gg/objects.go

package gg

type ObjectMap map[Object] struct{}

// The structure to store objects
// with O(1) add, remove and search operations.
type Objects struct {
	// The place to store all the objects.
	store []Object

	// Find index by Object.
	searchMap map[Object] int

	tagMap map[Tag] ObjectMap

	// Available nil values in the store.
	freeIndexes []int
}

func NewObjects() *Objects {
	ret := &Objects{}
	ret.searchMap = map[Object] int {}
	ret.tagMap = map[Tag]ObjectMap{}
	return ret
}

func (objects *Objects) has(object Object) bool {
	_, ok := objects.searchMap[object]
	return ok
}

func (objects *Objects) add(object Object) bool {
	if objects.has(object) {
		return false
	}
	if len(objects.freeIndexes) > 0 {
		freeIndex := objects.freeIndexes[0]
		objects.freeIndexes = objects.freeIndexes[1:]

		objects.store[freeIndex] = object
		objects.searchMap[object] = freeIndex
	} else {
		objects.store = append(objects.store, object)
		objects.searchMap[object] = len(objects.store)-1
	}
	return true
}

func (objects *Objects) remove(object Object) bool {
	objectIndex, ok := objects.searchMap[object]
	if !ok {
		return false
	}

	objects.store[objectIndex] = nil
	objects.freeIndexes = append(
		objects.freeIndexes,
		objectIndex,
	)

	return true
}

func (objects *Objects) FindByTags(
	t Tag, rest ...Tag,
) []Object {
	tagMap := objects.tagMap
	objectMap := tagMap[t]
	retMap := map[Object]struct{}{}
	for object := range objectMap {
		retMap[object] = struct{}{}
	}

	for _, tag := range rest {
		m, ok := tagMap[tag]
		if !ok {
			continue
		}
		for object := range m {
			_, ok := m[object]
			if !ok {
				delete(retMap, object)
			}
		}
	}

	ret := []Object{}
	for object := range retMap {
		ret = append(ret, object)
	}

	return ret
}

func (objects *Objects) updateObjects(c Context){
	for _, object := range objects.store {
		if object == nil {
			continue
		}
		object.OnUpdate(c)
	}
}

func (objects *Objects) updateTags(c Context) {
	tagMap := objects.tagMap
	updateMap := make(map[Tag]ObjectMap, len(tagMap))

	for _, object := range objects.store {
		tags := object.GetTags(c)
		for tag := range tags {
			tm, ok := updateMap[tag]
			if ok {
				tm[object] = struct{}{}
			} else {
				updateMap[tag] = ObjectMap{
					object: struct{}{},
				}
			}

		}
	}
	objects.tagMap = updateMap
}