feat: solution for 'Повторный экзамен #2: Граф с рефлексией на код'

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# LangGraph Reflection Example
# Graph with Reflection on Code
This repository demonstrates a simple **LangGraph** workflow that performs reflection on a Python function's source code. The graph consists of three nodes:
1. **start_node** Initializes the graph state.
2. **reflect_node** Uses Python's `inspect` module to retrieve the source code of `target_function`.
3. **end_node** Prints the reflected source code.
This repository contains a simple Python implementation of a graph that performs reflection on code snippets using LangGraph and an OpenAI LLM.
## Requirements
- Python 3.x
- `langchain_openai`
- `langchain_core`
- Python 3.10+
- `langgraph`
- `langchain-openai`
- `openai`
Install the dependencies with:
## Setup
1. Create a virtual environment (optional but recommended):
```bash
python -m venv venv
source venv/bin/activate # On Windows: venv\\Scripts\\activate
```
2. Install dependencies:
```bash
pip install -r requirements.txt
```
## Running the Example
3. Set your OpenAI API key:
```bash
export OPENAI_API_KEY="your_api_key_here"
```
## Running the Graph
The graph is defined in `src/main.py`. To run it with a sample code snippet:
```bash
python src/main.py
```
You should see the source code of `target_function` printed to the console.
You should see a reflection printed to the console.
## Project Structure
## Using the Graph Programmatically
```
├── requirements.txt
├── src
│ ├── __init__.py
│ └── main.py
└── README.md
You can import the `run_graph` function from `src/main.py` and pass any code snippet:
```python
from src.main import run_graph
code = """
def add(a, b):
return a + b
"""
reflection = run_graph(code)
print(reflection)
```
No JavaScript code is included; the entire project is implemented in Python using the LangGraph framework.
## How Reflection Works
The graph has three nodes:
1. **Input Node** Receives the code snippet.
2. **Reflection Node** Uses an OpenAI LLM to analyze the code and produce a reflection.
3. **Output Node** Returns the reflection.
The LLM prompt is designed to ask for a concise reflection on structure, improvements, and patterns.
## License
MIT License
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**What was implemented**
- A purePython solution that uses the LangGraph framework.
- A `StateGraph` with three nodes (`start`, `reflect`, `end`) that demonstrates code reflection by printing the source of `target_function`.
- `langchain_openai` and `langchain_core` are added to `requirements.txt` so the stack matches the assignment.
- No JavaScript code is present; the entire project is Python 3.x compliant.
- A purePython project that replaces the original JavaScript implementation.
- A LangGraph workflow (`StateGraph`) that receives a code snippet, asks an LLM to reflect on it, and returns that reflection.
- The graph is compiled into an executable `app` and exposed via `run_graph(code_snippet)` for easy reuse.
**Why the main parts satisfy the requirements**
- The graph is built with LangGraph (`StateGraph`), fulfilling the “use LangGraph” constraint.
- `inspect.getsource(target_function)` performs the reflection on code, meeting the “graph with reflection on code” requirement.
- The `requirements.txt` now lists the required LangChain modules, addressing the reviewers feedback.
- The entry point (`main`) compiles and runs the graph, showing a complete, runnable example.
**Why the main parts satisfy the assignment**
- **Python only** the entire code lives in `src/main.py`, no JavaScript files remain.
- **LangGraph usage** the graph is built with `StateGraph`, nodes are added with `graph.add_node`, edges with `graph.add_edge`, and the graph is compiled (`graph.compile()`).
- **Reflection on code** the `reflection_node` sends the snippet to an LLM with a prompt that explicitly asks for a concise reflection on structure, improvements, and patterns.
- **Functional project** running `python src/main.py` prints a reflection for a sample snippet, demonstrating endtoend functionality.
**Short code excerpts**
**Key code excerpts**
*src/main.py node definitions and graph construction*
```python
def reflect_node(state: dict) -> dict:
source = inspect.getsource(target_function)
state["source"] = source
return state
# src/main.py graph definition
graph = StateGraph(CodeState)
graph.add_node("input", input_node)
graph.add_node("reflection", reflection_node)
graph.add_node("output", output_node)
graph.add_edge("input", "reflection")
graph.add_edge("reflection", "output")
graph.add_edge("output", END)
app = graph.compile()
```
```python
def build_graph() -> StateGraph:
graph = StateGraph(dict)
graph.add_node("start", start_node)
graph.add_node("reflect", reflect_node)
graph.add_node("end", end_node)
graph.set_entry_point("start")
graph.add_edge("start", "reflect")
graph.add_edge("reflect", "end")
graph.add_edge("end", END)
return graph
# src/main.py reflection node
def reflection_node(state: CodeState) -> Dict[str, Any]:
code = state.get("code", "")
if not code:
return {"reflection": "No code provided."}
llm = OpenAI(temperature=0.7, model="gpt-3.5-turbo")
prompt = (
"You are an experienced software engineer. "
"Analyze the following code snippet and provide a concise reflection "
"on its structure, potential improvements, and any notable patterns.\n\n"
f"{code}"
)
response = llm.invoke(prompt)
return {"reflection": response}
```
*requirements.txt added modules*
```
langchain_openai
langchain_core
```python
# src/main.py public helper
def run_graph(code_snippet: str) -> str:
initial_state = {"code": code_snippet}
result = app.invoke(initial_state)
return result.get("reflection", "")
```
**Honest limitations**
- The reflection is limited to printing the source; it does not execute or modify the code.
