Support constructing Position objects from FEN strings.

[remoteglot] / Position.pm

diff --git a/Position.pm b/Position.pm
index 272cadb78d2124275556e16df5bc7403b19cbe6d..6840e7fdd6dd342ff883bbbd45aa2e6ff7546716 100644 (file)
--- a/Position.pm
+++ b/Position.pm
@@ -50,6 +50,39 @@ sub start_pos {
        return $class->new("<12> rnbqkbnr pppppppp -------- -------- -------- -------- PPPPPPPP RNBQKBNR W -1 1 1 1 1 0 dummygamenum $white $black -2 dummytime dummyincrement 39 39 dummytime dummytime 1 none (0:00) none 0 0 0");
 }
 
+sub from_fen {
+       my ($class, $fen) = @_;
+       my ($board, $toplay, $castling, $ep_square, $halfmove_clock, $fullmove_clock) = split / /, $fen;
+
+       my $pos = {};
+       $board =~ s/(\d)/"-"x$1/ge;
+       $pos->{'board'} = Board->new(split /\//, $board);
+       $pos->{'toplay'} = uc($toplay);
+
+       if ($ep_square =~ /^([a-h])/) {
+               $pos->{'ep_file_num'} = ord($1) - ord('a');
+       } else {
+               $pos->{'ep_file_num'} = -1;
+       }
+
+       $pos->{'white_castle_k'} = ($castling =~ /K/) ? 1 : 0;
+       $pos->{'white_castle_q'} = ($castling =~ /Q/) ? 1 : 0;
+       $pos->{'black_castle_k'} = ($castling =~ /k/) ? 1 : 0;
+       $pos->{'black_castle_q'} = ($castling =~ /q/) ? 1 : 0;
+       $pos->{'time_since_100move_rule_reset'} = $halfmove_clock // 0;
+       $pos->{'player_w'} = 'white';
+       $pos->{'player_b'} = 'black';
+       $pos->{'white_clock'} = 0;
+       $pos->{'black_clock'} = 0;
+       $pos->{'move_num'} = $fullmove_clock // 0;
+       $pos->{'last_move_uci'} = undef;
+       $pos->{'last_move'} = undef;
+       $pos->{'prettyprint_cache'} = {};
+       
+       bless $pos, $class;
+       return $pos;
+}
+
 sub fen {
        my $pos = shift;