# Copyright (c) OpenMMLab. All rights reserved.
import inspect
import sys
import warnings
from collections.abc import Callable
from typing import Any, Dict, List, Optional, Tuple, Type, Union
from ..config import Config, ConfigDict
from ..logging.logger import MMLogger
from ..utils import ManagerMixin, is_seq_of
from .default_scope import DefaultScope
def build_from_cfg(
cfg: Union[dict, ConfigDict, Config],
registry: 'Registry',
default_args: Optional[Union[dict, ConfigDict, Config]] = None) -> Any:
"""Build a module from config dict.
At least one of the ``cfg`` and ``default_args`` contains the key "type"
which type should be either str or class. If they all contain it, the key
in ``cfg`` will be used because ``cfg`` has a high priority than
``default_args`` that means if a key exist in both of them, the value of
the key will be ``cfg[key]``. They will be merged first and the key "type"
will be popped up and the remaining keys will be used as initialization
arguments.
Examples:
>>> from mmengine import Registry, build_from_cfg
>>> MODELS = Registry('models')
>>> @MODELS.register_module()
>>> class ResNet:
>>> def __init__(self, depth, stages=4):
>>> self.depth = depth
>>> self.stages = stages
>>> cfg = dict(type='ResNet', depth=50)
>>> model = build_from_cfg(cfg, MODELS)
Args:
cfg (dict or ConfigDict or Config): Config dict. It should at least
contain the key "type".
registry (:obj:`Registry`): The registry to search the type from.
default_args (dict or ConfigDict or Config, optional): Default
initialization arguments. Defaults to None.
Returns:
object: The constructed object.
"""
if not isinstance(cfg, (dict, ConfigDict, Config)):
raise TypeError(
f'cfg should be a dict, ConfigDict or Config, but got {type(cfg)}')
if 'type' not in cfg:
if default_args is None or 'type' not in default_args:
raise KeyError(
'`cfg` or `default_args` must contain the key "type", '
f'but got {cfg}\n{default_args}')
if not isinstance(registry, Registry):
raise TypeError('registry must be a mmengine.Registry object, '
f'but got {type(registry)}')
if not (isinstance(default_args,
(dict, ConfigDict, Config)) or default_args is None):
raise TypeError(
'default_args should be a dict, ConfigDict, Config or None, '
f'but got {type(default_args)}')
args = cfg.copy()
if default_args is not None:
for name, value in default_args.items():
args.setdefault(name, value)
obj_type = args.pop('type')
if isinstance(obj_type, str):
obj_cls = registry.get(obj_type)
if obj_cls is None:
raise KeyError(
f'{obj_type} is not in the {registry.name} registry. '
f'Please check whether the value of `{obj_type}` is correct or'
' it was registered as expected. More details can be found at'
' https://mmengine.readthedocs.io/en/latest/tutorials/config.html#import-custom-python-modules' # noqa: E501
)
elif inspect.isclass(obj_type):
obj_cls = obj_type
else:
raise TypeError(
f'type must be a str or valid type, but got {type(obj_type)}')
try:
# If `obj_cls` inherits from `ManagerMixin`, it should be instantiated
# by `ManagerMixin.get_instance` to ensure that it can be accessed
# globally.
if issubclass(obj_cls, ManagerMixin): # type: ignore
obj = obj_cls.get_instance(**args) # type: ignore
else:
obj = obj_cls(**args) # type: ignore
logger: MMLogger = MMLogger.get_current_instance()
logger.info(
f'An `{obj_cls.__name__}` instance is built from ' # type: ignore
f'registry, its implementation can be found in '
f'{obj_cls.__module__}') # type: ignore
return obj
except Exception as e:
# Normal TypeError does not print class name.
cls_location = '/'.join(obj_cls.__module__.split('.')) # type: ignore
raise type(e)(
f'class `{obj_cls.__name__}` in ' # type: ignore
f'{cls_location}.py: {e}')
class Registry:
"""A registry to map strings to classes.
Registered objects could be built from registry.
