unified config loader

common/loader/loader.go

@@ -0,0 +1,47 @@
+package loader
+
+import (
+	"errors"
+)
+
+var (
+	ErrConfigIDKeyNotFound = errors.New("Config ID key is not found.")
+	ErrConfigIDExists      = errors.New("Config ID already exists.")
+	ErrUnknownConfigID     = errors.New("Unknown config ID.")
+)
+
+type ConfigCreator func() interface{}
+
+type ConfigLoader interface {
+	RegisterCreator(string, ConfigCreator) error
+	CreateConfig(string) (interface{}, error)
+	Load([]byte) (interface{}, error)
+	LoadWithID([]byte, string) (interface{}, error)
+}
+
+type BaseConfigLoader struct {
+	creators map[string]ConfigCreator
+}
+
+func NewBaseConfigLoader() *BaseConfigLoader {
+	return &BaseConfigLoader{
+		creators: make(map[string]ConfigCreator),
+	}
+}
+
+func (this *BaseConfigLoader) RegisterCreator(id string, creator ConfigCreator) error {
+	if _, found := this.creators[id]; found {
+		return ErrConfigIDExists
+	}
+
+	this.creators[id] = creator
+	return nil
+}
+
+func (this *BaseConfigLoader) CreateConfig(id string) (interface{}, error) {
+	creator, found := this.creators[id]
+	if !found {
+		return nil, ErrUnknownConfigID
+	}
+	return creator(), nil
+}