Add Component.First and Component.EachEntity methods (#87)

Add component.First and component.EachEntity methods

README.md

@@ -80,7 +80,7 @@ var Velocity = donburi.NewComponentType[VelocityData]()
 
 // Create an entity by specifying components that the entity will have.
 // Component data will be initialized by default value of the struct.
-entity = world.Create(Position, Velocity);
+entity = world.Create(Position, Velocity)
 
 // We can use entity (it's a wrapper of int64) to get an Entry object from World
 // which allows you to access the components that belong to the entity.
@@ -101,10 +101,10 @@ Components can be added and removed through `Entry` objects.
 
 ```go
 // Fetch the first entity with PlayerTag component
-query := query.NewQuery(filter.Contains(PlayerTag))
+query := donburi.NewQuery(filter.Contains(PlayerTag))
 // Query.FirstEntity() returns only the first entity that 
 // matches the query.
-if entry, ok := query.FirstEntity(world); ok {
+if entry, ok := donburi.FirstEntity(world); ok {
   donburi.Add(entry, Position, &PositionData{
     X: 100,
     Y: 100,
@@ -126,13 +126,46 @@ if SomeLogic.IsDead(world, someEntity) {
 }
 ```
 
+Entities can be retrieved using the `First` and `EachEntity` methods of Components as follows:
+
+```go
+// GameState Component
+type GameStateData struct {
+  // .. some data
+}
+var GameState = donburi.NewComponentType[GameStateData]()
+
+// Bullet Component
+type BulletData struct {
+  // .. some data
+}
+var Bullet = donburi.NewComponentType[BulletData]()
+
+// Init the world and create entities
+world := donburi.NewWorld()
+world.Create(GameState)
+world.CreateMany(100, Bullet)
+
+// Query the first GameState entity
+if entry, ok := GameState.First(world); ok {
+  gameState := GameState.Get(entry)
+  // .. do stuff with the gameState entity
+}
+
+// Query all Bullet entities
+Bullet.EachEntity(world, func(entry *donburi.Entry) {
+  bullet := Bullet.Get(entry)
+  // .. do stuff with the bullet entity
+})
+```
+
 ### Queries
 
 Queries allow for high performance and expressive iteration through the entities in a world, to get component references, test if an entity has a component or to add and remove components.
 
 ```go
 // Define a query by declaring what componet you want to find.
-query := query.NewQuery(filter.Contains(Position, Velocity))
+query := donburi.NewQuery(filter.Contains(Position, Velocity))
 
 // Iterate through the entities found in the world
 query.EachEntity(world, func(entry *donburi.Entry) {
@@ -151,7 +184,7 @@ For example:
 
 ```go
 // This query retrieves entities that have an NpcTag and no Position component.
-query := query.NewQuery(filter.And(
+query := donburi.NewQuery(filter.And(
   filter.Contains(NpcTag),
   filter.Not(filter.Contains(Position))))
 ```
@@ -162,7 +195,7 @@ For example:
 
 ```go
 // We have a query for all entities that have Position and Size, but also any of Sprite, Text or Shape.
-query := query.NewQuery(
+query := donburi.NewQuery(
   filter.And(
     filter.Contains(Position, Size),
     filter.Or(
@@ -218,8 +251,7 @@ var EnemyTag = donburi.NewTag()
 world.CreateMany(100, EnemyTag, Position, Velocity)
 
