# coding=utf-8
# Copyright 2021 The HuggingFace Inc. team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Factory function to build auto-model classes."""
import copy
import importlib
import os
import warnings
from collections import OrderedDict

from ...configuration_utils import PretrainedConfig
from ...dynamic_module_utils import get_class_from_dynamic_module, resolve_trust_remote_code
from ...utils import copy_func, logging, requires_backends
from .configuration_auto import AutoConfig, model_type_to_module_name, replace_list_option_in_docstrings


logger = logging.get_logger(__name__)


CLASS_DOCSTRING = """
    This is a generic model class that will be instantiated as one of the model classes of the library when created
    with the [`~BaseAutoModelClass.from_pretrained`] class method or the [`~BaseAutoModelClass.from_config`] class
    method.

    This class cannot be instantiated directly using `__init__()` (throws an error).
"""

FROM_CONFIG_DOCSTRING = """
        Instantiates one of the model classes of the library from a configuration.

        Note:
            Loading a model from its configuration file does **not** load the model weights. It only affects the
            model's configuration. Use [`~BaseAutoModelClass.from_pretrained`] to load the model weights.

        Args:
            config ([`PretrainedConfig`]):
                The model class to instantiate is selected based on the configuration class:

                List options

        Examples:

        ```python
        >>> from transformers import AutoConfig, BaseAutoModelClass

        >>> # Download configuration from huggingface.co and cache.
        >>> config = AutoConfig.from_pretrained("checkpoint_placeholder")
        >>> model = BaseAutoModelClass.from_config(config)
        ```
"""

FROM_PRETRAINED_TORCH_DOCSTRING = """
        Instantiate one of the model classes of the library from a pretrained model.

        The model class to instantiate is selected based on the `model_type` property of the config object (either
        passed as an argument or loaded from `pretrained_model_name_or_path` if possible), or when it's missing, by
        falling back to using pattern matching on `pretrained_model_name_or_path`:

        List options

        The model is set in evaluation mode by default using `model.eval()` (so for instance, dropout modules are
        deactivated). To train the model, you should first set it back in training mode with `model.train()`

        Args:
            pretrained_model_name_or_path (`str` or `os.PathLike`):
                Can be either:

                    - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co.
                      Valid model ids can be located at the root-level, like `bert-base-uncased`, or namespaced under a
                      user or organization name, like `dbmdz/bert-base-german-cased`.
                    - A path to a *directory* containing model weights saved using
                      [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
                    - A path or url to a *tensorflow index checkpoint file* (e.g, `./tf_model/model.ckpt.index`). In
                      this case, `from_tf` should be set to `True` and a configuration object should be provided as
                      `config` argument. This loading path is slower than converting the TensorFlow checkpoint in a
                      PyTorch model using the provided conversion scripts and loading the PyTorch model afterwards.
            model_args (additional positional arguments, *optional*):
                Will be passed along to the underlying model `__init__()` method.
            config ([`PretrainedConfig`], *optional*):
                Configuration for the model to use instead of an automatically loaded configuration. Configuration can
                be automatically loaded when:

                    - The model is a model provided by the library (loaded with the *model id* string of a pretrained
                      model).
                    - The model was saved using [`~PreTrainedModel.save_pretrained`] and is reloaded by supplying the
                      save directory.
                    - The model is loaded by supplying a local directory as `pretrained_model_name_or_path` and a
                      configuration JSON file named *config.json* is found in the directory.
            state_dict (*Dict[str, torch.Tensor]*, *optional*):
                A state dictionary to use instead of a state dictionary loaded from saved weights file.