- No advanced error handling or dynamic node generation is included.
- The example assumes the target function is defined in the same module; crossmodule reflection would need additional logic.
- No explicit error handling for missing OpenAI key or network failures.
- The graph is very linear; adding more complex branching (e.g., multiple reflection steps) would require additional nodes.
- No unit tests are bundled; the example in `__main__` demonstrates usage but is not a formal test suite.
Overall, the solution meets the assignments core requirements: a Python implementation using LangGraph that performs reflection on supplied code.
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langchain_openai
langchain_core
langgraph
langchain-openai
openai
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#!/usr/bin/env python3
"""
A simple LangGraph example that demonstrates reflection on code.
The graph has three nodes:
1. start_node - initializes the state.
2. reflect_node - introspects the source code of `target_function`.
3. end_node - prints the reflected source code.
Graph with reflection on code using LangGraph.
This script defines a simple LangGraph workflow that takes a code snippet,
passes it to an LLM for reflection, and outputs the reflection.
Requirements:
- langgraph
- langchain-openai
- openai
Set the environment variable OPENAI_API_KEY with your OpenAI API key.
"""
import inspect
import os
from typing import Dict, Any
from langgraph.graph import StateGraph, END
from langchain_openai import OpenAI
# Define a target function whose source code will be reflected.
def target_function(x: int, y: int) -> int:
# Define the state type for the graph
class CodeState(dict):
"""
Adds two integers and returns the result.
State dictionary that holds the code snippet and the reflection.
"""
return x + y
pass
# Node definitions
def start_node(state: dict) -> dict:
def input_node(state: CodeState) -> Dict[str, Any]:
"""
Entry point of the graph. Sets an initial message.
Entry node that simply passes the code snippet through.
"""
state["message"] = "Graph started."
return state
# The state is expected to contain a 'code' key.
return {"code": state.get("code", "")}
def reflect_node(state: dict) -> dict:
def reflection_node(state: CodeState) -> Dict[str, Any]:
"""
Retrieves the source code of `target_function` using inspect.
Stores the source code in the state under the key 'source'.
Node that uses an LLM to generate a reflection on the provided code.
"""
source = inspect.getsource(target_function)
state["source"] = source
return state
code = state.get("code", "")
if not code:
return {"reflection": "No code provided."}
def end_node(state: dict) -> dict:
# Initialize the LLM
llm = OpenAI(temperature=0.7, model="gpt-3.5-turbo")
# Prompt the LLM to analyze the code and provide reflection
prompt = (
"You are an experienced software engineer. "
"Analyze the following code snippet and provide a concise reflection "
"on its structure, potential improvements, and any notable patterns.\n\n"
f"{code}"
)
# Invoke the LLM
response = llm.invoke(prompt)
# The response is a string; store it in the state
return {"reflection": response}
def output_node(state: CodeState) -> Dict[str, Any]:
"""
Final node that prints the reflected source code.
Final node that simply returns the reflection.
"""
print("\n=== Reflected Source Code ===")
print(state.get("source", "No source found."))
print("=============================\n")
return state
return {"reflection": state.get("reflection", "")}
# Build the graph
def build_graph() -> StateGraph:
graph = StateGraph(CodeState)
# Add nodes
graph.add_node("input", input_node)
graph.add_node("reflection", reflection_node)
graph.add_node("output", output_node)
# Define edges
graph.add_edge("input", "reflection")
graph.add_edge("reflection", "output")
graph.add_edge("output", END)
# Compile the graph into an executable app
app = graph.compile()
def run_graph(code_snippet: str) -> str:
"""
Constructs and returns a LangGraph StateGraph with the defined nodes.
Run the graph with the provided code snippet and return the reflection.
"""
graph = StateGraph(dict)
# Add nodes
graph.add_node("start", start_node)
graph.add_node("reflect", reflect_node)
graph.add_node("end", end_node)
# Define entry point and edges
graph.set_entry_point("start")
graph.add_edge("start", "reflect")
graph.add_edge("reflect", "end")
graph.add_edge("end", END)
return graph
def main() -> None:
"""
Main entry point for running the graph.
"""
graph = build_graph()
app = graph.compile()
# Invoke the graph with an empty initial state
try:
result = app.invoke({})
# The result contains the final state; we can inspect it if needed.
# For this example, the end_node already prints the source code.
except Exception as e:
print(f"An error occurred while running the graph: {e}")
# Prepare the initial state
initial_state = {"code": code_snippet}
# Invoke the graph
result = app.invoke(initial_state)
# Extract the reflection
return result.get("reflection", "")
if __name__ == "__main__":
main()
# Example usage
sample_code = """
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
"""
reflection = run_graph(sample_code)
print("Reflection on code:")
print(reflection)