tokenization_utils_base.py

# coding=utf-8
# Copyright 2020 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.
"""
Base classes common to both the slow and the fast tokenization classes: PreTrainedTokenizerBase (host all the user
fronting encoding methods) Special token mixing (host the special tokens logic) and BatchEncoding (wrap the dictionary
of output with special method for the Fast tokenizers)
"""

import copy
import json
import os
import re
import warnings
from collections import UserDict
from collections.abc import Mapping, Sized
from contextlib import contextmanager
from dataclasses import dataclass
from functools import lru_cache
from typing import TYPE_CHECKING, Any, Dict, List, NamedTuple, Optional, Sequence, Tuple, Union

import numpy as np
from packaging import version

from . import __version__
from .dynamic_module_utils import custom_object_save
from .utils import (
    ExplicitEnum,
    PaddingStrategy,
    PushToHubMixin,
    TensorType,
    add_end_docstrings,
    add_model_info_to_auto_map,
    cached_file,
    copy_func,
    download_url,
    extract_commit_hash,
    is_flax_available,
    is_jax_tensor,
    is_numpy_array,
    is_offline_mode,
    is_remote_url,
    is_tf_available,
    is_tf_tensor,
    is_tokenizers_available,
    is_torch_available,
    is_torch_device,
    is_torch_tensor,
    logging,
    requires_backends,
    to_py_obj,
)


if TYPE_CHECKING:
    if is_torch_available():
        import torch
    if is_tf_available():
        import tensorflow as tf
    if is_flax_available():
        import jax.numpy as jnp  # noqa: F401
    from .pipelines.conversational import Conversation


if is_tokenizers_available():
    from tokenizers import AddedToken
    from tokenizers import Encoding as EncodingFast
else:

    @dataclass(frozen=False, eq=True)
    class AddedToken:
        """
        AddedToken represents a token to be added to a Tokenizer An AddedToken can have special options defining the
        way it should behave.

        The `normalized` will default to `not special` if it is not specified, similarly to the definition in
        `tokenizers`.
        """

        def __init__(
            self, content: str, single_word=False, lstrip=False, rstrip=False, special=False, normalized=None
        ):
            self.content = content
            self.single_word = single_word
            self.lstrip = lstrip
            self.rstrip = rstrip
            self.special = special
            self.normalized = normalized if normalized is not None else not special

        def __getstate__(self):
            return self.__dict__

        def __str__(self):
            return self.content

    @dataclass
    class EncodingFast:
        """This is dummy class because without the `tokenizers` library we don't have these objects anyway"""

        pass


logger = logging.get_logger(__name__)

VERY_LARGE_INTEGER = int(1e30)  # This is used to set the max input length for a model with infinite size input
LARGE_INTEGER = int(1e20)  # This is used when we need something big but slightly smaller than VERY_LARGE_INTEGER

# Define type aliases and NamedTuples
TextInput = str
PreTokenizedInput = List[str]
EncodedInput = List[int]
TextInputPair = Tuple[str, str]
PreTokenizedInputPair = Tuple[List[str], List[str]]
EncodedInputPair = Tuple[List[int], List[int]]


# Slow tokenizers used to be saved in three separated files
SPECIAL_TOKENS_MAP_FILE = "special_tokens_map.json"
ADDED_TOKENS_FILE = "added_tokens.json"
TOKENIZER_CONFIG_FILE = "tokenizer_config.json"

# Fast tokenizers (provided by HuggingFace tokenizer's library) can be saved in a single file
FULL_TOKENIZER_FILE = "tokenizer.json"
_re_tokenizer_file = re.compile(r"tokenizer\.(.*)\.json")


class TruncationStrategy(ExplicitEnum):
    """
    Possible values for the `truncation` argument in [`PreTrainedTokenizerBase.__call__`]. Useful for tab-completion in
    an IDE.
    """

    ONLY_FIRST = "only_first"
    ONLY_SECOND = "only_second"
    LONGEST_FIRST = "longest_first"
    DO_NOT_TRUNCATE = "do_not_truncate"


class CharSpan(NamedTuple):
    """
    Character span in the original string.

    Args:
        start (`int`): Index of the first character in the original string.
        end (`int`): Index of the character following the last character in the original string.
    """

    start: int
    end: int


class TokenSpan(NamedTuple):
    """
    Token span in an encoded string (list of tokens).

    Args:
        start (`int`): Index of the first token in the span.
        end (`int`): Index of the token following the last token in the span.
    """

    start: int
    end: int


class BatchEncoding(UserDict):
    """
    Holds the output of the [`~tokenization_utils_base.PreTrainedTokenizerBase.__call__`],
    [`~tokenization_utils_base.PreTrainedTokenizerBase.encode_plus`] and
    [`~tokenization_utils_base.PreTrainedTokenizerBase.batch_encode_plus`] methods (tokens, attention_masks, etc).

    This class is derived from a python dictionary and can be used as a dictionary. In addition, this class exposes
    utility methods to map from word/character space to token space.

    Args:
        data (`dict`):
            Dictionary of lists/arrays/tensors returned by the `__call__`/`encode_plus`/`batch_encode_plus` methods
            ('input_ids', 'attention_mask', etc.).
        encoding (`tokenizers.Encoding` or `Sequence[tokenizers.Encoding]`, *optional*):
            If the tokenizer is a fast tokenizer which outputs additional information like mapping from word/character
            space to token space the `tokenizers.Encoding` instance or list of instance (for batches) hold this
            information.
        tensor_type (`Union[None, str, TensorType]`, *optional*):
            You can give a tensor_type here to convert the lists of integers in PyTorch/TensorFlow/Numpy Tensors at
            initialization.
        prepend_batch_axis (`bool`, *optional*, defaults to `False`):
            Whether or not to add a batch axis when converting to tensors (see `tensor_type` above).
        n_sequences (`Optional[int]`, *optional*):
            You can give a tensor_type here to convert the lists of integers in PyTorch/TensorFlow/Numpy Tensors at
            initialization.
    """

    def __init__(
        self,
        data: Optional[Dict[str, Any]] = None,
        encoding: Optional[Union[EncodingFast, Sequence[EncodingFast]]] = None,
        tensor_type: Union[None, str, TensorType] = None,
        prepend_batch_axis: bool = False,
        n_sequences: Optional[int] = None,
    ):
        super().__init__(data)

        if isinstance(encoding, EncodingFast):
            encoding = [encoding]

        self._encodings = encoding

        if n_sequences is None and encoding is not None and len(encoding):
            n_sequences = encoding[0].n_sequences

        self._n_sequences = n_sequences

        self.convert_to_tensors(tensor_type=tensor_type, prepend_batch_axis=prepend_batch_axis)

    @property
    def n_sequences(self) -> Optional[int]:
        """
        `Optional[int]`: The number of sequences used to generate each sample from the batch encoded in this
        [`BatchEncoding`]. Currently can be one of `None` (unknown), `1` (a single sentence) or `2` (a pair of
        sentences)
        """
        return self._n_sequences

    @property
    def is_fast(self) -> bool:
        """
        `bool`: Indicate whether this [`BatchEncoding`] was generated from the result of a [`PreTrainedTokenizerFast`]
        or not.
        """
        return self._encodings is not None

    def __getitem__(self, item: Union[int, str]) -> Union[Any, EncodingFast]:
        """
        If the key is a string, returns the value of the dict associated to `key` ('input_ids', 'attention_mask',
        etc.).

        If the key is an integer, get the `tokenizers.Encoding` for batch item with index `key`.

        If the key is a slice, returns the value of the dict associated to `key` ('input_ids', 'attention_mask', etc.)
        with the constraint of slice.
        """
        if isinstance(item, str):
            return self.data[item]
        elif self._encodings is not None:
            return self._encodings[item]
        elif isinstance(item, slice):
            return {key: self.data[key][item] for key in self.data.keys()}
        else:
            raise KeyError(
                "Invalid key. Only three types of key are available: "
                "(1) string, (2) integers for backend Encoding, and (3) slices for data subsetting."
            )

    def __getattr__(self, item: str):
        try:
            return self.data[item]
        except KeyError:
            raise AttributeError

    def __getstate__(self):
        return {"data": self.data, "encodings": self._encodings}

    def __setstate__(self, state):
        if "data" in state:
            self.data = state["data"]

        if "encodings" in state:
            self._encodings = state["encodings"]

    def keys(self):
        return self.data.keys()

    def values(self):
        return self.data.values()

    def items(self):
        return self.data.items()

    # After this point:
    # Extended properties and methods only available for fast (Rust-based) tokenizers
    # provided by HuggingFace tokenizers library.

    @property
    def encodings(self) -> Optional[List[EncodingFast]]:
        """
        `Optional[List[tokenizers.Encoding]]`: The list all encodings from the tokenization process. Returns `None` if
        the input was tokenized through Python (i.e., not a fast) tokenizer.
        """
        return self._encodings

    def tokens(self, batch_index: int = 0) -> List[str]:
        """
        Return the list of tokens (sub-parts of the input strings after word/subword splitting and before conversion to
        integer indices) at a given batch index (only works for the output of a fast tokenizer).

        Args:
            batch_index (`int`, *optional*, defaults to 0): The index to access in the batch.

        Returns:
            `List[str]`: The list of tokens at that index.
        """
        if not self._encodings:
            raise ValueError(
                "tokens() is not available when using non-fast tokenizers (e.g. instance of a `XxxTokenizerFast`"
                " class)."
            )
        return self._encodings[batch_index].tokens

    def sequence_ids(self, batch_index: int = 0) -> List[Optional[int]]:
        """
        Return a list mapping the tokens to the id of their original sentences:

            - `None` for special tokens added around or between sequences,
            - `0` for tokens corresponding to words in the first sequence,
            - `1` for tokens corresponding to words in the second sequence when a pair of sequences was jointly
              encoded.

        Args:
            batch_index (`int`, *optional*, defaults to 0): The index to access in the batch.

        Returns:
            `List[Optional[int]]`: A list indicating the sequence id corresponding to each token. Special tokens added
            by the tokenizer are mapped to `None` and other tokens are mapped to the index of their corresponding
            sequence.
        """
        if not self._encodings:
            raise ValueError(
                "sequence_ids() is not available when using non-fast tokenizers (e.g. instance of a `XxxTokenizerFast`"
                " class)."
            )
        return self._encodings[batch_index].sequence_ids

    def words(self, batch_index: int = 0) -> List[Optional[int]]:
        """
        Return a list mapping the tokens to their actual word in the initial sentence for a fast tokenizer.

        Args:
            batch_index (`int`, *optional*, defaults to 0): The index to access in the batch.

        Returns:
            `List[Optional[int]]`: A list indicating the word corresponding to each token. Special tokens added by the
            tokenizer are mapped to `None` and other tokens are mapped to the index of their corresponding word
            (several tokens will be mapped to the same word index if they are parts of that word).
        """
        if not self._encodings:
            raise ValueError(
                "words() is not available when using non-fast tokenizers (e.g. instance of a `XxxTokenizerFast`"
                " class)."
            )
        warnings.warn(
            "`BatchEncoding.words()` property is deprecated and should be replaced with the identical, "
            "but more self-explanatory `BatchEncoding.word_ids()` property.",
            FutureWarning,
        )
        return self.word_ids(batch_index)

    def word_ids(self, batch_index: int = 0) -> List[Optional[int]]:
        """
        Return a list mapping the tokens to their actual word in the initial sentence for a fast tokenizer.

        Args:
            batch_index (`int`, *optional*, defaults to 0): The index to access in the batch.

        Returns:
            `List[Optional[int]]`: A list indicating the word corresponding to each token. Special tokens added by the
            tokenizer are mapped to `None` and other tokens are mapped to the index of their corresponding word
            (several tokens will be mapped to the same word index if they are parts of that word).
        """
        if not self._encodings:
            raise ValueError(
                "word_ids() is not available when using non-fast tokenizers (e.g. instance of a `XxxTokenizerFast`"
                " class)."
            )
        return self._encodings[batch_index].word_ids

    def token_to_sequence(self, batch_or_token_index: int, token_index: Optional[int] = None) -> int:
        """
        Get the index of the sequence represented by the given token. In the general use case, this method returns `0`
        for a single sequence or the first sequence of a pair, and `1` for the second sequence of a pair

        Can be called as:

        - `self.token_to_sequence(token_index)` if batch size is 1
        - `self.token_to_sequence(batch_index, token_index)` if batch size is greater than 1

        This method is particularly suited when the input sequences are provided as pre-tokenized sequences (i.e.,
        words are defined by the user). In this case it allows to easily associate encoded tokens with provided
        tokenized words.

        Args:
            batch_or_token_index (`int`):
                Index of the sequence in the batch. If the batch only comprises one sequence, this can be the index of
                the token in the sequence.
            token_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the token in the
                sequence.

        Returns:
            `int`: Index of the word in the input sequence.
        """

        if not self._encodings:
            raise ValueError("token_to_sequence() is not available when using Python based tokenizers")
        if token_index is not None:
            batch_index = batch_or_token_index
        else:
            batch_index = 0
            token_index = batch_or_token_index
        if batch_index < 0:
            batch_index = self._batch_size + batch_index
        if token_index < 0:
            token_index = self._seq_len + token_index
        return self._encodings[batch_index].token_to_sequence(token_index)

    def token_to_word(self, batch_or_token_index: int, token_index: Optional[int] = None) -> int:
        """
        Get the index of the word corresponding (i.e. comprising) to an encoded token in a sequence of the batch.

        Can be called as:

        - `self.token_to_word(token_index)` if batch size is 1
        - `self.token_to_word(batch_index, token_index)` if batch size is greater than 1

        This method is particularly suited when the input sequences are provided as pre-tokenized sequences (i.e.,
        words are defined by the user). In this case it allows to easily associate encoded tokens with provided
        tokenized words.

        Args:
            batch_or_token_index (`int`):
                Index of the sequence in the batch. If the batch only comprise one sequence, this can be the index of
                the token in the sequence.
            token_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the token in the
                sequence.

        Returns:
            `int`: Index of the word in the input sequence.
        """

        if not self._encodings:
            raise ValueError("token_to_word() is not available when using Python based tokenizers")
        if token_index is not None:
            batch_index = batch_or_token_index
        else:
            batch_index = 0
            token_index = batch_or_token_index
        if batch_index < 0:
            batch_index = self._batch_size + batch_index
        if token_index < 0:
            token_index = self._seq_len + token_index
        return self._encodings[batch_index].token_to_word(token_index)

    def word_to_tokens(
        self, batch_or_word_index: int, word_index: Optional[int] = None, sequence_index: int = 0
    ) -> Optional[TokenSpan]:
        """
        Get the encoded token span corresponding to a word in a sequence of the batch.

        Token spans are returned as a [`~tokenization_utils_base.TokenSpan`] with:

        - **start** -- Index of the first token.
        - **end** -- Index of the token following the last token.

        Can be called as:

        - `self.word_to_tokens(word_index, sequence_index: int = 0)` if batch size is 1
        - `self.word_to_tokens(batch_index, word_index, sequence_index: int = 0)` if batch size is greater or equal to
          1

        This method is particularly suited when the input sequences are provided as pre-tokenized sequences (i.e. words
        are defined by the user). In this case it allows to easily associate encoded tokens with provided tokenized
        words.

        Args:
            batch_or_word_index (`int`):
                Index of the sequence in the batch. If the batch only comprises one sequence, this can be the index of
                the word in the sequence.
            word_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the word in the
                sequence.
            sequence_index (`int`, *optional*, defaults to 0):
                If pair of sequences are encoded in the batch this can be used to specify which sequence in the pair (0
                or 1) the provided word index belongs to.

        Returns:
            ([`~tokenization_utils_base.TokenSpan`], *optional*): Span of tokens in the encoded sequence. Returns
            `None` if no tokens correspond to the word. This can happen especially when the token is a special token
            that has been used to format the tokenization. For example when we add a class token at the very beginning
            of the tokenization.
        """

        if not self._encodings:
            raise ValueError("word_to_tokens() is not available when using Python based tokenizers")
        if word_index is not None:
            batch_index = batch_or_word_index
        else:
            batch_index = 0
            word_index = batch_or_word_index
        if batch_index < 0:
            batch_index = self._batch_size + batch_index
        if word_index < 0:
            word_index = self._seq_len + word_index
        span = self._encodings[batch_index].word_to_tokens(word_index, sequence_index)
        return TokenSpan(*span) if span is not None else None

    def token_to_chars(self, batch_or_token_index: int, token_index: Optional[int] = None) -> CharSpan:
        """
        Get the character span corresponding to an encoded token in a sequence of the batch.

        Character spans are returned as a [`~tokenization_utils_base.CharSpan`] with:

        - **start** -- Index of the first character in the original string associated to the token.
        - **end** -- Index of the character following the last character in the original string associated to the
          token.

        Can be called as:

        - `self.token_to_chars(token_index)` if batch size is 1
        - `self.token_to_chars(batch_index, token_index)` if batch size is greater or equal to 1

        Args:
            batch_or_token_index (`int`):
                Index of the sequence in the batch. If the batch only comprise one sequence, this can be the index of
                the token in the sequence.
            token_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the token or tokens in
                the sequence.