                This option can be used if you want to create a model from a pretrained configuration but load your own
                weights. In this case though, you should check if using [`~PreTrainedModel.save_pretrained`] and
                [`~PreTrainedModel.from_pretrained`] is not a simpler option.
            cache_dir (`str` or `os.PathLike`, *optional*):
                Path to a directory in which a downloaded pretrained model configuration should be cached if the
                standard cache should not be used.
            from_tf (`bool`, *optional*, defaults to `False`):
                Load the model weights from a TensorFlow checkpoint save file (see docstring of
                `pretrained_model_name_or_path` argument).
            force_download (`bool`, *optional*, defaults to `False`):
                Whether or not to force the (re-)download of the model weights and configuration files, overriding the
                cached versions if they exist.
            resume_download (`bool`, *optional*, defaults to `False`):
                Whether or not to delete incompletely received files. Will attempt to resume the download if such a
                file exists.
            proxies (`Dict[str, str]`, *optional*):
                A dictionary of proxy servers to use by protocol or endpoint, e.g., `{'http': 'foo.bar:3128',
                'http://hostname': 'foo.bar:4012'}`. The proxies are used on each request.
            output_loading_info(`bool`, *optional*, defaults to `False`):
                Whether ot not to also return a dictionary containing missing keys, unexpected keys and error messages.
            local_files_only(`bool`, *optional*, defaults to `False`):
                Whether or not to only look at local files (e.g., not try downloading the model).
            revision (`str`, *optional*, defaults to `"main"`):
                The specific model version to use. It can be a branch name, a tag name, or a commit id, since we use a
                git-based system for storing models and other artifacts on huggingface.co, so `revision` can be any
                identifier allowed by git.
            trust_remote_code (`bool`, *optional*, defaults to `False`):
                Whether or not to allow for custom models defined on the Hub in their own modeling files. This option
                should only be set to `True` for repositories you trust and in which you have read the code, as it will
                execute code present on the Hub on your local machine.
            code_revision (`str`, *optional*, defaults to `"main"`):
                The specific revision to use for the code on the Hub, if the code leaves in a different repository than
                the rest of the model. It can be a branch name, a tag name, or a commit id, since we use a git-based
                system for storing models and other artifacts on huggingface.co, so `revision` can be any identifier
                allowed by git.
            kwargs (additional keyword arguments, *optional*):
                Can be used to update the configuration object (after it being loaded) and initiate the model (e.g.,
                `output_attentions=True`). Behaves differently depending on whether a `config` is provided or
                automatically loaded:

                    - If a configuration is provided with `config`, `**kwargs` will be directly passed to the
                      underlying model's `__init__` method (we assume all relevant updates to the configuration have
                      already been done)
                    - If a configuration is not provided, `kwargs` will be first passed to the configuration class
                      initialization function ([`~PretrainedConfig.from_pretrained`]). Each key of `kwargs` that
                      corresponds to a configuration attribute will be used to override said attribute with the
                      supplied `kwargs` value. Remaining keys that do not correspond to any configuration attribute
                      will be passed to the underlying model's `__init__` function.

        Examples:

        ```python
        >>> from transformers import AutoConfig, BaseAutoModelClass

        >>> # Download model and configuration from huggingface.co and cache.
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder")

        >>> # Update configuration during loading
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder", output_attentions=True)
        >>> model.config.output_attentions
        True

        >>> # Loading from a TF checkpoint file instead of a PyTorch model (slower)
        >>> config = AutoConfig.from_pretrained("./tf_model/shortcut_placeholder_tf_model_config.json")
        >>> model = BaseAutoModelClass.from_pretrained(
        ...     "./tf_model/shortcut_placeholder_tf_checkpoint.ckpt.index", from_tf=True, config=config
        ... )
        ```
"""

FROM_PRETRAINED_TF_DOCSTRING = """
        Instantiate one of the model classes of the library from a pretrained model.

        The model class to instantiate is selected based on the `model_type` property of the config object (either
        passed as an argument or loaded from `pretrained_model_name_or_path` if possible), or when it's missing, by
        falling back to using pattern matching on `pretrained_model_name_or_path`:

        List options

        Args:
            pretrained_model_name_or_path (`str` or `os.PathLike`):
                Can be either:

