00000000_00000000_00000000_00000000_00000000_00000000_00001110_00001010,
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0b00000000_00000000_00000000_00000000_00000000_00000000_00011100_00010100,
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0b00000000_00000000_00000000_00000000_00000000_00000000_00111000_00101000,
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0b00000000_00000000_00000000_00000000_00000000_00000000_01110000_01010000,
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0b00000000_00000000_00000000_00000000_00000000_00000000_11100000_10100000,
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0b00000000_00000000_00000000_00000000_00000000_00000000_11000000_01000000,
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0b00000000_00000000_00000000_00000000_00000000_00000011_00000010_00000011,
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0b00000000_00000000_00000000_00000000_00000000_00000111_00000101_00000111,
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0b00000000_00000000_00000000_00000000_00000000_00001110_00001010_00001110,
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0b00000000_00000000_00000000_00000000_00000000_00011100_00010100_00011100,
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0b00000000_00000000_00000000_00000000_00000000_00111000_00101000_00111000,
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0b00000000_00000000_00000000_00000000_00000000_01110000_01010000_01110000,
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0b00000000_00000000_00000000_00000000_00000000_11100000_10100000_11100000,
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0b00000000_00000000_00000000_00000000_00000000_11000000_01000000_11000000,
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0b00000000_00000000_00000000_00000000_00000011_00000010_00000011_00000000,
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0b00000000_00000000_00000000_00000000_00000111_00000101_00000111_00000000,
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0b00000000_00000000_00000000_00000000_00001110_00001010_00001110_00000000,
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0b00000000_00000000_00000000_00000000_00011100_00010100_00011100_00000000,
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0b00000000_00000000_00000000_00000000_00111000_00101000_00111000_00000000,
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0b00000000_00000000_00000000_00000000_01110000_01010000_01110000_00000000,
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0b00000000_00000000_00000000_00000000_11100000_10100000_11100000_00000000,
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0b00000000_00000000_00000000_00000000_11000000_01000000_11000000_00000000,
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0b00000000_00000000_00000000_00000011_00000010_00000011_00000000_00000000,
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0b00000000_00000000_00000000_00000111_00000101_00000111_00000000_00000000,
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0b00000000_00000000_00000000_00001110_00001010_00001110_00000000_00000000,
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0b00000000_00000000_00000000_00011100_00010100_00011100_00000000_00000000,
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0b00000000_00000000_00000000_00111000_00101000_00111000_00000000_00000000,
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0b00000000_00000000_00000000_01110000_01010000_01110000_00000000_00000000,
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0b00000000_00000000_00000000_11100000_10100000_11100000_00000000_00000000,
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0b00000000_00000000_00000000_11000000_01000000_11000000_00000000_00000000,
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0b00000000_00000000_00000011_00000010_00000011_00000000_00000000_00000000,
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0b00000000_00000000_00000111_00000101_00000111_00000000_00000000_00000000,
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0b00000000_00000000_00001110_00001010_00001110_00000000_00000000_00000000,
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0b00000000_00000000_00011100_00010100_00011100_00000000_00000000_00000000,
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0b00000000_00000000_00111000_00101000_00111000_00000000_00000000_00000000,
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0b00000000_00000000_01110000_01010000_01110000_00000000_00000000_00000000,
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0b00000000_00000000_11100000_10100000_11100000_00000000_00000000_00000000,
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0b00000000_00000000_11000000_01000000_11000000_00000000_00000000_00000000,
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0b00000000_00000011_00000010_00000011_00000000_00000000_00000000_00000000,
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0b00000000_00000111_00000101_00000111_00000000_00000000_00000000_00000000,
