- // parse_uci_move() takes a position and a string as input, and attempts to
- // convert the string to a move, using simple coordinate notation (g1f3,
- // a7a8q, etc.). In order to correctly parse en passant captures and castling
- // moves, we need the position. This function is not robust, and expects that
- // the input move is legal and correctly formatted.
-
- Move parse_uci_move(const Position& pos, const std::string& str) {
-
- Square from, to;
- Piece piece;
- Color us = pos.side_to_move();
-
- if (str.length() < 4)
- return MOVE_NONE;
-
- // Read the from and to squares
- from = make_square(file_from_char(str[0]), rank_from_char(str[1]));
- to = make_square(file_from_char(str[2]), rank_from_char(str[3]));
-
- // Find the moving piece
- piece = pos.piece_on(from);
-
- // If the string has more than 4 characters, try to interpret the 5th
- // character as a promotion.
- if (str.length() > 4 && piece == piece_of_color_and_type(us, PAWN))
- {
- switch (tolower(str[4])) {
- case 'n':
- return make_promotion_move(from, to, KNIGHT);
- case 'b':
- return make_promotion_move(from, to, BISHOP);
- case 'r':
- return make_promotion_move(from, to, ROOK);
- case 'q':
- return make_promotion_move(from, to, QUEEN);
- }
- }
-
- // En passant move? We assume that a pawn move is an en passant move
- // if the destination square is epSquare.
- if (to == pos.ep_square() && piece == piece_of_color_and_type(us, PAWN))
- return make_ep_move(from, to);
-
- // Is this a castling move? A king move is assumed to be a castling move
- // if the destination square is occupied by a friendly rook, or if the
- // distance between the source and destination squares is more than 1.
- if (piece == piece_of_color_and_type(us, KING))
- {
- if (pos.piece_on(to) == piece_of_color_and_type(us, ROOK))
- return make_castle_move(from, to);
-
- if (square_distance(from, to) > 1)
- {
- // This is a castling move, but we have to translate it to the
- // internal "king captures rook" representation.
- SquareDelta delta = (to > from ? DELTA_E : DELTA_W);
- Square s = from;
-
- do s += delta;
- while ( pos.piece_on(s) != piece_of_color_and_type(us, ROOK)
- && relative_rank(us, s) == RANK_1);
-
- return relative_rank(us, s) == RANK_1 ? make_castle_move(from, s) : MOVE_NONE;
- }
- }