                    - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co.
                      Valid model ids can be located at the root-level, like `bert-base-uncased`, or namespaced under a
                      user or organization name, like `dbmdz/bert-base-german-cased`.
                    - A path to a *directory* containing model weights saved using
                      [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
                    - A path or url to a *PyTorch state_dict save file* (e.g, `./pt_model/pytorch_model.bin`). In this
                      case, `from_pt` should be set to `True` and a configuration object should be provided as `config`
                      argument. This loading path is slower than converting the PyTorch model in a TensorFlow model
                      using the provided conversion scripts and loading the TensorFlow model afterwards.
            model_args (additional positional arguments, *optional*):
                Will be passed along to the underlying model `__init__()` method.
            config ([`PretrainedConfig`], *optional*):
                Configuration for the model to use instead of an automatically loaded configuration. Configuration can
                be automatically loaded when:

                    - The model is a model provided by the library (loaded with the *model id* string of a pretrained
                      model).
                    - The model was saved using [`~PreTrainedModel.save_pretrained`] and is reloaded by supplying the
                      save directory.
                    - The model is loaded by supplying a local directory as `pretrained_model_name_or_path` and a
                      configuration JSON file named *config.json* is found in the directory.
            cache_dir (`str` or `os.PathLike`, *optional*):
                Path to a directory in which a downloaded pretrained model configuration should be cached if the
                standard cache should not be used.
            from_pt (`bool`, *optional*, defaults to `False`):
                Load the model weights from a PyTorch checkpoint save file (see docstring of
                `pretrained_model_name_or_path` argument).
            force_download (`bool`, *optional*, defaults to `False`):
                Whether or not to force the (re-)download of the model weights and configuration files, overriding the
                cached versions if they exist.
            resume_download (`bool`, *optional*, defaults to `False`):
                Whether or not to delete incompletely received files. Will attempt to resume the download if such a
                file exists.
            proxies (`Dict[str, str]`, *optional*):
                A dictionary of proxy servers to use by protocol or endpoint, e.g., `{'http': 'foo.bar:3128',
                'http://hostname': 'foo.bar:4012'}`. The proxies are used on each request.
            output_loading_info(`bool`, *optional*, defaults to `False`):
                Whether ot not to also return a dictionary containing missing keys, unexpected keys and error messages.
            local_files_only(`bool`, *optional*, defaults to `False`):
                Whether or not to only look at local files (e.g., not try downloading the model).
            revision (`str`, *optional*, defaults to `"main"`):
                The specific model version to use. It can be a branch name, a tag name, or a commit id, since we use a
                git-based system for storing models and other artifacts on huggingface.co, so `revision` can be any
                identifier allowed by git.
            trust_remote_code (`bool`, *optional*, defaults to `False`):
                Whether or not to allow for custom models defined on the Hub in their own modeling files. This option
                should only be set to `True` for repositories you trust and in which you have read the code, as it will
                execute code present on the Hub on your local machine.
            code_revision (`str`, *optional*, defaults to `"main"`):
                The specific revision to use for the code on the Hub, if the code leaves in a different repository than
                the rest of the model. It can be a branch name, a tag name, or a commit id, since we use a git-based
                system for storing models and other artifacts on huggingface.co, so `revision` can be any identifier
                allowed by git.
            kwargs (additional keyword arguments, *optional*):
                Can be used to update the configuration object (after it being loaded) and initiate the model (e.g.,
                `output_attentions=True`). Behaves differently depending on whether a `config` is provided or
                automatically loaded:

                    - If a configuration is provided with `config`, `**kwargs` will be directly passed to the
                      underlying model's `__init__` method (we assume all relevant updates to the configuration have
                      already been done)
                    - If a configuration is not provided, `kwargs` will be first passed to the configuration class
                      initialization function ([`~PretrainedConfig.from_pretrained`]). Each key of `kwargs` that
                      corresponds to a configuration attribute will be used to override said attribute with the
                      supplied `kwargs` value. Remaining keys that do not correspond to any configuration attribute
                      will be passed to the underlying model's `__init__` function.

        Examples:

        ```python
        >>> from transformers import AutoConfig, BaseAutoModelClass

        >>> # Download model and configuration from huggingface.co and cache.
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder")

        >>> # Update configuration during loading
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder", output_attentions=True)
        >>> model.config.output_attentions
        True

        >>> # Loading from a PyTorch checkpoint file instead of a TensorFlow model (slower)
        >>> config = AutoConfig.from_pretrained("./pt_model/shortcut_placeholder_pt_model_config.json")
        >>> model = BaseAutoModelClass.from_pretrained(
        ...     "./pt_model/shortcut_placeholder_pytorch_model.bin", from_pt=True, config=config
        ... )
        ```
"""

FROM_PRETRAINED_FLAX_DOCSTRING = """
        Instantiate one of the model classes of the library from a pretrained model.

