my $nb = [];
for my $row (0..7) {
- for my $col (0..7) {
- $nb->[$row][$col] = $board->[$row][$col];
- }
+ $nb->[$row] = [ @{$board->[$row]} ];
}
return bless $nb;
# Returns a new board.
sub make_move {
my ($board, $from_row, $from_col, $to_row, $to_col, $promo) = @_;
- my $move = _move_to_uci_notation($from_row, $from_col, $to_row, $to_col, $promo);
+ my $move = move_to_uci_notation($from_row, $from_col, $to_row, $to_col, $promo);
my $piece = $board->[$from_row][$from_col];
my $nb = $board->clone();
die "Invalid move $move";
}
- # white short castling
- if ($move eq 'e1g1' && $piece eq 'K') {
- # king
- $nb->[7][4] = '-';
- $nb->[7][6] = $piece;
+ if ($piece eq 'K') {
+ # Convert to Chess960 king-takes-rook.
+ $to_col = 7 if ($move eq 'e1g1');
+ $to_col = 0 if ($move eq 'e1c1');
- # rook
- $nb->[7][7] = '-';
- $nb->[7][5] = 'R';
+ my $dst_piece = $board->[$to_row][$to_col];
- return $nb;
- }
+ # White short castling.
+ if ($dst_piece eq 'R' && $to_col > $from_col) {
+ # king
+ $nb->[7][$from_col] = '-';
+ $nb->[7][$to_col] = '-';
+ $nb->[7][6] = 'K';
+ $nb->[7][5] = 'R';
- # white long castling
- if ($move eq 'e1c1' && $piece eq 'K') {
- # king
- $nb->[7][4] = '-';
- $nb->[7][2] = $piece;
+ return $nb;
+ }
- # rook
- $nb->[7][0] = '-';
- $nb->[7][3] = 'R';
+ # Black short castling.
+ if ($dst_piece eq 'R' && $to_col < $from_col) {
+ $nb->[7][$from_col] = '-';
+ $nb->[7][$to_col] = '-';
+ $nb->[7][2] = 'K';
+ $nb->[7][3] = 'R';
- return $nb;
- }
-
- # black short castling
- if ($move eq 'e8g8' && $piece eq 'k') {
- # king
- $nb->[0][4] = '-';
- $nb->[0][6] = $piece;
+ return $nb;
+ }
+ } elsif ($piece eq 'k') {
+ # Convert to Chess960 king-takes-rook.
+ $to_col = 7 if ($move eq 'e8g8');
+ $to_col = 0 if ($move eq 'e8c8');
- # rook
- $nb->[0][7] = '-';
- $nb->[0][5] = 'r';
+ my $dst_piece = $board->[$to_row][$to_col];
- return $nb;
- }
+ # Black short castling.
+ if ($dst_piece eq 'r' && $to_col > $from_col) {
+ $nb->[0][$from_col] = '-';
+ $nb->[0][$to_col] = '-';
+ $nb->[0][6] = 'k';
+ $nb->[0][5] = 'r';
- # black long castling
- if ($move eq 'e8c8' && $piece eq 'k') {
- # king
- $nb->[0][4] = '-';
- $nb->[0][2] = $piece;
+ return $nb;
+ }
- # rook
- $nb->[0][0] = '-';
- $nb->[0][3] = 'r';
+ # Black long castling.
+ if ($dst_piece eq 'r' && $to_col < $from_col) {
+ # king
+ $nb->[0][$from_col] = '-';
+ $nb->[0][$to_col] = '-';
+ $nb->[0][2] = 'k';
+ $nb->[0][3] = 'r';
- return $nb;
+ return $nb;
