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import inspect
import sys
import warnings
from . import _tracing
from ._callers import _Result, _multicall
from ._hooks import HookImpl, _HookRelay, _HookCaller, normalize_hookimpl_opts
if sys.version_info >= (3, 8):
from importlib import metadata as importlib_metadata
else:
import importlib_metadata
def _warn_for_function(warning, function):
warnings.warn_explicit(
warning,
type(warning),
lineno=function.__code__.co_firstlineno,
filename=function.__code__.co_filename,
)
class PluginValidationError(Exception):
"""plugin failed validation.
:param object plugin: the plugin which failed validation,
may be a module or an arbitrary object.
"""
def __init__(self, plugin, message):
self.plugin = plugin
super(Exception, self).__init__(message)
class DistFacade:
"""Emulate a pkg_resources Distribution"""
def __init__(self, dist):
self._dist = dist
@property
def project_name(self):
return self.metadata["name"]
def __getattr__(self, attr, default=None):
return getattr(self._dist, attr, default)
def __dir__(self):
return sorted(dir(self._dist) + ["_dist", "project_name"])
class PluginManager:
"""Core :py:class:`.PluginManager` class which manages registration
of plugin objects and 1:N hook calling.
You can register new hooks by calling :py:meth:`add_hookspecs(module_or_class)
<.PluginManager.add_hookspecs>`.
You can register plugin objects (which contain hooks) by calling
:py:meth:`register(plugin) <.PluginManager.register>`. The :py:class:`.PluginManager`
is initialized with a prefix that is searched for in the names of the dict
of registered plugin objects.
For debugging purposes you can call :py:meth:`.PluginManager.enable_tracing`
which will subsequently send debug information to the trace helper.
"""
def __init__(self, project_name):
self.project_name = project_name
self._name2plugin = {}
self._plugin2hookcallers = {}
self._plugin_distinfo = []
self.trace = _tracing.TagTracer().get("pluginmanage")
self.hook = _HookRelay()
self._inner_hookexec = _multicall
def _hookexec(self, hook_name, methods, kwargs, firstresult):
# called from all hookcaller instances.
# enable_tracing will set its own wrapping function at self._inner_hookexec
return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
def register(self, plugin, name=None):
"""Register a plugin and return its canonical name or ``None`` if the name
is blocked from registering. Raise a :py:class:`ValueError` if the plugin
is already registered."""
plugin_name = name or self.get_canonical_name(plugin)
if plugin_name in self._name2plugin or plugin in self._plugin2hookcallers:
if self._name2plugin.get(plugin_name, -1) is None:
return # blocked plugin, return None to indicate no registration
raise ValueError(
"Plugin already registered: %s=%s\n%s"
% (plugin_name, plugin, self._name2plugin)
)
# XXX if an error happens we should make sure no state has been
# changed at point of return
self._name2plugin[plugin_name] = plugin
# register matching hook implementations of the plugin
self._plugin2hookcallers[plugin] = hookcallers = []
for name in dir(plugin):
hookimpl_opts = self.parse_hookimpl_opts(plugin, name)
if hookimpl_opts is not None:
normalize_hookimpl_opts(hookimpl_opts)
method = getattr(plugin, name)
hookimpl = HookImpl(plugin, plugin_name, method, hookimpl_opts)
name = hookimpl_opts.get("specname") or name
hook = getattr(self.hook, name, None)
if hook is None:
hook = _HookCaller(name, self._hookexec)
setattr(self.hook, name, hook)
elif hook.has_spec():
self._verify_hook(hook, hookimpl)
hook._maybe_apply_history(hookimpl)
hook._add_hookimpl(hookimpl)
hookcallers.append(hook)
return plugin_name
def parse_hookimpl_opts(self, plugin, name):
method = getattr(plugin, name)
if not inspect.isroutine(method):
return
try:
res = getattr(method, self.project_name + "_impl", None)
except Exception:
res = {}
if res is not None and not isinstance(res, dict):
# false positive
res = None
return res
def unregister(self, plugin=None, name=None):
"""unregister a plugin object and all its contained hook implementations
from internal data structures."""