        The model class to instantiate is selected based on the `model_type` property of the config object (either
        passed as an argument or loaded from `pretrained_model_name_or_path` if possible), or when it's missing, by
        falling back to using pattern matching on `pretrained_model_name_or_path`:

        List options

        Args:
            pretrained_model_name_or_path (`str` or `os.PathLike`):
                Can be either:

                    - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co.
                      Valid model ids can be located at the root-level, like `bert-base-uncased`, or namespaced under a
                      user or organization name, like `dbmdz/bert-base-german-cased`.
                    - A path to a *directory* containing model weights saved using
                      [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
                    - A path or url to a *PyTorch state_dict save file* (e.g, `./pt_model/pytorch_model.bin`). In this
                      case, `from_pt` should be set to `True` and a configuration object should be provided as `config`
                      argument. This loading path is slower than converting the PyTorch model in a TensorFlow model
                      using the provided conversion scripts and loading the TensorFlow model afterwards.
            model_args (additional positional arguments, *optional*):
                Will be passed along to the underlying model `__init__()` method.
            config ([`PretrainedConfig`], *optional*):
                Configuration for the model to use instead of an automatically loaded configuration. Configuration can
                be automatically loaded when:

                    - The model is a model provided by the library (loaded with the *model id* string of a pretrained
                      model).
                    - The model was saved using [`~PreTrainedModel.save_pretrained`] and is reloaded by supplying the
                      save directory.
                    - The model is loaded by supplying a local directory as `pretrained_model_name_or_path` and a
                      configuration JSON file named *config.json* is found in the directory.
            cache_dir (`str` or `os.PathLike`, *optional*):
                Path to a directory in which a downloaded pretrained model configuration should be cached if the
                standard cache should not be used.
            from_pt (`bool`, *optional*, defaults to `False`):
                Load the model weights from a PyTorch checkpoint save file (see docstring of
                `pretrained_model_name_or_path` argument).
            force_download (`bool`, *optional*, defaults to `False`):
                Whether or not to force the (re-)download of the model weights and configuration files, overriding the
                cached versions if they exist.
            resume_download (`bool`, *optional*, defaults to `False`):
                Whether or not to delete incompletely received files. Will attempt to resume the download if such a
                file exists.
            proxies (`Dict[str, str]`, *optional*):
                A dictionary of proxy servers to use by protocol or endpoint, e.g., `{'http': 'foo.bar:3128',
                'http://hostname': 'foo.bar:4012'}`. The proxies are used on each request.
            output_loading_info(`bool`, *optional*, defaults to `False`):
                Whether ot not to also return a dictionary containing missing keys, unexpected keys and error messages.
            local_files_only(`bool`, *optional*, defaults to `False`):
                Whether or not to only look at local files (e.g., not try downloading the model).
            revision (`str`, *optional*, defaults to `"main"`):
                The specific model version to use. It can be a branch name, a tag name, or a commit id, since we use a
                git-based system for storing models and other artifacts on huggingface.co, so `revision` can be any
                identifier allowed by git.
            trust_remote_code (`bool`, *optional*, defaults to `False`):
                Whether or not to allow for custom models defined on the Hub in their own modeling files. This option
                should only be set to `True` for repositories you trust and in which you have read the code, as it will
                execute code present on the Hub on your local machine.
            code_revision (`str`, *optional*, defaults to `"main"`):
                The specific revision to use for the code on the Hub, if the code leaves in a different repository than
                the rest of the model. It can be a branch name, a tag name, or a commit id, since we use a git-based
                system for storing models and other artifacts on huggingface.co, so `revision` can be any identifier
                allowed by git.
            kwargs (additional keyword arguments, *optional*):
                Can be used to update the configuration object (after it being loaded) and initiate the model (e.g.,
                `output_attentions=True`). Behaves differently depending on whether a `config` is provided or
                automatically loaded:

                    - If a configuration is provided with `config`, `**kwargs` will be directly passed to the
                      underlying model's `__init__` method (we assume all relevant updates to the configuration have
                      already been done)
                    - If a configuration is not provided, `kwargs` will be first passed to the configuration class
                      initialization function ([`~PretrainedConfig.from_pretrained`]). Each key of `kwargs` that
                      corresponds to a configuration attribute will be used to override said attribute with the
                      supplied `kwargs` value. Remaining keys that do not correspond to any configuration attribute
                      will be passed to the underlying model's `__init__` function.