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0b00000000_00001110_00001010_00001110_00000000_00000000_00000000_00000000,
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0b00000000_00011100_00010100_00011100_00000000_00000000_00000000_00000000,
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0b00000000_00111000_00101000_00111000_00000000_00000000_00000000_00000000,
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0b00000000_01110000_01010000_01110000_00000000_00000000_00000000_00000000,
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0b00000000_11100000_10100000_11100000_00000000_00000000_00000000_00000000,
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0b00000000_11000000_01000000_11000000_00000000_00000000_00000000_00000000,
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0b00000011_00000010_00000011_00000000_00000000_00000000_00000000_00000000,
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0b00000111_00000101_00000111_00000000_00000000_00000000_00000000_00000000,
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0b00001110_00001010_00001110_00000000_00000000_00000000_00000000_00000000,
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0b00011100_00010100_00011100_00000000_00000000_00000000_00000000_00000000,
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0b00111000_00101000_00111000_00000000_00000000_00000000_00000000_00000000,
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0b01110000_01010000_01110000_00000000_00000000_00000000_00000000_00000000,
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0b11100000_10100000_11100000_00000000_00000000_00000000_00000000_00000000,
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0b11000000_01000000_11000000_00000000_00000000_00000000_00000000_00000000,
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0b00000010_00000011_00000000_00000000_00000000_00000000_00000000_00000000,
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0b00000101_00000111_00000000_00000000_00000000_00000000_00000000_00000000,
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0b00001010_00001110_00000000_00000000_00000000_00000000_00000000_00000000,
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0b00010100_00011100_00000000_00000000_00000000_00000000_00000000_00000000,
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0b00101000_00111000_00000000_00000000_00000000_00000000_00000000_00000000,
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0b01010000_01110000_00000000_00000000_00000000_00000000_00000000_00000000,
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0b10100000_11100000_00000000_00000000_00000000_00000000_00000000_00000000,
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0b01000000_11000000_00000000_00000000_00000000_00000000_00000000_00000000,
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];
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// Generated by gen_knight_rays.py.
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/// Pre-computed knight rays.
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const KNIGHT_RAYS: [Bitboard; 64] = [
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@ -477,6 +546,10 @@ impl Board {
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KNIGHT_RAYS[square as usize] & !self.by_color(color)
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}
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pub fn get_king_rays(&self, square: Square, color: Color) -> Bitboard {
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KING_RAYS[square as usize] & !self.by_color(color)
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}
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/// Debug only: write a text view of the board.
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pub(crate) fn draw(&self, f: &mut dyn std::io::Write) {
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let cbb = self.combined();
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235
src/rules.rs
235
src/rules.rs
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@ -178,37 +178,15 @@ fn get_bishop_moves(
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color: Color,
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pseudo_legal: bool,
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) -> Vec<Move> {
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let (f, r) = (sq_file(square), sq_rank(square));
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let mut views = [true; 4]; // Store diagonals where a piece blocks commit.
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let mut moves = Vec::with_capacity(8);
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for dist in 1..=7 {
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for (dir, offset) in [(1, -1), (1, 1), (-1, 1), (-1, -1)].iter().enumerate() {
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if !views[dir] {
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continue
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}
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// If this position is out of the board, stop looking in that direction.