+ }
}
# check if the from-piece is a pawn
# en passant?
if ($board->[$to_row][$to_col] eq '-') {
if ($piece eq 'p') {
- $nb->[$to_row + 1][$to_col] = '-';
- } else {
$nb->[$to_row - 1][$to_col] = '-';
- }
- }
- } else {
- if (defined($promo) && $promo ne '') {
- if ($piece eq 'p') {
- $piece = $promo;
} else {
- $piece = uc($promo);
+ $nb->[$to_row + 1][$to_col] = '-';
}
}
}
+ if (defined($promo) && $promo ne '') {
+ if ($piece eq 'p') {
+ $piece = lc($promo);
+ } else {
+ $piece = uc($promo);
+ }
+ }
}
# update the board
return 7 - (ord(shift) - ord('1'));
}
+use Carp;
+
sub _square_to_pos {
my ($square) = @_;
- $square =~ /^([a-h])([1-8])$/ or die "Invalid square $square";
+ #$square =~ /^([a-h])([1-8])$/ or die "Invalid square $square";
+ $square =~ /^([a-h])([1-8])$/ or Carp::confess("Invalid square $square");
return (_row_letter_to_num($2), _col_letter_to_num($1));
}
-sub _move_to_uci_notation {
+sub move_to_uci_notation {
my ($from_row, $from_col, $to_row, $to_col, $promo) = @_;
$promo //= "";
return _pos_to_square($from_row, $from_col) . _pos_to_square($to_row, $to_col) . $promo;
}
+sub _find_piece_col {
+ my ($row, $piece) = @_;
+ for my $col (0..7) {
+ return $col if ($row->[$col] eq $piece);
+ }
+ die "Could not find piece $piece";
+}
+
+# Note: This is in general not a validation that the move is actually allowed
+# (e.g. you can castle even though you're in check).
sub parse_pretty_move {
- my ($board, $move, $toplay) = @_;
+ my ($board, $move, $toplay, $chess960, $white_castle_k, $white_castle_q, $black_castle_k, $black_castle_q) = @_;
# Strip check or mate
$move =~ s/[+#]$//;
if ($move eq '0-0' or $move eq 'O-O') {
if ($toplay eq 'W') {
- return (_square_to_pos('e1'), _square_to_pos('g1'));
+ if ($chess960) {
+ # King takes rook.
+ return (7, _find_piece_col($board->[7], 'K'), _square_to_pos($white_castle_k . '1'));
+ } else {
+ return (_square_to_pos('e1'), _square_to_pos('g1'));
+ }
} else {
- return (_square_to_pos('e8'), _square_to_pos('g8'));
+ if ($chess960) {
+ # King takes rook.
+ return (0, _find_piece_col($board->[0], 'k'), _square_to_pos($black_castle_k . '8'));
+ } else {
+ return (_square_to_pos('e8'), _square_to_pos('g8'));
+ }
}
} elsif ($move eq '0-0-0' or $move eq 'O-O-O') {
if ($toplay eq 'W') {
- return (_square_to_pos('e1'), _square_to_pos('c1'));
+ if ($chess960) {
+ # King takes rook.
+ return (7, _find_piece_col($board->[7], 'K'), _square_to_pos($white_castle_q . '1'));
+ } else {
+ return (_square_to_pos('e1'), _square_to_pos('c1'));
+ }
} else {
- return (_square_to_pos('e8'), _square_to_pos('c8'));
+ if ($chess960) {
+ # King takes rook.
+ return (0, _find_piece_col($board->[0], 'k'), _square_to_pos($black_castle_q . '8'));
+ } else {
+ return (_square_to_pos('e8'), _square_to_pos('c8'));
+ }
}
}
# Parse promo
my $promo;
- if ($move =~ s/=([QRNB])$//) {
+ if ($move =~ s/=?([QRNB])$//) {
$promo = $1;
}
$move =~ /^([KQRBN])?([a-h])?([1-8])?x?([a-h][1-8])$/ or die "Invalid move $move";
- my $piece = $1 // 'P';
+ my $piece = $1;
my $from_col = defined($2) ? _col_letter_to_num($2) : undef;
my $from_row = defined($3) ? _row_letter_to_num($3) : undef;
+ if (!defined($piece) && (!defined($from_col) || !defined($from_row))) {
+ $piece = 'P';
+ }
my ($to_row, $to_col) = _square_to_pos($4);
# Find all possible from-squares that could have been meant.
my @squares = ();
+ my $side = 'K';
if ($toplay eq 'B') {
- $piece = lc($piece);
+ $piece = lc($piece) if defined($piece);
+ $side = 'k';
}
for my $row (0..7) {
next if (defined($from_row) && $from_row != $row);
for my $col (0..7) {
next if (defined($from_col) && $from_col != $col);
- next if ($board->[$row][$col] ne $piece);
- next if (!$board->can_reach($piece, $row, $col, $to_row, $to_col));
+ next if (defined($piece) && $board->[$row][$col] ne $piece);
push @squares, [ $row, $col ];
}
}
+ if (scalar @squares > 1) {
+ # Filter out pieces which cannot reach this square.