        Examples:

        ```python
        >>> from transformers import AutoConfig, BaseAutoModelClass

        >>> # Download model and configuration from huggingface.co and cache.
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder")

        >>> # Update configuration during loading
        >>> model = BaseAutoModelClass.from_pretrained("checkpoint_placeholder", output_attentions=True)
        >>> model.config.output_attentions
        True

        >>> # Loading from a PyTorch checkpoint file instead of a TensorFlow model (slower)
        >>> config = AutoConfig.from_pretrained("./pt_model/shortcut_placeholder_pt_model_config.json")
        >>> model = BaseAutoModelClass.from_pretrained(
        ...     "./pt_model/shortcut_placeholder_pytorch_model.bin", from_pt=True, config=config
        ... )
        ```
"""


def _get_model_class(config, model_mapping):
    supported_models = model_mapping[type(config)]
    if not isinstance(supported_models, (list, tuple)):
        return supported_models

    name_to_model = {model.__name__: model for model in supported_models}
    architectures = getattr(config, "architectures", [])
    for arch in architectures:
        if arch in name_to_model:
            return name_to_model[arch]
        elif f"TF{arch}" in name_to_model:
            return name_to_model[f"TF{arch}"]
        elif f"Flax{arch}" in name_to_model:
            return name_to_model[f"Flax{arch}"]

    # If not architecture is set in the config or match the supported models, the first element of the tuple is the
    # defaults.
    return supported_models[0]


class _BaseAutoModelClass:
    # Base class for auto models.
    _model_mapping = None

    def __init__(self, *args, **kwargs):
        raise EnvironmentError(
            f"{self.__class__.__name__} is designed to be instantiated "
            f"using the `{self.__class__.__name__}.from_pretrained(pretrained_model_name_or_path)` or "
            f"`{self.__class__.__name__}.from_config(config)` methods."
        )

    @classmethod
    def from_config(cls, config, **kwargs):
        trust_remote_code = kwargs.pop("trust_remote_code", None)
        has_remote_code = hasattr(config, "auto_map") and cls.__name__ in config.auto_map
        has_local_code = type(config) in cls._model_mapping.keys()
        trust_remote_code = resolve_trust_remote_code(
            trust_remote_code, config._name_or_path, has_local_code, has_remote_code
        )

        if has_remote_code and trust_remote_code:
            class_ref = config.auto_map[cls.__name__]
            if "--" in class_ref:
                repo_id, class_ref = class_ref.split("--")
            else:
                repo_id = config.name_or_path
            model_class = get_class_from_dynamic_module(class_ref, repo_id, **kwargs)
            if os.path.isdir(config._name_or_path):
                model_class.register_for_auto_class(cls.__name__)
            else:
                cls.register(config.__class__, model_class, exist_ok=True)
            _ = kwargs.pop("code_revision", None)
            return model_class._from_config(config, **kwargs)
        elif type(config) in cls._model_mapping.keys():
            model_class = _get_model_class(config, cls._model_mapping)
            return model_class._from_config(config, **kwargs)

        raise ValueError(
            f"Unrecognized configuration class {config.__class__} for this kind of AutoModel: {cls.__name__}.\n"
            f"Model type should be one of {', '.join(c.__name__ for c in cls._model_mapping.keys())}."
        )

