bool force );

                          bool force, bool swapping = false );

// swapping    - player is swapping with a monster at (x,y)

                          bool force )

                          bool force, bool swapping )

    ASSERT(mgrd[x][y] == NON_MONSTER
           || mons_is_submerged( &menv[ mgrd[x][y] ] ));

    ASSERT(swapping && mgrd[x][y] != NON_MONSTER ||
           !swapping && (mgrd[x][y] == NON_MONSTER
                         || mons_is_submerged( &menv[ mgrd[x][y] ])));

bool swap_places(monsters *monster, const coord_def &loc);
bool swap_check(monsters *monster, coord_def &loc);

    coord_def loc;
    if (swap_check(monster, loc))
    {
        swap_places(monster, loc);
        return true;
    }
    return false;
}
// Swap monster to this location.  Player is swapped elsewhere.
bool swap_places(monsters *monster, const coord_def &loc)
{
    ASSERT(map_bounds(loc));
    ASSERT(_habitat_okay(monster, grd(loc)));
    mpr("You swap places.");
    mgrd[monster->x][monster->y] = NON_MONSTER;
    monster->x = loc.x;
    monster->y = loc.y;
    mgrd[monster->x][monster->y] = monster_index(monster);
    return true;
}
// Returns true if this is a valid swap for this monster.  If true, then
// the valid location is set in loc.
bool swap_check(monsters *monster, coord_def &loc)
{

        mpr("You swap places.");
        mgrd[monster->x][monster->y] = NON_MONSTER;
        monster->x = loc_x;
        monster->y = loc_y;
        mgrd[monster->x][monster->y] = monster_index(monster);

        loc.x = loc_x;
        loc.y = loc_y;

    coord_def mon_swap_dest;

            if (swap_places( mon ))

            if (swap_check(mon, mon_swap_dest))

        if (!move_player_to_grid(targ_x, targ_y, true, false, swap))

        if (!move_player_to_grid(targ_x, targ_y, true, false, swap, swap))

        if (swap)
            swap_places(&menv[targ_monst], mon_swap_dest);