Args:
name (str): Registry name.
build_func (callable, optional): A function to construct instance
from Registry. :func:`build_from_cfg` is used if neither ``parent``
or ``build_func`` is specified. If ``parent`` is specified and
``build_func`` is not given, ``build_func`` will be inherited
from ``parent``. Defaults to None.
parent (:obj:`Registry`, optional): Parent registry. The class
registered in children registry could be built from parent.
Defaults to None.
scope (str, optional): The scope of registry. It is the key to search
for children registry. If not specified, scope will be the name of
the package where class is defined, e.g. mmdet, mmcls, mmseg.
Defaults to None.
Examples:
>>> # define a registry
>>> MODELS = Registry('models')
>>> # registry the `ResNet` to `MODELS`
>>> @MODELS.register_module()
>>> class ResNet:
>>> pass
>>> # build model from `MODELS`
>>> resnet = MODELS.build(dict(type='ResNet'))
>>> # hierarchical registry
>>> DETECTORS = Registry('detectors', parent=MODELS, scope='det')
>>> @DETECTORS.register_module()
>>> class FasterRCNN:
>>> pass
>>> fasterrcnn = DETECTORS.build(dict(type='FasterRCNN'))
More advanced usages can be found at
https://mmengine.readthedocs.io/en/latest/tutorials/registry.html.
"""
def __init__(self,
name: str,
build_func: Optional[Callable] = None,
parent: Optional['Registry'] = None,
scope: Optional[str] = None):
self._name = name
self._module_dict: Dict[str, Type] = dict()
self._children: Dict[str, 'Registry'] = dict()
if scope is not None:
assert isinstance(scope, str)
self._scope = scope
else:
self._scope = self.infer_scope() if scope is None else scope
# See https://mypy.readthedocs.io/en/stable/common_issues.html#
# variables-vs-type-aliases for the use
self.parent: Optional['Registry']
if parent is not None:
assert isinstance(parent, Registry)
parent._add_child(self)
self.parent = parent
else:
self.parent = None
# self.build_func will be set with the following priority:
# 1. build_func
# 2. parent.build_func
# 3. build_from_cfg
self.build_func: Callable
if build_func is None:
if self.parent is not None:
self.build_func = self.parent.build_func
else:
self.build_func = build_from_cfg
else:
self.build_func = build_func
def __len__(self):
return len(self._module_dict)
def __contains__(self, key):
return self.get(key) is not None
def __repr__(self):
format_str = self.__class__.__name__ + \
f'(name={self._name}, ' \
f'items={self._module_dict})'
return format_str
@staticmethod
def infer_scope() -> str:
"""Infer the scope of registry.
The name of the package where registry is defined will be returned.
Returns:
str: The inferred scope name.
Examples:
>>> # in mmdet/models/backbone/resnet.py
>>> MODELS = Registry('models')
>>> @MODELS.register_module()
>>> class ResNet:
>>> pass
>>> # The scope of ``ResNet`` will be ``mmdet``.
"""
# `sys._getframe` returns the frame object that many calls below the
# top of the stack. The call stack for `infer_scope` can be listed as
# follow:
# frame-0: `infer_scope` itself
# frame-1: `__init__` of `Registry` which calls the `infer_scope`
# frame-2: Where the `Registry(...)` is called
filename = inspect.getmodule(sys._getframe(2)).__name__ # type: ignore
split_filename = filename.split('.')
return split_filename[0]
@staticmethod
def split_scope_key(key: str) -> Tuple[Optional[str], str]:
"""Split scope and key.
The first scope will be split from key.
Return:
tuple[str | None, str]: The former element is the first scope of
the key, which can be ``None``. The latter is the remaining key.
