A simple sequential direction implementation of LangGraph solution

multi_tool_non_agent.py

from typing import List, Dict, Any, Optional, TypedDict
import re

from langchain.chains.question_answering.map_reduce_prompt import messages
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import PromptTemplate
from langchain_core.messages import HumanMessage
from langchain_core.runnables import RunnablePassthrough
from langchain_ollama import ChatOllama
from langgraph.graph import StateGraph, END, START
from langgraph.prebuilt import ToolNode


# --------------------------
# TOOL IMPLEMENTATIONS
# --------------------------
def extract_positive_numbers(sentence: str) -> Dict[str, Any]:
    """Extract positive integers from the sentence."""
    numbers = [int(n) for n in re.findall(r"\b\d+\b", sentence) if int(n) > 0]
    print(f"Extracted numbers - {numbers}")
    if not numbers:
        return {"numbers": [], "message": "No positive numbers found. Cannot proceed with operations."}
    return {"numbers": numbers, "message": None}


def add_two_numbers(numbers: List[int]) -> Dict[str, Any]:
    if len(numbers) < 2:
        return {"add": None, "message": "Need at least 2 numbers for addition."}
    return {"add": numbers[0] + numbers[1], "message": None}


def subtract_two_numbers(numbers: List[int]) -> Dict[str, Any]:
    if len(numbers) < 2:
        return {"subtract": None, "message": "Need at least 2 numbers for subtraction."}
    return {"subtract": numbers[0] - numbers[1], "message": None}


def multiply_two_numbers(numbers: List[int]) -> Dict[str, Any]:
    if len(numbers) < 2:
        return {"multiply": None, "message": "Need at least 2 numbers for multiplication."}
    return {"multiply": numbers[0] * numbers[1], "message": None}


# --------------------------
# LANGGRAPH STATE
# --------------------------
class CalcState(TypedDict):
    sentence: str
    message: str
    stop_message: str
    numbers: []
    add: int
    subtract: int
    multiply: int
    final_result: {}


# --------------------------
# WRAPPER FUNCTIONS FOR TOOLS
# --------------------------
def tool1_node(state: CalcState) -> CalcState:
    print(f"Current state is - {state}")
    result = extract_positive_numbers(state["sentence"])
    if result["message"]:
        state["stop_message"] = result["message"]
        state["numbers"] = []
        return state
    state["numbers"] = result["numbers"]
    return state


def tool2_node(state: CalcState) -> CalcState:
    if "stop_message" in state:
        return state
    result = add_two_numbers(state["numbers"])
    state["add"] = result["add"]
    return state


def tool3_node(state: CalcState) -> CalcState:
    if "stop_message" in state:
        return state
    result = subtract_two_numbers(state["numbers"])
    state["subtract"] = result["subtract"]
    return state


def tool4_node(state: CalcState) -> CalcState:
    if "stop_message" in state:
        return state
    result = multiply_two_numbers(state["numbers"])
    state["multiply"] = result["multiply"]
    return state


def final_node(state: CalcState) -> CalcState:
    if "stop_message" in state:
        state["final_result"] = state["stop_message"]
    else:
        state["final_result"] = {
            "numbers": state["numbers"],
            "add": state["add"],
            "subtract": state["subtract"],
            "multiply": state["multiply"]
        }
    return state


# --------------------------
# BUILD GRAPH
# --------------------------
graph = StateGraph(CalcState)
graph.add_node("tool1", tool1_node)
graph.add_node("tool2", tool2_node)
graph.add_node("tool3", tool3_node)
graph.add_node("tool4", tool4_node)
graph.add_node("final", final_node)

graph.add_edge(START, "tool1")
graph.add_edge("tool1", "tool2")
graph.add_edge("tool2", "tool3")
graph.add_edge("tool3", "tool4")
graph.add_edge("tool4", "final")
graph.add_edge("final", END)

app = graph.compile()

# --------------------------
# TEST RUNS
# --------------------------
print("=== Example 1: With numbers ===")
input_prompt = "I have 8 apples and 3 oranges"
result1 = app.invoke({"sentence": "I have 8 apples and 3 oranges"})
print(result1["final_result"])

# print("\n=== Example 2: Without numbers ===")
# result2 = app.invoke({"sentence": "I have apples and oranges"})
# print(result2["final_result"])