    @classmethod
    def from_pretrained(cls, pretrained_model_name_or_path, *model_args, **kwargs):
        config = kwargs.pop("config", None)
        trust_remote_code = kwargs.pop("trust_remote_code", None)
        kwargs["_from_auto"] = True
        hub_kwargs_names = [
            "cache_dir",
            "code_revision",
            "force_download",
            "local_files_only",
            "proxies",
            "resume_download",
            "revision",
            "subfolder",
            "use_auth_token",
            "token",
        ]
        hub_kwargs = {name: kwargs.pop(name) for name in hub_kwargs_names if name in kwargs}

        token = hub_kwargs.pop("token", None)
        use_auth_token = hub_kwargs.pop("use_auth_token", None)
        if use_auth_token is not None:
            warnings.warn(
                "The `use_auth_token` argument is deprecated and will be removed in v5 of Transformers.", FutureWarning
            )
            if token is not None:
                raise ValueError(
                    "`token` and `use_auth_token` are both specified. Please set only the argument `token`."
                )
            token = use_auth_token

        if token is not None:
            hub_kwargs["token"] = token

        if not isinstance(config, PretrainedConfig):
            kwargs_orig = copy.deepcopy(kwargs)
            # ensure not to pollute the config object with torch_dtype="auto" - since it's
            # meaningless in the context of the config object - torch.dtype values are acceptable
            if kwargs.get("torch_dtype", None) == "auto":
                _ = kwargs.pop("torch_dtype")

            config, kwargs = AutoConfig.from_pretrained(
                pretrained_model_name_or_path,
                return_unused_kwargs=True,
                trust_remote_code=trust_remote_code,
                **hub_kwargs,
                **kwargs,
            )

            # if torch_dtype=auto was passed here, ensure to pass it on
            if kwargs_orig.get("torch_dtype", None) == "auto":
                kwargs["torch_dtype"] = "auto"

        has_remote_code = hasattr(config, "auto_map") and cls.__name__ in config.auto_map
        has_local_code = type(config) in cls._model_mapping.keys()
        trust_remote_code = resolve_trust_remote_code(
            trust_remote_code, pretrained_model_name_or_path, has_local_code, has_remote_code
        )
        if has_remote_code and trust_remote_code:
            class_ref = config.auto_map[cls.__name__]
            model_class = get_class_from_dynamic_module(
                class_ref, pretrained_model_name_or_path, **hub_kwargs, **kwargs
            )
            _ = hub_kwargs.pop("code_revision", None)
            if os.path.isdir(pretrained_model_name_or_path):
                model_class.register_for_auto_class(cls.__name__)
            else:
                cls.register(config.__class__, model_class, exist_ok=True)
            return model_class.from_pretrained(
                pretrained_model_name_or_path, *model_args, config=config, **hub_kwargs, **kwargs
            )
        elif type(config) in cls._model_mapping.keys():
            model_class = _get_model_class(config, cls._model_mapping)
            return model_class.from_pretrained(
                pretrained_model_name_or_path, *model_args, config=config, **hub_kwargs, **kwargs
            )
        raise ValueError(
            f"Unrecognized configuration class {config.__class__} for this kind of AutoModel: {cls.__name__}.\n"
            f"Model type should be one of {', '.join(c.__name__ for c in cls._model_mapping.keys())}."
        )

    @classmethod
    def register(cls, config_class, model_class, exist_ok=False):
        """
        Register a new model for this class.

        Args:
            config_class ([`PretrainedConfig`]):
                The configuration corresponding to the model to register.
            model_class ([`PreTrainedModel`]):
                The model to register.
        """
        if hasattr(model_class, "config_class") and model_class.config_class != config_class:
            raise ValueError(
                "The model class you are passing has a `config_class` attribute that is not consistent with the "
                f"config class you passed (model has {model_class.config_class} and you passed {config_class}. Fix "
                "one of those so they match!"
            )
        cls._model_mapping.register(config_class, model_class, exist_ok=exist_ok)


class _BaseAutoBackboneClass(_BaseAutoModelClass):
    # Base class for auto backbone models.
    _model_mapping = None

