Files
langchain-python/langchain/chains/base.py
T
Samantha Whitmore a408ed3ea3 Samantha/add conversation chain (#166)
Add MemoryChain and ConversationChain as chains that take a docstore in
addition to the prompt, and use the docstore to stuff context into the
prompt. This can be used to have an ongoing conversation with a chatbot.

Probably needs a bit of refactoring for code quality

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>
2022-11-23 16:35:38 -08:00

113 lines
3.9 KiB
Python

"""Base interface that all chains should implement."""
from abc import ABC, abstractmethod
from typing import Any, Dict, List, Optional
from pydantic import BaseModel, Extra
class Memory(BaseModel, ABC):
"""Base interface for memory in chains."""
class Config:
"""Configuration for this pydantic object."""
extra = Extra.forbid
arbitrary_types_allowed = True
@property
@abstractmethod
def dynamic_keys(self) -> List[str]:
"""Input keys this memory class will load dynamically."""
@abstractmethod
def _load_dynamic_keys(self, inputs: Dict[str, Any]) -> Dict[str, str]:
"""Return key-value pairs given the text input to the chain."""
@abstractmethod
def _save_context(self, inputs: Dict[str, Any], outputs: Dict[str, str]) -> None:
"""Save the context of this model run to memory."""
class Chain(BaseModel, ABC):
"""Base interface that all chains should implement."""
memory: Optional[Memory] = None
verbose: bool = False
"""Whether to print out response text."""
@property
@abstractmethod
def input_keys(self) -> List[str]:
"""Input keys this chain expects."""
@property
@abstractmethod
def output_keys(self) -> List[str]:
"""Output keys this chain expects."""
def _validate_inputs(self, inputs: Dict[str, str]) -> None:
"""Check that all inputs are present."""
missing_keys = set(self.input_keys).difference(inputs)
if missing_keys:
raise ValueError(f"Missing some input keys: {missing_keys}")
def _validate_outputs(self, outputs: Dict[str, str]) -> None:
if set(outputs) != set(self.output_keys):
raise ValueError(
f"Did not get output keys that were expected. "
f"Got: {set(outputs)}. Expected: {set(self.output_keys)}."
)
@abstractmethod
def _call(self, inputs: Dict[str, str]) -> Dict[str, str]:
"""Run the logic of this chain and return the output."""
def __call__(
self, inputs: Dict[str, Any], return_only_outputs: bool = False
) -> Dict[str, str]:
"""Run the logic of this chain and add to output if desired.
Args:
inputs: Dictionary of inputs.
return_only_outputs: boolean for whether to return only outputs in the
response. If True, only new keys generated by this chain will be
returned. If False, both input keys and new keys generated by this
chain will be returned. Defaults to False.
"""
if self.memory is not None:
external_context = self.memory._load_dynamic_keys(inputs)
inputs = dict(inputs, **external_context)
self._validate_inputs(inputs)
if self.verbose:
print("\n\n\033[1m> Entering new chain...\033[0m")
outputs = self._call(inputs)
if self.verbose:
print("\n\033[1m> Finished chain.\033[0m")
self._validate_outputs(outputs)
if self.memory is not None:
self.memory._save_context(inputs, outputs)
if return_only_outputs:
return outputs
else:
return {**inputs, **outputs}
def apply(self, input_list: List[Dict[str, Any]]) -> List[Dict[str, str]]:
"""Call the chain on all inputs in the list."""
return [self(inputs) for inputs in input_list]
def run(self, text: str) -> str:
"""Run text in, text out (if applicable)."""
if len(self.input_keys) != 1:
raise ValueError(
f"`run` not supported when there is not exactly "
f"one input key, got {self.input_keys}."
)
if len(self.output_keys) != 1:
raise ValueError(
f"`run` not supported when there is not exactly "
f"one output key, got {self.output_keys}."
)
return self({self.input_keys[0]: text})[self.output_keys[0]]