Tiny optimization in _find_kings.

[remoteglot] / Board.pm

diff --git a/Board.pm b/Board.pm
index 1838f7dd492846c858cdc10f5c66707311c89f09..8cf603d0f5be052c762d3f127d7bba87dc047196 100644 (file)
--- a/Board.pm
+++ b/Board.pm
@@ -25,9 +25,7 @@ sub clone {
        my $nb = [];
 
        for my $row (0..7) {
-               for my $col (0..7) {
-                       $nb->[$row][$col] = $board->[$row][$col];
-               }
+               $nb->[$row] = [ @{$board->[$row]} ];
        }
 
        return bless $nb;
@@ -36,7 +34,7 @@ sub clone {
 # Returns a new board.
 sub make_move {
        my ($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();
 
@@ -103,20 +101,19 @@ sub make_move {
                        # 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
@@ -145,7 +142,7 @@ sub _square_to_pos {
        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) . $promo;
@@ -298,7 +295,6 @@ sub can_reach {
                        can_reach($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 == $from_row + 1) {
@@ -309,7 +305,12 @@ sub can_reach {
                        return ($dest_piece eq '-' && $middle_piece eq '-');
                }
                if (abs($to_col - $from_col) == 1 && $to_row == $from_row + 1) {
-                       return ($dest_piece ne '-');
+                       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;
        }
@@ -323,7 +324,12 @@ sub can_reach {
                        return ($dest_piece eq '-' && $middle_piece eq '-');
                }
                if (abs($to_col - $from_col) == 1 && $to_row == $from_row - 1) {
-                       return ($dest_piece ne '-');
+                       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;
        }
@@ -372,6 +378,7 @@ sub _find_kings {
        my ($wkr, $wkc, $bkr, $bkc);
 
        for my $row (0..7) {
+               next unless grep { $_ eq 'K' || $_ eq 'k' } @{$board->[$row]};
                for my $col (0..7) {
                        my $piece = $board->[$row][$col];
                        if ($piece eq 'K') {
@@ -387,8 +394,7 @@ sub _find_kings {
 
 # Returns if any side is in mate.
 sub in_mate {
-       my $board = shift;
-       my $check = $board->in_check();
+       my ($board, $check) = @_;
        return 0 if ($check eq 'none');
 
        # try all possible moves for the side in check
@@ -428,9 +434,10 @@ sub prettyprint_move {
        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 $check = $nb->in_check();
+       if ($nb->in_mate($check)) {
                $pretty .= '#';
-       } elsif ($nb->in_check() ne 'none') {
+       } elsif ($check ne 'none') {
                $pretty .= '+';
        }
        return ($pretty, $nb);
@@ -439,7 +446,7 @@ sub prettyprint_move {
 sub _prettyprint_move_no_check_or_mate {
         my ($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";