+ @squares = grep { $board->can_reach($piece, $_->[0], $_->[1], $to_row, $to_col) } @squares;
+ }
+ if (scalar @squares > 1) {
+ # See if doing this move would put us in check
+ # (yes, there are clients that expect us to do this).
+ @squares = grep { !$board->make_move($_->[0], $_->[1], $to_row, $to_col, $promo)->in_check($side) } @squares;
+ }
+ if (scalar @squares == 0) {
+ die "Impossible move $move";
+ }
if (scalar @squares != 1) {
- die "Ambigious or impossible move $move";
+ die "Ambigious move $move";
}
return (@{$squares[0]}, $to_row, $to_col, $promo);
}
sub can_reach {
my ($board, $piece, $from_row, $from_col, $to_row, $to_col) = @_;
- # can't eat your own piece
+ # Can't eat your own piece (Chess960 uses king-takes-rook for castling,
+ # but castling is irrelevant for reachability)
my $dest_piece = $board->[$to_row][$to_col];
if ($dest_piece ne '-') {
return 0 if (($piece eq lc($piece)) == ($dest_piece eq lc($dest_piece)));
}
-
- if (lc($piece) eq 'k') {
- return (abs($from_row - $to_row) <= 1 && abs($from_col - $to_col) <= 1);
+
+ if ($piece eq 'p') {
+ # black pawn
+ if ($to_col == $from_col && $to_row == $from_row + 1) {
+ return ($dest_piece eq '-');
+ }
+ if ($to_col == $from_col && $from_row == 1 && $to_row == 3) {
+ my $middle_piece = $board->[2][$to_col];
+ return ($dest_piece eq '-' && $middle_piece eq '-');
+ }
+ if (abs($to_col - $from_col) == 1 && $to_row == $from_row + 1) {
+ if ($dest_piece eq '-') {
+ # En passant. TODO: check that the last move was indeed an EP move
+ return ($to_row == 5 && $board->[4][$to_col] eq 'P');
+ } else {
+ return 1;
+ }
+ }
+ return 0;
+ }
+ if ($piece eq 'P') {
+ # white pawn
+ if ($to_col == $from_col && $to_row == $from_row - 1) {
+ return ($dest_piece eq '-');
+ }
+ if ($to_col == $from_col && $from_row == 6 && $to_row == 4) {
+ my $middle_piece = $board->[5][$to_col];
+ return ($dest_piece eq '-' && $middle_piece eq '-');
+ }
+ if (abs($to_col - $from_col) == 1 && $to_row == $from_row - 1) {
+ if ($dest_piece eq '-') {
+ # En passant. TODO: check that the last move was indeed an EP move
+ return ($to_row == 2 && $board->[3][$to_col] eq 'p');
+ } else {
+ return 1;
+ }
+ }
+ return 0;
}
+
if (lc($piece) eq 'r') {
return 0 unless ($from_row == $to_row || $from_col == $to_col);
return (can_reach($board, 'R', $from_row, $from_col, $to_row, $to_col) ||
can_reach($board, 'B', $from_row, $from_col, $to_row, $to_col));
}
-
- # TODO: en passant
- if ($piece eq 'p') {
- # black pawn
- if ($to_col == $from_col && $to_row == $from_row + 1) {
- return ($dest_piece eq '-');
- }
- if ($to_col == $from_col && $from_row == 1 && $to_row == 3) {
- my $middle_piece = $board->[2][$to_col];
- return ($dest_piece eq '-' && $middle_piece eq '-');
- }
- if (abs($to_col - $from_col) == 1 && $to_row == $from_row + 1) {
- return ($dest_piece ne '-');
- }
- return 0;
- }
- if ($piece eq 'P') {
- # white pawn
- if ($to_col == $from_col && $to_row == $from_row - 1) {
- return ($dest_piece eq '-');
- }
- if ($to_col == $from_col && $from_row == 6 && $to_row == 4) {
- my $middle_piece = $board->[5][$to_col];
- return ($dest_piece eq '-' && $middle_piece eq '-');
- }
- if (abs($to_col - $from_col) == 1 && $to_row == $from_row - 1) {
- return ($dest_piece ne '-');
- }
- return 0;
+ if (lc($piece) eq 'k') {
+ return (abs($from_row - $to_row) <= 1 && abs($from_col - $to_col) <= 1);
}
-
+
# unknown piece
return 0;
}
-# Returns 'none', 'white', 'black' or 'both', depending on which sides are in check.
