size_t operator() (const Search_node *a) const { const Tile_coord t = a->get_tile(); return ((t.tz << 16) + (t.ty << 8) + t.tx);
bool operator() (const Search_node *a, const Search_node *b) const { Tile_coord ta = a->get_tile(), tb = b->get_tile(); return ta == tb;
	size_t operator() (const Search_node *a) const		{		const Tile_coord t = a->get_tile();		return ((t.tz << 16) + (t.ty << 8) + t.tx);		}