        Returns:
            [`~tokenization_utils_base.CharSpan`]: Span of characters in the original string, or None, if the token
            (e.g. <s>, </s>) doesn't correspond to any chars in the origin string.
        """

        if not self._encodings:
            raise ValueError("token_to_chars() is not available when using Python based tokenizers")
        if token_index is not None:
            batch_index = batch_or_token_index
        else:
            batch_index = 0
            token_index = batch_or_token_index
        span_indices = self._encodings[batch_index].token_to_chars(token_index)

        return CharSpan(*span_indices) if span_indices is not None else None

    def char_to_token(
        self, batch_or_char_index: int, char_index: Optional[int] = None, sequence_index: int = 0
    ) -> int:
        """
        Get the index of the token in the encoded output comprising a character in the original string for a sequence
        of the batch.

        Can be called as:

        - `self.char_to_token(char_index)` if batch size is 1
        - `self.char_to_token(batch_index, char_index)` if batch size is greater or equal to 1

        This method is particularly suited when the input sequences are provided as pre-tokenized sequences (i.e. words
        are defined by the user). In this case it allows to easily associate encoded tokens with provided tokenized
        words.

        Args:
            batch_or_char_index (`int`):
                Index of the sequence in the batch. If the batch only comprise one sequence, this can be the index of
                the word in the sequence
            char_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the word in the
                sequence.
            sequence_index (`int`, *optional*, defaults to 0):
                If pair of sequences are encoded in the batch this can be used to specify which sequence in the pair (0
                or 1) the provided character index belongs to.


        Returns:
            `int`: Index of the token.
        """

        if not self._encodings:
            raise ValueError("char_to_token() is not available when using Python based tokenizers")
        if char_index is not None:
            batch_index = batch_or_char_index
        else:
            batch_index = 0
            char_index = batch_or_char_index
        return self._encodings[batch_index].char_to_token(char_index, sequence_index)

    def word_to_chars(
        self, batch_or_word_index: int, word_index: Optional[int] = None, sequence_index: int = 0
    ) -> CharSpan:
        """
        Get the character span in the original string corresponding to given word in a sequence of the batch.

        Character spans are returned as a CharSpan NamedTuple with:

        - start: index of the first character in the original string
        - end: index of the character following the last character in the original string

        Can be called as:

        - `self.word_to_chars(word_index)` if batch size is 1
        - `self.word_to_chars(batch_index, word_index)` if batch size is greater or equal to 1

        Args:
            batch_or_word_index (`int`):
                Index of the sequence in the batch. If the batch only comprise one sequence, this can be the index of
                the word in the sequence
            word_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the word in the
                sequence.
            sequence_index (`int`, *optional*, defaults to 0):
                If pair of sequences are encoded in the batch this can be used to specify which sequence in the pair (0
                or 1) the provided word index belongs to.

        Returns:
            `CharSpan` or `List[CharSpan]`: Span(s) of the associated character or characters in the string. CharSpan
            are NamedTuple with:

                - start: index of the first character associated to the token in the original string
                - end: index of the character following the last character associated to the token in the original
                  string
        """

        if not self._encodings:
            raise ValueError("word_to_chars() is not available when using Python based tokenizers")
        if word_index is not None:
            batch_index = batch_or_word_index
        else:
            batch_index = 0
            word_index = batch_or_word_index
        return CharSpan(*(self._encodings[batch_index].word_to_chars(word_index, sequence_index)))

    def char_to_word(self, batch_or_char_index: int, char_index: Optional[int] = None, sequence_index: int = 0) -> int:
        """
        Get the word in the original string corresponding to a character in the original string of a sequence of the
        batch.

        Can be called as:

        - `self.char_to_word(char_index)` if batch size is 1
        - `self.char_to_word(batch_index, char_index)` if batch size is greater than 1

        This method is particularly suited when the input sequences are provided as pre-tokenized sequences (i.e. words
        are defined by the user). In this case it allows to easily associate encoded tokens with provided tokenized
        words.

        Args:
            batch_or_char_index (`int`):
                Index of the sequence in the batch. If the batch only comprise one sequence, this can be the index of
                the character in the original string.
            char_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the character in the
                original string.
            sequence_index (`int`, *optional*, defaults to 0):
                If pair of sequences are encoded in the batch this can be used to specify which sequence in the pair (0
                or 1) the provided character index belongs to.


        Returns:
            `int` or `List[int]`: Index or indices of the associated encoded token(s).
        """

        if not self._encodings:
            raise ValueError("char_to_word() is not available when using Python based tokenizers")
        if char_index is not None:
            batch_index = batch_or_char_index
        else:
            batch_index = 0
            char_index = batch_or_char_index
        return self._encodings[batch_index].char_to_word(char_index, sequence_index)

    def convert_to_tensors(
        self, tensor_type: Optional[Union[str, TensorType]] = None, prepend_batch_axis: bool = False
    ):
        """
        Convert the inner content to tensors.

        Args:
            tensor_type (`str` or [`~utils.TensorType`], *optional*):
                The type of tensors to use. If `str`, should be one of the values of the enum [`~utils.TensorType`]. If
                `None`, no modification is done.
            prepend_batch_axis (`int`, *optional*, defaults to `False`):
                Whether or not to add the batch dimension during the conversion.
        """
        if tensor_type is None:
            return self

        # Convert to TensorType
        if not isinstance(tensor_type, TensorType):
            tensor_type = TensorType(tensor_type)

        # Get a function reference for the correct framework
        if tensor_type == TensorType.TENSORFLOW:
            if not is_tf_available():
                raise ImportError(
                    "Unable to convert output to TensorFlow tensors format, TensorFlow is not installed."
                )
            import tensorflow as tf

            as_tensor = tf.constant
            is_tensor = tf.is_tensor
        elif tensor_type == TensorType.PYTORCH:
            if not is_torch_available():
                raise ImportError("Unable to convert output to PyTorch tensors format, PyTorch is not installed.")
            import torch

            is_tensor = torch.is_tensor

            def as_tensor(value, dtype=None):
                if isinstance(value, list) and isinstance(value[0], np.ndarray):
                    return torch.tensor(np.array(value))
                return torch.tensor(value)

        elif tensor_type == TensorType.JAX:
            if not is_flax_available():
                raise ImportError("Unable to convert output to JAX tensors format, JAX is not installed.")
            import jax.numpy as jnp  # noqa: F811

            as_tensor = jnp.array
            is_tensor = is_jax_tensor
        else:

            def as_tensor(value, dtype=None):
                if isinstance(value, (list, tuple)) and isinstance(value[0], (list, tuple, np.ndarray)):
                    value_lens = [len(val) for val in value]
                    if len(set(value_lens)) > 1 and dtype is None:
                        # we have a ragged list so handle explicitly
                        value = as_tensor([np.asarray(val) for val in value], dtype=object)
                return np.asarray(value, dtype=dtype)

            is_tensor = is_numpy_array

        # Do the tensor conversion in batch
        for key, value in self.items():
            try:
                if prepend_batch_axis:
                    value = [value]

                if not is_tensor(value):
                    tensor = as_tensor(value)

                    # Removing this for now in favor of controlling the shape with `prepend_batch_axis`
                    # # at-least2d
                    # if tensor.ndim > 2:
                    #     tensor = tensor.squeeze(0)
                    # elif tensor.ndim < 2:
                    #     tensor = tensor[None, :]

                    self[key] = tensor
            except Exception as e:
                if key == "overflowing_tokens":
                    raise ValueError(
                        "Unable to create tensor returning overflowing tokens of different lengths. "
                        "Please see if a fast version of this tokenizer is available to have this feature available."
                    ) from e
                raise ValueError(
                    "Unable to create tensor, you should probably activate truncation and/or padding with"
                    " 'padding=True' 'truncation=True' to have batched tensors with the same length. Perhaps your"
                    f" features (`{key}` in this case) have excessive nesting (inputs type `list` where type `int` is"
                    " expected)."
                ) from e

        return self

    def to(self, device: Union[str, "torch.device"]) -> "BatchEncoding":
        """
        Send all values to device by calling `v.to(device)` (PyTorch only).

        Args:
            device (`str` or `torch.device`): The device to put the tensors on.

        Returns:
            [`BatchEncoding`]: The same instance after modification.
        """
        requires_backends(self, ["torch"])

        # This check catches things like APEX blindly calling "to" on all inputs to a module
        # Otherwise it passes the casts down and casts the LongTensor containing the token idxs
        # into a HalfTensor
        if isinstance(device, str) or is_torch_device(device) or isinstance(device, int):
            self.data = {k: v.to(device=device) for k, v in self.data.items()}
        else:
            logger.warning(f"Attempting to cast a BatchEncoding to type {str(device)}. This is not supported.")
        return self


class SpecialTokensMixin:
    """
    A mixin derived by [`PreTrainedTokenizer`] and [`PreTrainedTokenizerFast`] to handle specific behaviors related to
    special tokens. In particular, this class hold the attributes which can be used to directly access these special
    tokens in a model-independent manner and allow to set and update the special tokens.

    Args:
        bos_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the beginning of a sentence.
        eos_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the end of a sentence.
        unk_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing an out-of-vocabulary token.
        sep_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token separating two different sentences in the same input (used by BERT for instance).
        pad_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token used to make arrays of tokens the same size for batching purpose. Will then be ignored by
            attention mechanisms or loss computation.
        cls_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the class of the input (used by BERT for instance).
        mask_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing a masked token (used by masked-language modeling pretraining objectives, like
            BERT).
        additional_special_tokens (tuple or list of `str` or `tokenizers.AddedToken`, *optional*):
            A tuple or a list of additional tokens, which will be marked as `special`, meaning that they will be
            skipped when decoding if `skip_special_tokens` is set to `True`.
    """

    SPECIAL_TOKENS_ATTRIBUTES = [
        "bos_token",
        "eos_token",
        "unk_token",
        "sep_token",
        "pad_token",
        "cls_token",
        "mask_token",
        "additional_special_tokens",
    ]

    def __init__(self, verbose=True, **kwargs):
        self._bos_token = None
        self._eos_token = None
        self._unk_token = None
        self._sep_token = None
        self._pad_token = None
        self._cls_token = None
        self._mask_token = None
        self._pad_token_type_id = 0
        self._additional_special_tokens = []
        self.verbose = verbose

        # We directly set the hidden value to allow initialization with special tokens
        # which are not yet in the vocabulary. Necessary for serialization/de-serialization
        # TODO clean this up at some point (probably by switching to fast tokenizers)

        for key, value in kwargs.items():
            if value is None:
                continue
            if key in self.SPECIAL_TOKENS_ATTRIBUTES:
                if key == "additional_special_tokens":
                    # TODO THIS IS NASTY! Will always reset tokens to default rstrip and lstrip because self.set_attr on strings
                    # will not check the addedtokens decoder. WILL FIX TOMORROW
                    assert isinstance(value, (list, tuple)), f"Value {value} is not a list or tuple"
                    assert all(
                        isinstance(t, (str, AddedToken)) for t in value
                    ), "One of the tokens is not a string or an AddedToken"
                    if hasattr(self, "added_tokens_encoder"):
                        extended_token = []
                        for token in value:
                            if isinstance(token, str) and str(token) in self.added_tokens_encoder:
                                extended_token.append(self.added_tokens_decoder[self.added_tokens_encoder[str(token)]])
                            else:
                                extended_token.append(token)
                        value = extended_token
                    setattr(self, key, value)
                elif isinstance(value, (str)):
                    value = AddedToken(value, normalized=False, special=True)
                    setattr(self, key, value)
                elif isinstance(value, AddedToken):
                    setattr(self, key, value)
                else:
                    raise TypeError(f"Special token {key} has to be either str or AddedToken but got: {type(value)}")

    def sanitize_special_tokens(self) -> int:
        """
        The `sanitize_special_tokens` is now deprecated kept for backward compatibility and will be removed in
        transformers v5.
        """
        logger.warning_once("The `sanitize_special_tokens` will be removed in transformers v5.")
        return self.add_tokens(self.all_special_tokens_extended, special_tokens=True)

    def add_special_tokens(
        self, special_tokens_dict: Dict[str, Union[str, AddedToken]], replace_additional_special_tokens=True
    ) -> int:
        """
        Add a dictionary of special tokens (eos, pad, cls, etc.) to the encoder and link them to class attributes. If
        special tokens are NOT in the vocabulary, they are added to it (indexed starting from the last index of the
        current vocabulary).

        When adding new tokens to the vocabulary, you should make sure to also resize the token embedding matrix of the
        model so that its embedding matrix matches the tokenizer.

        In order to do that, please use the [`~PreTrainedModel.resize_token_embeddings`] method.

        Using `add_special_tokens` will ensure your special tokens can be used in several ways:

        - Special tokens can be skipped when decoding using `skip_special_tokens = True`.
        - Special tokens are carefully handled by the tokenizer (they are never split), similar to `AddedTokens`.
        - You can easily refer to special tokens using tokenizer class attributes like `tokenizer.cls_token`. This
          makes it easy to develop model-agnostic training and fine-tuning scripts.

        When possible, special tokens are already registered for provided pretrained models (for instance
        [`BertTokenizer`] `cls_token` is already registered to be :obj*'[CLS]'* and XLM's one is also registered to be
        `'</s>'`).

        Args:
            special_tokens_dict (dictionary *str* to *str* or `tokenizers.AddedToken`):
                Keys should be in the list of predefined special attributes: [`bos_token`, `eos_token`, `unk_token`,
                `sep_token`, `pad_token`, `cls_token`, `mask_token`, `additional_special_tokens`].

                Tokens are only added if they are not already in the vocabulary (tested by checking if the tokenizer
                assign the index of the `unk_token` to them).
            replace_additional_special_tokens (`bool`, *optional*,, defaults to `True`):
                If `True`, the existing list of additional special tokens will be replaced by the list provided in
                `special_tokens_dict`. Otherwise, `self._additional_special_tokens` is just extended. In the former
                case, the tokens will NOT be removed from the tokenizer's full vocabulary - they are only being flagged
                as non-special tokens. Remember, this only affects which tokens are skipped during decoding, not the
                `added_tokens_encoder` and `added_tokens_decoder`. This means that the previous
                `additional_special_tokens` are still added tokens, and will not be split by the model.

        Returns:
            `int`: Number of tokens added to the vocabulary.

        Examples:

        ```python
        # Let's see how to add a new classification token to GPT-2
        tokenizer = GPT2Tokenizer.from_pretrained("gpt2")
        model = GPT2Model.from_pretrained("gpt2")

        special_tokens_dict = {"cls_token": "<CLS>"}

        num_added_toks = tokenizer.add_special_tokens(special_tokens_dict)
        print("We have added", num_added_toks, "tokens")
        # Notice: resize_token_embeddings expect to receive the full size of the new vocabulary, i.e., the length of the tokenizer.
        model.resize_token_embeddings(len(tokenizer))

        assert tokenizer.cls_token == "<CLS>"
        ```"""
        if not special_tokens_dict:
            return 0

        added_tokens = []
        for key, value in special_tokens_dict.items():
            assert key in self.SPECIAL_TOKENS_ATTRIBUTES, f"Key {key} is not a special token"

            if self.verbose:
                logger.info(f"Assigning {value} to the {key} key of the tokenizer")

            if key == "additional_special_tokens":
                assert isinstance(value, (list, tuple)) and all(
                    isinstance(t, (str, AddedToken)) for t in value
                ), f"Tokens {value} for key {key} should all be str or AddedToken instances"

                to_add = set()
                for token in value:
                    if isinstance(token, str):
                        # for legacy purpose we default to stripping. `test_add_tokens_tokenizer` depends on this
                        token = AddedToken(token, normalized=False, rstrip=True, lstrip=True)
                    if str(token) not in self.additional_special_tokens:
                        to_add.add(token)
                if replace_additional_special_tokens:
                    setattr(self, key, list(to_add))
                else:
                    self._additional_special_tokens.extend(to_add)
                added_tokens += to_add

            else:
                if not isinstance(value, (str, AddedToken)):
                    raise ValueError(f"Token {value} for key {key} should be a str or an AddedToken instance")
                if isinstance(value, (str)):
                    # for legacy purpose we default to stripping. `test_add_tokens_tokenizer` depends on this
                    value = AddedToken(value, normalized=False, rstrip=True, lstrip=True)
                if isinstance(value, AddedToken):
                    setattr(self, key, value)
                if value not in added_tokens:
                    added_tokens.append(value)

        # if we are adding tokens that were not part of the vocab, we ought to add them
        added_tokens = self.add_tokens(added_tokens, special_tokens=True)
        return added_tokens

    def add_tokens(
        self, new_tokens: Union[str, AddedToken, List[Union[str, AddedToken]]], special_tokens: bool = False
    ) -> int:
        """
        Add a list of new tokens to the tokenizer class. If the new tokens are not in the vocabulary, they are added to
        it with indices starting from length of the current vocabulary and and will be isolated before the tokenization
        algorithm is applied. Added tokens and tokens from the vocabulary of the tokenization algorithm are therefore
        not treated in the same way.

