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"""
Call loop machinery
"""
from __future__ import annotations
from typing import cast
from typing import Generator
from typing import Mapping
from typing import Sequence
from typing import Tuple
from typing import TYPE_CHECKING
from typing import Union
from ._result import _raise_wrapfail
from ._result import _Result
from ._result import HookCallError
if TYPE_CHECKING:
from ._hooks import HookImpl
# Need to distinguish between old- and new-style hook wrappers.
# Wrapping one a singleton tuple is the fastest type-safe way I found to do it.
Teardown = Union[
Tuple[Generator[None, _Result[object], None]],
Generator[None, object, object],
]
def _multicall(
hook_name: str,
hook_impls: Sequence[HookImpl],
caller_kwargs: Mapping[str, object],
firstresult: bool,
) -> object | list[object]:
"""Execute a call into multiple python functions/methods and return the
result(s).
``caller_kwargs`` comes from _HookCaller.__call__().
"""
__tracebackhide__ = True
results: list[object] = []
exception = None
only_new_style_wrappers = True
try: # run impl and wrapper setup functions in a loop
teardowns: list[Teardown] = []
try:
for hook_impl in reversed(hook_impls):
try:
args = [caller_kwargs[argname] for argname in hook_impl.argnames]
except KeyError:
for argname in hook_impl.argnames:
if argname not in caller_kwargs:
raise HookCallError(
f"hook call must provide argument {argname!r}"
)
if hook_impl.hookwrapper:
only_new_style_wrappers = False
try:
# If this cast is not valid, a type error is raised below,
# which is the desired response.
res = hook_impl.function(*args)
wrapper_gen = cast(Generator[None, _Result[object], None], res)
next(wrapper_gen) # first yield
teardowns.append((wrapper_gen,))
except StopIteration:
_raise_wrapfail(wrapper_gen, "did not yield")
elif hook_impl.wrapper:
try:
# If this cast is not valid, a type error is raised below,
# which is the desired response.
res = hook_impl.function(*args)
function_gen = cast(Generator[None, object, object], res)
next(function_gen) # first yield
teardowns.append(function_gen)
except StopIteration:
_raise_wrapfail(function_gen, "did not yield")
else:
res = hook_impl.function(*args)
if res is not None:
results.append(res)
if firstresult: # halt further impl calls
break
except BaseException as exc:
exception = exc
finally:
# Fast path - only new-style wrappers, no _Result.
if only_new_style_wrappers:
if firstresult: # first result hooks return a single value
result = results[0] if results else None
else:
result = results
# run all wrapper post-yield blocks
for teardown in reversed(teardowns):
try:
if exception is not None:
teardown.throw(exception) # type: ignore[union-attr]
else:
teardown.send(result) # type: ignore[union-attr]
# Following is unreachable for a well behaved hook wrapper.
# Try to force finalizers otherwise postponed till GC action.
# Note: close() may raise if generator handles GeneratorExit.
teardown.close() # type: ignore[union-attr]
except StopIteration as si:
result = si.value
exception = None
continue
except BaseException as e:
exception = e
continue
_raise_wrapfail(teardown, "has second yield") # type: ignore[arg-type]
if exception is not None:
raise exception.with_traceback(exception.__traceback__)
else:
return result
# Slow path - need to support old-style wrappers.
else:
if firstresult: # first result hooks return a single value
outcome: _Result[object | list[object]] = _Result(
results[0] if results else None, exception
)
else:
outcome = _Result(results, exception)
# run all wrapper post-yield blocks
for teardown in reversed(teardowns):
if isinstance(teardown, tuple):
try:
teardown[0].send(outcome)
_raise_wrapfail(teardown[0], "has second yield")
except StopIteration:
pass
else:
try:
if outcome._exception is not None:
teardown.throw(outcome._exception)
else:
teardown.send(outcome._result)
# Following is unreachable for a well behaved hook wrapper.
# Try to force finalizers otherwise postponed till GC action.
# Note: close() may raise if generator handles GeneratorExit.
teardown.close()
except StopIteration as si:
outcome.force_result(si.value)
continue
except BaseException as e:
outcome.force_exception(e)
continue
_raise_wrapfail(teardown, "has second yield")
return outcome.get_result()