抽象的な工場パターン

import std ;using std :: array ; using std :: shared_ptr ; using std :: unique_ptr ; using std :: vector ;class MapSite { public : enum class Direction : char { NORTH , SOUTH , EAST , WEST , };virtual void enter () = 0 ; virtual ~ MapSite () = default ; };class Room : public MapSite { private : int roomNumber ; shared_ptr < array < MapSite , 4 >> sides ; public : explicit Room ( int n = 0 ) : roomNumber { n } {}~ Room () =デフォルト;Room & setSide ( MapSite :: Direction d , MapSite & ms ) { sides [ std :: to_underlying ( d )] = std :: move ( ms ); std :: println ( "Room::setSide {} ms" , d ); return * this ; }virtual void enter () override = 0 ;Room ( const Room & ) = delete ; Room & operator = ( const Room & ) = delete ; };class Wall : public MapSite { public : explicit Wall ( int n = 0 ) : MapSite ( n ) {}~ Wall () =デフォルト;void enter () override { // ... } };class Door : public MapSite { private : shared_ptr < Room > room1 ; shared_ptr < Room > room2 ; public : explicit Door ( int n = 0 , shared_ptr < Room > r1 = nullptr , shared_ptr < Room > r2 = nullptr ) : MapSite ( n ), room1 { std :: move ( r1 )}, room2 { std :: move ( r2 )} {}~ Door () =デフォルト;void enter () override { // ... }Door ( const Door & ) = delete ; Door & operator = ( const Door & ) = delete ; };class Maze { private : vector < shared_ptr < Room >> rooms ; public : Maze () = default ; ~ Maze () = default ;Maze & addRoom ( shared_ptr < Room > r ) { std :: println ( "Maze::addRoom {}" , reinterpret_cast < void *> ( r . get ())); rooms . push_back ( std :: move ( r )); return * this ; } shared_ptr < Room > roomNo ( int n ) const { for ( const Room & r : rooms ) { // 実際のルックアップロジックはここに記述... } return nullptr ; } };class MazeFactory { public : MazeFactory () = default ;virtual ~ MazeFactory () = default ;[[ nodiscard ]] unique_ptr < Maze > makeMaze () const { return std :: make_unique < Maze > (); }[[ nodiscard ]] shared_ptr < Wall > makeWall () const { return std :: make_shared < Wall > (); }[[ nodiscard ]] shared_ptr < Room > makeRoom ( int n ) const { return std :: make_shared < Room > ( new Room ( n )); } [[ nodiscard ]] shared_ptr < Door > makeDoor ( shared_ptr < Room > r1 , shared_ptr < Room > r2 ) const { return std :: make_shared < Door > ( std :: move ( r1 ), std :: move ( r2 )); } };// createMaze に、部屋、壁、ドアを作成するために使用するオブジェクトをパラメータとして渡すと、別のパラメータを渡すことで、部屋、壁、ドアのクラスを変更できます。これは、抽象ファクトリー (99) パターンの例です。class MazeGame { public : Maze () = default ; ~ Maze () = default ;[[ nodiscard ]] unique_ptr < Maze > createMaze ( MazeFactory & factory ) { unique_ptr < Maze > maze = factory . makeMaze (); shared_ptr < Room > r1 = factory . makeRoom ( 1 ); shared_ptr < Room > r2 = factory . makeRoom ( 2 ); shared_ptr < Door > door = factory . makeDoor ( r1 , r2 ); maze -> addRoom ( r1 ) . addRoom ( r2 ) . setSide ( MapSite :: Direction :: NORTH , factory . makeWall ()) . setSide ( MapSite :: Direction :: EAST , door ) . setSide ( MapSite :: Direction :: SOUTH , factory . makeWall ()) . setSide ( MapSite :: Direction :: WEST 、factory .makeWall ( )) 。setSide ( MapSite :: Direction :: NORTH 、factory .makeWall ( )) 。setSide ( MapSite :: Direction :: EAST 、factory .makeWall ( )) 。setSide ( MapSite :: Direction :: SOUTH 、factory .makeWall ( )) 。setSide ( MapSite ::方向:: WEST ,ドア);戻る迷路。} };int main ( int argc , char * argv [ ]) { MazeGame game ; unique_ptr <Maze> maze = game.createMaze ( MazeFactory ( ) ) ; }