        Note, when adding new tokens to the vocabulary, you should make sure to also resize the token embedding matrix
        of the model so that its embedding matrix matches the tokenizer.

        In order to do that, please use the [`~PreTrainedModel.resize_token_embeddings`] method.

        Args:
            new_tokens (`str`, `tokenizers.AddedToken` or a list of *str* or `tokenizers.AddedToken`):
                Tokens are only added if they are not already in the vocabulary. `tokenizers.AddedToken` wraps a string
                token to let you personalize its behavior: whether this token should only match against a single word,
                whether this token should strip all potential whitespaces on the left side, whether this token should
                strip all potential whitespaces on the right side, etc.
            special_tokens (`bool`, *optional*, defaults to `False`):
                Can be used to specify if the token is a special token. This mostly change the normalization behavior
                (special tokens like CLS or [MASK] are usually not lower-cased for instance).

                See details for `tokenizers.AddedToken` in HuggingFace tokenizers library.

        Returns:
            `int`: Number of tokens added to the vocabulary.

        Examples:

        ```python
        # Let's see how to increase the vocabulary of Bert model and tokenizer
        tokenizer = BertTokenizerFast.from_pretrained("bert-base-uncased")
        model = BertModel.from_pretrained("bert-base-uncased")

        num_added_toks = tokenizer.add_tokens(["new_tok1", "my_new-tok2"])
        print("We have added", num_added_toks, "tokens")
        # Notice: resize_token_embeddings expect to receive the full size of the new vocabulary, i.e., the length of the tokenizer.
        model.resize_token_embeddings(len(tokenizer))
        ```"""
        if not new_tokens:
            return 0

        if not isinstance(new_tokens, (list, tuple)):
            new_tokens = [new_tokens]

        return self._add_tokens(new_tokens, special_tokens=special_tokens)

    def _add_tokens(self, new_tokens: Union[List[str], List[AddedToken]], special_tokens: bool = False) -> int:
        raise NotImplementedError

    @property
    def bos_token(self) -> str:
        """
        `str`: Beginning of sentence token. Log an error if used while not having been set.
        """
        if self._bos_token is None:
            if self.verbose:
                logger.error("Using bos_token, but it is not set yet.")
            return None
        return str(self._bos_token)

    @property
    def eos_token(self) -> str:
        """
        `str`: End of sentence token. Log an error if used while not having been set.
        """
        if self._eos_token is None:
            if self.verbose:
                logger.error("Using eos_token, but it is not set yet.")
            return None
        return str(self._eos_token)

    @property
    def unk_token(self) -> str:
        """
        `str`: Unknown token. Log an error if used while not having been set.
        """
        if self._unk_token is None:
            if self.verbose:
                logger.error("Using unk_token, but it is not set yet.")
            return None
        return str(self._unk_token)

    @property
    def sep_token(self) -> str:
        """
        `str`: Separation token, to separate context and query in an input sequence. Log an error if used while not
        having been set.
        """
        if self._sep_token is None:
            if self.verbose:
                logger.error("Using sep_token, but it is not set yet.")
            return None
        return str(self._sep_token)

    @property
    def pad_token(self) -> str:
        """
        `str`: Padding token. Log an error if used while not having been set.
        """
        if self._pad_token is None:
            if self.verbose:
                logger.error("Using pad_token, but it is not set yet.")
            return None
        return str(self._pad_token)

    @property
    def cls_token(self) -> str:
        """
        `str`: Classification token, to extract a summary of an input sequence leveraging self-attention along the full
        depth of the model. Log an error if used while not having been set.
        """
        if self._cls_token is None:
            if self.verbose:
                logger.error("Using cls_token, but it is not set yet.")
            return None
        return str(self._cls_token)

    @property
    def mask_token(self) -> str:
        """
        `str`: Mask token, to use when training a model with masked-language modeling. Log an error if used while not
        having been set.
        """
        if self._mask_token is None:
            if self.verbose:
                logger.error("Using mask_token, but it is not set yet.")
            return None
        return str(self._mask_token)

    @property
    def additional_special_tokens(self) -> List[str]:
        """
        `List[str]`: All the additional special tokens you may want to use. Log an error if used while not having been
        set.
        """
        if self._additional_special_tokens is None:
            if self.verbose:
                logger.error("Using additional_special_tokens, but it is not set yet.")
            return None
        return [str(tok) for tok in self._additional_special_tokens]

    @bos_token.setter
    def bos_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the BOS token")
        self._bos_token = value

    @eos_token.setter
    def eos_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the EOS token")
        self._eos_token = value

    @unk_token.setter
    def unk_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the UNK token")
        self._unk_token = value

    @sep_token.setter
    def sep_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the SEP token")
        self._sep_token = value

    @pad_token.setter
    def pad_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the PAD token")
        self._pad_token = value

    @cls_token.setter
    def cls_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the CLS token")
        self._cls_token = value

    @mask_token.setter
    def mask_token(self, value):
        if isinstance(value, str) and value != "":
            value = AddedToken(value, normalized=False, rstrip=True, lstrip=True, special=True)
        elif not isinstance(value, AddedToken) and value is not None:
            raise ValueError("Cannot set a non-string value as the MASK token")
        self._mask_token = value

    @additional_special_tokens.setter
    def additional_special_tokens(self, value):
        if value is None:
            self._additional_special_tokens = value
            return
        if self._additional_special_tokens is None:
            self._additional_special_tokens = []
        # We store the `AddedToken` to allow adding tokens via `tokenizer.add_special_tokens`
        for token in value:
            if isinstance(token, str) and token != "":
                token = AddedToken(token, normalized=False, rstrip=True, lstrip=True, special=True)
            elif not isinstance(token, AddedToken):
                raise ValueError(f"Cannot add instance of type {type(value)} to additional_special_tokens!")
            self._additional_special_tokens.append(token)

    @property
    def bos_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the beginning of sentence token in the vocabulary. Returns `None` if the token has not
        been set.
        """
        if self._bos_token is None:
            return None
        return self.convert_tokens_to_ids(self.bos_token)

    @property
    def eos_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the end of sentence token in the vocabulary. Returns `None` if the token has not been
        set.
        """
        if self._eos_token is None:
            return None
        return self.convert_tokens_to_ids(self.eos_token)

    @property
    def unk_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the unknown token in the vocabulary. Returns `None` if the token has not been set.
        """
        if self._unk_token is None:
            return None
        return self.convert_tokens_to_ids(self.unk_token)

    @property
    def sep_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the separation token in the vocabulary, to separate context and query in an input
        sequence. Returns `None` if the token has not been set.
        """
        if self._sep_token is None:
            return None
        return self.convert_tokens_to_ids(self.sep_token)

    @property
    def pad_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the padding token in the vocabulary. Returns `None` if the token has not been set.
        """
        if self._pad_token is None:
            return None
        return self.convert_tokens_to_ids(self.pad_token)

    @property
    def pad_token_type_id(self) -> int:
        """
        `int`: Id of the padding token type in the vocabulary.
        """
        return self._pad_token_type_id

    @property
    def cls_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the classification token in the vocabulary, to extract a summary of an input sequence
        leveraging self-attention along the full depth of the model.

        Returns `None` if the token has not been set.
        """
        if self._cls_token is None:
            return None
        return self.convert_tokens_to_ids(self.cls_token)

    @property
    def mask_token_id(self) -> Optional[int]:
        """
        `Optional[int]`: Id of the mask token in the vocabulary, used when training a model with masked-language
        modeling. Returns `None` if the token has not been set.
        """
        if self._mask_token is None:
            return None
        return self.convert_tokens_to_ids(self.mask_token)

    @property
    def additional_special_tokens_ids(self) -> List[int]:
        """
        `List[int]`: Ids of all the additional special tokens in the vocabulary. Log an error if used while not having
        been set.
        """
        return self.convert_tokens_to_ids(self.additional_special_tokens)

    @bos_token_id.setter
    def bos_token_id(self, value):
        self._bos_token = self.convert_ids_to_tokens(value) if value is not None else None

    @eos_token_id.setter
    def eos_token_id(self, value):
        self._eos_token = self.convert_ids_to_tokens(value) if value is not None else None

    @unk_token_id.setter
    def unk_token_id(self, value):
        self._unk_token = self.convert_ids_to_tokens(value) if value is not None else None

    @sep_token_id.setter
    def sep_token_id(self, value):
        self._sep_token = self.convert_ids_to_tokens(value) if value is not None else None

    @pad_token_id.setter
    def pad_token_id(self, value):
        self._pad_token = self.convert_ids_to_tokens(value) if value is not None else None

    @cls_token_id.setter
    def cls_token_id(self, value):
        self._cls_token = self.convert_ids_to_tokens(value) if value is not None else None

    @mask_token_id.setter
    def mask_token_id(self, value):
        self._mask_token = self.convert_ids_to_tokens(value) if value is not None else None

    @additional_special_tokens_ids.setter
    def additional_special_tokens_ids(self, values):
        self._additional_special_tokens = [self.convert_ids_to_tokens(value) for value in values]

    @property
    def special_tokens_map(self) -> Dict[str, Union[str, List[str]]]:
        """
        `Dict[str, Union[str, List[str]]]`: A dictionary mapping special token class attributes (`cls_token`,
        `unk_token`, etc.) to their values (`'<unk>'`, `'<cls>'`, etc.).

        Convert potential tokens of `tokenizers.AddedToken` type to string.
        """
        set_attr = {}
        for attr in self.SPECIAL_TOKENS_ATTRIBUTES:
            attr_value = getattr(self, attr)
            if attr_value:
                set_attr[attr] = attr_value
        return set_attr

    @property
    def special_tokens_map_extended(self) -> Dict[str, Union[str, AddedToken, List[Union[str, AddedToken]]]]:
        """
        `Dict[str, Union[str, tokenizers.AddedToken, List[Union[str, tokenizers.AddedToken]]]]`: A dictionary mapping
        special token class attributes (`cls_token`, `unk_token`, etc.) to their values (`'<unk>'`, `'<cls>'`, etc.).

        Don't convert tokens of `tokenizers.AddedToken` type to string so they can be used to control more finely how
        special tokens are tokenized.
        """
        set_attr = {}
        for attr in self.SPECIAL_TOKENS_ATTRIBUTES:
            attr_value = getattr(self, "_" + attr)
            if attr_value:
                set_attr[attr] = attr_value
        return set_attr

    @property
    def all_special_tokens_extended(self) -> List[Union[str, AddedToken]]:
        """
        `List[Union[str, tokenizers.AddedToken]]`: All the special tokens (`'<unk>'`, `'<cls>'`, etc.), the order has
        nothing to do with the index of each tokens. If you want to know the correct indices, check
        `self.added_tokens_encoder`. We can't create an order anymore as the keys are `AddedTokens` and not `Strings`.

        Don't convert tokens of `tokenizers.AddedToken` type to string so they can be used to control more finely how
        special tokens are tokenized.
        """
        all_tokens = []
        seen = set()
        for value in self.special_tokens_map_extended.values():
            if isinstance(value, (list, tuple)):
                tokens_to_add = [token for token in value if str(token) not in seen]
            else:
                tokens_to_add = [value] if str(value) not in seen else []
            seen.update(map(str, tokens_to_add))
            all_tokens.extend(tokens_to_add)
        return all_tokens

    @property
    def all_special_tokens(self) -> List[str]:
        """
        `List[str]`: A list of the unique special tokens (`'<unk>'`, `'<cls>'`, ..., etc.).

        Convert tokens of `tokenizers.AddedToken` type to string.
        """
        all_toks = [str(s) for s in self.all_special_tokens_extended]
        return all_toks

    @property
    def all_special_ids(self) -> List[int]:
        """
        `List[int]`: List the ids of the special tokens(`'<unk>'`, `'<cls>'`, etc.) mapped to class attributes.
        """
        all_toks = self.all_special_tokens
        all_ids = self.convert_tokens_to_ids(all_toks)
        return all_ids


ENCODE_KWARGS_DOCSTRING = r"""
            add_special_tokens (`bool`, *optional*, defaults to `True`):
                Whether or not to add special tokens when encoding the sequences. This will use the underlying
                `PretrainedTokenizerBase.build_inputs_with_special_tokens` function, which defines which tokens are
                automatically added to the input ids. This is usefull if you want to add `bos` or `eos` tokens
                automatically.
            padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `False`):
                Activates and controls padding. Accepts the following values:

                - `True` or `'longest'`: Pad to the longest sequence in the batch (or no padding if only a single
                  sequence if provided).
                - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
                  acceptable input length for the model if that argument is not provided.
                - `False` or `'do_not_pad'` (default): No padding (i.e., can output a batch with sequences of different
                  lengths).
            truncation (`bool`, `str` or [`~tokenization_utils_base.TruncationStrategy`], *optional*, defaults to `False`):
                Activates and controls truncation. Accepts the following values:

                - `True` or `'longest_first'`: Truncate to a maximum length specified with the argument `max_length` or
                  to the maximum acceptable input length for the model if that argument is not provided. This will
                  truncate token by token, removing a token from the longest sequence in the pair if a pair of
                  sequences (or a batch of pairs) is provided.
                - `'only_first'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the first sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `'only_second'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the second sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `False` or `'do_not_truncate'` (default): No truncation (i.e., can output batch with sequence lengths
                  greater than the model maximum admissible input size).
            max_length (`int`, *optional*):
                Controls the maximum length to use by one of the truncation/padding parameters.

                If left unset or set to `None`, this will use the predefined model maximum length if a maximum length
                is required by one of the truncation/padding parameters. If the model has no specific maximum input
                length (like XLNet) truncation/padding to a maximum length will be deactivated.
            stride (`int`, *optional*, defaults to 0):
                If set to a number along with `max_length`, the overflowing tokens returned when
                `return_overflowing_tokens=True` will contain some tokens from the end of the truncated sequence
                returned to provide some overlap between truncated and overflowing sequences. The value of this
                argument defines the number of overlapping tokens.
            is_split_into_words (`bool`, *optional*, defaults to `False`):
                Whether or not the input is already pre-tokenized (e.g., split into words). If set to `True`, the
                tokenizer assumes the input is already split into words (for instance, by splitting it on whitespace)
                which it will tokenize. This is useful for NER or token classification.
            pad_to_multiple_of (`int`, *optional*):
                If set will pad the sequence to a multiple of the provided value. Requires `padding` to be activated.
                This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability
                `>= 7.5` (Volta).
            return_tensors (`str` or [`~utils.TensorType`], *optional*):
                If set, will return tensors instead of list of python integers. Acceptable values are:

                - `'tf'`: Return TensorFlow `tf.constant` objects.
                - `'pt'`: Return PyTorch `torch.Tensor` objects.
                - `'np'`: Return Numpy `np.ndarray` objects.
"""

ENCODE_PLUS_ADDITIONAL_KWARGS_DOCSTRING = r"""
            return_token_type_ids (`bool`, *optional*):
                Whether to return token type IDs. If left to the default, will return the token type IDs according to
                the specific tokenizer's default, defined by the `return_outputs` attribute.

                [What are token type IDs?](../glossary#token-type-ids)
            return_attention_mask (`bool`, *optional*):
                Whether to return the attention mask. If left to the default, will return the attention mask according
                to the specific tokenizer's default, defined by the `return_outputs` attribute.

                [What are attention masks?](../glossary#attention-mask)
            return_overflowing_tokens (`bool`, *optional*, defaults to `False`):
                Whether or not to return overflowing token sequences. If a pair of sequences of input ids (or a batch
                of pairs) is provided with `truncation_strategy = longest_first` or `True`, an error is raised instead
                of returning overflowing tokens.
            return_special_tokens_mask (`bool`, *optional*, defaults to `False`):
                Whether or not to return special tokens mask information.
            return_offsets_mapping (`bool`, *optional*, defaults to `False`):
                Whether or not to return `(char_start, char_end)` for each token.

                This is only available on fast tokenizers inheriting from [`PreTrainedTokenizerFast`], if using
                Python's tokenizer, this method will raise `NotImplementedError`.
            return_length  (`bool`, *optional*, defaults to `False`):
                Whether or not to return the lengths of the encoded inputs.
            verbose (`bool`, *optional*, defaults to `True`):
                Whether or not to print more information and warnings.
            **kwargs: passed to the `self.tokenize()` method

        Return:
            [`BatchEncoding`]: A [`BatchEncoding`] with the following fields:

            - **input_ids** -- List of token ids to be fed to a model.

              [What are input IDs?](../glossary#input-ids)

            - **token_type_ids** -- List of token type ids to be fed to a model (when `return_token_type_ids=True` or
              if *"token_type_ids"* is in `self.model_input_names`).

              [What are token type IDs?](../glossary#token-type-ids)

            - **attention_mask** -- List of indices specifying which tokens should be attended to by the model (when
              `return_attention_mask=True` or if *"attention_mask"* is in `self.model_input_names`).