    @classmethod
    def _load_timm_backbone_from_pretrained(cls, pretrained_model_name_or_path, *model_args, **kwargs):
        requires_backends(cls, ["vision", "timm"])
        from ...models.timm_backbone import TimmBackboneConfig

        config = kwargs.pop("config", TimmBackboneConfig())

        use_timm = kwargs.pop("use_timm_backbone", True)
        if not use_timm:
            raise ValueError("`use_timm_backbone` must be `True` for timm backbones")

        if kwargs.get("out_features", None) is not None:
            raise ValueError("Cannot specify `out_features` for timm backbones")

        if kwargs.get("output_loading_info", False):
            raise ValueError("Cannot specify `output_loading_info=True` when loading from timm")

        num_channels = kwargs.pop("num_channels", config.num_channels)
        features_only = kwargs.pop("features_only", config.features_only)
        use_pretrained_backbone = kwargs.pop("use_pretrained_backbone", config.use_pretrained_backbone)
        out_indices = kwargs.pop("out_indices", config.out_indices)
        config = TimmBackboneConfig(
            backbone=pretrained_model_name_or_path,
            num_channels=num_channels,
            features_only=features_only,
            use_pretrained_backbone=use_pretrained_backbone,
            out_indices=out_indices,
        )
        return super().from_config(config, **kwargs)

    @classmethod
    def from_pretrained(cls, pretrained_model_name_or_path, *model_args, **kwargs):
        if kwargs.get("use_timm_backbone", False):
            return cls._load_timm_backbone_from_pretrained(pretrained_model_name_or_path, *model_args, **kwargs)

        return super().from_pretrained(pretrained_model_name_or_path, *model_args, **kwargs)


def insert_head_doc(docstring, head_doc=""):
    if len(head_doc) > 0:
        return docstring.replace(
            "one of the model classes of the library ",
            f"one of the model classes of the library (with a {head_doc} head) ",
        )
    return docstring.replace(
        "one of the model classes of the library ", "one of the base model classes of the library "
    )


def auto_class_update(cls, checkpoint_for_example="bert-base-cased", head_doc=""):
    # Create a new class with the right name from the base class
    model_mapping = cls._model_mapping
    name = cls.__name__
    class_docstring = insert_head_doc(CLASS_DOCSTRING, head_doc=head_doc)
    cls.__doc__ = class_docstring.replace("BaseAutoModelClass", name)

    # Now we need to copy and re-register `from_config` and `from_pretrained` as class methods otherwise we can't
    # have a specific docstrings for them.
    from_config = copy_func(_BaseAutoModelClass.from_config)
    from_config_docstring = insert_head_doc(FROM_CONFIG_DOCSTRING, head_doc=head_doc)
    from_config_docstring = from_config_docstring.replace("BaseAutoModelClass", name)
    from_config_docstring = from_config_docstring.replace("checkpoint_placeholder", checkpoint_for_example)
    from_config.__doc__ = from_config_docstring
    from_config = replace_list_option_in_docstrings(model_mapping._model_mapping, use_model_types=False)(from_config)
    cls.from_config = classmethod(from_config)

    if name.startswith("TF"):
        from_pretrained_docstring = FROM_PRETRAINED_TF_DOCSTRING
    elif name.startswith("Flax"):
        from_pretrained_docstring = FROM_PRETRAINED_FLAX_DOCSTRING
    else:
        from_pretrained_docstring = FROM_PRETRAINED_TORCH_DOCSTRING
    from_pretrained = copy_func(_BaseAutoModelClass.from_pretrained)
    from_pretrained_docstring = insert_head_doc(from_pretrained_docstring, head_doc=head_doc)
    from_pretrained_docstring = from_pretrained_docstring.replace("BaseAutoModelClass", name)
    from_pretrained_docstring = from_pretrained_docstring.replace("checkpoint_placeholder", checkpoint_for_example)
    shortcut = checkpoint_for_example.split("/")[-1].split("-")[0]
    from_pretrained_docstring = from_pretrained_docstring.replace("shortcut_placeholder", shortcut)
    from_pretrained.__doc__ = from_pretrained_docstring
    from_pretrained = replace_list_option_in_docstrings(model_mapping._model_mapping)(from_pretrained)
    cls.from_pretrained = classmethod(from_pretrained)
    return cls


