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374 | class CondenseQuestionChatEngine(BaseChatEngine):
"""
Condense Question Chat Engine.
First generate a standalone question from conversation context and last message,
then query the query engine for a response.
"""
def __init__(
self,
query_engine: BaseQueryEngine,
condense_question_prompt: BasePromptTemplate,
memory: BaseMemory,
llm: LLM,
verbose: bool = False,
callback_manager: Optional[CallbackManager] = None,
) -> None:
self._query_engine = query_engine
self._condense_question_prompt = condense_question_prompt
self._memory = memory
self._llm = llm
self._verbose = verbose
self.callback_manager = callback_manager or CallbackManager([])
@classmethod
def from_defaults(
cls,
query_engine: BaseQueryEngine,
condense_question_prompt: Optional[BasePromptTemplate] = None,
chat_history: Optional[List[ChatMessage]] = None,
memory: Optional[BaseMemory] = None,
memory_cls: Type[BaseMemory] = ChatMemoryBuffer,
verbose: bool = False,
system_prompt: Optional[str] = None,
prefix_messages: Optional[List[ChatMessage]] = None,
llm: Optional[LLM] = None,
**kwargs: Any,
) -> "CondenseQuestionChatEngine":
"""Initialize a CondenseQuestionChatEngine from default parameters."""
condense_question_prompt = condense_question_prompt or DEFAULT_PROMPT
llm = llm or Settings.llm
chat_history = chat_history or []
memory = memory or memory_cls.from_defaults(chat_history=chat_history, llm=llm)
if system_prompt is not None:
raise NotImplementedError(
"system_prompt is not supported for CondenseQuestionChatEngine."
)
if prefix_messages is not None:
raise NotImplementedError(
"prefix_messages is not supported for CondenseQuestionChatEngine."
)
return cls(
query_engine,
condense_question_prompt,
memory,
llm,
verbose=verbose,
callback_manager=Settings.callback_manager,
)
def _condense_question(
self, chat_history: List[ChatMessage], last_message: str
) -> str:
"""
Generate standalone question from conversation context and last message.
"""
if not chat_history:
# Keep the question as is if there's no conversation context.
return last_message
chat_history_str = messages_to_history_str(chat_history)
logger.debug(chat_history_str)
return self._llm.predict(
self._condense_question_prompt,
question=last_message,
chat_history=chat_history_str,
)
async def _acondense_question(
self, chat_history: List[ChatMessage], last_message: str
) -> str:
"""
Generate standalone question from conversation context and last message.
"""
if not chat_history:
# Keep the question as is if there's no conversation context.
return last_message
chat_history_str = messages_to_history_str(chat_history)
logger.debug(chat_history_str)
return await self._llm.apredict(
self._condense_question_prompt,
question=last_message,
chat_history=chat_history_str,
)
def _get_tool_output_from_response(
self, query: str, response: RESPONSE_TYPE
) -> ToolOutput:
if isinstance(response, (StreamingResponse, AsyncStreamingResponse)):
return ToolOutput(
content="",
tool_name="query_engine",
raw_input={"query": query},
raw_output=response,
)
else:
return ToolOutput(
content=str(response),
tool_name="query_engine",
raw_input={"query": query},
raw_output=response,
)
@trace_method("chat")
def chat(
self, message: str, chat_history: Optional[List[ChatMessage]] = None
) -> AgentChatResponse:
chat_history = chat_history or self._memory.get(input=message)
# Generate standalone question from conversation context and last message
condensed_question = self._condense_question(chat_history, message)
log_str = f"Querying with: {condensed_question}"
logger.info(log_str)
if self._verbose:
print(log_str)
# TODO: right now, query engine uses class attribute to configure streaming,
# we are moving towards separate streaming and non-streaming methods.
# In the meanwhile, use this hack to toggle streaming.
from llama_index.core.query_engine.retriever_query_engine import (
RetrieverQueryEngine,
)
if isinstance(self._query_engine, RetrieverQueryEngine):
is_streaming = self._query_engine._response_synthesizer._streaming
self._query_engine._response_synthesizer._streaming = False
# Query with standalone question
query_response = self._query_engine.query(condensed_question)
# NOTE: reset streaming flag
if isinstance(self._query_engine, RetrieverQueryEngine):
self._query_engine._response_synthesizer._streaming = is_streaming
tool_output = self._get_tool_output_from_response(
condensed_question, query_response
)
# Record response
self._memory.put(ChatMessage(role=MessageRole.USER, content=message))
self._memory.put(
ChatMessage(role=MessageRole.ASSISTANT, content=str(query_response))
)
return AgentChatResponse(response=str(query_response), sources=[tool_output])
@trace_method("chat")
def stream_chat(
self, message: str, chat_history: Optional[List[ChatMessage]] = None
) -> StreamingAgentChatResponse:
chat_history = chat_history or self._memory.get(input=message)
# Generate standalone question from conversation context and last message
condensed_question = self._condense_question(chat_history, message)
log_str = f"Querying with: {condensed_question}"
logger.info(log_str)
if self._verbose:
print(log_str)
