Scan uses visitor pattern

engine/billboard.go

@@ -51,12 +51,12 @@ func (b *Billboard) Prepare(g *Game) error {
 	return nil
 }
 
-// Scan returns a slice containing Src.
-//func (b *Billboard) Scan() []interface{} { return []interface{}{&b.Src} }
+// Scan visits &b.Src.
 func (b *Billboard) Scan(visit func(interface{}) error) error {
 	return visit(&b.Src)
 }
 
+// String returns "Billboard@(b.Pos)".
 func (b *Billboard) String() string {
 	return fmt.Sprintf("Billboard@%v", b.Pos)
 }

engine/camera.go

@@ -85,8 +85,7 @@ func (c *Camera) Prepare(game *Game) error {
 	return nil
 }
 
-// Scan returns s.Child.
-//func (c *Camera) Scan() []interface{} { return []interface{}{c.Child} }
+// Scan visits c.Child.
 func (c *Camera) Scan(visit func(interface{}) error) error {
 	return visit(c.Child)
 }

engine/container.go

@@ -5,11 +5,10 @@ var _ interface {
 	Scanner
 } = &Container{}
 
-// Container contains many components.
+// Container contains many components, in order.
 type Container []interface{}
 
-// Scan returns c.
-//func (c Container) Scan() []interface{} { return c }
+// Scan visits every component in the container.
 func (c Container) Scan(visit func(interface{}) error) error {
 	for _, x := range c {
 		if err := visit(x); err != nil {

engine/drawdag.go

@@ -114,7 +114,7 @@ func (d *DrawDAG) Prepare(game *Game) error {
 	return d.Register(d, nil)
 }
 
-//func (d *DrawDAG) Scan() []interface{} { return []interface{}{d.Child} }
+// Scan visits d.Child.
 func (d *DrawDAG) Scan(visit func(interface{}) error) error {
 	return visit(d.Child)
 }

engine/drawdfs.go

@@ -57,7 +57,7 @@ func (d *DrawDFS) draw(component interface{}, screen *ebiten.Image, opts ebiten.
 	}
 }
 
-//func (d *DrawDFS) Scan() []interface{} { return []interface{}{d.Child} }
+// Scan visits d.Child.
 func (d *DrawDFS) Scan(visit func(interface{}) error) error {
 	return visit(d.Child)
 }

engine/game.go

@@ -170,8 +170,7 @@ func (g *Game) Query(ancestor interface{}, behaviour reflect.Type) map[interface
 	return g.byAB[abKey{ancestor, behaviour}]
 }
 
-// Scan returns g.Root.
-//func (g *Game) Scan() []interface{} { return []interface{}{g.Root} }
+// Scan visits g.Root.
 func (g *Game) Scan(visit func(interface{}) error) error {
 	return visit(g.Root)
 }

engine/parallax.go

@@ -38,8 +38,7 @@ func (p *Parallax) Prepare(game *Game) error {
 	return nil
 }
 
-// Scan returns the child component.
-//func (p *Parallax) Scan() []interface{} { return []interface{}{p.Child} }
+// Scan visits p.Child.
 func (p *Parallax) Scan(visit func(interface{}) error) error {
 	return visit(p.Child)
 }

engine/prisms.go

@@ -112,15 +112,7 @@ func (m *PrismMap) Prepare(g *Game) error {
 	return nil
 }
 
-// Scan returns the Sheet and all the Prisms.
-/*func (m *PrismMap) Scan() []interface{} {
-	c := make([]interface{}, 1, len(m.Map)+1)
-	c[0] = &m.Sheet
-	for _, prism := range m.Map {
-		c = append(c, prism)
-	}
-	return c
-}*/
+// Scan visits &m.Sheet and all Prisms.
 func (m *PrismMap) Scan(visit func(interface{}) error) error {
 	if err := visit(&m.Sheet); err != nil {
 		return err

engine/scene.go

@@ -38,7 +38,7 @@ type Scene struct {
 	Hides
 }
 
-//func (s *Scene) Scan() []interface{} { return []interface{}{s.Child} }
+// Scan visits s.Child.
 func (s *Scene) Scan(visit func(interface{}) error) error {
 	return visit(s.Child)
 }

