File: move.h

Move utils and move history utils.
Assumes that a history list and the board it's used with are consistent.

Boardhistory:
A move event consists of a series of board changes and a "move done",
namely BoardChange.where == (boardsize = move_done), which is pushed last for each move event.

Author: Ken Rouwas
Date 2017-09-14

const size_t move_done = board_size;

struct Move {
    ssize_t from;
    ssize_t to;
    Move(ssize_t, ssize_t);
    Move();

};

struct BoardChange {
    size_t where;
    Square old_square;
};

using Boardhistory = std::list<BoardChange>;
using MoveSet = std::vector<Move>;

void undo_move(Board&, Boardhistory&);

/* Castling is identified by king move to its castling destination if permitted.
   Pawn promotion move deduced.
   All other moves are unconditional moves.
*/
void do_move(Move, Board&, Boardhistory&, Piece pawn_promotion = Piece::queen);

MoveSet valid_moves(Board&, Color turn); // This is the move generator