 // Search entities with EnemyTag
-query := query.NewQuery(filter.Contains(EnemyTag))
-query.EachEntity(world, func(entry *donburi.Entry) {
+EnemyTag.EachEntity(world, func(entry *donburi.Entry) {
   // Perform some operation on the Entities with the EnemyTag component.
 }
 ```

component.go

@@ -5,7 +5,8 @@ import (
 	"reflect"
 	"unsafe"
 
-	"github.com/yohamta/donburi/internal/component"
+	"github.com/yohamta/donburi/component"
+	"github.com/yohamta/donburi/filter"
 )
 
 // IComponentType is an interface for component types.
@@ -30,6 +31,7 @@ type ComponentType[T any] struct {
 	typ        reflect.Type
 	name       string
 	defaultVal interface{}
+	query      *Query
 }
 
 // Get returns component data from the entry.
@@ -42,6 +44,16 @@ func (c *ComponentType[T]) Set(entry *Entry, compoennt *T) {
 	entry.SetComponent(c, unsafe.Pointer(compoennt))
 }
 
+// EachEntity iterates over the entities that have the component.
+func (c *ComponentType[T]) EachEntity(w World, callback func(*Entry)) {
+	c.query.EachEntity(w, callback)
+}
+
+// FirstEntity returns the first entity that has the component.
+func (c *ComponentType[T]) FirstEntity(w World) (*Entry, bool) {
+	return c.query.FirstEntity(w)
+}
+
 // SetValue sets the value of the component.
 func (c *ComponentType[T]) SetValue(entry *Entry, value T) {
 	comp := c.Get(entry)
@@ -102,6 +114,7 @@ func newComponentType[T any](s T, defaultVal interface{}) *ComponentType[T] {
 		name:       reflect.TypeOf(s).Name(),
 		defaultVal: defaultVal,
 	}
+	componentType.query = NewQuery(filter.Contains(componentType))
 	if defaultVal != nil {
 		componentType.validateDefaultVal()
 	}

ecs/ecs.go

@@ -4,7 +4,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 // LayerID is used to specify a layer.
@@ -25,12 +24,12 @@ type ECS struct {
 }
 
 // NewQuery creates a new query.
-func NewQuery(l LayerID, f filter.LayoutFilter) *query.Query {
+func NewQuery(l LayerID, f filter.LayoutFilter) *donburi.Query {
 	layerFilter := filter.Contains(getLayer(l).tag)
 	if f == nil {
-		return query.NewQuery(layerFilter)
+		return donburi.NewQuery(layerFilter)
 	}
-	return query.NewQuery(filter.And(layerFilter, f))
+	return donburi.NewQuery(filter.And(layerFilter, f))
 }
 
 // NewECS creates a new ECS with the specified world.

ecs/ecs_test.go

@@ -6,7 +6,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 func TestECS(t *testing.T) {
@@ -124,7 +123,7 @@ type testSystem struct {
 	DrawImage        *ebiten.Image
 	UpdateCount      int
 	DrawCount        int
-	Query            *query.Query
+	Query            *donburi.Query
 	QueryCountUpdate int
 	QueryCountDraw   int
 }

entry.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"unsafe"
 
-	"github.com/yohamta/donburi/internal/component"
+	"github.com/yohamta/donburi/component"
 	"github.com/yohamta/donburi/internal/entity"
 	"github.com/yohamta/donburi/internal/storage"
 )

examples/bunnymark/system/bounce.go

@@ -7,18 +7,17 @@ import (
 	"github.com/yohamta/donburi/examples/bunnymark/component"
 	"github.com/yohamta/donburi/examples/bunnymark/helper"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type Bounce struct {
 	bounds *image.Rectangle
-	query  *query.Query
+	query  *donburi.Query
 }
 
 func NewBounce(bounds *image.Rectangle) *Bounce {
 	return &Bounce{
 		bounds: bounds,
-		query: query.NewQuery(filter.Contains(
+		query: donburi.NewQuery(filter.Contains(
 			component.Position,
 			component.Velocity,
 			component.Sprite,

examples/bunnymark/system/gravity.go

@@ -4,16 +4,15 @@ import (
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/examples/bunnymark/component"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type Gravity struct {
-	query *query.Query
+	query *donburi.Query
 }
 
 func NewGravity() *Gravity {
 	return &Gravity{
-		query: query.NewQuery(filter.Contains(component.Velocity, component.Gravity)),
+		query: donburi.NewQuery(filter.Contains(component.Velocity, component.Gravity)),
 	}
 }
 

examples/bunnymark/system/metrics.go

@@ -10,8 +10,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/text"
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/examples/bunnymark/component"
-	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 	"golang.org/x/image/colornames"
 	"golang.org/x/image/font/basicfont"
 )
@@ -29,10 +27,11 @@ func NewMetrics(bounds *image.Rectangle) *Metrics {
 