-# The latter naturally indicates an invalid position.
-sub in_check {
- my $board = shift;
- my ($black_check, $white_check) = (0, 0);
+# Like can_reach, but also checks the move doesn't put the side in check.
+# We use this in prettyprint_move to reduce the disambiguation, because Chess.js
+# needs moves to be in minimally disambiguated form.
+sub can_legally_reach {
+ my ($board, $piece, $from_row, $from_col, $to_row, $to_col) = @_;
+
+ return 0 if (!can_reach($board, $piece, $from_row, $from_col, $to_row, $to_col));
- my ($wkr, $wkc, $bkr, $bkc) = _find_kings($board);
+ my $nb = $board->make_move($from_row, $from_col, $to_row, $to_col);
+ my $side = ($piece eq lc($piece)) ? 'k' : 'K';
+
+ return !in_check($nb, $side);
+}
- # check all pieces for the possibility of threatening the two kings
+my %pieces_against_side = (
+ k => { K => 1, Q => 1, R => 1, N => 1, B => 1, P => 1 },
+ K => { k => 1, q => 1, r => 1, n => 1, b => 1, p => 1 },
+);
+
+# Returns whether the given side (given as k or K for black and white) is in check.
+sub in_check {
+ my ($board, $side) = @_;
+ my ($kr, $kc) = _find_piece($board, $side);
+
+ # check all pieces for the possibility of threatening this king
for my $row (0..7) {
+ next unless grep { exists($pieces_against_side{$side}{$_}) } @{$board->[$row]};
for my $col (0..7) {
my $piece = $board->[$row][$col];
next if ($piece eq '-');
-
- if (uc($piece) eq $piece) {
- # white piece
- $black_check = 1 if ($board->can_reach($piece, $row, $col, $bkr, $bkc));
- } else {
- # black piece
- $white_check = 1 if ($board->can_reach($piece, $row, $col, $wkr, $wkc));
- }
+ return 1 if ($board->can_reach($piece, $row, $col, $kr, $kc));
}
}
- if ($black_check && $white_check) {
- return 'both';
- } elsif ($black_check) {
- return 'black';
- } elsif ($white_check) {
- return 'white';
- } else {
- return 'none';
- }
+ return 0;
}
-sub _find_kings {
- my $board = shift;
- my ($wkr, $wkc, $bkr, $bkc);
+sub _find_piece {
+ my ($board, $piece) = @_;
for my $row (0..7) {
+ next unless grep { $_ eq $piece } @{$board->[$row]};
for my $col (0..7) {
- my $piece = $board->[$row][$col];
- if ($piece eq 'K') {
- ($wkr, $wkc) = ($row, $col);
- } elsif ($piece eq 'k') {
- ($bkr, $bkc) = ($row, $col);
+ if ($board->[$row][$col] eq $piece) {
+ return ($row, $col);
}
}
}
- return ($wkr, $wkc, $bkr, $bkc);
+ return (undef, undef);
}
-# Returns if any side is in mate.
+# Returns if the given side (given as k or K) is in mate.
