"""Implementation of the RunnablePassthrough."""
from __future__ import annotations
import asyncio
import inspect
import threading
from typing import (
TYPE_CHECKING,
Any,
AsyncIterator,
Awaitable,
Callable,
Dict,
Iterator,
List,
Mapping,
Optional,
Type,
Union,
cast,
)
from langchain_core.pydantic_v1 import BaseModel, create_model
from langchain_core.runnables.base import (
Other,
Runnable,
RunnableParallel,
RunnableSerializable,
)
from langchain_core.runnables.config import (
RunnableConfig,
acall_func_with_variable_args,
call_func_with_variable_args,
ensure_config,
get_executor_for_config,
patch_config,
)
from langchain_core.runnables.graph import Graph
from langchain_core.runnables.utils import AddableDict, ConfigurableFieldSpec
from langchain_core.utils.aiter import atee, py_anext
from langchain_core.utils.iter import safetee
if TYPE_CHECKING:
from langchain_core.callbacks.manager import (
AsyncCallbackManagerForChainRun,
CallbackManagerForChainRun,
)
[docs]def identity(x: Other) -> Other:
"""An identity function"""
return x
[docs]async def aidentity(x: Other) -> Other:
"""An async identity function"""
return x
[docs]class RunnablePassthrough(RunnableSerializable[Other, Other]):
"""A runnable to passthrough inputs unchanged or with additional keys.
This runnable behaves almost like the identity function, except that it
can be configured to add additional keys to the output, if the input is a
dict.
The examples below demonstrate this runnable works using a few simple
chains. The chains rely on simple lambdas to make the examples easy to execute
and experiment with.
Examples:
.. code-block:: python
from langchain_core.runnables import (
RunnableLambda,
RunnableParallel,
RunnablePassthrough,
)
runnable = RunnableParallel(
origin=RunnablePassthrough(),
modified=lambda x: x+1
)
runnable.invoke(1) # {'origin': 1, 'modified': 2}
def fake_llm(prompt: str) -> str: # Fake LLM for the example
return "completion"
chain = RunnableLambda(fake_llm) | {
'original': RunnablePassthrough(), # Original LLM output
'parsed': lambda text: text[::-1] # Parsing logic
}
chain.invoke('hello') # {'original': 'completion', 'parsed': 'noitelpmoc'}
In some cases, it may be useful to pass the input through while adding some
keys to the output. In this case, you can use the `assign` method:
.. code-block:: python
from langchain_core.runnables import RunnablePassthrough, RunnableParallel
def fake_llm(prompt: str) -> str: # Fake LLM for the example
return "completion"
runnable = {
'llm1': fake_llm,
'llm2': fake_llm,
}
| RunnablePassthrough.assign(
total_chars=lambda inputs: len(inputs['llm1'] + inputs['llm2'])
)
runnable.invoke('hello')
# {'llm1': 'completion', 'llm2': 'completion', 'total_chars': 20}
"""
input_type: Optional[Type[Other]] = None
func: Optional[
Union[Callable[[Other], None], Callable[[Other, RunnableConfig], None]]
] = None
afunc: Optional[
Union[
Callable[[Other], Awaitable[None]],
Callable[[Other, RunnableConfig], Awaitable[None]],
]
] = None
def __repr_args__(self) -> Any:
# Without this repr(self) raises a RecursionError
# See https://github.com/pydantic/pydantic/issues/7327
return []
def __init__(
self,
func: Optional[
Union[
Union[Callable[[Other], None], Callable[[Other, RunnableConfig], None]],
Union[
Callable[[Other], Awaitable[None]],
Callable[[Other, RunnableConfig], Awaitable[None]],
],
]
] = None,
afunc: Optional[
Union[
Callable[[Other], Awaitable[None]],
Callable[[Other, RunnableConfig], Awaitable[None]],
]
] = None,
*,
input_type: Optional[Type[Other]] = None,
**kwargs: Any,
) -> None:
if inspect.iscoroutinefunction(func):
afunc = func
func = None
super().__init__(func=func, afunc=afunc, input_type=input_type, **kwargs)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
@property
def InputType(self) -> Any:
return self.input_type or Any
@property
def OutputType(self) -> Any:
return self.input_type or Any
[docs] @classmethod
def assign(
cls,
**kwargs: Union[
Runnable[Dict[str, Any], Any],
Callable[[Dict[str, Any]], Any],
Mapping[
str,
Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any]],
],
],
) -> "RunnableAssign":
"""Merge the Dict input with the output produced by the mapping argument.
