llmatch 2025.4.181303

Reliable LLM interaction with pattern matching and retries.

LLM Match

LLM Match (llmatch) is a Python utility function designed to reliably interact with Language Models integrated via LangChain (langchain-core, langchain-llm7). It ensures the LLM's responses conform to a specified regular expression pattern, implementing automatic retries with exponential backoff for increased robustness against transient issues or non-conforming responses.

It's particularly useful when you need structured data or specific formatting from an LLM and want to enforce that structure programmatically.

Installation

To install llmatch, use pip. This will also install necessary dependencies like langchain-core and langchain-llm7.

pip install llmatch langchain-llm7 langchain-core

(Note: You need to have a compatible LangChain LLM environment set up for llmatch to make actual LLM calls. The default ChatLLM7() might be a placeholder or require specific configuration.)

Usage

Using llmatch involves providing a query, optional context, and a regex pattern you expect the LLM's response to match. It will handle the LLM invocation and retries until a matching response is found or the maximum retries are exceeded.

Here's a more meaningful example where we ask the LLM to summarize a piece of code and return the summary enclosed in specific XML-like tags:

# Import the function and potentially your configured LLM
from llmatch import llmatch
# from langchain_your_provider import YourChatLLM # Example if not using default

# Example context: A Python code snippet
code_context = """
import logging
import sys

def setup_logger(log_file_path="app.log"):
    logger = logging.getLogger(__name__)
    logger.setLevel(logging.INFO) # Set root logger level

    # Prevent duplicate handlers if logger is already configured
    if logger.hasHandlers():
        logger.handlers.clear()

    # Console Handler
    console_handler = logging.StreamHandler(sys.stdout)
    console_handler.setLevel(logging.INFO) # Console level

    try:
        # File Handler - Append Mode
        file_handler = logging.FileHandler(log_file_path, mode='a')
        file_handler.setLevel(logging.ERROR) # Log only errors and critical to file

        # Create formatter and add to handlers
        formatter = logging.Formatter('%(asctime)s %(levelname)s %(name)s %(message)s')
        console_handler.setFormatter(formatter)
        file_handler.setFormatter(formatter)

        # Add handlers to logger
        logger.addHandler(console_handler)
        logger.addHandler(file_handler)

        logger.info(f"Logging initialized. INFO to console, ERROR to {log_file_path}")

    except Exception as log_error:
        print(f"WARNING: Error setting up log file: {log_error}")
        # Fallback to console-only logging
        logger.addHandler(console_handler)
        logger.info("Logging initialized to console only.")

    return logger

# Example usage of the logger setup
# if __name__ == "__main__":
#     my_logger = setup_logger()
#     my_logger.info("This is an info message.")
#     my_logger.error("This is an error message.")
"""

# Define the query for the LLM
query = "Summarize the purpose of the following Python code in one sentence."

# Define the regex pattern to extract the summary from within <summary> tags
# We expect the LLM to respond like: "Some text... <summary>The summary text.</summary> ...more text"
pattern = r"<summary>(.*?)</summary>"

# Initialize your LangChain LLM (replace ChatLLM7() if necessary)
# llm_instance = YourChatLLM(temperature=0.7)
# For this example, we'll use the default which might be a dummy/placeholder
# from langchain_llm7 import ChatLLM7
# llm_instance = ChatLLM7()

# Call llmatch
# Note: We might need to explicitly pass the llm_instance if not using the default
result = llmatch(
    # llm=llm_instance, # Pass your configured LLM here
    query=query,
    context=code_context,
    pattern=pattern, # Specify the desired pattern for extraction
    max_retries=3,    # Limit retries for the example
    verbose=False     # Set to True for detailed logs
)

# Process the result
print("\n--- LLMatch Result ---")
if result["success"]:
    print("Successfully extracted summary:")
    # findall returns a list, get the first match
    extracted_summary = result["extracted_data"][0]
    print(f"> {extracted_summary}")
    # print("\nFull LLM Response:")
    # print(result["final_content"])
else:
    print(f"Failed to get a matching response after {result['retries_attempted']} retries.")
    print(f"Error: {result['error_message']}")
    # print("\nLast LLM Response Attempt:")
    # print(result["final_content"])

In this example, llmatch repeatedly prompts the LLM with the query and context, checking each response against the <summary>(.*?)</summary> pattern. It only returns successfully once the LLM provides a response containing that structure, extracting the text within the tags.

Features

• Reliable LLM Interaction: Automatically retries LLM calls on failure or non-matching responses.
• Exponential Backoff: Waits progressively longer between retries to handle transient load or rate limits.
• Response Validation: Uses regular expressions (pattern) to ensure the LLM response conforms to the desired structure.
• Data Extraction: Extracts specific parts of the LLM response using regex capture groups.
• Configurable: Allows customization of the query, context, regex pattern, prompt template, retry attempts, and delay parameters.
• LangChain Integration: Designed to work with LangChain LLM objects (tested with langchain-llm7 and langchain-core).
• Debugging: Includes a verbose mode for detailed logging of the process.

Contributing

Contributions, issues, and feature requests are welcome! Feel free to check the issues page.

License

llmatch is licensed under the Apache License 2.0.