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from typing import Any, Callable, List, Optional, TypeVar
from reactivex import Observable, abc, typing
from reactivex.disposable import CompositeDisposable
_T = TypeVar("_T")
def do_action_(
on_next: Optional[typing.OnNext[_T]] = None,
on_error: Optional[typing.OnError] = None,
on_completed: Optional[typing.OnCompleted] = None,
) -> Callable[[Observable[_T]], Observable[_T]]:
def do_action(source: Observable[_T]) -> Observable[_T]:
"""Invokes an action for each element in the observable
sequence and invokes an action on graceful or exceptional
termination of the observable sequence. This method can be used
for debugging, logging, etc. of query behavior by intercepting
the message stream to run arbitrary actions for messages on the
pipeline.
Examples:
>>> do_action(send)(observable)
>>> do_action(on_next, on_error)(observable)
>>> do_action(on_next, on_error, on_completed)(observable)
Args:
on_next: [Optional] Action to invoke for each element in
the observable sequence.
on_error: [Optional] Action to invoke on exceptional
termination of the observable sequence.
on_completed: [Optional] Action to invoke on graceful
termination of the observable sequence.
Returns:
An observable source sequence with the side-effecting
behavior applied.
"""
def subscribe(
observer: abc.ObserverBase[_T],
scheduler: Optional[abc.SchedulerBase] = None,
) -> abc.DisposableBase:
def _on_next(x: _T) -> None:
if not on_next:
observer.on_next(x)
else:
try:
on_next(x)
except Exception as e: # pylint: disable=broad-except
observer.on_error(e)
observer.on_next(x)
def _on_error(exception: Exception) -> None:
if not on_error:
observer.on_error(exception)
else:
try:
on_error(exception)
except Exception as e: # pylint: disable=broad-except
observer.on_error(e)
observer.on_error(exception)
def _on_completed() -> None:
if not on_completed:
observer.on_completed()
else:
try:
on_completed()
except Exception as e: # pylint: disable=broad-except
observer.on_error(e)
observer.on_completed()
return source.subscribe(
_on_next, _on_error, _on_completed, scheduler=scheduler
)
return Observable(subscribe)
return do_action
def do_(observer: abc.ObserverBase[_T]) -> Callable[[Observable[_T]], Observable[_T]]:
"""Invokes an action for each element in the observable sequence and
invokes an action on graceful or exceptional termination of the
observable sequence. This method can be used for debugging, logging,
etc. of query behavior by intercepting the message stream to run
arbitrary actions for messages on the pipeline.
>>> do(observer)
Args:
observer: Observer
Returns:
An operator function that takes the source observable and
returns the source sequence with the side-effecting behavior
applied.
"""
return do_action_(observer.on_next, observer.on_error, observer.on_completed)
def do_after_next(
source: Observable[_T], after_next: typing.OnNext[_T]
) -> Observable[_T]:
"""Invokes an action with each element after it has been emitted downstream.
This can be helpful for debugging, logging, and other side effects.
after_next -- Action to invoke on each element after it has been emitted
"""
def subscribe(
observer: abc.ObserverBase[_T], scheduler: Optional[abc.SchedulerBase] = None
) -> abc.DisposableBase:
def on_next(value: _T):
try:
observer.on_next(value)
after_next(value)
except Exception as e: # pylint: disable=broad-except
observer.on_error(e)
return source.subscribe(on_next, observer.on_error, observer.on_completed)
return Observable(subscribe)
def do_on_subscribe(source: Observable[Any], on_subscribe: typing.Action):
"""Invokes an action on subscription.
This can be helpful for debugging, logging, and other side effects
on the start of an operation.
Args:
on_subscribe: Action to invoke on subscription
"""
def subscribe(
observer: abc.ObserverBase[Any], scheduler: Optional[abc.SchedulerBase] = None
) -> abc.DisposableBase:
on_subscribe()
return source.subscribe(
observer.on_next,
observer.on_error,
observer.on_completed,
scheduler=scheduler,
)
return Observable(subscribe)
def do_on_dispose(source: Observable[Any], on_dispose: typing.Action):
"""Invokes an action on disposal.
