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Differential D4624 Diff 18077 rigify/utils/metaclass.py

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rigify/utils/metaclass.py

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#====================== BEGIN GPL LICENSE BLOCK ======================
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
#======================= END GPL LICENSE BLOCK ========================
# <pep8 compliant>
import collections
from types import FunctionType
from itertools import chain
#=============================================
# Class With Stages
#=============================================
def rigify_stage(stage):
"""Decorates the method with the specified stage."""
def process(method):
if not isinstance(method, FunctionType):
raise ValueError("Stage decorator must be applied to a method definition")
method._rigify_stage = stage
return method
return process
class StagedMetaclass(type):
"""
Metaclass for rigs that manages assignment of methods to stages via @stage.* decorators.
Using define_stages=True in the class definition will register all non-system
method names from that definition as valid stages. After that, subclasses can
register methods to those stages, to be called via rigify_invoke_stage.
"""
def __new__(metacls, class_name, bases, namespace, define_stages=None, **kwds):
# suppress keyword args to avoid issues with __init_subclass__
return super().__new__(metacls, class_name, bases, namespace, **kwds)
def __init__(self, class_name, bases, namespace, define_stages=None, **kwds):
super().__init__(class_name, bases, namespace, **kwds)
# Compute the set of stages defined by this class
if not define_stages:
define_stages = []
elif define_stages is True:
define_stages = [
name for name, item in namespace.items()
if name[0] != '_' and isinstance(item, FunctionType)
]
self.rigify_own_stages = frozenset(define_stages)
# Compute complete set of inherited stages
staged_bases = [ cls for cls in reversed(self.__mro__) if isinstance(cls, StagedMetaclass) ]
self.rigify_stages = stages = frozenset(chain.from_iterable(
cls.rigify_own_stages for cls in staged_bases
))
# Compute the inherited stage to method mapping
stage_map = collections.defaultdict(collections.OrderedDict)
own_stage_map = collections.defaultdict(collections.OrderedDict)
method_map = {}
self.rigify_own_stage_map = own_stage_map
for base in staged_bases:
for stage_name, methods in base.rigify_own_stage_map.items():
for method_name, method_class in methods.items():
if method_name in stages:
raise ValueError("Stage method '%s' inherited @stage.%s in class %s (%s)" %
(method_name, stage_name, class_name, self.__module__))
# Check consistency of inherited stage assignment to methods
if method_name in method_map:
if method_map[method_name] != stage_name:
print("RIGIFY CLASS %s (%s): method '%s' has inherited both @stage.%s and @stage.%s\n" %
(class_name, self.__module__, method_name, method_map[method_name], stage_name))
else:
method_map[method_name] = stage_name
stage_map[stage_name][method_name] = method_class
# Scan newly defined methods for stage decorations
for method_name, item in namespace.items():
if isinstance(item, FunctionType):
stage = getattr(item, '_rigify_stage', None)
if stage and method_name in stages:
print("RIGIFY CLASS %s (%s): cannot use stage decorator on the stage method '%s' (@stage.%s ignored)" %
(class_name, self.__module__, method_name, stage))
continue
# Ensure that decorators aren't lost when redefining methods
if method_name in method_map:
if not stage:
stage = method_map[method_name]
print("RIGIFY CLASS %s (%s): missing stage decorator on method '%s' (should be @stage.%s)" %
(class_name, self.__module__, method_name, stage))
# Check that the method is assigned to only one stage
elif stage != method_map[method_name]:
print("RIGIFY CLASS %s (%s): method '%s' has decorator @stage.%s, but inherited base has @stage.%s" %
(class_name, self.__module__, method_name, stage, method_map[method_name]))
# Assign the method to the stage, verifying that it's valid
if stage:
if stage not in stages:
raise ValueError("Invalid stage name '%s' for method '%s' in class %s (%s)" %
(stage, method_name, class_name, self.__module__))
else:
stage_map[stage][method_name] = self
own_stage_map[stage][method_name] = self
self.rigify_stage_map = stage_map
def make_stage_decorators(self):
return [(name, rigify_stage(name)) for name in self.rigify_stages]
class BaseStagedClass(object, metaclass=StagedMetaclass):
rigify_sub_objects = tuple()
def rigify_invoke_stage(self, stage):
"""Call all methods decorated with the given stage, followed by the callback."""
cls = self.__class__
assert isinstance(cls, StagedMetaclass)
assert stage in cls.rigify_stages
getattr(self, stage)()
for sub in self.rigify_sub_objects:
sub.rigify_invoke_stage(stage)
for method_name in cls.rigify_stage_map[stage]:
getattr(self, method_name)()
#=============================================
# Per-owner singleton class
#=============================================
class SingletonPluginMetaclass(StagedMetaclass):
"""Metaclass for maintaining one instance per owner object per constructor arg set."""
def __call__(cls, owner, *constructor_args):
key = (cls, *constructor_args)
try:
return owner.plugin_map[key]
except KeyError:
new_obj = super().__call__(owner, *constructor_args)
owner.plugin_map[key] = new_obj
owner.plugin_list.append(new_obj)
owner.plugin_list.sort(key=lambda obj: obj.priority, reverse=True)
return new_obj