"""
Internal hook annotation, representation and calling machinery.
"""
from __future__ import annotations
import inspect
import sys
import warnings
from types import ModuleType
from typing import AbstractSet
from typing import Any
from typing import Callable
from typing import Final
from typing import final
from typing import Generator
from typing import List
from typing import Mapping
from typing import Optional
from typing import overload
from typing import Sequence
from typing import Tuple
from typing import TYPE_CHECKING
from typing import TypedDict
from typing import TypeVar
from typing import Union
from ._result import Result
_T = TypeVar("_T")
_F = TypeVar("_F", bound=Callable[..., object])
_Namespace = Union[ModuleType, type]
_Plugin = object
_HookExec = Callable[
[str, Sequence["HookImpl"], Mapping[str, object], bool],
Union[object, List[object]],
]
_HookImplFunction = Callable[..., Union[_T, Generator[None, Result[_T], None]]]
[docs]
class HookspecOpts(TypedDict):
"""Options for a hook specification."""
#: Whether the hook is :ref:`first result only <firstresult>`.
firstresult: bool
#: Whether the hook is :ref:`historic <historic>`.
historic: bool
#: Whether the hook :ref:`warns when implemented <warn_on_impl>`.
warn_on_impl: Warning | None
[docs]
class HookimplOpts(TypedDict):
"""Options for a hook implementation."""
#: Whether the hook implementation is a :ref:`wrapper <hookwrapper>`.
wrapper: bool
#: Whether the hook implementation is an :ref:`old-style wrapper
#: <old_style_hookwrappers>`.
hookwrapper: bool
#: Whether validation against a hook specification is :ref:`optional
#: <optionalhook>`.
optionalhook: bool
#: Whether to try to order this hook implementation :ref:`first
#: <callorder>`.
tryfirst: bool
#: Whether to try to order this hook implementation :ref:`last
#: <callorder>`.
trylast: bool
#: The name of the hook specification to match, see :ref:`specname`.
specname: str | None
[docs]
@final
class HookspecMarker:
"""Decorator for marking functions as hook specifications.
Instantiate it with a project_name to get a decorator.
Calling :meth:`PluginManager.add_hookspecs` later will discover all marked
functions if the :class:`PluginManager` uses the same project name.
"""
__slots__ = ("project_name",)
def __init__(self, project_name: str) -> None:
self.project_name: Final = project_name
@overload
def __call__(
self,
function: _F,
firstresult: bool = False,
historic: bool = False,
warn_on_impl: Warning | None = None,
) -> _F:
...
@overload # noqa: F811
def __call__( # noqa: F811
self,
function: None = ...,
firstresult: bool = ...,
historic: bool = ...,
warn_on_impl: Warning | None = ...,
) -> Callable[[_F], _F]:
...
def __call__( # noqa: F811
self,
function: _F | None = None,
firstresult: bool = False,
historic: bool = False,
warn_on_impl: Warning | None = None,
) -> _F | Callable[[_F], _F]:
"""If passed a function, directly sets attributes on the function
which will make it discoverable to :meth:`PluginManager.add_hookspecs`.
If passed no function, returns a decorator which can be applied to a
function later using the attributes supplied.
:param firstresult:
If ``True``, the 1:N hook call (N being the number of registered
hook implementation functions) will stop at I<=N when the I'th
function returns a non-``None`` result. See :ref:`firstresult`.
:param historic:
If ``True``, every call to the hook will be memorized and replayed
on plugins registered after the call was made. See :ref:`historic`.
:param warn_on_impl:
If given, every implementation of this hook will trigger the given
warning. See :ref:`warn_on_impl`.
"""
def setattr_hookspec_opts(func: _F) -> _F:
if historic and firstresult:
raise ValueError("cannot have a historic firstresult hook")
opts: HookspecOpts = {
"firstresult": firstresult,
"historic": historic,
"warn_on_impl": warn_on_impl,
}
setattr(func, self.project_name + "_spec", opts)
return func
if function is not None:
return setattr_hookspec_opts(function)
else:
return setattr_hookspec_opts
[docs]
@final
class HookimplMarker:
"""Decorator for marking functions as hook implementations.