Examples:
>>> Registry.split_scope_key('mmdet.ResNet')
'mmdet', 'ResNet'
>>> Registry.split_scope_key('ResNet')
None, 'ResNet'
"""
split_index = key.find('.')
if split_index != -1:
return key[:split_index], key[split_index + 1:]
else:
return None, key
@property
def name(self):
return self._name
@property
def scope(self):
return self._scope
@property
def module_dict(self):
return self._module_dict
@property
def children(self):
return self._children
@property
def root(self):
return self._get_root_registry()
def _get_root_registry(self) -> 'Registry':
"""Return the root registry."""
root = self
while root.parent is not None:
root = root.parent
return root
def get(self, key: str) -> Optional[Type]:
"""Get the registry record.
The method will first parse :attr:`key` and check whether it contains
a scope name. The logic to search for :attr:`key`:
- ``key`` does not contain a scope name, i.e., it is purely a module
name like "ResNet": :meth:`get` will search for ``ResNet`` from the
current registry to its parent or ancestors until finding it.
- ``key`` contains a scope name and it is equal to the scope of the
current registry (e.g., "mmcls"), e.g., "mmcls.ResNet": :meth:`get`
will only search for ``ResNet`` in the current registry.
- ``key`` contains a scope name and it is not equal to the scope of
the current registry (e.g., "mmdet"), e.g., "mmcls.FCNet": If the
scope exists in its children, :meth:`get`will get "FCNet" from
them. If not, :meth:`get` will first get the root registry and root
registry call its own :meth:`get` method.
Args:
key (str): Name of the registered item, e.g., the class name in
string format.
Returns:
Type or None: Return the corresponding class if ``key`` exists,
otherwise return None.
Examples:
>>> # define a registry
>>> MODELS = Registry('models')
>>> # register `ResNet` to `MODELS`
>>> @MODELS.register_module()
>>> class ResNet:
>>> pass
>>> resnet_cls = MODELS.get('ResNet')
>>> # hierarchical registry
>>> DETECTORS = Registry('detector', parent=MODELS, scope='det')
>>> # `ResNet` does not exist in `DETECTORS` but `get` method
>>> # will try to search from its parenet or ancestors
>>> resnet_cls = DETECTORS.get('ResNet')
>>> CLASSIFIER = Registry('classifier', parent=MODELS, scope='cls')
>>> @CLASSIFIER.register_module()
>>> class MobileNet:
>>> pass
>>> # `get` from its sibling registries
>>> mobilenet_cls = DETECTORS.get('cls.MobileNet')
"""
scope, real_key = self.split_scope_key(key)
obj_cls = None
registry_name = self.name
scope_name = self.scope
if scope is None or scope == self._scope:
# get from self
if real_key in self._module_dict:
obj_cls = self._module_dict[real_key]
elif scope is None:
# try to get the target from its parent or ancestors
parent = self.parent
while parent is not None:
if real_key in parent._module_dict:
obj_cls = parent._module_dict[real_key]
registry_name = parent.name
scope_name = parent.scope
break
parent = parent.parent
else:
# get from self._children
if scope in self._children:
obj_cls = self._children[scope].get(real_key)
registry_name = self._children[scope].name
scope_name = scope
else:
root = self._get_root_registry()
if scope != root._scope and scope not in root._children:
# If not skip directly, `root.get(key)` will recursively
# call itself until RecursionError is thrown.
pass
else:
obj_cls = root.get(key)
if obj_cls is not None:
logger: MMLogger = MMLogger.get_current_instance()
logger.info(
f'Get class `{obj_cls.__name__}` from "{registry_name}"'
f' registry in "{scope_name}"')
return obj_cls
def _search_child(self, scope: str) -> Optional['Registry']:
"""Depth-first search for the corresponding registry in its children.
Note that the method only search for the corresponding registry from
the current registry. Therefore, if we want to search from the root
registry, :meth:`_get_root_registry` should be called to get the
root registry first.
Args:
scope (str): The scope name used for searching for its
corresponding registry.
Returns:
Registry or None: Return the corresponding registry if ``scope``
exists, otherwise return None.
"""
if self._scope == scope:
return self
for child in self._children.values():
registry = child._search_child(scope)
if registry is not None:
return registry
return None
def build(self, *args, **kwargs) -> Any:
"""Build an instance.
