Add some routines that are useful to parse PGNs.

[remoteglot] / Board.pm

diff --git a/Board.pm b/Board.pm
index 6af89f39819d16e520d4ff753f0b3db161b901e2..b925a388952ce6c5cc6e5ae1d35d00a5898d6171 100644 (file)
--- a/Board.pm
+++ b/Board.pm
@@ -109,7 +109,7 @@ sub make_move {
                                }
                        }
                } else {
-                       if ($promo ne '') {
+                       if (defined($promo) && $promo ne '') {
                                if ($piece eq 'p') {
                                        $piece = $promo;
                                } else {
@@ -131,12 +131,78 @@ sub _pos_to_square {
        return sprintf("%c%d", ord('a') + $col, 8 - $row);
 }
 
+sub _col_letter_to_num {
+        return ord(shift) - ord('a');
+}
+
+sub _row_letter_to_num {
+        return 7 - (ord(shift) - ord('1'));
+}
+
+sub _square_to_pos {
+       my ($square) = @_;
+       $square =~ /^([a-h])([1-8])$/ or die "Invalid square $square";  
+       return (_row_letter_to_num($2), _col_letter_to_num($1));
+}
+
 sub _move_to_uci_notation {
        my ($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 parse_pretty_move {
+       my ($board, $move, $toplay) = @_;
+
+       # 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'));
+               } 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'));
+               } else {
+                       return (_square_to_pos('e8'), _square_to_pos('c8'));
+               }
+       }
+
+       # Parse promo
+       my $promo;
+       if ($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 $from_col = defined($2) ? _col_letter_to_num($2) : undef;
+       my $from_row = defined($3) ? _row_letter_to_num($3) : undef;
+       my ($to_row, $to_col) = _square_to_pos($4);
+       
+       # Find all possible from-squares that could have been meant.
+       my @squares = ();
+       if ($toplay eq 'B') {
+               $piece = lc($piece);
+       }
+       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));
+                       push @squares, [ $row, $col ];
+               }
+       }
+       if (scalar @squares != 1) {
+               die "Ambigious or impossible move $move";
+       }
+       return (@{$squares[0]}, $to_row, $to_col, $promo);
+}
+
 sub fen {
        my ($board) = @_;
        my @rows = ();