This can be helpful for debugging, logging, and other side effects
on the disposal of an operation.
Args:
on_dispose: Action to invoke on disposal
"""
class OnDispose(abc.DisposableBase):
def dispose(self) -> None:
on_dispose()
def subscribe(
observer: abc.ObserverBase[Any], scheduler: Optional[abc.SchedulerBase] = None
) -> abc.DisposableBase:
composite_disposable = CompositeDisposable()
composite_disposable.add(OnDispose())
subscription = source.subscribe(
observer.on_next,
observer.on_error,
observer.on_completed,
scheduler=scheduler,
)
composite_disposable.add(subscription)
return composite_disposable
return Observable(subscribe)
def do_on_terminate(source: Observable[Any], on_terminate: typing.Action):
"""Invokes an action on an on_complete() or on_error() event.
This can be helpful for debugging, logging, and other side effects
when completion or an error terminates an operation.
on_terminate -- Action to invoke when on_complete or throw is called
"""
def subscribe(
observer: abc.ObserverBase[Any], scheduler: Optional[abc.SchedulerBase] = None
) -> abc.DisposableBase:
def on_completed():
try:
on_terminate()
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
else:
observer.on_completed()
def on_error(exception: Exception):
try:
on_terminate()
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
else:
observer.on_error(exception)
return source.subscribe(
observer.on_next, on_error, on_completed, scheduler=scheduler
)
return Observable(subscribe)
def do_after_terminate(source: Observable[Any], after_terminate: typing.Action):
"""Invokes an action after an on_complete() or on_error() event.
This can be helpful for debugging, logging, and other side effects
when completion or an error terminates an operation
on_terminate -- Action to invoke after on_complete or throw is called
"""
def subscribe(
observer: abc.ObserverBase[Any], scheduler: Optional[abc.SchedulerBase] = None
) -> abc.DisposableBase:
def on_completed():
observer.on_completed()
try:
after_terminate()
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
def on_error(exception: Exception) -> None:
observer.on_error(exception)
try:
after_terminate()
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
return source.subscribe(
observer.on_next, on_error, on_completed, scheduler=scheduler
)
return Observable(subscribe)
def do_finally(
finally_action: typing.Action,
) -> Callable[[Observable[_T]], Observable[_T]]:
"""Invokes an action after an on_complete(), on_error(), or disposal
event occurs.
This can be helpful for debugging, logging, and other side effects
when completion, an error, or disposal terminates an operation.
Note this operator will strive to execute the finally_action once,
and prevent any redudant calls
Args:
finally_action -- Action to invoke after on_complete, on_error,
or disposal is called
"""
class OnDispose(abc.DisposableBase):
def __init__(self, was_invoked: List[bool]):
self.was_invoked = was_invoked
def dispose(self) -> None:
if not self.was_invoked[0]:
finally_action()
self.was_invoked[0] = True
def partial(source: Observable[_T]) -> Observable[_T]:
def subscribe(
observer: abc.ObserverBase[_T],
scheduler: Optional[abc.SchedulerBase] = None,
) -> abc.DisposableBase:
was_invoked = [False]
def on_completed():
observer.on_completed()
try:
if not was_invoked[0]:
finally_action()
was_invoked[0] = True
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
def on_error(exception: Exception):
observer.on_error(exception)
try:
if not was_invoked[0]:
finally_action()
was_invoked[0] = True
except Exception as err: # pylint: disable=broad-except
observer.on_error(err)
composite_disposable = CompositeDisposable()
composite_disposable.add(OnDispose(was_invoked))
subscription = source.subscribe(
observer.on_next, on_error, on_completed, scheduler=scheduler
)
composite_disposable.add(subscription)
return composite_disposable
return Observable(subscribe)
return partial
__all__ = [
"do_",
"do_action_",
"do_after_next",
"do_finally",
"do_on_dispose",
"do_on_subscribe",
"do_on_terminate",
"do_after_terminate",
]
|