              [What are attention masks?](../glossary#attention-mask)

            - **overflowing_tokens** -- List of overflowing tokens sequences (when a `max_length` is specified and
              `return_overflowing_tokens=True`).
            - **num_truncated_tokens** -- Number of tokens truncated (when a `max_length` is specified and
              `return_overflowing_tokens=True`).
            - **special_tokens_mask** -- List of 0s and 1s, with 1 specifying added special tokens and 0 specifying
              regular sequence tokens (when `add_special_tokens=True` and `return_special_tokens_mask=True`).
            - **length** -- The length of the inputs (when `return_length=True`)
"""


INIT_TOKENIZER_DOCSTRING = r"""
    Class attributes (overridden by derived classes)

        - **vocab_files_names** (`Dict[str, str]`) -- A dictionary with, as keys, the `__init__` keyword name of each
          vocabulary file required by the model, and as associated values, the filename for saving the associated file
          (string).
        - **pretrained_vocab_files_map** (`Dict[str, Dict[str, str]]`) -- A dictionary of dictionaries, with the
          high-level keys being the `__init__` keyword name of each vocabulary file required by the model, the
          low-level being the `short-cut-names` of the pretrained models with, as associated values, the `url` to the
          associated pretrained vocabulary file.
        - **max_model_input_sizes** (`Dict[str, Optional[int]]`) -- A dictionary with, as keys, the `short-cut-names`
          of the pretrained models, and as associated values, the maximum length of the sequence inputs of this model,
          or `None` if the model has no maximum input size.
        - **pretrained_init_configuration** (`Dict[str, Dict[str, Any]]`) -- A dictionary with, as keys, the
          `short-cut-names` of the pretrained models, and as associated values, a dictionary of specific arguments to
          pass to the `__init__` method of the tokenizer class for this pretrained model when loading the tokenizer
          with the [`~tokenization_utils_base.PreTrainedTokenizerBase.from_pretrained`] method.
        - **model_input_names** (`List[str]`) -- A list of inputs expected in the forward pass of the model.
        - **padding_side** (`str`) -- The default value for the side on which the model should have padding applied.
          Should be `'right'` or `'left'`.
        - **truncation_side** (`str`) -- The default value for the side on which the model should have truncation
          applied. Should be `'right'` or `'left'`.

    Args:
        model_max_length (`int`, *optional*):
            The maximum length (in number of tokens) for the inputs to the transformer model. When the tokenizer is
            loaded with [`~tokenization_utils_base.PreTrainedTokenizerBase.from_pretrained`], this will be set to the
            value stored for the associated model in `max_model_input_sizes` (see above). If no value is provided, will
            default to VERY_LARGE_INTEGER (`int(1e30)`).
        padding_side (`str`, *optional*):
            The side on which the model should have padding applied. Should be selected between ['right', 'left'].
            Default value is picked from the class attribute of the same name.
        truncation_side (`str`, *optional*):
            The side on which the model should have truncation applied. Should be selected between ['right', 'left'].
            Default value is picked from the class attribute of the same name.
        chat_template (`str`, *optional*):
            A Jinja template string that will be used to format lists of chat messages. See
            https://huggingface.co/docs/transformers/chat_templating for a full description.
        model_input_names (`List[string]`, *optional*):
            The list of inputs accepted by the forward pass of the model (like `"token_type_ids"` or
            `"attention_mask"`). Default value is picked from the class attribute of the same name.
        bos_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the beginning of a sentence. Will be associated to `self.bos_token` and
            `self.bos_token_id`.
        eos_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the end of a sentence. Will be associated to `self.eos_token` and
            `self.eos_token_id`.
        unk_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing an out-of-vocabulary token. Will be associated to `self.unk_token` and
            `self.unk_token_id`.
        sep_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token separating two different sentences in the same input (used by BERT for instance). Will be
            associated to `self.sep_token` and `self.sep_token_id`.
        pad_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token used to make arrays of tokens the same size for batching purpose. Will then be ignored by
            attention mechanisms or loss computation. Will be associated to `self.pad_token` and `self.pad_token_id`.
        cls_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing the class of the input (used by BERT for instance). Will be associated to
            `self.cls_token` and `self.cls_token_id`.
        mask_token (`str` or `tokenizers.AddedToken`, *optional*):
            A special token representing a masked token (used by masked-language modeling pretraining objectives, like
            BERT). Will be associated to `self.mask_token` and `self.mask_token_id`.
        additional_special_tokens (tuple or list of `str` or `tokenizers.AddedToken`, *optional*):
            A tuple or a list of additional special tokens. Add them here to ensure they are skipped when decoding with
            `skip_special_tokens` is set to True. If they are not part of the vocabulary, they will be added at the end
            of the vocabulary.
        clean_up_tokenization_spaces (`bool`, *optional*, defaults to `True`):
            Whether or not the model should cleanup the spaces that were added when splitting the input text during the
            tokenization process.
        split_special_tokens (`bool`, *optional*, defaults to `False`):
            Whether or not the special tokens should be split during the tokenization process. The default behavior is
            to not split special tokens. This means that if `<s>` is the `bos_token`, then `tokenizer.tokenize("<s>") =
            ['<s>`]. Otherwise, if `split_special_tokens=True`, then `tokenizer.tokenize("<s>")` will be give `['<',
            's', '>']`. This argument is only supported for `slow` tokenizers for the moment.
"""


@add_end_docstrings(INIT_TOKENIZER_DOCSTRING)
class PreTrainedTokenizerBase(SpecialTokensMixin, PushToHubMixin):
    """
    Base class for [`PreTrainedTokenizer`] and [`PreTrainedTokenizerFast`].

    Handles shared (mostly boiler plate) methods for those two classes.
    """

    vocab_files_names: Dict[str, str] = {}
    pretrained_vocab_files_map: Dict[str, Dict[str, str]] = {}
    pretrained_init_configuration: Dict[str, Dict[str, Any]] = {}
    max_model_input_sizes: Dict[str, Optional[int]] = {}
    _auto_class: Optional[str] = None

    # first name has to correspond to main model input name
    # to make sure `tokenizer.pad(...)` works correctly
    model_input_names: List[str] = ["input_ids", "token_type_ids", "attention_mask"]
    padding_side: str = "right"
    truncation_side: str = "right"
    slow_tokenizer_class = None

    def __init__(self, **kwargs):
        # inputs and kwargs for saving and re-loading (see ``from_pretrained`` and ``save_pretrained``)
        self.init_inputs = ()
        self.init_kwargs = copy.deepcopy(kwargs)
        self.name_or_path = kwargs.pop("name_or_path", "")
        self._processor_class = kwargs.pop("processor_class", None)

        # For backward compatibility we fallback to set model_max_length from max_len if provided
        model_max_length = kwargs.pop("model_max_length", kwargs.pop("max_len", None))
        self.model_max_length = model_max_length if model_max_length is not None else VERY_LARGE_INTEGER

        # Padding and truncation side are right by default and overridden in subclasses. If specified in the kwargs, it
        # is changed.
        self.padding_side = kwargs.pop("padding_side", self.padding_side)
        if self.padding_side not in ["right", "left"]:
            raise ValueError(
                f"Padding side should be selected between 'right' and 'left', current value: {self.padding_side}"
            )

        self.truncation_side = kwargs.pop("truncation_side", self.truncation_side)
        if self.truncation_side not in ["right", "left"]:
            raise ValueError(
                f"Padding side should be selected between 'right' and 'left', current value: {self.truncation_side}"
            )

        self.model_input_names = kwargs.pop("model_input_names", self.model_input_names)

        # By default, cleaning tokenization spaces for both fast and slow tokenizers
        self.clean_up_tokenization_spaces = kwargs.pop("clean_up_tokenization_spaces", True)

        # By default, do not split special tokens for both fast and slow tokenizers
        self.split_special_tokens = kwargs.pop("split_special_tokens", False)

        self.deprecation_warnings = (
            {}
        )  # Use to store when we have already noticed a deprecation warning (avoid overlogging).
        self._in_target_context_manager = False

        # Stores a Jinja template that formats chat histories into tokenizable strings
        self.chat_template = kwargs.pop("chat_template", None)

        super().__init__(**kwargs)

    @property
    def max_len_single_sentence(self) -> int:
        """
        `int`: The maximum length of a sentence that can be fed to the model.
        """
        return self.model_max_length - self.num_special_tokens_to_add(pair=False)

    @property
    def max_len_sentences_pair(self) -> int:
        """
        `int`: The maximum combined length of a pair of sentences that can be fed to the model.
        """
        return self.model_max_length - self.num_special_tokens_to_add(pair=True)

    @max_len_single_sentence.setter
    def max_len_single_sentence(self, value) -> int:
        # For backward compatibility, allow to try to setup 'max_len_single_sentence'.
        if value == self.model_max_length - self.num_special_tokens_to_add(pair=False) and self.verbose:
            if not self.deprecation_warnings.get("max_len_single_sentence", False):
                logger.warning(
                    "Setting 'max_len_single_sentence' is now deprecated. This value is automatically set up."
                )
            self.deprecation_warnings["max_len_single_sentence"] = True
        else:
            raise ValueError(
                "Setting 'max_len_single_sentence' is now deprecated. This value is automatically set up."
            )

    @max_len_sentences_pair.setter
    def max_len_sentences_pair(self, value) -> int:
        # For backward compatibility, allow to try to setup 'max_len_sentences_pair'.
        if value == self.model_max_length - self.num_special_tokens_to_add(pair=True) and self.verbose:
            if not self.deprecation_warnings.get("max_len_sentences_pair", False):
                logger.warning(
                    "Setting 'max_len_sentences_pair' is now deprecated. This value is automatically set up."
                )
            self.deprecation_warnings["max_len_sentences_pair"] = True
        else:
            raise ValueError("Setting 'max_len_sentences_pair' is now deprecated. This value is automatically set up.")

    def _set_processor_class(self, processor_class: str):
        """Sets processor class as an attribute."""
        self._processor_class = processor_class

    @property
    def added_tokens_decoder(self) -> Dict[int, AddedToken]:
        raise NotImplementedError()

    def __repr__(self) -> str:
        added_tokens_decoder_rep = "\n\t".join([f"{k}: {v.__repr__()}," for k, v in self.added_tokens_decoder.items()])
        return (
            f"{self.__class__.__name__}(name_or_path='{self.name_or_path}',"
            f" vocab_size={self.vocab_size}, model_max_length={self.model_max_length}, is_fast={self.is_fast},"
            f" padding_side='{self.padding_side}', truncation_side='{self.truncation_side}',"
            f" special_tokens={self.special_tokens_map}, clean_up_tokenization_spaces={self.clean_up_tokenization_spaces}), "
            " added_tokens_decoder={\n\t" + added_tokens_decoder_rep + "\n}"
        )

    def __len__(self) -> int:
        raise NotImplementedError()

    def get_vocab(self) -> Dict[str, int]:
        """
        Returns the vocabulary as a dictionary of token to index.

        `tokenizer.get_vocab()[token]` is equivalent to `tokenizer.convert_tokens_to_ids(token)` when `token` is in the
        vocab.

        Returns:
            `Dict[str, int]`: The vocabulary.
        """
        raise NotImplementedError()

    def apply_chat_template(
        self,
        conversation: Union[List[Dict[str, str]], "Conversation"],
        chat_template: Optional[str] = None,
        tokenize: bool = True,
        padding: bool = False,
        truncation: bool = False,
        max_length: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        **tokenizer_kwargs,
    ) -> Union[str, List[int]]:
        """
        Converts a Conversation object or a list of dictionaries with `"role"` and `"content"` keys to a list of token
        ids. This method is intended for use with chat models, and will read the tokenizer's chat_template attribute to
        determine the format and control tokens to use when converting. When chat_template is None, it will fall back
        to the default_chat_template specified at the class level.

        Args:
            conversation (Union[List[Dict[str, str]], "Conversation"]): A Conversation object or list of dicts
                with "role" and "content" keys, representing the chat history so far.
            chat_template (str, *optional*): A Jinja template to use for this conversion. If
                this is not passed, the model's default chat template will be used instead.
            tokenize (`bool`, defaults to `True`):
                Whether to tokenize the output. If `False`, the output will be a string.
            padding (`bool`, defaults to `False`):
                Whether to pad sequences to the maximum length. Has no effect if tokenize is `False`.
            truncation (`bool`, defaults to `False`):
                Whether to truncate sequences at the maximum length. Has no effect if tokenize is `False`.
            max_length (`int`, *optional*):
                Maximum length (in tokens) to use for padding or truncation. Has no effect if tokenize is `False`. If
                not specified, the tokenizer's `max_length` attribute will be used as a default.
            return_tensors (`str` or [`~utils.TensorType`], *optional*):
                If set, will return tensors of a particular framework. Has no effect if tokenize is `False`. Acceptable
                values are:
                - `'tf'`: Return TensorFlow `tf.Tensor` objects.
                - `'pt'`: Return PyTorch `torch.Tensor` objects.
                - `'np'`: Return NumPy `np.ndarray` objects.
                - `'jax'`: Return JAX `jnp.ndarray` objects.
            **tokenizer_kwargs: Additional kwargs to pass to the tokenizer.

        Returns:
            `List[int]`: A list of token ids representing the tokenized chat so far, including control tokens. This
            output is ready to pass to the model, either directly or via methods like `generate()`.
        """

        if hasattr(conversation, "messages"):
            # Indicates it's a Conversation object
            conversation = conversation.messages

        # priority: `chat_template` argument > `tokenizer.chat_template` > `tokenizer.default_chat_template`
        if chat_template is None:
            if self.chat_template is not None:
                chat_template = self.chat_template
            else:
                chat_template = self.default_chat_template

        # Compilation function uses a cache to avoid recompiling the same template
        compiled_template = self._compile_jinja_template(chat_template)

        rendered = compiled_template.render(messages=conversation, **self.special_tokens_map)

        if padding is True:
            padding = "max_length"  # There's only one sequence here, so "longest" makes no sense
        if tokenize:
            return self.encode(
                rendered,
                add_special_tokens=False,
                padding=padding,
                truncation=truncation,
                max_length=max_length,
                return_tensors=return_tensors,
                **tokenizer_kwargs,
            )
        else:
            return rendered

    @lru_cache
    def _compile_jinja_template(self, chat_template):
        try:
            from jinja2.exceptions import TemplateError
            from jinja2.sandbox import ImmutableSandboxedEnvironment
        except ImportError:
            raise ImportError("apply_chat_template requires jinja2 to be installed.")

        def raise_exception(message):
            raise TemplateError(message)

        jinja_env = ImmutableSandboxedEnvironment(trim_blocks=True, lstrip_blocks=True)
        jinja_env.globals["raise_exception"] = raise_exception
        return jinja_env.from_string(chat_template)

    @property
    def default_chat_template(self):
        """
        This template formats inputs in the standard ChatML format. See
        https://github.com/openai/openai-python/blob/main/chatml.md
        """
        return (
            "{% for message in messages %}"
            "{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}"
            "{% endfor %}"
        )

    @classmethod
    def from_pretrained(
        cls,
        pretrained_model_name_or_path: Union[str, os.PathLike],
        *init_inputs,
        cache_dir: Optional[Union[str, os.PathLike]] = None,
        force_download: bool = False,
        local_files_only: bool = False,
        token: Optional[Union[str, bool]] = None,
        revision: str = "main",
        **kwargs,
    ):
        r"""
        Instantiate a [`~tokenization_utils_base.PreTrainedTokenizerBase`] (or a derived class) from a predefined
        tokenizer.

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

                - A string, the *model id* of a predefined tokenizer 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 vocabulary files required by the tokenizer, for instance saved
                  using the [`~tokenization_utils_base.PreTrainedTokenizerBase.save_pretrained`] method, e.g.,
                  `./my_model_directory/`.
                - (**Deprecated**, not applicable to all derived classes) A path or url to a single saved vocabulary
                  file (if and only if the tokenizer only requires a single vocabulary file like Bert or XLNet), e.g.,
                  `./my_model_directory/vocab.txt`.
            cache_dir (`str` or `os.PathLike`, *optional*):
                Path to a directory in which a downloaded predefined tokenizer vocabulary files should be cached if the
                standard cache should not be used.
            force_download (`bool`, *optional*, defaults to `False`):
                Whether or not to force the (re-)download the vocabulary files and override the cached versions if they
                exist.
            resume_download (`bool`, *optional*, defaults to `False`):
                Whether or not to delete incompletely received files. 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.
            token (`str` or *bool*, *optional*):
                The token to use as HTTP bearer authorization for remote files. If `True`, will use the token generated
                when running `huggingface-cli login` (stored in `~/.huggingface`).
            local_files_only (`bool`, *optional*, defaults to `False`):
                Whether or not to only rely on local files and not to attempt to download any files.
            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.
            subfolder (`str`, *optional*):
                In case the relevant files are located inside a subfolder of the model repo on huggingface.co (e.g. for
                facebook/rag-token-base), specify it here.
            inputs (additional positional arguments, *optional*):
                Will be passed along to the Tokenizer `__init__` method.
            kwargs (additional keyword arguments, *optional*):
                Will be passed to the Tokenizer `__init__` method. Can be used to set special tokens like `bos_token`,
                `eos_token`, `unk_token`, `sep_token`, `pad_token`, `cls_token`, `mask_token`,
                `additional_special_tokens`. See parameters in the `__init__` for more details.

