refactor: how to add a node type in workflow (#558)

backend/domain/workflow/internal/schema/node_builder.go

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2025 coze-dev Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package schema
+
+import (
+	"context"
+
+	"github.com/cloudwego/eino/compose"
+)
+
+type BuildOptions struct {
+	WS    *WorkflowSchema
+	Inner compose.Runnable[map[string]any, map[string]any]
+}
+
+func GetBuildOptions(opts ...BuildOption) *BuildOptions {
+	bo := &BuildOptions{}
+	for _, o := range opts {
+		o(bo)
+	}
+	return bo
+}
+
+type BuildOption func(options *BuildOptions)
+
+func WithWorkflowSchema(ws *WorkflowSchema) BuildOption {
+	return func(options *BuildOptions) {
+		options.WS = ws
+	}
+}
+
+func WithInnerWorkflow(inner compose.Runnable[map[string]any, map[string]any]) BuildOption {
+	return func(options *BuildOptions) {
+		options.Inner = inner
+	}
+}
+
+// NodeBuilder takes a NodeSchema and several BuildOption to build an executable node instance.
+// The result 'executable' MUST implement at least one of the execute interfaces:
+// - nodes.InvokableNode
+// - nodes.StreamableNode
+// - nodes.CollectableNode
+// - nodes.TransformableNode
+// - nodes.InvokableNodeWOpt
+// - nodes.StreamableNodeWOpt
+// - nodes.CollectableNodeWOpt
+// - nodes.TransformableNodeWOpt
+// NOTE: the 'normal' version does not take NodeOption, while the 'WOpt' versions take NodeOption.
+// NOTE: a node should either implement the 'normal' versions, or the 'WOpt' versions, not mix them up.
+type NodeBuilder interface {
+	Build(ctx context.Context, ns *NodeSchema, opts ...BuildOption) (
+		executable any, err error)
+}
+
+// BranchBuilder builds the extractor function that maps node output to port index.
+type BranchBuilder interface {
+	BuildBranch(ctx context.Context) (extractor func(ctx context.Context,
+		nodeOutput map[string]any) (int64, bool /*if is default branch*/, error), hasBranch bool)
+}