crewAI/src/crewai/llms/base_llm.py

from abc import ABC, abstractmethod
from typing import Any, Dict, List, Optional, Union


class BaseLLM(ABC):
    """Abstract base class for LLM implementations.

    This class defines the interface that all LLM implementations must follow.
    Users can extend this class to create custom LLM implementations that don't
    rely on litellm's authentication mechanism.

    Custom LLM implementations should handle error cases gracefully, including
    timeouts, authentication failures, and malformed responses. They should also
    implement proper validation for input parameters and provide clear error
    messages when things go wrong.

    Attributes:
        stop (list): A list of stop sequences that the LLM should use to stop generation.
            This is used by the CrewAgentExecutor and other components.
    """

    model: str
    temperature: Optional[float] = None

    def __init__(self, model: str, temperature: Optional[float] = None):
        """Initialize the BaseLLM with default attributes.

        This constructor sets default values for attributes that are expected
        by the CrewAgentExecutor and other components.

        All custom LLM implementations should call super().__init__() to ensure
        that these default attributes are properly initialized.
        """
        self.model = model
        self.temperature = temperature

    @abstractmethod
    def call(
        self,
        messages: Union[str, List[Dict[str, str]]],
        tools: Optional[List[dict]] = None,
        callbacks: Optional[List[Any]] = None,
        available_functions: Optional[Dict[str, Any]] = None,
    ) -> Union[str, Any]:
        """Call the LLM with the given messages.

        Args:
            messages: Input messages for the LLM.
                     Can be a string or list of message dictionaries.
                     If string, it will be converted to a single user message.
                     If list, each dict must have 'role' and 'content' keys.
            tools: Optional list of tool schemas for function calling.
                  Each tool should define its name, description, and parameters.
            callbacks: Optional list of callback functions to be executed
                      during and after the LLM call.
            available_functions: Optional dict mapping function names to callables
                               that can be invoked by the LLM.

        Returns:
            Either a text response from the LLM (str) or
            the result of a tool function call (Any).

        Raises:
            ValueError: If the messages format is invalid.
            TimeoutError: If the LLM request times out.
            RuntimeError: If the LLM request fails for other reasons.
        """
        pass

    @abstractmethod
    def supports_function_calling(self) -> bool:
        """Check if the LLM supports function calling.

        This method should return True if the LLM implementation supports
        function calling (tools), and False otherwise. If this method returns
        True, the LLM should be able to handle the 'tools' parameter in the
        call() method.

        Returns:
            True if the LLM supports function calling, False otherwise.
        """
        pass

    @abstractmethod
    def supports_stop_words(self) -> bool:
        """Check if the LLM supports stop words.

        This method should return True if the LLM implementation supports
        stop words, and False otherwise. If this method returns True, the
        LLM should respect the 'stop' attribute when generating responses.

        Returns:
            True if the LLM supports stop words, False otherwise.
        """
        pass

    @abstractmethod
    def get_context_window_size(self) -> int:
        """Get the context window size of the LLM.

        This method should return the maximum number of tokens that the LLM
        can process in a single request. This is used by CrewAI to ensure
        that messages don't exceed the LLM's context window.

        Returns:
            The context window size as an integer.
        """
        pass

    @abstractmethod
    def set_callbacks(self, callbacks: List[Any]) -> None:
        """Set callback functions for the LLM.

        Args:
            callbacks: List of callback functions to be executed during
                     and after LLM calls.
        """
        pass