        <Tip>

        Passing `token=True` is required when you want to use a private model.

        </Tip>

        Examples:

        ```python
        # We can't instantiate directly the base class *PreTrainedTokenizerBase* so let's show our examples on a derived class: BertTokenizer
        # Download vocabulary from huggingface.co and cache.
        tokenizer = BertTokenizer.from_pretrained("bert-base-uncased")

        # Download vocabulary from huggingface.co (user-uploaded) and cache.
        tokenizer = BertTokenizer.from_pretrained("dbmdz/bert-base-german-cased")

        # If vocabulary files are in a directory (e.g. tokenizer was saved using *save_pretrained('./test/saved_model/')*)
        tokenizer = BertTokenizer.from_pretrained("./test/saved_model/")

        # If the tokenizer uses a single vocabulary file, you can point directly to this file
        tokenizer = BertTokenizer.from_pretrained("./test/saved_model/my_vocab.txt")

        # You can link tokens to special vocabulary when instantiating
        tokenizer = BertTokenizer.from_pretrained("bert-base-uncased", unk_token="<unk>")
        # You should be sure '<unk>' is in the vocabulary when doing that.
        # Otherwise use tokenizer.add_special_tokens({'unk_token': '<unk>'}) instead)
        assert tokenizer.unk_token == "<unk>"
        ```"""
        resume_download = kwargs.pop("resume_download", False)
        proxies = kwargs.pop("proxies", None)
        use_auth_token = kwargs.pop("use_auth_token", None)
        subfolder = kwargs.pop("subfolder", None)
        from_pipeline = kwargs.pop("_from_pipeline", None)
        from_auto_class = kwargs.pop("_from_auto", False)
        commit_hash = kwargs.pop("_commit_hash", 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

        user_agent = {"file_type": "tokenizer", "from_auto_class": from_auto_class, "is_fast": "Fast" in cls.__name__}
        if from_pipeline is not None:
            user_agent["using_pipeline"] = from_pipeline

        if is_offline_mode() and not local_files_only:
            logger.info("Offline mode: forcing local_files_only=True")
            local_files_only = True

        pretrained_model_name_or_path = str(pretrained_model_name_or_path)
        vocab_files = {}
        init_configuration = {}

        is_local = os.path.isdir(pretrained_model_name_or_path)
        single_file_id = None
        if os.path.isfile(pretrained_model_name_or_path) or is_remote_url(pretrained_model_name_or_path):
            if len(cls.vocab_files_names) > 1:
                raise ValueError(
                    f"Calling {cls.__name__}.from_pretrained() with the path to a single file or url is not "
                    "supported for this tokenizer. Use a model identifier or the path to a directory instead."
                )
            warnings.warn(
                f"Calling {cls.__name__}.from_pretrained() with the path to a single file or url is deprecated and "
                "won't be possible anymore in v5. Use a model identifier or the path to a directory instead.",
                FutureWarning,
            )
            file_id = list(cls.vocab_files_names.keys())[0]

            vocab_files[file_id] = pretrained_model_name_or_path
            single_file_id = file_id
        else:
            # At this point pretrained_model_name_or_path is either a directory or a model identifier name
            additional_files_names = {
                "added_tokens_file": ADDED_TOKENS_FILE,  # kept only for legacy
                "special_tokens_map_file": SPECIAL_TOKENS_MAP_FILE,  # kept only for legacy
                "tokenizer_config_file": TOKENIZER_CONFIG_FILE,
                # tokenizer_file used to initialize a slow from a fast. Properly copy the `addedTokens` instead of adding in random orders
                "tokenizer_file": FULL_TOKENIZER_FILE,
            }
            vocab_files = {**cls.vocab_files_names, **additional_files_names}
            if "tokenizer_file" in vocab_files:
                # Try to get the tokenizer config to see if there are versioned tokenizer files.
                fast_tokenizer_file = FULL_TOKENIZER_FILE
                resolved_config_file = cached_file(
                    pretrained_model_name_or_path,
                    TOKENIZER_CONFIG_FILE,
                    cache_dir=cache_dir,
                    force_download=force_download,
                    resume_download=resume_download,
                    proxies=proxies,
                    token=token,
                    revision=revision,
                    local_files_only=local_files_only,
                    subfolder=subfolder,
                    user_agent=user_agent,
                    _raise_exceptions_for_missing_entries=False,
                    _raise_exceptions_for_connection_errors=False,
                    _commit_hash=commit_hash,
                )
                commit_hash = extract_commit_hash(resolved_config_file, commit_hash)
                if resolved_config_file is not None:
                    with open(resolved_config_file, encoding="utf-8") as reader:
                        tokenizer_config = json.load(reader)
                        if "fast_tokenizer_files" in tokenizer_config:
                            fast_tokenizer_file = get_fast_tokenizer_file(tokenizer_config["fast_tokenizer_files"])
                vocab_files["tokenizer_file"] = fast_tokenizer_file

        # Get files from url, cache, or disk depending on the case
        resolved_vocab_files = {}
        unresolved_files = []
        for file_id, file_path in vocab_files.items():
            if file_path is None:
                resolved_vocab_files[file_id] = None
            elif single_file_id == file_id:
                if os.path.isfile(file_path):
                    resolved_vocab_files[file_id] = file_path
                elif is_remote_url(file_path):
                    resolved_vocab_files[file_id] = download_url(file_path, proxies=proxies)
            else:
                resolved_vocab_files[file_id] = cached_file(
                    pretrained_model_name_or_path,
                    file_path,
                    cache_dir=cache_dir,
                    force_download=force_download,
                    proxies=proxies,
                    resume_download=resume_download,
                    local_files_only=local_files_only,
                    token=token,
                    user_agent=user_agent,
                    revision=revision,
                    subfolder=subfolder,
                    _raise_exceptions_for_missing_entries=False,
                    _raise_exceptions_for_connection_errors=False,
                    _commit_hash=commit_hash,
                )
                commit_hash = extract_commit_hash(resolved_vocab_files[file_id], commit_hash)

        if len(unresolved_files) > 0:
            logger.info(
                f"Can't load following files from cache: {unresolved_files} and cannot check if these "
                "files are necessary for the tokenizer to operate."
            )

        if all(full_file_name is None for full_file_name in resolved_vocab_files.values()):
            raise EnvironmentError(
                f"Can't load tokenizer for '{pretrained_model_name_or_path}'. If you were trying to load it from "
                "'https://huggingface.co/models', make sure you don't have a local directory with the same name. "
                f"Otherwise, make sure '{pretrained_model_name_or_path}' is the correct path to a directory "
                f"containing all relevant files for a {cls.__name__} tokenizer."
            )

        for file_id, file_path in vocab_files.items():
            if file_id not in resolved_vocab_files:
                continue

            if is_local:
                logger.info(f"loading file {file_path}")
            else:
                logger.info(f"loading file {file_path} from cache at {resolved_vocab_files[file_id]}")

        return cls._from_pretrained(
            resolved_vocab_files,
            pretrained_model_name_or_path,
            init_configuration,
            *init_inputs,
            token=token,
            cache_dir=cache_dir,
            local_files_only=local_files_only,
            _commit_hash=commit_hash,
            _is_local=is_local,
            **kwargs,
        )

    @classmethod
    def _from_pretrained(
        cls,
        resolved_vocab_files,
        pretrained_model_name_or_path,
        init_configuration,
        *init_inputs,
        token=None,
        cache_dir=None,
        local_files_only=False,
        _commit_hash=None,
        _is_local=False,
        **kwargs,
    ):
        # We instantiate fast tokenizers based on a slow tokenizer if we don't have access to the tokenizer.json
        # file or if `from_slow` is set to True.
        from_slow = kwargs.get("from_slow", False)
        has_tokenizer_file = resolved_vocab_files.get("tokenizer_file", None) is not None
        if (from_slow or not has_tokenizer_file) and cls.slow_tokenizer_class is not None:
            slow_tokenizer = (cls.slow_tokenizer_class)._from_pretrained(
                copy.deepcopy(resolved_vocab_files),
                pretrained_model_name_or_path,
                copy.deepcopy(init_configuration),
                *init_inputs,
                token=token,
                cache_dir=cache_dir,
                local_files_only=local_files_only,
                _commit_hash=_commit_hash,
                **(copy.deepcopy(kwargs)),
            )
        else:
            slow_tokenizer = None

        # Prepare tokenizer initialization kwargs
        # Did we saved some inputs and kwargs to reload ?
        tokenizer_config_file = resolved_vocab_files.pop("tokenizer_config_file", None)
        if tokenizer_config_file is not None:
            with open(tokenizer_config_file, encoding="utf-8") as tokenizer_config_handle:
                init_kwargs = json.load(tokenizer_config_handle)
            # First attempt. We get tokenizer_class from tokenizer_config to check mismatch between tokenizers.
            config_tokenizer_class = init_kwargs.get("tokenizer_class")
            init_kwargs.pop("tokenizer_class", None)
            if not has_tokenizer_file:
                init_kwargs.pop("tokenizer_file", None)
            saved_init_inputs = init_kwargs.pop("init_inputs", ())
            if not init_inputs:
                init_inputs = saved_init_inputs
        else:
            config_tokenizer_class = None
            init_kwargs = init_configuration

        if "auto_map" in init_kwargs and not _is_local:
            # For backward compatibility with odl format.
            if isinstance(init_kwargs["auto_map"], (tuple, list)):
                init_kwargs["auto_map"] = {"AutoTokenizer": init_kwargs["auto_map"]}
            init_kwargs["auto_map"] = add_model_info_to_auto_map(
                init_kwargs["auto_map"], pretrained_model_name_or_path
            )

        if config_tokenizer_class is None:
            from .models.auto.configuration_auto import AutoConfig  # tests_ignore

            # Second attempt. If we have not yet found tokenizer_class, let's try to use the config.
            try:
                config = AutoConfig.from_pretrained(
                    pretrained_model_name_or_path,
                    token=token,
                    cache_dir=cache_dir,
                    local_files_only=local_files_only,
                    _commit_hash=_commit_hash,
                )
                config_tokenizer_class = config.tokenizer_class
            except (OSError, ValueError, KeyError):
                # skip if an error occurred.
                config = None
            if config_tokenizer_class is None:
                # Third attempt. If we have not yet found the original type of the tokenizer,
                # we are loading we see if we can infer it from the type of the configuration file
                from .models.auto.tokenization_auto import TOKENIZER_MAPPING_NAMES  # tests_ignore

                if hasattr(config, "model_type"):
                    model_type = config.model_type
                else:
                    # Fallback: use pattern matching on the string.
                    model_type = None
                    for pattern in TOKENIZER_MAPPING_NAMES.keys():
                        if pattern in str(pretrained_model_name_or_path):
                            model_type = pattern
                            break

                if model_type is not None:
                    config_tokenizer_class, config_tokenizer_class_fast = TOKENIZER_MAPPING_NAMES.get(
                        model_type, (None, None)
                    )
                    if config_tokenizer_class is None:
                        config_tokenizer_class = config_tokenizer_class_fast

        if config_tokenizer_class is not None:
            if cls.__name__.replace("Fast", "") != config_tokenizer_class.replace("Fast", ""):
                logger.warning(
                    "The tokenizer class you load from this checkpoint is not the same type as the class this"
                    " function is called from. It may result in unexpected tokenization. \nThe tokenizer class you"
                    f" load from this checkpoint is '{config_tokenizer_class}'. \nThe class this function is called"
                    f" from is '{cls.__name__}'."
                )

        # Update with newly provided kwargs
        init_kwargs.update(kwargs)

        # Set max length if needed
        if pretrained_model_name_or_path in cls.max_model_input_sizes:
            # if we're using a pretrained model, ensure the tokenizer
            # wont index sequences longer than the number of positional embeddings

            model_max_length = cls.max_model_input_sizes[pretrained_model_name_or_path]
            if model_max_length is not None and isinstance(model_max_length, (int, float)):
                model_max_length = min(init_kwargs.get("model_max_length", int(1e30)), model_max_length)
                # TODO(PVP) - uncomment following line in Transformers v5
                # init_kwargs["model_max_length"] = model_max_length
                # TODO(PVP) - remove in Transformers v5
                # ---
                init_kwargs["model_max_length"] = cls._eventually_correct_t5_max_length(
                    pretrained_model_name_or_path, model_max_length, init_kwargs.get("model_max_length")
                )
                # ---

        # Merge resolved_vocab_files arguments in init_kwargs.
        added_tokens_file = resolved_vocab_files.pop("added_tokens_file", None)
        special_tokens_map_file = resolved_vocab_files.pop("special_tokens_map_file", None)
        for args_name, file_path in resolved_vocab_files.items():
            if args_name not in init_kwargs:
                init_kwargs[args_name] = file_path

        if slow_tokenizer is not None:
            init_kwargs["__slow_tokenizer"] = slow_tokenizer
        init_kwargs["name_or_path"] = pretrained_model_name_or_path

        additional_special_tokens = init_kwargs.pop("additional_special_tokens", None) or []
        added_tokens_decoder = {}
        legacy_saved = "added_tokens_decoder" not in init_kwargs
        if not legacy_saved:
            for idx, token in init_kwargs["added_tokens_decoder"].items():
                if isinstance(token, dict):
                    token = AddedToken(**token)
                if isinstance(token, AddedToken):
                    added_tokens_decoder[int(idx)] = token
                    if str(token) in additional_special_tokens:
                        # at this point the token is in `additional_special_tokens` as an str, let's add the AddedToken info
                        additional_special_tokens.remove(str(token))
                    if token.special and token not in additional_special_tokens:
                        additional_special_tokens.append(token)
                else:
                    raise ValueError(
                        f"Found a {token.__class__} in the saved `added_tokens_decoder`, should be a dictionary."
                    )
        else:
            # begin legacy: read the added_tokens_file and update kwargs with special_tokens_map if modified
            if special_tokens_map_file is not None:
                with open(special_tokens_map_file, encoding="utf-8") as special_tokens_map_handle:
                    special_tokens_map = json.load(special_tokens_map_handle)
                    for key, value in special_tokens_map.items():
                        if key in kwargs and kwargs[key]:
                            # This value has already been redefined by the kwargs
                            # We keep this new value and ignore the one stored in the special_tokens_map_file
                            continue
                        if isinstance(value, dict):
                            value = AddedToken(**value)
                            init_kwargs[key] = value
                        elif key == "additional_special_tokens" and isinstance(value, list):
                            for token in value:
                                token = AddedToken(**token) if isinstance(token, dict) else token
                                if token not in additional_special_tokens:
                                    additional_special_tokens.append(token)
                        else:
                            init_kwargs[key] = value
            # slow -> slow|fast, legacy: convert the `"added_tokens.json"` file to `added_tokens_decoder`.
            if added_tokens_file is not None:
                with open(added_tokens_file, encoding="utf-8") as added_tokens_handle:
                    added_tok_encoder = json.load(added_tokens_handle)
                # legacy: we have to init with (rstrip=True, lstrip=True)
                strip = True if "Fast" not in cls.__name__ else False
                added_tokens_decoder = {
                    index: AddedToken(token, rstrip=strip, lstrip=strip) for token, index in added_tok_encoder.items()
                }
            # end legacy

        # slow -> fast, non-legacy: we need to make sure the `added_tokens_decoder` is used to add tokens if the `fast` was not properly saved!
        # thus we delay adding special tokens in the init using `slow_to_fast` flag.
        if added_tokens_decoder is not {} and "Fast" in cls.__name__:
            init_kwargs["slow_to_fast"] = True
        if len(additional_special_tokens) > 0:
            init_kwargs["additional_special_tokens"] = additional_special_tokens
        init_kwargs["added_tokens_decoder"] = added_tokens_decoder

        # convert {'__type': 'AddedToken', 'content': '<ent>', 'lstrip': False, 'normalized': True, ...} to AddedTokens
        init_kwargs = cls.convert_added_tokens(init_kwargs, False)
        # Instantiate the tokenizer.
        try:
            tokenizer = cls(*init_inputs, **init_kwargs)
        except OSError:
            raise OSError(
                "Unable to load vocabulary from file. "
                "Please check that the provided vocabulary is accessible and not corrupted."
            )

        # allows converting a fast -> slow: add the `tokenizer.json`'s `"added_tokens"` to the slow tokenizer
        # if `added_tokens_decoder` not in `tokenizer_config.json` and  `added_tokens.json` is `None`
        tokenizer_file = resolved_vocab_files.pop("tokenizer_file", None)
        if legacy_saved and "Fast" not in cls.__name__ and added_tokens_file is None and tokenizer_file is not None:
            tokens_to_add_from_fast = []
            with open(tokenizer_file, encoding="utf-8") as tokenizer_file_handle:
                tokenizer_file_handle = json.load(tokenizer_file_handle)
                added_tokens = tokenizer_file_handle.pop("added_tokens")
            for serialized_tokens in added_tokens:
                serialized_tokens.pop("id")
                # for legacy purpose, we ignore whether or not these tokens are special.
                serialized_tokens.pop("special")
                tokens_to_add_from_fast.append(AddedToken(**serialized_tokens))
            tokenizer.add_tokens(tokens_to_add_from_fast)

        # allows converting a slow -> fast, non-legacy: if the `tokenizer.json` does not have all the added tokens
        # uses the information stored in `added_tokens_decoder`. Checks after addition that we have the same ids
        if init_kwargs.get("slow_to_fast", False):
            tokenizer.add_tokens([token for _, token in sorted(added_tokens_decoder.items(), key=lambda x: x[0])])
            # finally we add all the special_tokens to make sure eveything is initialized
            tokenizer.add_tokens(tokenizer.all_special_tokens_extended, special_tokens=True)

        if len(added_tokens_decoder) > 0:
            logger.warning_advice(
                "Special tokens have been added in the vocabulary, make sure the associated word embeddings are"
                " fine-tuned or trained."
            )
        return tokenizer

    @staticmethod
    def _eventually_correct_t5_max_length(pretrained_model_name_or_path, max_model_length, init_max_model_length):
        # This method should be deleted in Transformers v5
        # Its only purpose is to potentially throw a warning
        # that incorrectly defined max lengths of T5's tokenizer are used
        # which we will correct in Transformers v5.
        return max_model_length

    @classmethod
    def convert_added_tokens(cls, obj: Union[AddedToken, Any], add_type_field=True):
        if isinstance(obj, dict) and "__type" in obj and obj["__type"] == "AddedToken":
            obj.pop("__type")
            return AddedToken(**obj)
        if isinstance(obj, AddedToken):
            if add_type_field:
                obj = obj.content
            return obj
        elif isinstance(obj, (list, tuple)):
            return [cls.convert_added_tokens(o, add_type_field=add_type_field) for o in obj]
        elif isinstance(obj, dict):
            return {k: cls.convert_added_tokens(v, add_type_field=add_type_field) for k, v in obj.items()}
        return obj

    def save_pretrained(
        self,
        save_directory: Union[str, os.PathLike],
        legacy_format: Optional[bool] = None,
        filename_prefix: Optional[str] = None,
        push_to_hub: bool = False,
        **kwargs,
    ) -> Tuple[str]:
        """
        Save the full tokenizer state.