Instantiate it with a ``project_name`` to get a decorator.
Calling :meth:`PluginManager.register` later will discover all marked
functions if the :class:`PluginManager` uses the same project name.
"""
__slots__ = ("project_name",)
def __init__(self, project_name: str) -> None:
self.project_name: Final = project_name
@overload
def __call__(
self,
function: _F,
hookwrapper: bool = ...,
optionalhook: bool = ...,
tryfirst: bool = ...,
trylast: bool = ...,
specname: str | None = ...,
wrapper: bool = ...,
) -> _F:
...
@overload # noqa: F811
def __call__( # noqa: F811
self,
function: None = ...,
hookwrapper: bool = ...,
optionalhook: bool = ...,
tryfirst: bool = ...,
trylast: bool = ...,
specname: str | None = ...,
wrapper: bool = ...,
) -> Callable[[_F], _F]:
...
def __call__( # noqa: F811
self,
function: _F | None = None,
hookwrapper: bool = False,
optionalhook: bool = False,
tryfirst: bool = False,
trylast: bool = False,
specname: str | None = None,
wrapper: bool = False,
) -> _F | Callable[[_F], _F]:
"""If passed a function, directly sets attributes on the function
which will make it discoverable to :meth:`PluginManager.register`.
If passed no function, returns a decorator which can be applied to a
function later using the attributes supplied.
:param optionalhook:
If ``True``, a missing matching hook specification will not result
in an error (by default it is an error if no matching spec is
found). See :ref:`optionalhook`.
:param tryfirst:
If ``True``, this hook implementation will run as early as possible
in the chain of N hook implementations for a specification. See
:ref:`callorder`.
:param trylast:
If ``True``, this hook implementation will run as late as possible
in the chain of N hook implementations for a specification. See
:ref:`callorder`.
:param wrapper:
If ``True`` ("new-style hook wrapper"), the hook implementation
needs to execute exactly one ``yield``. The code before the
``yield`` is run early before any non-hook-wrapper function is run.
The code after the ``yield`` is run after all non-hook-wrapper
functions have run. The ``yield`` receives the result value of the
inner calls, or raises the exception of inner calls (including
earlier hook wrapper calls). The return value of the function
becomes the return value of the hook, and a raised exception becomes
the exception of the hook. See :ref:`hookwrapper`.
:param hookwrapper:
If ``True`` ("old-style hook wrapper"), the hook implementation
needs to execute exactly one ``yield``. The code before the
``yield`` is run early before any non-hook-wrapper function is run.
The code after the ``yield`` is run after all non-hook-wrapper
function have run The ``yield`` receives a :class:`Result` object
representing the exception or result outcome of the inner calls
(including earlier hook wrapper calls). This option is mutually
exclusive with ``wrapper``. See :ref:`old_style_hookwrapper`.
:param specname:
If provided, the given name will be used instead of the function
name when matching this hook implementation to a hook specification
during registration. See :ref:`specname`.
.. versionadded:: 1.2.0
The ``wrapper`` parameter.
"""
def setattr_hookimpl_opts(func: _F) -> _F:
opts: HookimplOpts = {
"wrapper": wrapper,
"hookwrapper": hookwrapper,
"optionalhook": optionalhook,
"tryfirst": tryfirst,
"trylast": trylast,
"specname": specname,
}
setattr(func, self.project_name + "_impl", opts)
return func
if function is None:
return setattr_hookimpl_opts
else:
return setattr_hookimpl_opts(function)
def normalize_hookimpl_opts(opts: HookimplOpts) -> None:
opts.setdefault("tryfirst", False)
opts.setdefault("trylast", False)
opts.setdefault("wrapper", False)
opts.setdefault("hookwrapper", False)
opts.setdefault("optionalhook", False)
opts.setdefault("specname", None)
_PYPY = hasattr(sys, "pypy_version_info")
def varnames(func: object) -> tuple[tuple[str, ...], tuple[str, ...]]:
"""Return tuple of positional and keywrord argument names for a function,
method, class or callable.