 func (m *Metrics) Update(w donburi.World) {
 	if m.settings == nil {
-		query := query.NewQuery(filter.Contains(component.Settings))
-		query.EachEntity(w, func(entry *donburi.Entry) {
+		if entry, ok := component.Settings.FirstEntity(w); ok {
 			m.settings = component.Settings.Get(entry)
-		})
+		} else {
+			panic("no settings")
+		}
 	}
 	select {
 	case <-m.settings.Ticker.C:

examples/bunnymark/system/render.go

@@ -6,16 +6,15 @@ import (
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/examples/bunnymark/component"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type Render struct {
-	query *query.Query
+	query *donburi.Query
 }
 
 func NewRender() *Render {
 	return &Render{
-		query: query.NewQuery(filter.Contains(
+		query: donburi.NewQuery(filter.Contains(
 			component.Position,
 			component.Hue,
 			component.Sprite,

examples/bunnymark/system/spawn.go

@@ -8,8 +8,6 @@ import (
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/examples/bunnymark/component"
 	"github.com/yohamta/donburi/examples/bunnymark/helper"
-	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type Spawn struct {
@@ -45,10 +43,11 @@ func (s *Spawn) Update(w donburi.World) {
 
 func (s *Spawn) addBunnies(w donburi.World) {
 	if s.settings == nil {
-		query := query.NewQuery(filter.Contains(component.Settings))
-		query.EachEntity(w, func(entry *donburi.Entry) {
+		if entry, ok := component.Settings.FirstEntity(w); ok {
 			s.settings = component.Settings.Get(entry)
-		})
+		} else {
+			panic("no settings")
+		}
 	}
 
 	entities := w.CreateMany(

examples/bunnymark/system/velocity.go

@@ -4,16 +4,15 @@ import (
 	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/examples/bunnymark/component"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type Velocity struct {
-	query *query.Query
+	query *donburi.Query
 }
 
 func NewVelocity() *Velocity {
 	return &Velocity{
-		query: query.NewQuery(filter.Contains(component.Position, component.Velocity)),
+		query: donburi.NewQuery(filter.Contains(component.Position, component.Velocity)),
 	}
 }
 

examples/bunnymark_ecs/system/bounce.go

@@ -8,18 +8,17 @@ import (
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/component"
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/helper"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type bounce struct {
 	bounds *image.Rectangle
-	query  *query.Query
+	query  *donburi.Query
 }
 
 func NewBounce(bounds *image.Rectangle) *bounce {
 	return &bounce{
 		bounds: bounds,
-		query: query.NewQuery(
+		query: donburi.NewQuery(
 			filter.Contains(
 				component.Position,
 				component.Velocity,

examples/bunnymark_ecs/system/gravity.go

@@ -5,15 +5,14 @@ import (
 	"github.com/yohamta/donburi/ecs"
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/component"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type gravity struct {
-	query *query.Query
+	query *donburi.Query
 }
 
 var Gravity *gravity = &gravity{
-	query: query.NewQuery(
+	query: donburi.NewQuery(
 		filter.Contains(
 			component.Velocity,
 			component.Gravity,

examples/bunnymark_ecs/system/metrics.go

@@ -8,11 +8,8 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
 	"github.com/hajimehoshi/ebiten/v2/text"
-	"github.com/yohamta/donburi"
 	"github.com/yohamta/donburi/ecs"
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/component"
-	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 	"golang.org/x/image/colornames"
 	"golang.org/x/image/font/basicfont"
 )
@@ -30,10 +27,9 @@ func NewMetrics(bounds *image.Rectangle) *Metrics {
 
 func (m *Metrics) Update(ecs *ecs.ECS) {
 	if m.settings == nil {
-		query := query.NewQuery(filter.Contains(component.Settings))
-		query.EachEntity(ecs.World, func(entry *donburi.Entry) {
+		if entry, ok := component.Settings.FirstEntity(ecs.World); ok {
 			m.settings = component.Settings.Get(entry)
-		})
+		}
 	}
 	select {
 	case <-m.settings.Ticker.C:

examples/bunnymark_ecs/system/render.go

@@ -8,11 +8,10 @@ import (
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/component"
 	"github.com/yohamta/donburi/examples/bunnymark_ecs/layers"
 	"github.com/yohamta/donburi/filter"
-	"github.com/yohamta/donburi/query"
 )
 
 type render struct {
-	query *query.Query
+	query *donburi.Query
 }
 
 var Render = &render{