        This method make sure the full tokenizer can then be re-loaded using the
        [`~tokenization_utils_base.PreTrainedTokenizer.from_pretrained`] class method..

        Warning,None This won't save modifications you may have applied to the tokenizer after the instantiation (for
        instance, modifying `tokenizer.do_lower_case` after creation).

        Args:
            save_directory (`str` or `os.PathLike`): The path to a directory where the tokenizer will be saved.
            legacy_format (`bool`, *optional*):
                Only applicable for a fast tokenizer. If unset (default), will save the tokenizer in the unified JSON
                format as well as in legacy format if it exists, i.e. with tokenizer specific vocabulary and a separate
                added_tokens files.

                If `False`, will only save the tokenizer in the unified JSON format. This format is incompatible with
                "slow" tokenizers (not powered by the *tokenizers* library), so the tokenizer will not be able to be
                loaded in the corresponding "slow" tokenizer.

                If `True`, will save the tokenizer in legacy format. If the "slow" tokenizer doesn't exits, a value
                error is raised.
            filename_prefix (`str`, *optional*):
                A prefix to add to the names of the files saved by the tokenizer.
            push_to_hub (`bool`, *optional*, defaults to `False`):
                Whether or not to push your model to the Hugging Face model hub after saving it. You can specify the
                repository you want to push to with `repo_id` (will default to the name of `save_directory` in your
                namespace).
            kwargs (`Dict[str, Any]`, *optional*):
                Additional key word arguments passed along to the [`~utils.PushToHubMixin.push_to_hub`] method.

        Returns:
            A tuple of `str`: The files saved.
        """
        use_auth_token = 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 kwargs.get("token", None) is not None:
                raise ValueError(
                    "`token` and `use_auth_token` are both specified. Please set only the argument `token`."
                )
            kwargs["token"] = use_auth_token

        if os.path.isfile(save_directory):
            logger.error(f"Provided path ({save_directory}) should be a directory, not a file")
            return

        os.makedirs(save_directory, exist_ok=True)

        if push_to_hub:
            commit_message = kwargs.pop("commit_message", None)
            repo_id = kwargs.pop("repo_id", save_directory.split(os.path.sep)[-1])
            repo_id = self._create_repo(repo_id, **kwargs)
            files_timestamps = self._get_files_timestamps(save_directory)

        special_tokens_map_file = os.path.join(
            save_directory, (filename_prefix + "-" if filename_prefix else "") + SPECIAL_TOKENS_MAP_FILE
        )
        tokenizer_config_file = os.path.join(
            save_directory, (filename_prefix + "-" if filename_prefix else "") + TOKENIZER_CONFIG_FILE
        )

        tokenizer_config = copy.deepcopy(self.init_kwargs)

        target_keys = list(self.init_kwargs.keys())
        target_keys += ["model_max_length", "clean_up_tokenization_spaces", "additional_special_tokens"]
        for k in target_keys:
            if hasattr(self, k):
                tokenizer_config[k] = getattr(self, k)

        if self.chat_template is not None:
            tokenizer_config["chat_template"] = self.chat_template

        if len(self.init_inputs) > 0:
            tokenizer_config["init_inputs"] = copy.deepcopy(self.init_inputs)
        for file_id in self.vocab_files_names.keys():
            tokenizer_config.pop(file_id, None)

        # add_type_field=True to allow dicts in the kwargs / differentiate from AddedToken serialization
        tokenizer_config = self.convert_added_tokens(tokenizer_config, add_type_field=True)

        added_tokens = {}
        for key, value in self.added_tokens_decoder.items():
            added_tokens[key] = value.__getstate__()
        tokenizer_config["added_tokens_decoder"] = added_tokens

        # Add tokenizer class to the tokenizer config to be able to reload it with from_pretrained
        tokenizer_class = self.__class__.__name__
        # Remove the Fast at the end unless we have a special `PreTrainedTokenizerFast`
        if tokenizer_class.endswith("Fast") and tokenizer_class != "PreTrainedTokenizerFast":
            tokenizer_class = tokenizer_class[:-4]
        tokenizer_config["tokenizer_class"] = tokenizer_class
        if getattr(self, "_auto_map", None) is not None:
            tokenizer_config["auto_map"] = self._auto_map
        if getattr(self, "_processor_class", None) is not None:
            tokenizer_config["processor_class"] = self._processor_class

        # If we have a custom model, we copy the file defining it in the folder and set the attributes so it can be
        # loaded from the Hub.
        if self._auto_class is not None:
            custom_object_save(self, save_directory, config=tokenizer_config)

        # remove private information
        if "name_or_path" in tokenizer_config:
            tokenizer_config.pop("name_or_path")
            tokenizer_config.pop("special_tokens_map_file", None)

        with open(tokenizer_config_file, "w", encoding="utf-8") as f:
            out_str = json.dumps(tokenizer_config, indent=2, sort_keys=True, ensure_ascii=False) + "\n"
            f.write(out_str)
        logger.info(f"tokenizer config file saved in {tokenizer_config_file}")

        # Sanitize AddedTokens in special_tokens_map

        # kept for forward compatibility, will be removed in transoformers 5
        write_dict = self.convert_added_tokens(self.special_tokens_map_extended, add_type_field=True)
        with open(special_tokens_map_file, "w", encoding="utf-8") as f:
            out_str = json.dumps(write_dict, indent=2, sort_keys=True, ensure_ascii=False) + "\n"
            f.write(out_str)
        logger.info(f"Special tokens file saved in {special_tokens_map_file}")

        file_names = (tokenizer_config_file, special_tokens_map_file)

        save_files = self._save_pretrained(
            save_directory=save_directory,
            file_names=file_names,
            legacy_format=legacy_format,
            filename_prefix=filename_prefix,
        )

        if push_to_hub:
            self._upload_modified_files(
                save_directory,
                repo_id,
                files_timestamps,
                commit_message=commit_message,
                token=kwargs.get("token"),
            )

        return save_files

    def _save_pretrained(
        self,
        save_directory: Union[str, os.PathLike],
        file_names: Tuple[str],
        legacy_format: Optional[bool] = None,
        filename_prefix: Optional[str] = None,
    ) -> Tuple[str]:
        """
        Save a tokenizer using the slow-tokenizer/legacy format: vocabulary + added tokens.

        Fast tokenizers can also be saved in a unique JSON file containing {config + vocab + added-tokens} using the
        specific [`~tokenization_utils_fast.PreTrainedTokenizerFast._save_pretrained`]
        """
        if legacy_format is False:
            raise ValueError(
                "Only fast tokenizers (instances of PreTrainedTokenizerFast) can be saved in non legacy format."
            )

        save_directory = str(save_directory)

        added_tokens_file = os.path.join(
            save_directory, (filename_prefix + "-" if filename_prefix else "") + ADDED_TOKENS_FILE
        )
        added_vocab = self.get_added_vocab()
        if added_vocab:
            with open(added_tokens_file, "w", encoding="utf-8") as f:
                out_str = json.dumps(added_vocab, indent=2, sort_keys=True, ensure_ascii=False) + "\n"
                f.write(out_str)
                logger.info(f"added tokens file saved in {added_tokens_file}")

        vocab_files = self.save_vocabulary(save_directory, filename_prefix=filename_prefix)

        return file_names + vocab_files + (added_tokens_file,)

    def save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]:
        """
        Save only the vocabulary of the tokenizer (vocabulary + added tokens).

        This method won't save the configuration and special token mappings of the tokenizer. Use
        [`~PreTrainedTokenizerFast._save_pretrained`] to save the whole state of the tokenizer.

        Args:
            save_directory (`str`):
                The directory in which to save the vocabulary.
            filename_prefix (`str`, *optional*):
                An optional prefix to add to the named of the saved files.

        Returns:
            `Tuple(str)`: Paths to the files saved.
        """
        raise NotImplementedError

    def tokenize(self, text: str, pair: Optional[str] = None, add_special_tokens: bool = False, **kwargs) -> List[str]:
        """
        Converts a string in a sequence of tokens, replacing unknown tokens with the `unk_token`.

        Args:
            text (`str`):
                The sequence to be encoded.
            pair (`str`, *optional*):
                A second sequence to be encoded with the first.
            add_special_tokens (`bool`, *optional*, defaults to `False`):
                Whether or not to add the special tokens associated with the corresponding model.
            kwargs (additional keyword arguments, *optional*):
                Will be passed to the underlying model specific encode method. See details in
                [`~PreTrainedTokenizerBase.__call__`]

        Returns:
            `List[str]`: The list of tokens.
        """
        raise NotImplementedError

    @add_end_docstrings(
        ENCODE_KWARGS_DOCSTRING,
        """
            **kwargs: Passed along to the `.tokenize()` method.
        """,
        """
        Returns:
            `List[int]`, `torch.Tensor`, `tf.Tensor` or `np.ndarray`: The tokenized ids of the text.
        """,
    )
    def encode(
        self,
        text: Union[TextInput, PreTokenizedInput, EncodedInput],
        text_pair: Optional[Union[TextInput, PreTokenizedInput, EncodedInput]] = None,
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        return_tensors: Optional[Union[str, TensorType]] = None,
        **kwargs,
    ) -> List[int]:
        """
        Converts a string to a sequence of ids (integer), using the tokenizer and vocabulary.

        Same as doing `self.convert_tokens_to_ids(self.tokenize(text))`.

        Args:
            text (`str`, `List[str]` or `List[int]`):
                The first sequence to be encoded. This can be a string, a list of strings (tokenized string using the
                `tokenize` method) or a list of integers (tokenized string ids using the `convert_tokens_to_ids`
                method).
            text_pair (`str`, `List[str]` or `List[int]`, *optional*):
                Optional second sequence to be encoded. This can be a string, a list of strings (tokenized string using
                the `tokenize` method) or a list of integers (tokenized string ids using the `convert_tokens_to_ids`
                method).
        """
        encoded_inputs = self.encode_plus(
            text,
            text_pair=text_pair,
            add_special_tokens=add_special_tokens,
            padding=padding,
            truncation=truncation,
            max_length=max_length,
            stride=stride,
            return_tensors=return_tensors,
            **kwargs,
        )

        return encoded_inputs["input_ids"]

    def num_special_tokens_to_add(self, pair: bool = False) -> int:
        raise NotImplementedError

    def _get_padding_truncation_strategies(
        self, padding=False, truncation=None, max_length=None, pad_to_multiple_of=None, verbose=True, **kwargs
    ):
        """
        Find the correct padding/truncation strategy with backward compatibility for old arguments (truncation_strategy
        and pad_to_max_length) and behaviors.
        """
        old_truncation_strategy = kwargs.pop("truncation_strategy", "do_not_truncate")
        old_pad_to_max_length = kwargs.pop("pad_to_max_length", False)

        # Backward compatibility for previous behavior, maybe we should deprecate it:
        # If you only set max_length, it activates truncation for max_length
        if max_length is not None and padding is False and truncation is None:
            if verbose:
                if not self.deprecation_warnings.get("Truncation-not-explicitly-activated", False):
                    logger.warning(
                        "Truncation was not explicitly activated but `max_length` is provided a specific value, please"
                        " use `truncation=True` to explicitly truncate examples to max length. Defaulting to"
                        " 'longest_first' truncation strategy. If you encode pairs of sequences (GLUE-style) with the"
                        " tokenizer you can select this strategy more precisely by providing a specific strategy to"
                        " `truncation`."
                    )
                self.deprecation_warnings["Truncation-not-explicitly-activated"] = True
            truncation = "longest_first"

        # Get padding strategy
        if padding is False and old_pad_to_max_length:
            if verbose:
                warnings.warn(
                    "The `pad_to_max_length` argument is deprecated and will be removed in a future version, "
                    "use `padding=True` or `padding='longest'` to pad to the longest sequence in the batch, or "
                    "use `padding='max_length'` to pad to a max length. In this case, you can give a specific "
                    "length with `max_length` (e.g. `max_length=45`) or leave max_length to None to pad to the "
                    "maximal input size of the model (e.g. 512 for Bert).",
                    FutureWarning,
                )
            if max_length is None:
                padding_strategy = PaddingStrategy.LONGEST
            else:
                padding_strategy = PaddingStrategy.MAX_LENGTH
        elif padding is not False:
            if padding is True:
                if verbose:
                    if max_length is not None and (
                        truncation is None or truncation is False or truncation == "do_not_truncate"
                    ):
                        warnings.warn(
                            "`max_length` is ignored when `padding`=`True` and there is no truncation strategy. "
                            "To pad to max length, use `padding='max_length'`."
                        )
                    if old_pad_to_max_length is not False:
                        warnings.warn("Though `pad_to_max_length` = `True`, it is ignored because `padding`=`True`.")
                padding_strategy = PaddingStrategy.LONGEST  # Default to pad to the longest sequence in the batch
            elif not isinstance(padding, PaddingStrategy):
                padding_strategy = PaddingStrategy(padding)
            elif isinstance(padding, PaddingStrategy):
                padding_strategy = padding
        else:
            padding_strategy = PaddingStrategy.DO_NOT_PAD

        # Get truncation strategy
        if truncation is None and old_truncation_strategy != "do_not_truncate":
            if verbose:
                warnings.warn(
                    "The `truncation_strategy` argument is deprecated and will be removed in a future version, use"
                    " `truncation=True` to truncate examples to a max length. You can give a specific length with"
                    " `max_length` (e.g. `max_length=45`) or leave max_length to None to truncate to the maximal input"
                    " size of the model (e.g. 512 for Bert).  If you have pairs of inputs, you can give a specific"
                    " truncation strategy selected among `truncation='only_first'` (will only truncate the first"
                    " sentence in the pairs) `truncation='only_second'` (will only truncate the second sentence in the"
                    " pairs) or `truncation='longest_first'` (will iteratively remove tokens from the longest sentence"
                    " in the pairs).",
                    FutureWarning,
                )
            truncation_strategy = TruncationStrategy(old_truncation_strategy)
        elif truncation is not False and truncation is not None:
            if truncation is True:
                truncation_strategy = (
                    TruncationStrategy.LONGEST_FIRST
                )  # Default to truncate the longest sequences in pairs of inputs
            elif not isinstance(truncation, TruncationStrategy):
                truncation_strategy = TruncationStrategy(truncation)
            elif isinstance(truncation, TruncationStrategy):
                truncation_strategy = truncation
        else:
            truncation_strategy = TruncationStrategy.DO_NOT_TRUNCATE

        # Set max length if needed
        if max_length is None:
            if padding_strategy == PaddingStrategy.MAX_LENGTH:
                if self.model_max_length > LARGE_INTEGER:
                    if verbose:
                        if not self.deprecation_warnings.get("Asking-to-pad-to-max_length", False):
                            logger.warning(
                                "Asking to pad to max_length but no maximum length is provided and the model has no"
                                " predefined maximum length. Default to no padding."
                            )
                        self.deprecation_warnings["Asking-to-pad-to-max_length"] = True
                    padding_strategy = PaddingStrategy.DO_NOT_PAD
                else:
                    max_length = self.model_max_length

            if truncation_strategy != TruncationStrategy.DO_NOT_TRUNCATE:
                if self.model_max_length > LARGE_INTEGER:
                    if verbose:
                        if not self.deprecation_warnings.get("Asking-to-truncate-to-max_length", False):
                            logger.warning(
                                "Asking to truncate to max_length but no maximum length is provided and the model has"
                                " no predefined maximum length. Default to no truncation."
                            )
                        self.deprecation_warnings["Asking-to-truncate-to-max_length"] = True
                    truncation_strategy = TruncationStrategy.DO_NOT_TRUNCATE
                else:
                    max_length = self.model_max_length

        # Test if we have a padding token
        if padding_strategy != PaddingStrategy.DO_NOT_PAD and (self.pad_token is None or self.pad_token_id < 0):
            raise ValueError(
                "Asking to pad but the tokenizer does not have a padding token. "
                "Please select a token to use as `pad_token` `(tokenizer.pad_token = tokenizer.eos_token e.g.)` "
                "or add a new pad token via `tokenizer.add_special_tokens({'pad_token': '[PAD]'})`."
            )

        # Check that we will truncate to a multiple of pad_to_multiple_of if both are provided
        if (
            truncation_strategy != TruncationStrategy.DO_NOT_TRUNCATE
            and padding_strategy != PaddingStrategy.DO_NOT_PAD
            and pad_to_multiple_of is not None
            and max_length is not None
            and (max_length % pad_to_multiple_of != 0)
        ):
            raise ValueError(
                "Truncation and padding are both activated but "
                f"truncation length ({max_length}) is not a multiple of pad_to_multiple_of ({pad_to_multiple_of})."
            )

        return padding_strategy, truncation_strategy, max_length, kwargs

    @add_end_docstrings(ENCODE_KWARGS_DOCSTRING, ENCODE_PLUS_ADDITIONAL_KWARGS_DOCSTRING)
    def __call__(
        self,
        text: Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]] = None,
        text_pair: Optional[Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]]] = None,
        text_target: Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]] = None,
        text_pair_target: Optional[
            Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]]
        ] = None,
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        """
        Main method to tokenize and prepare for the model one or several sequence(s) or one or several pair(s) of
        sequences.

