gohan/component.go

package gohan

import (
	"sync"
)

var componentMutex sync.Mutex

// ComponentID is a component identifier. Each Component is assigned a unique ID
// via NewComponentID, and implements a ComponentID method returning its ID.
type ComponentID int

// Component represents data for an entity, and how it interacts with the world.
type Component interface {
	ComponentID() ComponentID
}

var maxComponentID ComponentID

// NewComponentID returns the next available ComponentID.
func NewComponentID() ComponentID {
	mutex.Lock()
	defer mutex.Unlock()

	entityMutex.Lock()
	defer entityMutex.Unlock()

	componentMutex.Lock()
	defer componentMutex.Unlock()

	maxComponentID++

	for i := Entity(1); i < maxEntityID; i++ {
		gameComponents[i] = append(gameComponents[i], nil)
	}

	return maxComponentID
}

// AddComponent adds a Component to an Entity.
func (entity Entity) AddComponent(component Component) {
	componentID := component.ComponentID()

	gameComponents[entity][componentID] = component

	entityMutex.Lock()
	defer entityMutex.Unlock()
	modifiedEntities = append(modifiedEntities, entity)
}

// Component gets a Component of an Entity.
func (entity Entity) Component(componentID ComponentID) interface{} {
	components := gameComponents[entity]
	if components == nil {
		return nil
	}
	return components[componentID]
}