if name is None:
assert plugin is not None, "one of name or plugin needs to be specified"
name = self.get_name(plugin)
if plugin is None:
plugin = self.get_plugin(name)
# if self._name2plugin[name] == None registration was blocked: ignore
if self._name2plugin.get(name):
del self._name2plugin[name]
for hookcaller in self._plugin2hookcallers.pop(plugin, []):
hookcaller._remove_plugin(plugin)
return plugin
def set_blocked(self, name):
"""block registrations of the given name, unregister if already registered."""
self.unregister(name=name)
self._name2plugin[name] = None
def is_blocked(self, name):
"""return ``True`` if the given plugin name is blocked."""
return name in self._name2plugin and self._name2plugin[name] is None
def add_hookspecs(self, module_or_class):
"""add new hook specifications defined in the given ``module_or_class``.
Functions are recognized if they have been decorated accordingly."""
names = []
for name in dir(module_or_class):
spec_opts = self.parse_hookspec_opts(module_or_class, name)
if spec_opts is not None:
hc = getattr(self.hook, name, None)
if hc is None:
hc = _HookCaller(name, self._hookexec, module_or_class, spec_opts)
setattr(self.hook, name, hc)
else:
# plugins registered this hook without knowing the spec
hc.set_specification(module_or_class, spec_opts)
for hookfunction in hc.get_hookimpls():
self._verify_hook(hc, hookfunction)
names.append(name)
if not names:
raise ValueError(
f"did not find any {self.project_name!r} hooks in {module_or_class!r}"
)
def parse_hookspec_opts(self, module_or_class, name):
method = getattr(module_or_class, name)
return getattr(method, self.project_name + "_spec", None)
def get_plugins(self):
"""return the set of registered plugins."""
return set(self._plugin2hookcallers)
def is_registered(self, plugin):
"""Return ``True`` if the plugin is already registered."""
return plugin in self._plugin2hookcallers
def get_canonical_name(self, plugin):
"""Return canonical name for a plugin object. Note that a plugin
may be registered under a different name which was specified
by the caller of :py:meth:`register(plugin, name) <.PluginManager.register>`.
To obtain the name of an registered plugin use :py:meth:`get_name(plugin)
<.PluginManager.get_name>` instead."""
return getattr(plugin, "__name__", None) or str(id(plugin))
def get_plugin(self, name):
"""Return a plugin or ``None`` for the given name."""
return self._name2plugin.get(name)
def has_plugin(self, name):
"""Return ``True`` if a plugin with the given name is registered."""
return self.get_plugin(name) is not None
def get_name(self, plugin):
"""Return name for registered plugin or ``None`` if not registered."""
for name, val in self._name2plugin.items():
if plugin == val:
return name
def _verify_hook(self, hook, hookimpl):
if hook.is_historic() and hookimpl.hookwrapper:
raise PluginValidationError(
hookimpl.plugin,
"Plugin %r\nhook %r\nhistoric incompatible to hookwrapper"
% (hookimpl.plugin_name, hook.name),
)
if hook.spec.warn_on_impl:
_warn_for_function(hook.spec.warn_on_impl, hookimpl.function)
# positional arg checking
notinspec = set(hookimpl.argnames) - set(hook.spec.argnames)
if notinspec:
raise PluginValidationError(
hookimpl.plugin,
"Plugin %r for hook %r\nhookimpl definition: %s\n"
"Argument(s) %s are declared in the hookimpl but "
"can not be found in the hookspec"
% (
hookimpl.plugin_name,
hook.name,
_formatdef(hookimpl.function),
notinspec,
),
)
if hookimpl.hookwrapper and not inspect.isgeneratorfunction(hookimpl.function):
raise PluginValidationError(
hookimpl.plugin,
"Plugin %r for hook %r\nhookimpl definition: %s\n"
"Declared as hookwrapper=True but function is not a generator function"
% (hookimpl.plugin_name, hook.name, _formatdef(hookimpl.function)),
)
def check_pending(self):
"""Verify that all hooks which have not been verified against
a hook specification are optional, otherwise raise :py:class:`.PluginValidationError`."""