Build an instance by calling :attr:`build_func`. If the global
variable default scope (:obj:`DefaultScope`) exists ,
:meth:`build` will firstly get the responding registry and then call
its own :meth:`build`.
Examples:
>>> from mmengine import Registry
>>> MODELS = Registry('models')
>>> @MODELS.register_module()
>>> class ResNet:
>>> def __init__(self, depth, stages=4):
>>> self.depth = depth
>>> self.stages = stages
>>> cfg = dict(type='ResNet', depth=50)
>>> model = MODELS.build(cfg)
"""
# get the global default scope
default_scope = DefaultScope.get_current_instance()
if default_scope is not None:
scope_name = default_scope.scope_name
root = self._get_root_registry()
registry = root._search_child(scope_name)
if registry is None:
# if `default_scope` can not be found, fallback to use self
warnings.warn(
f'Failed to search registry with scope "{scope_name}" in '
f'the "{root.name}" registry tree. '
f'As a workaround, the current "{self.name}" registry in '
f'"{self.scope}" is used to build instance. This may '
f'cause unexpected failure when running the built '
f'modules. Please check whether "{scope_name}" is a '
f'correct scope, or whether the registry is initialized.')
registry = self
else:
registry = self
return registry.build_func(*args, **kwargs, registry=registry)
def _add_child(self, registry: 'Registry') -> None:
"""Add a child for a registry.
Args:
registry (:obj:`Registry`): The ``registry`` will be added as a
child of the ``self``.
"""
assert isinstance(registry, Registry)
assert registry.scope is not None
assert registry.scope not in self.children, \
f'scope {registry.scope} exists in {self.name} registry'
self.children[registry.scope] = registry
def _register_module(self,
module_class: Type,
module_name: Optional[Union[str, List[str]]] = None,
force: bool = False) -> None:
"""Register a module.
Args:
module_class (type): Module class to be registered.
module_name (str or list of str, optional): The module name to be
registered. If not specified, the class name will be used.
Defaults to None.
force (bool): Whether to override an existing class with the same
name. Defaults to False.
"""
if not inspect.isclass(module_class):
raise TypeError('module must be a class, '
f'but got {type(module_class)}')
if module_name is None:
module_name = module_class.__name__
if isinstance(module_name, str):
module_name = [module_name]
for name in module_name:
if not force and name in self._module_dict:
raise KeyError(f'{name} is already registered '
f'in {self.name}')
self._module_dict[name] = module_class
def register_module(
self,
name: Optional[Union[str, List[str]]] = None,
force: bool = False,
module: Optional[Type] = None) -> Union[type, Callable]:
"""Register a module.
A record will be added to ``self._module_dict``, whose key is the class
name or the specified name, and value is the class itself.
It can be used as a decorator or a normal function.
Args:
name (str or list of str, optional): The module name to be
registered. If not specified, the class name will be used.
force (bool): Whether to override an existing class with the same
name. Default to False.
module (type, optional): Module class to be registered. Defaults to
None.
Examples:
>>> backbones = Registry('backbone')
>>> # as a decorator
>>> @backbones.register_module()
>>> class ResNet:
>>> pass
>>> backbones = Registry('backbone')
>>> @backbones.register_module(name='mnet')
>>> class MobileNet:
>>> pass
>>> # as a normal function
>>> class ResNet:
>>> pass
>>> backbones.register_module(module=ResNet)
"""
if not isinstance(force, bool):
raise TypeError(f'force must be a boolean, but got {type(force)}')
# raise the error ahead of time
if not (name is None or isinstance(name, str) or is_seq_of(name, str)):
raise TypeError(
'name must be None, an instance of str, or a sequence of str, '
f'but got {type(name)}')
# use it as a normal method: x.register_module(module=SomeClass)
if module is not None:
self._register_module(
module_class=module, module_name=name, force=force)
return module
# use it as a decorator: @x.register_module()
def _register(cls):
self._register_module(
module_class=cls, module_name=name, force=force)
return cls
return _register