stockfish/src/movepick.h

/*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad

  Stockfish is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Stockfish is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#if !defined MOVEPICK_H_INCLUDED
#define MOVEPICK_H_INCLUDED

#include "history.h"
#include "position.h"
#include "search.h"
#include "types.h"

/// MovePicker is a class which is used to pick one pseudo legal move at a time
/// from the current position. It is initialized with a Position object and a few
/// moves we have reason to believe are good. The most important method is
/// MovePicker::next_move(), which returns a new pseudo legal move each time
/// it is called, until there are no moves left, when MOVE_NONE is returned.
/// In order to improve the efficiency of the alpha beta algorithm, MovePicker
/// attempts to return the moves which are most likely to get a cut-off first.

class MovePicker {

  MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC

public:
  MovePicker(const Position&, Move, Depth, const History&, Search::Stack*, Value);
  MovePicker(const Position&, Move, Depth, const History&, Square recaptureSq);
  MovePicker(const Position&, Move, const History&, PieceType parentCapture);
  Move next_move();

private:
  void score_captures();
  void score_noncaptures();
  void score_evasions();
  void go_next_phase();

  const Position& pos;
  const History& H;
  Depth depth;
  Move ttMove;
  MoveStack killers[2];
  Square recaptureSquare;
  int captureThreshold, phase;
  MoveStack *curMove, *lastMove, *lastNonCapture, *badCaptures;
  MoveStack moves[MAX_MOVES];
};

#endif // !defined(MOVEPICK_H_INCLUDED)