Args:
mapping: A mapping from keys to runnables or callables.
Returns:
A runnable that merges the Dict input with the output produced by the
mapping argument.
"""
return RunnableAssign(RunnableParallel(kwargs))
[docs] def invoke(
self, input: Other, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> Other:
if self.func is not None:
call_func_with_variable_args(
self.func, input, ensure_config(config), **kwargs
)
return self._call_with_config(identity, input, config)
[docs] async def ainvoke(
self,
input: Other,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Other:
if self.afunc is not None:
await acall_func_with_variable_args(
self.afunc, input, ensure_config(config), **kwargs
)
elif self.func is not None:
call_func_with_variable_args(
self.func, input, ensure_config(config), **kwargs
)
return await self._acall_with_config(aidentity, input, config)
[docs] def stream(
self,
input: Other,
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Other]:
return self.transform(iter([input]), config, **kwargs)
[docs] async def astream(
self,
input: Other,
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Other]:
async def input_aiter() -> AsyncIterator[Other]:
yield input
async for chunk in self.atransform(input_aiter(), config, **kwargs):
yield chunk
_graph_passthrough: RunnablePassthrough = RunnablePassthrough()
[docs]class RunnableAssign(RunnableSerializable[Dict[str, Any], Dict[str, Any]]):
"""
A runnable that assigns key-value pairs to Dict[str, Any] inputs.
"""
mapper: RunnableParallel[Dict[str, Any]]
def __init__(self, mapper: RunnableParallel[Dict[str, Any]], **kwargs: Any) -> None:
super().__init__(mapper=mapper, **kwargs)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
name = (
name or self.name or f"RunnableAssign<{','.join(self.mapper.steps.keys())}>"
)
return super().get_name(suffix, name=name)
[docs] def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
map_input_schema = self.mapper.get_input_schema(config)
map_output_schema = self.mapper.get_output_schema(config)
if (
not map_input_schema.__custom_root_type__
and not map_output_schema.__custom_root_type__
):
# ie. both are dicts
return create_model( # type: ignore[call-overload]
"RunnableAssignOutput",
**{
k: (v.type_, v.default)
for s in (map_input_schema, map_output_schema)
for k, v in s.__fields__.items()
},
)
elif not map_output_schema.__custom_root_type__:
# ie. only map output is a dict
# ie. input type is either unknown or inferred incorrectly
return map_output_schema
return super().get_output_schema(config)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return self.mapper.config_specs
[docs] def get_graph(self, config: RunnableConfig | None = None) -> Graph:
# get graph from mapper
graph = self.mapper.get_graph(config)
# add passthrough node and edges
input_node = graph.first_node()
output_node = graph.last_node()
if input_node is not None and output_node is not None:
passthrough_node = graph.add_node(_graph_passthrough)
graph.add_edge(input_node, passthrough_node)
graph.add_edge(passthrough_node, output_node)
return graph
def _invoke(
self,
input: Dict[str, Any],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Dict[str, Any]:
assert isinstance(
input, dict
), "The input to RunnablePassthrough.assign() must be a dict."
return {
**input,
**self.mapper.invoke(
input,
patch_config(config, callbacks=run_manager.get_child()),
**kwargs,
),
}
[docs] def invoke(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Dict[str, Any]:
return self._call_with_config(self._invoke, input, config, **kwargs)
async def _ainvoke(
self,
input: Dict[str, Any],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Dict[str, Any]:
assert isinstance(
input, dict
), "The input to RunnablePassthrough.assign() must be a dict."
return {
**input,
**await self.mapper.ainvoke(
input,
patch_config(config, callbacks=run_manager.get_child()),
**kwargs,
),
}
[docs] async def ainvoke(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Dict[str, Any]:
return await self._acall_with_config(self._ainvoke, input, config, **kwargs)
def _transform(
self,
input: Iterator[Dict[str, Any]],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Iterator[Dict[str, Any]]:
# collect mapper keys
mapper_keys = set(self.mapper.steps.keys())
# create two streams, one for the map and one for the passthrough
for_passthrough, for_map = safetee(input, 2, lock=threading.Lock())
# create map output stream
map_output = self.mapper.transform(
for_map,
patch_config(
config,
callbacks=run_manager.get_child(),
),
**kwargs,
)
# get executor to start map output stream in background
with get_executor_for_config(config) as executor:
# start map output stream
first_map_chunk_future = executor.submit(
next,
map_output, # type: ignore
None,
)
# consume passthrough stream
for chunk in for_passthrough:
assert isinstance(
chunk, dict
), "The input to RunnablePassthrough.assign() must be a dict."