sub in_mate {
- my $board = shift;
- my $check = $board->in_check();
- return 0 if ($check eq 'none');
+ my ($board, $side, $in_check) = @_;
+ return 0 if (!$in_check);
# try all possible moves for the side in check
for my $row (0..7) {
my $piece = $board->[$row][$col];
next if ($piece eq '-');
- if ($check eq 'white') {
+ if ($side eq 'K') {
next if ($piece eq lc($piece));
} else {
next if ($piece eq uc($piece));
next if ($row == $dest_row && $col == $dest_col);
next unless ($board->can_reach($piece, $row, $col, $dest_row, $dest_col));
- my $nb = $board->clone();
- $nb->[$row][$col] = '-';
- $nb->[$dest_row][$dest_col] = $piece;
- my $new_check = $nb->in_check();
- return 0 if ($new_check ne $check && $new_check ne 'both');
+ my $nb = $board->make_move($row, $col, $dest_row, $dest_col);
+ return 0 if (!$nb->in_check($side));
}
}
}
my $pretty = $board->_prettyprint_move_no_check_or_mate($from_row, $from_col, $to_row, $to_col, $promo);
my $nb = $board->make_move($from_row, $from_col, $to_row, $to_col, $promo);
- if ($nb->in_mate()) {
+
+ my $piece = $board->[$from_row][$from_col];
+ my $other_side = (uc($piece) eq $piece) ? 'k' : 'K';
+ my $in_check = $nb->in_check($other_side);
+ if ($nb->in_mate($other_side, $in_check)) {
$pretty .= '#';
- } elsif ($nb->in_check() ne 'none') {
+ } elsif ($in_check) {
$pretty .= '+';
}
return ($pretty, $nb);
}
+sub num_pieces {
+ my ($board) = @_;
+
+ my $num = 0;
+ for my $row (0..7) {
+ for my $col (0..7) {
+ my $piece = $board->[$row][$col];
+ ++$num if ($piece ne '-');
+ }
+ }
+ return $num;
+}
+
sub _prettyprint_move_no_check_or_mate {
my ($board, $from_row, $from_col, $to_row, $to_col, $promo) = @_;
my $piece = $board->[$from_row][$from_col];
- my $move = _move_to_uci_notation($from_row, $from_col, $to_row, $to_col, $promo);
+ my $move = move_to_uci_notation($from_row, $from_col, $to_row, $to_col, $promo);
if ($piece eq '-') {
die "Invalid move $move";
}
- # white short castling
- if ($move eq 'e1g1' && $piece eq 'K') {
- return '0-0';
- }
-
- # white long castling
- if ($move eq 'e1c1' && $piece eq 'K') {
- return '0-0-0';
- }
-
- # black short castling
- if ($move eq 'e8g8' && $piece eq 'k') {
- return '0-0';
- }
+ if ($piece eq 'K') {
+ # white short/long castling
+ return 'O-O' if ($move eq 'e1g1');
+ return 'O-O-O' if ($move eq 'e1c1');
- # black long castling
- if ($move eq 'e8c8' && $piece eq 'k') {
- return '0-0-0';
+ # white short/long chess960-style castling (king takes own rook)
+ my $dst_piece = $board->[$to_row][$to_col];
+ if ($dst_piece eq 'R') {
+ return ($to_col > $from_col) ? 'O-O' : 'O-O-O';
+ }
+ } elsif ($piece eq 'k') {
+ # black short/long castling
+ return 'O-O' if ($move eq 'e8g8');
+ return 'O-O-O' if ($move eq 'e8c8');
+
+ # black short/long chess960-style castling (king takes own rook)
+ my $dst_piece = $board->[$to_row][$to_col];
+ if ($dst_piece eq 'r') {
+ return ($to_col > $from_col) ? 'O-O' : 'O-O-O';
+ }
}
my $pretty;
$pretty = substr($move, 0, 1) . 'x' . _pos_to_square($to_row, $to_col);
} else {
$pretty = _pos_to_square($to_row, $to_col);
+ }
- if (defined($promo) && $promo ne '') {
- # promotion
- $pretty .= "=";
- $pretty .= $promo;
- }
+ if (defined($promo) && $promo ne '') {
+ # promotion
+ $pretty .= "=";
+ $pretty .= uc($promo);
}
return $pretty;
}
for my $col (0..7) {
for my $row (0..7) {
next unless ($board->[$row][$col] eq $piece);
- ++$num_total if ($board->can_reach($piece, $row, $col, $to_row, $to_col));
+ ++$num_total if ($board->can_legally_reach($piece, $row, $col, $to_row, $to_col));
}
}
my $num_row = 0;
for my $col (0..7) {
next unless ($board->[$from_row][$col] eq $piece);
- ++$num_row if ($board->can_reach($piece, $from_row, $col, $to_row, $to_col));
+ ++$num_row if ($board->can_legally_reach($piece, $from_row, $col, $to_row, $to_col));
}
# and same for columns
my $num_col = 0;
for my $row (0..7) {
next unless ($board->[$row][$from_col] eq $piece);
- ++$num_col if ($board->can_reach($piece, $row, $from_col, $to_row, $to_col));
+ ++$num_col if ($board->can_legally_reach($piece, $row, $from_col, $to_row, $to_col));
}
# see if we need to disambiguate
projects / remoteglot / blobdiff