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let ray_f = f + offset.0 * dist;
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if ray_f < POS_MIN || ray_f > POS_MAX {
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views[dir] = false;
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continue
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}
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let ray_r = r + offset.1 * dist;
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if ray_r < POS_MIN || ray_r > POS_MAX {
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views[dir] = false;
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continue
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}
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let ray_square = sq(ray_f, ray_r);
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match get_move_type(board, game_state, square, ray_square, color, pseudo_legal) {
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MoveType::Simple(m) => { moves.push(m) }
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MoveType::Capture(m) => { moves.push(m); views[dir] = false; }
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MoveType::CantTakeFriend => { views[dir] = false; }
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_ => {}
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}
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}
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}
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moves
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get_moves_from_bb(
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board,
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game_state,
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board.get_bishop_rays(square, color),
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square,
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color,
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BISHOP,
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pseudo_legal
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)
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}
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fn get_knight_moves(
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@ -218,25 +196,15 @@ fn get_knight_moves(
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color: Color,
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pseudo_legal: bool,
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) -> Vec<Move> {
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let (f, r) = (sq_file(square), sq_rank(square));
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let mut moves = Vec::with_capacity(8);
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for offset in [(1, 2), (2, 1), (2, -1), (1, -2), (-1, -2), (-2, -1), (-2, 1), (-1, 2)].iter() {
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let ray_f = f + offset.0;
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if ray_f < POS_MIN || ray_f > POS_MAX {
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continue
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}
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let ray_r = r + offset.1;
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if ray_r < POS_MIN || ray_r > POS_MAX {
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continue
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}
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let ray_square = sq(ray_f, ray_r);
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match get_move_type(board, game_state, square, ray_square, color, pseudo_legal) {
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MoveType::Simple(m) | MoveType::Capture(m) => moves.push(m),
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_ => {}
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}
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}
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moves
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get_moves_from_bb(
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board,
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game_state,
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board.get_knight_rays(square, color),
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square,
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color,
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KNIGHT,
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pseudo_legal
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)
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}
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fn get_rook_moves(
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@ -246,36 +214,15 @@ fn get_rook_moves(
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color: Color,
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pseudo_legal: bool,
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) -> Vec<Move> {
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let (f, r) = (sq_file(square), sq_rank(square));
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let mut moves = Vec::with_capacity(8);
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let mut views = [true; 4]; // Store lines where a piece blocks commit.
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for dist in 1..=7 {
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for (dir, offset) in [(0, 1), (1, 0), (0, -1), (-1, 0)].iter().enumerate() {
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if !views[dir] {
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continue
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}
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let ray_f = f + offset.0 * dist;
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if ray_f < POS_MIN || ray_f > POS_MAX {
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views[dir] = false;
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continue
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}
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let ray_r = r + offset.1 * dist;
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if ray_r < POS_MIN || ray_r > POS_MAX {
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views[dir] = false;
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continue
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}
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let ray_square = sq(ray_f, ray_r);
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match get_move_type(board, game_state, square, ray_square, color, pseudo_legal) {
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MoveType::Simple(m) => { moves.push(m) }
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MoveType::Capture(m) => { moves.push(m); views[dir] = false; }
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MoveType::CantTakeFriend => { views[dir] = false; }
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_ => {}
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}
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}
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}
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moves
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get_moves_from_bb(
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board,
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game_state,
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board.get_rook_rays(square, color),
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square,
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color,
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ROOK,
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pseudo_legal
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)
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}
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fn get_queen_moves(
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@ -285,11 +232,15 @@ fn get_queen_moves(
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color: Color,
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pseudo_legal: bool,
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) -> Vec<Move> {
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let mut moves = Vec::with_capacity(16);
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// Easy way to get queen moves, but may be a bit quicker if everything was rewritten here.
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moves.append(&mut get_bishop_moves(board, game_state, square, color, pseudo_legal));
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moves.append(&mut get_rook_moves(board, game_state, square, color, pseudo_legal));
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moves
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get_moves_from_bb(
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board,
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game_state,
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board.get_queen_rays(square, color),
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square,
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color,
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QUEEN,
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pseudo_legal
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)
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}
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fn get_king_moves(
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@ -299,24 +250,15 @@ fn get_king_moves(
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color: Color,
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pseudo_legal: bool,
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) -> Vec<Move> {
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let (f, r) = (sq_file(square), sq_rank(square));
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let mut moves = Vec::with_capacity(8);
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for offset in [(-1, 1), (0, 1), (1, 1), (-1, 0), (1, 0), (-1, -1), (0, -1), (1, -1)].iter() {
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let ray_f = f + offset.0;
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if ray_f < POS_MIN || ray_f > POS_MAX {
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continue
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}
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let ray_r = r + offset.1;
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if ray_r < POS_MIN || ray_r > POS_MAX {
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continue
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}
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let ray_square = sq(ray_f, ray_r);
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match get_move_type(board, game_state, square, ray_square, color, pseudo_legal) {
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MoveType::Simple(m) | MoveType::Capture(m) => moves.push(m),
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_ => {}
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}
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}
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let mut moves = get_moves_from_bb(
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board,
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game_state,
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board.get_king_rays(square, color),
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square,
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color,
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KING,
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pseudo_legal
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);
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// Stop here for pseudo legal moves as castling is not considered along with them.