# TODO: right now, query engine uses class attribute to configure streaming,
# we are moving towards separate streaming and non-streaming methods.
# In the meanwhile, use this hack to toggle streaming.
from llama_index.core.query_engine.retriever_query_engine import (
RetrieverQueryEngine,
)
if isinstance(self._query_engine, RetrieverQueryEngine):
is_streaming = self._query_engine._response_synthesizer._streaming
self._query_engine._response_synthesizer._streaming = True
# Query with standalone question
query_response = self._query_engine.query(condensed_question)
# NOTE: reset streaming flag
if isinstance(self._query_engine, RetrieverQueryEngine):
self._query_engine._response_synthesizer._streaming = is_streaming
tool_output = self._get_tool_output_from_response(
condensed_question, query_response
)
# Record response
if (
isinstance(query_response, StreamingResponse)
and query_response.response_gen is not None
):
# override the generator to include writing to chat history
self._memory.put(ChatMessage(role=MessageRole.USER, content=message))
response = StreamingAgentChatResponse(
chat_stream=response_gen_from_query_engine(query_response.response_gen),
sources=[tool_output],
)
thread = Thread(
target=response.write_response_to_history,
args=(self._memory,),
)
thread.start()
else:
raise ValueError("Streaming is not enabled. Please use chat() instead.")
return response
@trace_method("chat")
async def achat(
self, message: str, chat_history: Optional[List[ChatMessage]] = None
) -> AgentChatResponse:
chat_history = chat_history or self._memory.get(input=message)
# Generate standalone question from conversation context and last message
condensed_question = await self._acondense_question(chat_history, message)
log_str = f"Querying with: {condensed_question}"
logger.info(log_str)
if self._verbose:
print(log_str)
# TODO: right now, query engine uses class attribute to configure streaming,
# we are moving towards separate streaming and non-streaming methods.
# In the meanwhile, use this hack to toggle streaming.
from llama_index.core.query_engine.retriever_query_engine import (
RetrieverQueryEngine,
)
if isinstance(self._query_engine, RetrieverQueryEngine):
is_streaming = self._query_engine._response_synthesizer._streaming
self._query_engine._response_synthesizer._streaming = False
# Query with standalone question
query_response = await self._query_engine.aquery(condensed_question)
# NOTE: reset streaming flag
if isinstance(self._query_engine, RetrieverQueryEngine):
self._query_engine._response_synthesizer._streaming = is_streaming
tool_output = self._get_tool_output_from_response(
condensed_question, query_response
)
# Record response
await self._memory.aput(ChatMessage(role=MessageRole.USER, content=message))
await self._memory.aput(
ChatMessage(role=MessageRole.ASSISTANT, content=str(query_response))
)
return AgentChatResponse(response=str(query_response), sources=[tool_output])
@trace_method("chat")
async def astream_chat(
self, message: str, chat_history: Optional[List[ChatMessage]] = None
) -> StreamingAgentChatResponse:
chat_history = chat_history or self._memory.get(input=message)
# Generate standalone question from conversation context and last message
condensed_question = await self._acondense_question(chat_history, message)
log_str = f"Querying with: {condensed_question}"
logger.info(log_str)
if self._verbose:
print(log_str)
# TODO: right now, query engine uses class attribute to configure streaming,
# we are moving towards separate streaming and non-streaming methods.
# In the meanwhile, use this hack to toggle streaming.
from llama_index.core.query_engine.retriever_query_engine import (
RetrieverQueryEngine,
)
if isinstance(self._query_engine, RetrieverQueryEngine):
is_streaming = self._query_engine._response_synthesizer._streaming
self._query_engine._response_synthesizer._streaming = True
# Query with standalone question
query_response = await self._query_engine.aquery(condensed_question)
# NOTE: reset streaming flag
if isinstance(self._query_engine, RetrieverQueryEngine):
self._query_engine._response_synthesizer._streaming = is_streaming
tool_output = self._get_tool_output_from_response(
condensed_question, query_response
)
# Record response
if isinstance(query_response, AsyncStreamingResponse):
# override the generator to include writing to chat history
# TODO: query engine does not support async generator yet
await self._memory.aput(ChatMessage(role=MessageRole.USER, content=message))
response = StreamingAgentChatResponse(
achat_stream=aresponse_gen_from_query_engine(
query_response.async_response_gen()
),
sources=[tool_output],
)
asyncio.create_task(response.awrite_response_to_history(self._memory))
else:
raise ValueError("Streaming is not enabled. Please use achat() instead.")
return response
def reset(self) -> None:
# Clear chat history
self._memory.reset()
@property
def chat_history(self) -> List[ChatMessage]:
"""Get chat history."""
return self._memory.get_all()
|
