]> git.sesse.net Git - remoteglot/blobdiff - Board.pm
Fix a castling edge case in Chess960 positions where the kings start on the e-file...
[remoteglot] / Board.pm
index cb2bc71334ae19a10f37d2921a02cad129800369..6fb413ac906ed5670930f3d62750f8519260207f 100644 (file)
--- a/Board.pm
+++ b/Board.pm
@@ -42,56 +42,60 @@ sub make_move {
                die "Invalid move $move";
        }
 
-       # white short castling
-       if ($move eq 'e1g1' && $piece eq 'K') {
-               # king
-               $nb->[7][4] = '-';
-               $nb->[7][6] = $piece;
-
-               # rook
-               $nb->[7][7] = '-';
-               $nb->[7][5] = 'R';
-
-               return $nb;
-       }
-
-       # white long castling
-       if ($move eq 'e1c1' && $piece eq 'K') {
-               # king
-               $nb->[7][4] = '-';
-               $nb->[7][2] = $piece;
-
-               # rook
-               $nb->[7][0] = '-';
-               $nb->[7][3] = 'R';
+       if ($piece eq 'K') {
+               # Convert to Chess960 king-takes-rook.
+               $to_col = 7 if ($move eq 'e1g1' && $board->[$to_row][$to_col] ne 'R');
+               $to_col = 0 if ($move eq 'e1c1' && $board->[$to_row][$to_col] ne 'R');
+
+               my $dst_piece = $board->[$to_row][$to_col];
+
+               # White short castling.
+               if ($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';
+
+                       return $nb;
+               }
 
-               return $nb;
-       }
+               # Black short castling.
+               if ($dst_piece eq 'R' && $to_col < $from_col) {
+                       $nb->[7][$from_col] = '-';
+                       $nb->[7][$to_col] = '-';
+                       $nb->[7][2] = 'K';
+                       $nb->[7][3] = 'R';
 
-       # 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' && $board->[$to_row][$to_col] ne 'r');
+               $to_col = 0 if ($move eq 'e8c8' && $board->[$to_row][$to_col] ne 'r');
 
-               # 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
@@ -136,9 +140,12 @@ sub _row_letter_to_num {
         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));
 }
 
@@ -148,25 +155,53 @@ sub move_to_uci_notation {
        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'));
+                       }
                }
        }
 
@@ -233,7 +268,8 @@ sub fen {
 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)));
@@ -473,24 +509,26 @@ sub _prettyprint_move_no_check_or_mate {
                die "Invalid move $move";
        }
 
-       # white short castling
-       if ($move eq 'e1g1' && $piece eq 'K') {
-               return 'O-O';
-       }
-
-       # white long castling
-       if ($move eq 'e1c1' && $piece eq 'K') {
-               return 'O-O-O';
-       }
+       if ($piece eq 'K') {
+               # white short/long castling
+               return 'O-O' if ($move eq 'e1g1');
+               return 'O-O-O' if ($move eq 'e1c1');
 
-       # black short castling
-       if ($move eq 'e8g8' && $piece eq 'k') {
-               return 'O-O';
-       }
-
-       # black long castling
-       if ($move eq 'e8c8' && $piece eq 'k') {
-               return 'O-O-O';
+               # 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;