        Args:
            text (`str`, `List[str]`, `List[List[str]]`, *optional*):
                The sequence or batch of sequences to be encoded. Each sequence can be a string or a list of strings
                (pretokenized string). If the sequences are provided as list of strings (pretokenized), you must set
                `is_split_into_words=True` (to lift the ambiguity with a batch of sequences).
            text_pair (`str`, `List[str]`, `List[List[str]]`, *optional*):
                The sequence or batch of sequences to be encoded. Each sequence can be a string or a list of strings
                (pretokenized string). If the sequences are provided as list of strings (pretokenized), you must set
                `is_split_into_words=True` (to lift the ambiguity with a batch of sequences).
            text_target (`str`, `List[str]`, `List[List[str]]`, *optional*):
                The sequence or batch of sequences to be encoded as target texts. Each sequence can be a string or a
                list of strings (pretokenized string). If the sequences are provided as list of strings (pretokenized),
                you must set `is_split_into_words=True` (to lift the ambiguity with a batch of sequences).
            text_pair_target (`str`, `List[str]`, `List[List[str]]`, *optional*):
                The sequence or batch of sequences to be encoded as target texts. Each sequence can be a string or a
                list of strings (pretokenized string). If the sequences are provided as list of strings (pretokenized),
                you must set `is_split_into_words=True` (to lift the ambiguity with a batch of sequences).
        """
        # To avoid duplicating
        all_kwargs = {
            "add_special_tokens": add_special_tokens,
            "padding": padding,
            "truncation": truncation,
            "max_length": max_length,
            "stride": stride,
            "is_split_into_words": is_split_into_words,
            "pad_to_multiple_of": pad_to_multiple_of,
            "return_tensors": return_tensors,
            "return_token_type_ids": return_token_type_ids,
            "return_attention_mask": return_attention_mask,
            "return_overflowing_tokens": return_overflowing_tokens,
            "return_special_tokens_mask": return_special_tokens_mask,
            "return_offsets_mapping": return_offsets_mapping,
            "return_length": return_length,
            "verbose": verbose,
        }
        all_kwargs.update(kwargs)
        if text is None and text_target is None:
            raise ValueError("You need to specify either `text` or `text_target`.")
        if text is not None:
            # The context manager will send the inputs as normal texts and not text_target, but we shouldn't change the
            # input mode in this case.
            if not self._in_target_context_manager:
                self._switch_to_input_mode()
            encodings = self._call_one(text=text, text_pair=text_pair, **all_kwargs)
        if text_target is not None:
            self._switch_to_target_mode()
            target_encodings = self._call_one(text=text_target, text_pair=text_pair_target, **all_kwargs)
        # Leave back tokenizer in input mode
        self._switch_to_input_mode()

        if text_target is None:
            return encodings
        elif text is None:
            return target_encodings
        else:
            encodings["labels"] = target_encodings["input_ids"]
            return encodings

    def _call_one(
        self,
        text: Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]],
        text_pair: Optional[Union[TextInput, PreTokenizedInput, List[TextInput], List[PreTokenizedInput]]] = None,
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        # Input type checking for clearer error
        def _is_valid_text_input(t):
            if isinstance(t, str):
                # Strings are fine
                return True
            elif isinstance(t, (list, tuple)):
                # List are fine as long as they are...
                if len(t) == 0:
                    # ... empty
                    return True
                elif isinstance(t[0], str):
                    # ... list of strings
                    return True
                elif isinstance(t[0], (list, tuple)):
                    # ... list with an empty list or with a list of strings
                    return len(t[0]) == 0 or isinstance(t[0][0], str)
                else:
                    return False
            else:
                return False

        if not _is_valid_text_input(text):
            raise ValueError(
                "text input must of type `str` (single example), `List[str]` (batch or single pretokenized example) "
                "or `List[List[str]]` (batch of pretokenized examples)."
            )

        if text_pair is not None and not _is_valid_text_input(text_pair):
            raise ValueError(
                "text input must of type `str` (single example), `List[str]` (batch or single pretokenized example) "
                "or `List[List[str]]` (batch of pretokenized examples)."
            )

        if is_split_into_words:
            is_batched = isinstance(text, (list, tuple)) and text and isinstance(text[0], (list, tuple))
        else:
            is_batched = isinstance(text, (list, tuple))

        if is_batched:
            if isinstance(text_pair, str):
                raise TypeError(
                    "when tokenizing batches of text, `text_pair` must be a list or tuple with the same length as"
                    " `text`."
                )
            if text_pair is not None and len(text) != len(text_pair):
                raise ValueError(
                    f"batch length of `text`: {len(text)} does not match batch length of `text_pair`:"
                    f" {len(text_pair)}."
                )
            batch_text_or_text_pairs = list(zip(text, text_pair)) if text_pair is not None else text
            return self.batch_encode_plus(
                batch_text_or_text_pairs=batch_text_or_text_pairs,
                add_special_tokens=add_special_tokens,
                padding=padding,
                truncation=truncation,
                max_length=max_length,
                stride=stride,
                is_split_into_words=is_split_into_words,
                pad_to_multiple_of=pad_to_multiple_of,
                return_tensors=return_tensors,
                return_token_type_ids=return_token_type_ids,
                return_attention_mask=return_attention_mask,
                return_overflowing_tokens=return_overflowing_tokens,
                return_special_tokens_mask=return_special_tokens_mask,
                return_offsets_mapping=return_offsets_mapping,
                return_length=return_length,
                verbose=verbose,
                **kwargs,
            )
        else:
            return self.encode_plus(
                text=text,
                text_pair=text_pair,
                add_special_tokens=add_special_tokens,
                padding=padding,
                truncation=truncation,
                max_length=max_length,
                stride=stride,
                is_split_into_words=is_split_into_words,
                pad_to_multiple_of=pad_to_multiple_of,
                return_tensors=return_tensors,
                return_token_type_ids=return_token_type_ids,
                return_attention_mask=return_attention_mask,
                return_overflowing_tokens=return_overflowing_tokens,
                return_special_tokens_mask=return_special_tokens_mask,
                return_offsets_mapping=return_offsets_mapping,
                return_length=return_length,
                verbose=verbose,
                **kwargs,
            )

    @add_end_docstrings(ENCODE_KWARGS_DOCSTRING, ENCODE_PLUS_ADDITIONAL_KWARGS_DOCSTRING)
    def encode_plus(
        self,
        text: Union[TextInput, PreTokenizedInput, EncodedInput],
        text_pair: Optional[Union[TextInput, PreTokenizedInput, EncodedInput]] = None,
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        """
        Tokenize and prepare for the model a sequence or a pair of sequences.

        <Tip warning={true}>

        This method is deprecated, `__call__` should be used instead.

        </Tip>

        Args:
            text (`str`, `List[str]` or `List[int]` (the latter only for not-fast tokenizers)):
                The first sequence to be encoded. This can be a string, a list of strings (tokenized string using the
                `tokenize` method) or a list of integers (tokenized string ids using the `convert_tokens_to_ids`
                method).
            text_pair (`str`, `List[str]` or `List[int]`, *optional*):
                Optional second sequence to be encoded. This can be a string, a list of strings (tokenized string using
                the `tokenize` method) or a list of integers (tokenized string ids using the `convert_tokens_to_ids`
                method).
        """

        # Backward compatibility for 'truncation_strategy', 'pad_to_max_length'
        padding_strategy, truncation_strategy, max_length, kwargs = self._get_padding_truncation_strategies(
            padding=padding,
            truncation=truncation,
            max_length=max_length,
            pad_to_multiple_of=pad_to_multiple_of,
            verbose=verbose,
            **kwargs,
        )

        return self._encode_plus(
            text=text,
            text_pair=text_pair,
            add_special_tokens=add_special_tokens,
            padding_strategy=padding_strategy,
            truncation_strategy=truncation_strategy,
            max_length=max_length,
            stride=stride,
            is_split_into_words=is_split_into_words,
            pad_to_multiple_of=pad_to_multiple_of,
            return_tensors=return_tensors,
            return_token_type_ids=return_token_type_ids,
            return_attention_mask=return_attention_mask,
            return_overflowing_tokens=return_overflowing_tokens,
            return_special_tokens_mask=return_special_tokens_mask,
            return_offsets_mapping=return_offsets_mapping,
            return_length=return_length,
            verbose=verbose,
            **kwargs,
        )

    def _encode_plus(
        self,
        text: Union[TextInput, PreTokenizedInput, EncodedInput],
        text_pair: Optional[Union[TextInput, PreTokenizedInput, EncodedInput]] = None,
        add_special_tokens: bool = True,
        padding_strategy: PaddingStrategy = PaddingStrategy.DO_NOT_PAD,
        truncation_strategy: TruncationStrategy = TruncationStrategy.DO_NOT_TRUNCATE,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        raise NotImplementedError

    @add_end_docstrings(ENCODE_KWARGS_DOCSTRING, ENCODE_PLUS_ADDITIONAL_KWARGS_DOCSTRING)
    def batch_encode_plus(
        self,
        batch_text_or_text_pairs: Union[
            List[TextInput],
            List[TextInputPair],
            List[PreTokenizedInput],
            List[PreTokenizedInputPair],
            List[EncodedInput],
            List[EncodedInputPair],
        ],
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        """
        Tokenize and prepare for the model a list of sequences or a list of pairs of sequences.

        <Tip warning={true}>

        This method is deprecated, `__call__` should be used instead.

        </Tip>

        Args:
            batch_text_or_text_pairs (`List[str]`, `List[Tuple[str, str]]`, `List[List[str]]`, `List[Tuple[List[str], List[str]]]`, and for not-fast tokenizers, also `List[List[int]]`, `List[Tuple[List[int], List[int]]]`):
                Batch of sequences or pair of sequences to be encoded. This can be a list of
                string/string-sequences/int-sequences or a list of pair of string/string-sequences/int-sequence (see
                details in `encode_plus`).
        """

        # Backward compatibility for 'truncation_strategy', 'pad_to_max_length'
        padding_strategy, truncation_strategy, max_length, kwargs = self._get_padding_truncation_strategies(
            padding=padding,
            truncation=truncation,
            max_length=max_length,
            pad_to_multiple_of=pad_to_multiple_of,
            verbose=verbose,
            **kwargs,
        )

        return self._batch_encode_plus(
            batch_text_or_text_pairs=batch_text_or_text_pairs,
            add_special_tokens=add_special_tokens,
            padding_strategy=padding_strategy,
            truncation_strategy=truncation_strategy,
            max_length=max_length,
            stride=stride,
            is_split_into_words=is_split_into_words,
            pad_to_multiple_of=pad_to_multiple_of,
            return_tensors=return_tensors,
            return_token_type_ids=return_token_type_ids,
            return_attention_mask=return_attention_mask,
            return_overflowing_tokens=return_overflowing_tokens,
            return_special_tokens_mask=return_special_tokens_mask,
            return_offsets_mapping=return_offsets_mapping,
            return_length=return_length,
            verbose=verbose,
            **kwargs,
        )

    def _batch_encode_plus(
        self,
        batch_text_or_text_pairs: Union[
            List[TextInput],
            List[TextInputPair],
            List[PreTokenizedInput],
            List[PreTokenizedInputPair],
            List[EncodedInput],
            List[EncodedInputPair],
        ],
        add_special_tokens: bool = True,
        padding_strategy: PaddingStrategy = PaddingStrategy.DO_NOT_PAD,
        truncation_strategy: TruncationStrategy = TruncationStrategy.DO_NOT_TRUNCATE,
        max_length: Optional[int] = None,
        stride: int = 0,
        is_split_into_words: bool = False,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        raise NotImplementedError

    def pad(
        self,
        encoded_inputs: Union[
            BatchEncoding,
            List[BatchEncoding],
            Dict[str, EncodedInput],
            Dict[str, List[EncodedInput]],
            List[Dict[str, EncodedInput]],
        ],
        padding: Union[bool, str, PaddingStrategy] = True,
        max_length: Optional[int] = None,
        pad_to_multiple_of: Optional[int] = None,
        return_attention_mask: Optional[bool] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        verbose: bool = True,
    ) -> BatchEncoding:
        """
        Pad a single encoded input or a batch of encoded inputs up to predefined length or to the max sequence length
        in the batch.

        Padding side (left/right) padding token ids are defined at the tokenizer level (with `self.padding_side`,
        `self.pad_token_id` and `self.pad_token_type_id`).

        Please note that with a fast tokenizer, using the `__call__` method is faster than using a method to encode the
        text followed by a call to the `pad` method to get a padded encoding.

        <Tip>

        If the `encoded_inputs` passed are dictionary of numpy arrays, PyTorch tensors or TensorFlow tensors, the
        result will use the same type unless you provide a different tensor type with `return_tensors`. In the case of
        PyTorch tensors, you will lose the specific device of your tensors however.

        </Tip>

        Args:
            encoded_inputs ([`BatchEncoding`], list of [`BatchEncoding`], `Dict[str, List[int]]`, `Dict[str, List[List[int]]` or `List[Dict[str, List[int]]]`):
                Tokenized inputs. Can represent one input ([`BatchEncoding`] or `Dict[str, List[int]]`) or a batch of
                tokenized inputs (list of [`BatchEncoding`], *Dict[str, List[List[int]]]* or *List[Dict[str,
                List[int]]]*) so you can use this method during preprocessing as well as in a PyTorch Dataloader
                collate function.

                Instead of `List[int]` you can have tensors (numpy arrays, PyTorch tensors or TensorFlow tensors), see
                the note above for the return type.
            padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
                 Select a strategy to pad the returned sequences (according to the model's padding side and padding
                 index) among:

                - `True` or `'longest'`: Pad to the longest sequence in the batch (or no padding if only a single
                  sequence if provided).
                - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
                  acceptable input length for the model if that argument is not provided.
                - `False` or `'do_not_pad'` (default): No padding (i.e., can output a batch with sequences of different
                  lengths).
            max_length (`int`, *optional*):
                Maximum length of the returned list and optionally padding length (see above).
            pad_to_multiple_of (`int`, *optional*):
                If set will pad the sequence to a multiple of the provided value.

                This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability
                `>= 7.5` (Volta).
            return_attention_mask (`bool`, *optional*):
                Whether to return the attention mask. If left to the default, will return the attention mask according
                to the specific tokenizer's default, defined by the `return_outputs` attribute.

