refine code

metagpt/strategy/tot.py

@@ -2,6 +2,8 @@
 # @Date    : 12/23/2023 4:51 PM
 # @Author  : stellahong (stellahong@fuzhi.ai)
 # @Desc    :
+from __future__ import annotations
+
 import asyncio
 from typing import Any, List
 
@@ -31,7 +33,7 @@ Output a list of jsons following the format:
 class ThoughtSolverBase(BaseModel):
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
-    thought_tree: str = ""
+    thought_tree: ThoughtTree | None = None
     llm: BaseLLM = Field(default_factory=LLM, exclude=True)
     config: ThoughtSolverConfig = Field(default_factory=ThoughtSolverConfig)
 
@@ -60,7 +62,7 @@ class ThoughtSolverBase(BaseModel):
             current_state=current_state, **{"n_generate_sample": self.config.n_generate_sample}
         )
         rsp = await self.llm.aask(msg=state_prompt + "\n" + OUTPUT_FORMAT)
-        thoughts = CodeParser.parse_code(block=None, text=rsp)
+        thoughts = CodeParser.parse_code(block="", text=rsp)
         thoughts = eval(thoughts)
         # fixme 避免不跟随，生成过多nodes
         # valid_thoughts = [_node for idx, _node in enumerate(thoughts) if idx < self.n_generate_sample]
@@ -97,15 +99,16 @@ class ThoughtSolverBase(BaseModel):
         Returns:
             List[ThoughtNode]: List of selected nodes.
         """
-        # selection
+        # nodes to be selected
+        nodes = []
         if self.config.method_select == MethodSelect.SAMPLE:
             raise NotImplementedError
         elif self.config.method_select == MethodSelect.GREEDY:
-            select_nodes = sorted(thought_nodes, key=lambda x: x.value, reverse=True)[: self.config.n_select_sample]
+            nodes = sorted(thought_nodes, key=lambda x: x.value, reverse=True)[: self.config.n_select_sample]
         for node in thought_nodes:
-            if node not in select_nodes:
+            if node not in nodes:
                 node.parent = None  # 从树中删除节点
-        return select_nodes
+        return nodes
 
     def update_solution(self):
         """