engine/sheet.go

@@ -46,8 +46,7 @@ func (s *Sheet) Prepare(*Game) error {
 	return nil
 }
 
-// Scan returns the Src.
-//func (s *Sheet) Scan() []interface{} { return []interface{}{&s.Src} }
+// Scan visits &s.Src.
 func (s *Sheet) Scan(visit func(interface{}) error) error {
 	return visit(&s.Src)
 }

engine/sprite.go

@@ -40,13 +40,7 @@ func (s *Sprite) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
 	screen.DrawImage(s.Sheet.SubImage(s.anim.Cell()), opts)
 }
 
-// Scan returns the Actor and the Sheet.
-/*func (s *Sprite) Scan() []interface{} {
-	return []interface{}{
-		&s.Actor,
-		&s.Sheet,
-	}
-}*/
+// Scan visits &s.Actor and &s.Sheet.
 func (s *Sprite) Scan(visit func(interface{}) error) error {
 	if err := visit(&s.Actor); err != nil {
 		return err

engine/tiles.go

@@ -99,15 +99,7 @@ func (t *Tilemap) Load(fs.FS) error {
 	return nil
 }
 
-// Scan returns a slice containing Src and all non-nil tiles.
-/*func (t *Tilemap) Scan() []interface{} {
-	c := make([]interface{}, 1, len(t.Map)+1)
-	c[0] = &t.Sheet
-	for _, tile := range t.Map {
-		c = append(c, tile)
-	}
-	return c
-}*/
+// Scan visits &t.Sheet and all tiles.
 func (t *Tilemap) Scan(visit func(interface{}) error) error {
 	if err := visit(&t.Sheet); err != nil {
 		return err
@@ -162,8 +154,7 @@ type AnimatedTile struct {
 
 func (a *AnimatedTile) Cell() int { return a.anim.Cell() }
 
-// Scan returns a.anim.
-//func (a *AnimatedTile) Scan() []interface{} { return []interface{}{a.anim} }
+// Scan visits a.anim.
 func (a *AnimatedTile) Scan(visit func(interface{}) error) error {
 	return visit(a.anim)
 }

engine/walls.go

@@ -60,17 +60,7 @@ func (w *Wall) CollidesWith(b geom.Box) bool {
 	return false
 }
 
-// Scan returns the Sheet and all WallUnits.
-/*
-func (w *Wall) Scan() []interface{} {
-	c := make([]interface{}, 1, len(w.Units)+1)
-	c[0] = &w.Sheet
-	for _, unit := range w.Units {
-		c = append(c, unit)
-	}
-	return c
-}
-*/
+// Scan visits &w.Sheet and all WallUnits.
 func (w *Wall) Scan(visit func(interface{}) error) error {
 	if err := visit(&w.Sheet); err != nil {
 		return err
@@ -115,8 +105,7 @@ func (u *WallUnit) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
 	screen.DrawImage(u.wall.Sheet.SubImage(u.Tile.Cell()), opts)
 }
 
-// Scan returns the Tile.
-//func (u *WallUnit) Scan() []interface{} { return []interface{}{u.Tile} }
+// Scan visits u.Tile.
 func (u *WallUnit) Scan(visit func(interface{}) error) error {
 	return visit(u.Tile)
 }

game/aw.go

@@ -270,7 +270,6 @@ func (aw *Awakeman) Prepare(game *engine.Game) error {
 	return nil
 }
 
-//func (aw *Awakeman) Scan() []interface{} { return []interface{}{&aw.Sprite} }
 func (aw *Awakeman) Scan(visit func(interface{}) error) error {
 	return visit(&aw.Sprite)
 }

game/bubble.go

@@ -55,7 +55,6 @@ func NewBubble(pos geom.Int3) *Bubble {
 	}
 }
 
-//func (b *Bubble) Scan() []interface{} { return []interface{}{&b.Sprite} }
 func (b *Bubble) Scan(visit func(interface{}) error) error {
 	return visit(&b.Sprite)
 }