def get_values(model_mapping):
    result = []
    for model in model_mapping.values():
        if isinstance(model, (list, tuple)):
            result += list(model)
        else:
            result.append(model)

    return result


def getattribute_from_module(module, attr):
    if attr is None:
        return None
    if isinstance(attr, tuple):
        return tuple(getattribute_from_module(module, a) for a in attr)
    if hasattr(module, attr):
        return getattr(module, attr)
    # Some of the mappings have entries model_type -> object of another model type. In that case we try to grab the
    # object at the top level.
    transformers_module = importlib.import_module("transformers")

    if module != transformers_module:
        try:
            return getattribute_from_module(transformers_module, attr)
        except ValueError:
            raise ValueError(f"Could not find {attr} neither in {module} nor in {transformers_module}!")
    else:
        raise ValueError(f"Could not find {attr} in {transformers_module}!")


class _LazyAutoMapping(OrderedDict):
    """
    " A mapping config to object (model or tokenizer for instance) that will load keys and values when it is accessed.

    Args:
        - config_mapping: The map model type to config class
        - model_mapping: The map model type to model (or tokenizer) class
    """

    def __init__(self, config_mapping, model_mapping):
        self._config_mapping = config_mapping
        self._reverse_config_mapping = {v: k for k, v in config_mapping.items()}
        self._model_mapping = model_mapping
        self._model_mapping._model_mapping = self
        self._extra_content = {}
        self._modules = {}

    def __len__(self):
        common_keys = set(self._config_mapping.keys()).intersection(self._model_mapping.keys())
        return len(common_keys) + len(self._extra_content)

    def __getitem__(self, key):
        if key in self._extra_content:
            return self._extra_content[key]
        model_type = self._reverse_config_mapping[key.__name__]
        if model_type in self._model_mapping:
            model_name = self._model_mapping[model_type]
            return self._load_attr_from_module(model_type, model_name)

        # Maybe there was several model types associated with this config.
        model_types = [k for k, v in self._config_mapping.items() if v == key.__name__]
        for mtype in model_types:
            if mtype in self._model_mapping:
                model_name = self._model_mapping[mtype]
                return self._load_attr_from_module(mtype, model_name)
        raise KeyError(key)

    def _load_attr_from_module(self, model_type, attr):
        module_name = model_type_to_module_name(model_type)
        if module_name not in self._modules:
            self._modules[module_name] = importlib.import_module(f".{module_name}", "transformers.models")
        return getattribute_from_module(self._modules[module_name], attr)

    def keys(self):
        mapping_keys = [
            self._load_attr_from_module(key, name)
            for key, name in self._config_mapping.items()
            if key in self._model_mapping.keys()
        ]
        return mapping_keys + list(self._extra_content.keys())

    def get(self, key, default):
        try:
            return self.__getitem__(key)
        except KeyError:
            return default

    def __bool__(self):
        return bool(self.keys())

    def values(self):
        mapping_values = [
            self._load_attr_from_module(key, name)
            for key, name in self._model_mapping.items()
            if key in self._config_mapping.keys()
        ]
        return mapping_values + list(self._extra_content.values())

    def items(self):
        mapping_items = [
            (
                self._load_attr_from_module(key, self._config_mapping[key]),
                self._load_attr_from_module(key, self._model_mapping[key]),
            )
            for key in self._model_mapping.keys()
            if key in self._config_mapping.keys()
        ]
        return mapping_items + list(self._extra_content.items())

    def __iter__(self):
        return iter(self.keys())

    def __contains__(self, item):
        if item in self._extra_content:
            return True
        if not hasattr(item, "__name__") or item.__name__ not in self._reverse_config_mapping:
            return False
        model_type = self._reverse_config_mapping[item.__name__]
        return model_type in self._model_mapping

    def register(self, key, value, exist_ok=False):
        """
        Register a new model in this mapping.
        """
        if hasattr(key, "__name__") and key.__name__ in self._reverse_config_mapping:
            model_type = self._reverse_config_mapping[key.__name__]
            if model_type in self._model_mapping.keys() and not exist_ok:
                raise ValueError(f"'{key}' is already used by a Transformers model.")

        self._extra_content[key] = value
