implemented the en passant target support for FEN

strings

cpp/src/board.cpp

@@ -73,6 +73,16 @@ Board Board::setup_fen_position(std::string fen) {
         }
     }
 
+    // -- En passant target
+    if (fen[index] != '-') {
+        Coords c = Coords::from_algebraic(fen.substr(index, index + 2));
+        index += 2;
+        board.en_passant_target = c.to_index();
+    } else {
+        index++;
+    }
+
+
     return board;
 }
 
@@ -131,6 +141,12 @@ std::string Board::to_fen() const {
         if (b_castle_rights & CastleSide::QueenSide)
             ret += 'q';
     }
+    ret += ' ';
+
+    // En passant target
+    ret += en_passant_target == -1
+             ? "-"
+             : Coords::from_index(en_passant_target).to_algebraic();
 
     return ret;
 }

cpp/src/board.hpp

@@ -15,6 +15,7 @@ struct Board {
     bool white_to_play = true;
     int8_t w_castle_rights = CastleSide::NeitherSide;
     int8_t b_castle_rights = CastleSide::NeitherSide;
+    int8_t en_passant_target = -1;
 
     static Board setup_fen_position(std::string fen);
 

cpp/src/main.cpp

@@ -6,5 +6,6 @@ int main(int argc, char* argv[]) {
     std::string pos =
         "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
     Board b = Board::setup_fen_position(pos);
+    sizeof(b);
     return 0;
 }