In case of a class, its ``__init__`` method is considered.
For methods the ``self`` parameter is not included.
"""
if inspect.isclass(func):
try:
func = func.__init__
except AttributeError:
return (), ()
elif not inspect.isroutine(func): # callable object?
try:
func = getattr(func, "__call__", func)
except Exception:
return (), ()
try:
# func MUST be a function or method here or we won't parse any args.
sig = inspect.signature(
func.__func__ if inspect.ismethod(func) else func # type:ignore[arg-type]
)
except TypeError:
return (), ()
_valid_param_kinds = (
inspect.Parameter.POSITIONAL_ONLY,
inspect.Parameter.POSITIONAL_OR_KEYWORD,
)
_valid_params = {
name: param
for name, param in sig.parameters.items()
if param.kind in _valid_param_kinds
}
args = tuple(_valid_params)
defaults = (
tuple(
param.default
for param in _valid_params.values()
if param.default is not param.empty
)
or None
)
if defaults:
index = -len(defaults)
args, kwargs = args[:index], tuple(args[index:])
else:
kwargs = ()
# strip any implicit instance arg
# pypy3 uses "obj" instead of "self" for default dunder methods
if not _PYPY:
implicit_names: tuple[str, ...] = ("self",)
else:
implicit_names = ("self", "obj")
if args:
qualname: str = getattr(func, "__qualname__", "")
if inspect.ismethod(func) or ("." in qualname and args[0] in implicit_names):
args = args[1:]
return args, kwargs
[docs]
@final
class HookRelay:
"""Hook holder object for performing 1:N hook calls where N is the number
of registered plugins."""
__slots__ = ("__dict__",)
def __init__(self) -> None:
""":meta private:"""
if TYPE_CHECKING:
def __getattr__(self, name: str) -> HookCaller:
...
# Historical name (pluggy<=1.2), kept for backward compatibility.
_HookRelay = HookRelay
_CallHistory = List[Tuple[Mapping[str, object], Optional[Callable[[Any], None]]]]
[docs]
class HookCaller:
"""A caller of all registered implementations of a hook specification."""
__slots__ = (
"name",
"spec",
"_hookexec",
"_hookimpls",
"_call_history",
)
def __init__(
self,
name: str,
hook_execute: _HookExec,
specmodule_or_class: _Namespace | None = None,
spec_opts: HookspecOpts | None = None,
) -> None:
""":meta private:"""
#: Name of the hook getting called.
self.name: Final = name
self._hookexec: Final = hook_execute
# The hookimpls list. The caller iterates it *in reverse*. Format:
# 1. trylast nonwrappers
# 2. nonwrappers
# 3. tryfirst nonwrappers
# 4. trylast wrappers
# 5. wrappers
# 6. tryfirst wrappers
self._hookimpls: Final[list[HookImpl]] = []
self._call_history: _CallHistory | None = None
# TODO: Document, or make private.
self.spec: HookSpec | None = None
if specmodule_or_class is not None:
assert spec_opts is not None
self.set_specification(specmodule_or_class, spec_opts)
# TODO: Document, or make private.
def has_spec(self) -> bool:
return self.spec is not None
# TODO: Document, or make private.
def set_specification(
self,
specmodule_or_class: _Namespace,
spec_opts: HookspecOpts,
) -> None:
if self.spec is not None:
raise ValueError(
f"Hook {self.spec.name!r} is already registered "
f"within namespace {self.spec.namespace}"
)
self.spec = HookSpec(specmodule_or_class, self.name, spec_opts)
if spec_opts.get("historic"):
self._call_history = []
[docs]
def is_historic(self) -> bool:
"""Whether this caller is :ref:`historic <historic>`."""