for name in self.hook.__dict__:
if name[0] != "_":
hook = getattr(self.hook, name)
if not hook.has_spec():
for hookimpl in hook.get_hookimpls():
if not hookimpl.optionalhook:
raise PluginValidationError(
hookimpl.plugin,
"unknown hook %r in plugin %r"
% (name, hookimpl.plugin),
)
def load_setuptools_entrypoints(self, group, name=None):
"""Load modules from querying the specified setuptools ``group``.
:param str group: entry point group to load plugins
:param str name: if given, loads only plugins with the given ``name``.
:rtype: int
:return: return the number of loaded plugins by this call.
"""
count = 0
for dist in list(importlib_metadata.distributions()):
for ep in dist.entry_points:
if (
ep.group != group
or (name is not None and ep.name != name)
# already registered
or self.get_plugin(ep.name)
or self.is_blocked(ep.name)
):
continue
plugin = ep.load()
self.register(plugin, name=ep.name)
self._plugin_distinfo.append((plugin, DistFacade(dist)))
count += 1
return count
def list_plugin_distinfo(self):
"""return list of distinfo/plugin tuples for all setuptools registered
plugins."""
return list(self._plugin_distinfo)
def list_name_plugin(self):
"""return list of name/plugin pairs."""
return list(self._name2plugin.items())
def get_hookcallers(self, plugin):
"""get all hook callers for the specified plugin."""
return self._plugin2hookcallers.get(plugin)
def add_hookcall_monitoring(self, before, after):
"""add before/after tracing functions for all hooks
and return an undo function which, when called,
will remove the added tracers.
``before(hook_name, hook_impls, kwargs)`` will be called ahead
of all hook calls and receive a hookcaller instance, a list
of HookImpl instances and the keyword arguments for the hook call.
``after(outcome, hook_name, hook_impls, kwargs)`` receives the
same arguments as ``before`` but also a :py:class:`pluggy._callers._Result` object
which represents the result of the overall hook call.
"""
oldcall = self._inner_hookexec
def traced_hookexec(hook_name, hook_impls, kwargs, firstresult):
before(hook_name, hook_impls, kwargs)
outcome = _Result.from_call(
lambda: oldcall(hook_name, hook_impls, kwargs, firstresult)
)
after(outcome, hook_name, hook_impls, kwargs)
return outcome.get_result()
self._inner_hookexec = traced_hookexec
def undo():
self._inner_hookexec = oldcall
return undo
def enable_tracing(self):
"""enable tracing of hook calls and return an undo function."""
hooktrace = self.trace.root.get("hook")
def before(hook_name, methods, kwargs):
hooktrace.root.indent += 1
hooktrace(hook_name, kwargs)
def after(outcome, hook_name, methods, kwargs):
if outcome.excinfo is None:
hooktrace("finish", hook_name, "-->", outcome.get_result())
hooktrace.root.indent -= 1
return self.add_hookcall_monitoring(before, after)
def subset_hook_caller(self, name, remove_plugins):
"""Return a new :py:class:`._hooks._HookCaller` instance for the named method
which manages calls to all registered plugins except the
ones from remove_plugins."""
orig = getattr(self.hook, name)
plugins_to_remove = [plug for plug in remove_plugins if hasattr(plug, name)]
if plugins_to_remove:
hc = _HookCaller(
orig.name, orig._hookexec, orig.spec.namespace, orig.spec.opts
)
for hookimpl in orig.get_hookimpls():
plugin = hookimpl.plugin
if plugin not in plugins_to_remove:
hc._add_hookimpl(hookimpl)
# we also keep track of this hook caller so it
# gets properly removed on plugin unregistration
self._plugin2hookcallers.setdefault(plugin, []).append(hc)
return hc
return orig
def _formatdef(func):
return f"{func.__name__}{inspect.signature(func)}"