规则引擎

pkg/rule_engine/nodes/factory.go

@@ -0,0 +1,53 @@
+package nodes
+
+import (
+	"fmt"
+)
+
+const (
+	NODE_CATEGORY_FILTER     = "filter"
+	NODE_CATEGORY_ACTION     = "action"
+	NODE_CATEGORY_ENRICHMENT = "enrichment"
+	NODE_CATEGORY_TRANSFORM  = "transform"
+	NODE_CATEGORY_EXTERNAL   = "external"
+	NODE_CATEGORY_OTHERS     = "others"
+)
+
+// Factory is node's factory to create node based on metadata
+// factory also manage node's metadta description which can be used by other
+// service to present node in web
+type Factory interface {
+	Name() string
+	Category() string
+	Create(id string, meta Metadata) (Node, error)
+}
+
+var (
+	// allNodeFactories hold all node's factory
+	allNodeFactories map[string]Factory = make(map[string]Factory)
+
+	// allNodeCategories hold node's metadata by category
+	allNodeCategories map[string][]string = make(map[string][]string)
+)
+
+// RegisterFactory add a new node factory and classify its category for
+// metadata description
+func RegisterFactory(f Factory) {
+	allNodeFactories[f.Name()] = f
+
+	if allNodeCategories[f.Category()] == nil {
+		allNodeCategories[f.Category()] = []string{}
+	}
+	allNodeCategories[f.Category()] = append(allNodeCategories[f.Category()], f.Name())
+}
+
+// NewNode is the only way to create a new node
+func NewNode(nodeType string, id string, meta Metadata) (Node, error) {
+	if f, found := allNodeFactories[nodeType]; found {
+		return f.Create(id, meta)
+	}
+	return nil, fmt.Errorf("invalid node type '%s'", nodeType)
+}
+
+// GetCategoryNodes return specified category's all nodes
+func GetCategoryNodes() map[string][]string { return allNodeCategories }