return self._call_history is not None
def _remove_plugin(self, plugin: _Plugin) -> None:
for i, method in enumerate(self._hookimpls):
if method.plugin == plugin:
del self._hookimpls[i]
return
raise ValueError(f"plugin {plugin!r} not found")
[docs]
def get_hookimpls(self) -> list[HookImpl]:
"""Get all registered hook implementations for this hook."""
return self._hookimpls.copy()
def _add_hookimpl(self, hookimpl: HookImpl) -> None:
"""Add an implementation to the callback chain."""
for i, method in enumerate(self._hookimpls):
if method.hookwrapper or method.wrapper:
splitpoint = i
break
else:
splitpoint = len(self._hookimpls)
if hookimpl.hookwrapper or hookimpl.wrapper:
start, end = splitpoint, len(self._hookimpls)
else:
start, end = 0, splitpoint
if hookimpl.trylast:
self._hookimpls.insert(start, hookimpl)
elif hookimpl.tryfirst:
self._hookimpls.insert(end, hookimpl)
else:
# find last non-tryfirst method
i = end - 1
while i >= start and self._hookimpls[i].tryfirst:
i -= 1
self._hookimpls.insert(i + 1, hookimpl)
def __repr__(self) -> str:
return f"<HookCaller {self.name!r}>"
def _verify_all_args_are_provided(self, kwargs: Mapping[str, object]) -> None:
# This is written to avoid expensive operations when not needed.
if self.spec:
for argname in self.spec.argnames:
if argname not in kwargs:
notincall = ", ".join(
repr(argname)
for argname in self.spec.argnames
# Avoid self.spec.argnames - kwargs.keys() - doesn't preserve order.
if argname not in kwargs.keys()
)
warnings.warn(
"Argument(s) {} which are declared in the hookspec "
"cannot be found in this hook call".format(notincall),
stacklevel=2,
)
break
[docs]
def __call__(self, **kwargs: object) -> Any:
"""Call the hook.
Only accepts keyword arguments, which should match the hook
specification.
Returns the result(s) of calling all registered plugins, see
:ref:`calling`.
"""
assert (
not self.is_historic()
), "Cannot directly call a historic hook - use call_historic instead."
self._verify_all_args_are_provided(kwargs)
firstresult = self.spec.opts.get("firstresult", False) if self.spec else False
# Copy because plugins may register other plugins during iteration (#438).
return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
[docs]
def call_historic(
self,
result_callback: Callable[[Any], None] | None = None,
kwargs: Mapping[str, object] | None = None,
) -> None:
"""Call the hook with given ``kwargs`` for all registered plugins and
for all plugins which will be registered afterwards, see
:ref:`historic`.
:param result_callback:
If provided, will be called for each non-``None`` result obtained
from a hook implementation.
"""
assert self._call_history is not None
kwargs = kwargs or {}
self._verify_all_args_are_provided(kwargs)
self._call_history.append((kwargs, result_callback))
# Historizing hooks don't return results.
# Remember firstresult isn't compatible with historic.
# Copy because plugins may register other plugins during iteration (#438).
res = self._hookexec(self.name, self._hookimpls.copy(), kwargs, False)
if result_callback is None:
return
if isinstance(res, list):
for x in res:
result_callback(x)
def _maybe_apply_history(self, method: HookImpl) -> None:
"""Apply call history to a new hookimpl if it is marked as historic."""
if self.is_historic():
assert self._call_history is not None
for kwargs, result_callback in self._call_history:
res = self._hookexec(self.name, [method], kwargs, False)
if res and result_callback is not None:
# XXX: remember firstresult isn't compat with historic
assert isinstance(res, list)
result_callback(res[0])
# Historical name (pluggy<=1.2), kept for backward compatibility.
_HookCaller = HookCaller
class _SubsetHookCaller(HookCaller):
"""A proxy to another HookCaller which manages calls to all registered
plugins except the ones from remove_plugins."""