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if pseudo_legal {
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@ -338,6 +280,7 @@ fn get_king_moves(
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(7, CASTLING_BL_MASK)
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};
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let r = sq_rank(square);
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// Check for castling if the king is on its castling rank (R1)
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// and is not in check (R4).
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if
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@ -380,58 +323,58 @@ fn get_king_moves(
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moves
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}
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/// Get moves from this ray bitboard.
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fn get_moves_from_bb(
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board: &Board,
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game_state: &GameState,
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bitboard: Bitboard,
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square: Square,
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color: Color,
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piece: Piece,
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pseudo_legal: bool
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) -> Vec<Move> {
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let mut moves = Vec::with_capacity(count_bits(bitboard).into());
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for ray_square in 0..NUM_SQUARES {
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if ray_square == square || bitboard & bit_pos(ray_square) == 0 {
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continue
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}
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if let Some(mut m) = inspect_move(board, game_state, square, ray_square, pseudo_legal) {
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// Automatic queen promotion for pawns moving to the opposite rank.
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if
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piece == PAWN
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&& (color == WHITE && sq_rank(ray_square) == RANK_8)
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|| (color == BLACK && sq_rank(ray_square) == RANK_1)
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{
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m.promotion = Some(QUEEN);
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}
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moves.push(m);
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}
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}
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moves
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}
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/// Accept or ignore a move from `square` to `ray_square`.
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fn get_move_type(
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///
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/// This function checks that the move is legal, unless `pseudo_legal`
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/// is true. It assumes that `ray_square` is either empty or an enemy
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/// piece, but not a friend piece: they should have been filtered.
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///
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/// This function does not set promotions for pawns reaching last rank.
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fn inspect_move(
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board: &Board,
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game_state: &GameState,
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square: Square,
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ray_square: Square,
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color: Color,
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commit: bool
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) -> MoveType {
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if board.is_empty(ray_square) {
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let m = Move::new(square, ray_square);
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if is_legal(commit, board, game_state, &m) {
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MoveType::Simple(m)
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} else {
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MoveType::CantRegister
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}
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pseudo_legal: bool
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) -> Option<Move> {
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let m = Move::new(square, ray_square);
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if pseudo_legal || !is_illegal(board, game_state, &m) {
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Some(m)
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} else {
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let ray_color = board.get_color_on(ray_square);
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if let Some(m) = get_capture_move(color, square, ray_color, ray_square, false) {
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if is_legal(commit, board, game_state, &m) {
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MoveType::Capture(m)
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} else {
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MoveType::CantRegister
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}
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} else {
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MoveType::CantTakeFriend
|
||||
}
|
||||
None
|
||||
}
|
||||
}
|
||||
|
||||
enum MoveType {
|
||||
/// Move to an empty square.
|
||||
Simple(Move),
|
||||
/// Capture an enemy piece.
|
||||
Capture(Move),
|
||||
/// May be illegal, or should not be committed, e.g. to test rays.
|
||||
CantRegister,
|
||||
/// Can't capture a friend piece.
|
||||
CantTakeFriend,
|
||||
}
|
||||
|
||||
/// Return true if `pseudo_legal` is true, or the move is not illegal,
|
||||
///
|
||||
/// Committing a move means that it can be safely played afterwards.
|
||||
/// Sometimes it is not what is needed to accept a move in a collection
|
||||
/// of moves, e.g. when simply checking if some moves would make a
|
||||
/// previous move illegal.
|
||||
#[inline]
|
||||
fn is_legal(pseudo_legal: bool, board: &Board, game_state: &GameState, m: &Move) -> bool {
|
||||
pseudo_legal || !is_illegal(board, game_state, m)
|
||||
}
|
||||
|
||||
/// Return a move from `square1` to `square2` if colors are opposite.
|
||||
fn get_capture_move(
|
||||
color1: Color,
|
||||
|
|
|
|||
Reference in a new issue