# remove mapper keys from passthrough chunk, to be overwritten by map
filtered = AddableDict(
{k: v for k, v in chunk.items() if k not in mapper_keys}
)
if filtered:
yield filtered
# yield map output
yield cast(Dict[str, Any], first_map_chunk_future.result())
for chunk in map_output:
yield chunk
async def _atransform(
self,
input: AsyncIterator[Dict[str, Any]],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> AsyncIterator[Dict[str, Any]]:
# collect mapper keys
mapper_keys = set(self.mapper.steps.keys())
# create two streams, one for the map and one for the passthrough
for_passthrough, for_map = atee(input, 2, lock=asyncio.Lock())
# create map output stream
map_output = self.mapper.atransform(
for_map,
patch_config(
config,
callbacks=run_manager.get_child(),
),
**kwargs,
)
# start map output stream
first_map_chunk_task: asyncio.Task = asyncio.create_task(
py_anext(map_output, None), # type: ignore[arg-type]
)
# consume passthrough stream
async for chunk in for_passthrough:
assert isinstance(
chunk, dict
), "The input to RunnablePassthrough.assign() must be a dict."
# remove mapper keys from passthrough chunk, to be overwritten by map output
filtered = AddableDict(
{k: v for k, v in chunk.items() if k not in mapper_keys}
)
if filtered:
yield filtered
# yield map output
yield await first_map_chunk_task
async for chunk in map_output:
yield chunk
[docs] def stream(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Dict[str, Any]]:
return self.transform(iter([input]), config, **kwargs)
[docs] async def astream(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Dict[str, Any]]:
async def input_aiter() -> AsyncIterator[Dict[str, Any]]:
yield input
async for chunk in self.atransform(input_aiter(), config, **kwargs):
yield chunk
[docs]class RunnablePick(RunnableSerializable[Dict[str, Any], Dict[str, Any]]):
"""
A runnable that picks keys from Dict[str, Any] inputs.
"""
keys: Union[str, List[str]]
def __init__(self, keys: Union[str, List[str]], **kwargs: Any) -> None:
super().__init__(keys=keys, **kwargs)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
name = (
name
or self.name
or f"RunnablePick<{','.join([self.keys] if isinstance(self.keys, str) else self.keys)}>" # noqa: E501
)
return super().get_name(suffix, name=name)
def _pick(self, input: Dict[str, Any]) -> Any:
assert isinstance(
input, dict
), "The input to RunnablePassthrough.assign() must be a dict."
if isinstance(self.keys, str):
return input.get(self.keys)
else:
picked = {k: input.get(k) for k in self.keys if k in input}
if picked:
return AddableDict(picked)
else:
return None
def _invoke(
self,
input: Dict[str, Any],
) -> Dict[str, Any]:
return self._pick(input)
[docs] def invoke(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Dict[str, Any]:
return self._call_with_config(self._invoke, input, config, **kwargs)
async def _ainvoke(
self,
input: Dict[str, Any],
) -> Dict[str, Any]:
return self._pick(input)
[docs] async def ainvoke(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Dict[str, Any]:
return await self._acall_with_config(self._ainvoke, input, config, **kwargs)
def _transform(
self,
input: Iterator[Dict[str, Any]],
) -> Iterator[Dict[str, Any]]:
for chunk in input:
picked = self._pick(chunk)
if picked is not None:
yield picked
async def _atransform(
self,
input: AsyncIterator[Dict[str, Any]],
) -> AsyncIterator[Dict[str, Any]]:
async for chunk in input:
picked = self._pick(chunk)
if picked is not None:
yield picked
[docs] def stream(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Dict[str, Any]]:
return self.transform(iter([input]), config, **kwargs)
[docs] async def astream(
self,
input: Dict[str, Any],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Dict[str, Any]]:
async def input_aiter() -> AsyncIterator[Dict[str, Any]]:
yield input
async for chunk in self.atransform(input_aiter(), config, **kwargs):
yield chunk