+/// CapturePieceToHistory is like PieceToHistory, but is based on CapturePieceToBoards
+struct CapturePieceToHistory : public CapturePieceToBoards {
+
+ void update(Piece pc, Square to, PieceType captured, int bonus) {
+ StatCubes::update((*this)[pc][to][captured], bonus, 324, 2);
+ }
+};
+
+/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
+typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveHistory;
+
+/// ContinuationHistory is the history of a given pair of moves, usually the
+/// current one given a previous one. History table is based on PieceToBoards
+/// instead of ButterflyBoards.
+typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> ContinuationHistory;
+
+
+/// MovePicker class is used to pick one pseudo legal move at a time from the
+/// current position. The most important method is 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 {
+public:
+ MovePicker(const MovePicker&) = delete;
+ MovePicker& operator=(const MovePicker&) = delete;
+ MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const CapturePieceToHistory*, Square);
+ MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const CapturePieceToHistory*, const PieceToHistory**, Move, Move*);
+ Move next_move(bool skipQuiets = false);
+
+private:
+ template<GenType> void score();
+ ExtMove* begin() { return cur; }
+ ExtMove* end() { return endMoves; }
+
+ const Position& pos;
+ const ButterflyHistory* mainHistory;
+ const CapturePieceToHistory* captureHistory;
+ const PieceToHistory** contHistory;
+ Move ttMove, countermove, killers[2];
+ ExtMove *cur, *endMoves, *endBadCaptures;
+ int stage;
+ Square recaptureSquare;
+ Value threshold;
+ Depth depth;
+ ExtMove moves[MAX_MOVES];
+};