# This class is unusual: in inhertits from `HookCaller` so all of
# the *code* runs in the class, but it delegates all underlying *data*
# to the original HookCaller.
# `subset_hook_caller` used to be implemented by creating a full-fledged
# HookCaller, copying all hookimpls from the original. This had problems
# with memory leaks (#346) and historic calls (#347), which make a proxy
# approach better.
# An alternative implementation is to use a `_getattr__`/`__getattribute__`
# proxy, however that adds more overhead and is more tricky to implement.
__slots__ = (
"_orig",
"_remove_plugins",
)
def __init__(self, orig: HookCaller, remove_plugins: AbstractSet[_Plugin]) -> None:
self._orig = orig
self._remove_plugins = remove_plugins
self.name = orig.name # type: ignore[misc]
self._hookexec = orig._hookexec # type: ignore[misc]
@property # type: ignore[misc]
def _hookimpls(self) -> list[HookImpl]:
return [
impl
for impl in self._orig._hookimpls
if impl.plugin not in self._remove_plugins
]
@property
def spec(self) -> HookSpec | None: # type: ignore[override]
return self._orig.spec
@property
def _call_history(self) -> _CallHistory | None: # type: ignore[override]
return self._orig._call_history
def __repr__(self) -> str:
return f"<_SubsetHookCaller {self.name!r}>"
[docs]
@final
class HookImpl:
"""A hook implementation in a :class:`HookCaller`."""
__slots__ = (
"function",
"argnames",
"kwargnames",
"plugin",
"opts",
"plugin_name",
"wrapper",
"hookwrapper",
"optionalhook",
"tryfirst",
"trylast",
)
def __init__(
self,
plugin: _Plugin,
plugin_name: str,
function: _HookImplFunction[object],
hook_impl_opts: HookimplOpts,
) -> None:
""":meta private:"""
#: The hook implementation function.
self.function: Final = function
argnames, kwargnames = varnames(self.function)
#: The positional parameter names of ``function```.
self.argnames: Final = argnames
#: The keyword parameter names of ``function```.
self.kwargnames: Final = kwargnames
#: The plugin which defined this hook implementation.
self.plugin: Final = plugin
#: The :class:`HookimplOpts` used to configure this hook implementation.
self.opts: Final = hook_impl_opts
#: The name of the plugin which defined this hook implementation.
self.plugin_name: Final = plugin_name
#: Whether the hook implementation is a :ref:`wrapper <hookwrapper>`.
self.wrapper: Final = hook_impl_opts["wrapper"]
#: Whether the hook implementation is an :ref:`old-style wrapper
#: <old_style_hookwrappers>`.
self.hookwrapper: Final = hook_impl_opts["hookwrapper"]
#: Whether validation against a hook specification is :ref:`optional
#: <optionalhook>`.
self.optionalhook: Final = hook_impl_opts["optionalhook"]
#: Whether to try to order this hook implementation :ref:`first
#: <callorder>`.
self.tryfirst: Final = hook_impl_opts["tryfirst"]
#: Whether to try to order this hook implementation :ref:`last
#: <callorder>`.
self.trylast: Final = hook_impl_opts["trylast"]
def __repr__(self) -> str:
return f"<HookImpl plugin_name={self.plugin_name!r}, plugin={self.plugin!r}>"
@final
class HookSpec:
__slots__ = (
"namespace",
"function",
"name",
"argnames",
"kwargnames",
"opts",
"warn_on_impl",
)
def __init__(self, namespace: _Namespace, name: str, opts: HookspecOpts) -> None:
self.namespace = namespace
self.function: Callable[..., object] = getattr(namespace, name)
self.name = name
self.argnames, self.kwargnames = varnames(self.function)
self.opts = opts
self.warn_on_impl = opts.get("warn_on_impl")
