2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2009 Marco Costalba
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
36 /// move_from_string() takes a position and a string as input, and attempts to
37 /// convert the string to a move, using simple coordinate notation (g1f3,
38 /// a7a8q, etc.). In order to correctly parse en passant captures and castling
39 /// moves, we need the position. This function is not robust, and expects that
40 /// the input move is legal and correctly formatted.
42 Move move_from_string(const Position& pos, const std::string& str) {
46 Color us = pos.side_to_move();
51 // Read the from and to squares
52 from = square_from_string(str.substr(0, 2));
53 to = square_from_string(str.substr(2, 4));
55 // Find the moving piece
56 piece = pos.piece_on(from);
58 // If the string has more than 4 characters, try to interpret the 5th
59 // character as a promotion
60 if (type_of_piece(piece) == PAWN && str.length() > 4)
62 switch (tolower(str[4])) {
64 return make_promotion_move(from, to, KNIGHT);
66 return make_promotion_move(from, to, BISHOP);
68 return make_promotion_move(from, to, ROOK);
70 return make_promotion_move(from, to, QUEEN);
74 if (piece == piece_of_color_and_type(us, KING))
76 // Is this a castling move? A king move is assumed to be a castling
77 // move if the destination square is occupied by a friendly rook, or
78 // if the distance between the source and destination squares is more
80 if (pos.piece_on(to) == piece_of_color_and_type(us, ROOK))
81 return make_castle_move(from, to);
83 else if (square_distance(from, to) > 1)
85 // This is a castling move, but we have to translate it to the
86 // internal "king captures rook" representation.
87 SquareDelta delta = (to > from ? DELTA_E : DELTA_W);
88 Square s = from + delta;
89 while (relative_rank(us, s) == RANK_1 && pos.piece_on(s) != piece_of_color_and_type(us, ROOK))
92 return (relative_rank(us, s) == RANK_1 ? make_castle_move(from, s) : MOVE_NONE);
95 else if (piece == piece_of_color_and_type(us, PAWN))
97 // En passant move? We assume that a pawn move is an en passant move
98 // without further testing if the destination square is epSquare.
99 if (to == pos.ep_square())
100 return make_ep_move(from, to);
102 return make_move(from, to);
106 /// move_to_string() converts a move to a string in coordinate notation
107 /// (g1f3, a7a8q, etc.). The only special case is castling moves, where we
108 /// print in the e1g1 notation in normal chess mode, and in e1h1 notation in
111 const std::string move_to_string(Move move) {
114 Square from = move_from(move);
115 Square to = move_to(move);
117 if (move == MOVE_NONE)
119 else if (move == MOVE_NULL)
125 if (move_is_short_castle(move))
126 return (from == SQ_E1 ? "e1g1" : "e8g8");
128 if (move_is_long_castle(move))
129 return (from == SQ_E1 ? "e1c1" : "e8c8");
131 str = square_to_string(from) + square_to_string(to);
132 if (move_promotion(move))
133 str += piece_type_to_char(move_promotion(move), false);
139 /// Overload the << operator, to make it easier to print moves.
141 std::ostream &operator << (std::ostream& os, Move m) {
143 return os << move_to_string(m);
147 /// move_is_ok(), for debugging.
149 bool move_is_ok(Move m) {
151 return square_is_ok(move_from(m)) && square_is_ok(move_to(m));