# Returns a compact bit string describing the same data as fen().
# This is encoded using a Huffman-like encoding, and should be
# typically about 1/3 the number of bytes.
-sub bitpacked_fen {
- my ($board) = @_;
- my $bits = "";
-
- for my $row (0..7) {
- for my $col (0..7) {
- my $piece = $board->[$row][$col];
- if ($piece eq '-') {
- $bits .= "0";
- next;
- }
-
- my $color = (lc($piece) eq $piece) ? 0 : 1;
- $bits .= "1" . $color;
-
- if (lc($piece) eq 'p') {
- $bits .= "0";
- } elsif (lc($piece) eq 'n') {
- $bits .= "100";
- } elsif (lc($piece) eq 'b') {
- $bits .= "101";
- } elsif (lc($piece) eq 'r') {
- $bits .= "1110";
- } elsif (lc($piece) eq 'q') {
- $bits .= "11110";
- } elsif (lc($piece) eq 'k') {
- $bits .= "11111";
- } else {
- die "Unknown piece $piece";
- }
- }
- }
-
- return pack('b*', $bits);
-}
-
sub can_reach {
my ($board, $piece, $from_row, $from_col, $to_row, $to_col) = @_;
return 0;
}
+# Like can_reach, but also checks the move doesn't put the side in check.
+# We use this in prettyprint_move to reduce the disambiguation, because Chess.js
+# needs moves to be in minimally disambiguated form.
+sub can_legally_reach {
+ my ($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 $nb = $board->make_move($from_row, $from_col, $to_row, $to_col);
+ my $side = ($piece eq lc($piece)) ? 'k' : 'K';
+
+ return !in_check($nb, $side);
+}
+
my %pieces_against_side = (
k => { K => 1, Q => 1, R => 1, N => 1, B => 1, P => 1 },
K => { k => 1, q => 1, r => 1, n => 1, b => 1, p => 1 },
# white short castling
if ($move eq 'e1g1' && $piece eq 'K') {
- return '0-0';
+ return 'O-O';
}
# white long castling
if ($move eq 'e1c1' && $piece eq 'K') {
- return '0-0-0';
+ return 'O-O-O';
}
# black short castling
if ($move eq 'e8g8' && $piece eq 'k') {
- return '0-0';
+ return 'O-O';
}
# black long castling
if ($move eq 'e8c8' && $piece eq 'k') {
- return '0-0-0';
+ return '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 .= "=";
- $pretty .= uc($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