                [What are attention masks?](../glossary#attention-mask)
            return_tensors (`str` or [`~utils.TensorType`], *optional*):
                If set, will return tensors instead of list of python integers. Acceptable values are:

                - `'tf'`: Return TensorFlow `tf.constant` objects.
                - `'pt'`: Return PyTorch `torch.Tensor` objects.
                - `'np'`: Return Numpy `np.ndarray` objects.
            verbose (`bool`, *optional*, defaults to `True`):
                Whether or not to print more information and warnings.
        """
        if self.__class__.__name__.endswith("Fast"):
            if not self.deprecation_warnings.get("Asking-to-pad-a-fast-tokenizer", False):
                logger.warning_advice(
                    f"You're using a {self.__class__.__name__} tokenizer. Please note that with a fast tokenizer,"
                    " using the `__call__` method is faster than using a method to encode the text followed by a call"
                    " to the `pad` method to get a padded encoding."
                )
                self.deprecation_warnings["Asking-to-pad-a-fast-tokenizer"] = True

        # If we have a list of dicts, let's convert it in a dict of lists
        # We do this to allow using this method as a collate_fn function in PyTorch Dataloader
        if isinstance(encoded_inputs, (list, tuple)) and isinstance(encoded_inputs[0], Mapping):
            encoded_inputs = {key: [example[key] for example in encoded_inputs] for key in encoded_inputs[0].keys()}

        # The model's main input name, usually `input_ids`, has be passed for padding
        if self.model_input_names[0] not in encoded_inputs:
            raise ValueError(
                "You should supply an encoding or a list of encodings to this method "
                f"that includes {self.model_input_names[0]}, but you provided {list(encoded_inputs.keys())}"
            )

        required_input = encoded_inputs[self.model_input_names[0]]

        if required_input is None or (isinstance(required_input, Sized) and len(required_input) == 0):
            if return_attention_mask:
                encoded_inputs["attention_mask"] = []
            return encoded_inputs

        # If we have PyTorch/TF/NumPy tensors/arrays as inputs, we cast them as python objects
        # and rebuild them afterwards if no return_tensors is specified
        # Note that we lose the specific device the tensor may be on for PyTorch

        first_element = required_input[0]
        if isinstance(first_element, (list, tuple)):
            # first_element might be an empty list/tuple in some edge cases so we grab the first non empty element.
            for item in required_input:
                if len(item) != 0:
                    first_element = item[0]
                    break
        # At this state, if `first_element` is still a list/tuple, it's an empty one so there is nothing to do.
        if not isinstance(first_element, (int, list, tuple)):
            if is_tf_tensor(first_element):
                return_tensors = "tf" if return_tensors is None else return_tensors
            elif is_torch_tensor(first_element):
                return_tensors = "pt" if return_tensors is None else return_tensors
            elif isinstance(first_element, np.ndarray):
                return_tensors = "np" if return_tensors is None else return_tensors
            else:
                raise ValueError(
                    f"type of {first_element} unknown: {type(first_element)}. "
                    "Should be one of a python, numpy, pytorch or tensorflow object."
                )

            for key, value in encoded_inputs.items():
                encoded_inputs[key] = to_py_obj(value)

        # Convert padding_strategy in PaddingStrategy
        padding_strategy, _, max_length, _ = self._get_padding_truncation_strategies(
            padding=padding, max_length=max_length, verbose=verbose
        )

        required_input = encoded_inputs[self.model_input_names[0]]
        if required_input and not isinstance(required_input[0], (list, tuple)):
            encoded_inputs = self._pad(
                encoded_inputs,
                max_length=max_length,
                padding_strategy=padding_strategy,
                pad_to_multiple_of=pad_to_multiple_of,
                return_attention_mask=return_attention_mask,
            )
            return BatchEncoding(encoded_inputs, tensor_type=return_tensors)

        batch_size = len(required_input)
        assert all(
            len(v) == batch_size for v in encoded_inputs.values()
        ), "Some items in the output dictionary have a different batch size than others."

        if padding_strategy == PaddingStrategy.LONGEST:
            max_length = max(len(inputs) for inputs in required_input)
            padding_strategy = PaddingStrategy.MAX_LENGTH

        batch_outputs = {}
        for i in range(batch_size):
            inputs = {k: v[i] for k, v in encoded_inputs.items()}
            outputs = self._pad(
                inputs,
                max_length=max_length,
                padding_strategy=padding_strategy,
                pad_to_multiple_of=pad_to_multiple_of,
                return_attention_mask=return_attention_mask,
            )

            for key, value in outputs.items():
                if key not in batch_outputs:
                    batch_outputs[key] = []
                batch_outputs[key].append(value)

        return BatchEncoding(batch_outputs, tensor_type=return_tensors)

    def create_token_type_ids_from_sequences(
        self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None
    ) -> List[int]:
        """
        Create the token type IDs corresponding to the sequences passed. [What are token type
        IDs?](../glossary#token-type-ids)

        Should be overridden in a subclass if the model has a special way of building those.

        Args:
            token_ids_0 (`List[int]`): The first tokenized sequence.
            token_ids_1 (`List[int]`, *optional*): The second tokenized sequence.

        Returns:
            `List[int]`: The token type ids.
        """
        if token_ids_1 is None:
            return len(token_ids_0) * [0]
        return [0] * len(token_ids_0) + [1] * len(token_ids_1)

    def build_inputs_with_special_tokens(
        self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None
    ) -> List[int]:
        """
        Build model inputs from a sequence or a pair of sequence for sequence classification tasks by concatenating and
        adding special tokens.

        This implementation does not add special tokens and this method should be overridden in a subclass.

        Args:
            token_ids_0 (`List[int]`): The first tokenized sequence.
            token_ids_1 (`List[int]`, *optional*): The second tokenized sequence.

        Returns:
            `List[int]`: The model input with special tokens.
        """
        if token_ids_1 is None:
            return token_ids_0
        return token_ids_0 + token_ids_1

    @add_end_docstrings(ENCODE_KWARGS_DOCSTRING, ENCODE_PLUS_ADDITIONAL_KWARGS_DOCSTRING)
    def prepare_for_model(
        self,
        ids: List[int],
        pair_ids: Optional[List[int]] = None,
        add_special_tokens: bool = True,
        padding: Union[bool, str, PaddingStrategy] = False,
        truncation: Union[bool, str, TruncationStrategy] = None,
        max_length: Optional[int] = None,
        stride: int = 0,
        pad_to_multiple_of: Optional[int] = None,
        return_tensors: Optional[Union[str, TensorType]] = None,
        return_token_type_ids: Optional[bool] = None,
        return_attention_mask: Optional[bool] = None,
        return_overflowing_tokens: bool = False,
        return_special_tokens_mask: bool = False,
        return_offsets_mapping: bool = False,
        return_length: bool = False,
        verbose: bool = True,
        prepend_batch_axis: bool = False,
        **kwargs,
    ) -> BatchEncoding:
        """
        Prepares a sequence of input id, or a pair of sequences of inputs ids so that it can be used by the model. It
        adds special tokens, truncates sequences if overflowing while taking into account the special tokens and
        manages a moving window (with user defined stride) for overflowing tokens. Please Note, for *pair_ids*
        different than `None` and *truncation_strategy = longest_first* or `True`, it is not possible to return
        overflowing tokens. Such a combination of arguments will raise an error.

        Args:
            ids (`List[int]`):
                Tokenized input ids of the first sequence. Can be obtained from a string by chaining the `tokenize` and
                `convert_tokens_to_ids` methods.
            pair_ids (`List[int]`, *optional*):
                Tokenized input ids of the second sequence. Can be obtained from a string by chaining the `tokenize`
                and `convert_tokens_to_ids` methods.
        """

        # Backward compatibility for 'truncation_strategy', 'pad_to_max_length'
        padding_strategy, truncation_strategy, max_length, kwargs = self._get_padding_truncation_strategies(
            padding=padding,
            truncation=truncation,
            max_length=max_length,
            pad_to_multiple_of=pad_to_multiple_of,
            verbose=verbose,
            **kwargs,
        )

        pair = bool(pair_ids is not None)
        len_ids = len(ids)
        len_pair_ids = len(pair_ids) if pair else 0

        if return_token_type_ids and not add_special_tokens:
            raise ValueError(
                "Asking to return token_type_ids while setting add_special_tokens to False "
                "results in an undefined behavior. Please set add_special_tokens to True or "
                "set return_token_type_ids to None."
            )

        if (
            return_overflowing_tokens
            and truncation_strategy == TruncationStrategy.LONGEST_FIRST
            and pair_ids is not None
        ):
            raise ValueError(
                "Not possible to return overflowing tokens for pair of sequences with the "
                "`longest_first`. Please select another truncation strategy than `longest_first`, "
                "for instance `only_second` or `only_first`."
            )

        # Load from model defaults
        if return_token_type_ids is None:
            return_token_type_ids = "token_type_ids" in self.model_input_names
        if return_attention_mask is None:
            return_attention_mask = "attention_mask" in self.model_input_names

        encoded_inputs = {}

        # Compute the total size of the returned encodings
        total_len = len_ids + len_pair_ids + (self.num_special_tokens_to_add(pair=pair) if add_special_tokens else 0)

        # Truncation: Handle max sequence length
        overflowing_tokens = []
        if truncation_strategy != TruncationStrategy.DO_NOT_TRUNCATE and max_length and total_len > max_length:
            ids, pair_ids, overflowing_tokens = self.truncate_sequences(
                ids,
                pair_ids=pair_ids,
                num_tokens_to_remove=total_len - max_length,
                truncation_strategy=truncation_strategy,
                stride=stride,
            )

        if return_overflowing_tokens:
            encoded_inputs["overflowing_tokens"] = overflowing_tokens
            encoded_inputs["num_truncated_tokens"] = total_len - max_length

        # Add special tokens
        if add_special_tokens:
            sequence = self.build_inputs_with_special_tokens(ids, pair_ids)
            token_type_ids = self.create_token_type_ids_from_sequences(ids, pair_ids)
        else:
            sequence = ids + pair_ids if pair else ids
            token_type_ids = [0] * len(ids) + ([0] * len(pair_ids) if pair else [])

        # Build output dictionary
        encoded_inputs["input_ids"] = sequence
        if return_token_type_ids:
            encoded_inputs["token_type_ids"] = token_type_ids
        if return_special_tokens_mask:
            if add_special_tokens:
                encoded_inputs["special_tokens_mask"] = self.get_special_tokens_mask(ids, pair_ids)
            else:
                encoded_inputs["special_tokens_mask"] = [0] * len(sequence)

        # Check lengths
        self._eventual_warn_about_too_long_sequence(encoded_inputs["input_ids"], max_length, verbose)

        # Padding
        if padding_strategy != PaddingStrategy.DO_NOT_PAD or return_attention_mask:
            encoded_inputs = self.pad(
                encoded_inputs,
                max_length=max_length,
                padding=padding_strategy.value,
                pad_to_multiple_of=pad_to_multiple_of,
                return_attention_mask=return_attention_mask,
            )

        if return_length:
            encoded_inputs["length"] = len(encoded_inputs["input_ids"])

        batch_outputs = BatchEncoding(
            encoded_inputs, tensor_type=return_tensors, prepend_batch_axis=prepend_batch_axis
        )

        return batch_outputs

    def truncate_sequences(
        self,
        ids: List[int],
        pair_ids: Optional[List[int]] = None,
        num_tokens_to_remove: int = 0,
        truncation_strategy: Union[str, TruncationStrategy] = "longest_first",
        stride: int = 0,
    ) -> Tuple[List[int], List[int], List[int]]:
        """
        Truncates a sequence pair in-place following the strategy.

        Args:
            ids (`List[int]`):
                Tokenized input ids of the first sequence. Can be obtained from a string by chaining the `tokenize` and
                `convert_tokens_to_ids` methods.
            pair_ids (`List[int]`, *optional*):
                Tokenized input ids of the second sequence. Can be obtained from a string by chaining the `tokenize`
                and `convert_tokens_to_ids` methods.
            num_tokens_to_remove (`int`, *optional*, defaults to 0):
                Number of tokens to remove using the truncation strategy.
            truncation_strategy (`str` or [`~tokenization_utils_base.TruncationStrategy`], *optional*, defaults to `False`):
                The strategy to follow for truncation. Can be:

                - `'longest_first'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will truncate
                  token by token, removing a token from the longest sequence in the pair if a pair of sequences (or a
                  batch of pairs) is provided.
                - `'only_first'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the first sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `'only_second'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the second sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `'do_not_truncate'` (default): No truncation (i.e., can output batch with sequence lengths greater
                  than the model maximum admissible input size).
            stride (`int`, *optional*, defaults to 0):
                If set to a positive number, the overflowing tokens returned will contain some tokens from the main
                sequence returned. The value of this argument defines the number of additional tokens.

        Returns:
            `Tuple[List[int], List[int], List[int]]`: The truncated `ids`, the truncated `pair_ids` and the list of
            overflowing tokens. Note: The *longest_first* strategy returns empty list of overflowing tokens if a pair
            of sequences (or a batch of pairs) is provided.
        """
        if num_tokens_to_remove <= 0:
            return ids, pair_ids, []

        if not isinstance(truncation_strategy, TruncationStrategy):
            truncation_strategy = TruncationStrategy(truncation_strategy)

        overflowing_tokens = []
        if truncation_strategy == TruncationStrategy.ONLY_FIRST or (
            truncation_strategy == TruncationStrategy.LONGEST_FIRST and pair_ids is None
        ):
            if len(ids) > num_tokens_to_remove:
                window_len = min(len(ids), stride + num_tokens_to_remove)
                if self.truncation_side == "left":
                    overflowing_tokens = ids[:window_len]
                    ids = ids[num_tokens_to_remove:]
                elif self.truncation_side == "right":
                    overflowing_tokens = ids[-window_len:]
                    ids = ids[:-num_tokens_to_remove]
                else:
                    raise ValueError(f"invalid truncation strategy: {self.truncation_side}, use 'left' or 'right'.")

            else:
                error_msg = (
                    f"We need to remove {num_tokens_to_remove} to truncate the input "
                    f"but the first sequence has a length {len(ids)}. "
                )
                if truncation_strategy == TruncationStrategy.ONLY_FIRST:
                    error_msg = (
                        error_msg + "Please select another truncation strategy than "
                        f"{truncation_strategy}, for instance 'longest_first' or 'only_second'."
                    )
                logger.error(error_msg)
        elif truncation_strategy == TruncationStrategy.LONGEST_FIRST:
            logger.warning(
                "Be aware, overflowing tokens are not returned for the setting you have chosen,"
                f" i.e. sequence pairs with the '{TruncationStrategy.LONGEST_FIRST.value}' "
                "truncation strategy. So the returned list will always be empty even if some "
                "tokens have been removed."
            )
            for _ in range(num_tokens_to_remove):
                if pair_ids is None or len(ids) > len(pair_ids):
                    if self.truncation_side == "right":
                        ids = ids[:-1]
                    elif self.truncation_side == "left":
                        ids = ids[1:]
                    else:
                        raise ValueError("invalid truncation strategy:" + str(self.truncation_side))
                else:
                    if self.truncation_side == "right":
                        pair_ids = pair_ids[:-1]
                    elif self.truncation_side == "left":
                        pair_ids = pair_ids[1:]
                    else:
                        raise ValueError("invalid truncation strategy:" + str(self.truncation_side))
        elif truncation_strategy == TruncationStrategy.ONLY_SECOND and pair_ids is not None:
            if len(pair_ids) > num_tokens_to_remove:
                window_len = min(len(pair_ids), stride + num_tokens_to_remove)
                if self.truncation_side == "right":
                    overflowing_tokens = pair_ids[-window_len:]
                    pair_ids = pair_ids[:-num_tokens_to_remove]
                elif self.truncation_side == "left":
                    overflowing_tokens = pair_ids[:window_len]
                    pair_ids = pair_ids[num_tokens_to_remove:]
                else:
                    raise ValueError("invalid truncation strategy:" + str(self.truncation_side))
            else:
                logger.error(
                    f"We need to remove {num_tokens_to_remove} to truncate the input "
                    f"but the second sequence has a length {len(pair_ids)}. "
                    f"Please select another truncation strategy than {truncation_strategy}, "
                    "for instance 'longest_first' or 'only_first'."
                )

        return (ids, pair_ids, overflowing_tokens)

    def _pad(
        self,
        encoded_inputs: Union[Dict[str, EncodedInput], BatchEncoding],
        max_length: Optional[int] = None,
        padding_strategy: PaddingStrategy = PaddingStrategy.DO_NOT_PAD,
        pad_to_multiple_of: Optional[int] = None,
        return_attention_mask: Optional[bool] = None,
    ) -> dict:
        """
        Pad encoded inputs (on left/right and up to predefined length or max length in the batch)

        Args:
            encoded_inputs:
                Dictionary of tokenized inputs (`List[int]`) or batch of tokenized inputs (`List[List[int]]`).
            max_length: maximum length of the returned list and optionally padding length (see below).
                Will truncate by taking into account the special tokens.
            padding_strategy: PaddingStrategy to use for padding.

                - PaddingStrategy.LONGEST Pad to the longest sequence in the batch
                - PaddingStrategy.MAX_LENGTH: Pad to the max length (default)
                - PaddingStrategy.DO_NOT_PAD: Do not pad
                The tokenizer padding sides are defined in self.padding_side:

                    - 'left': pads on the left of the sequences
                    - 'right': pads on the right of the sequences
            pad_to_multiple_of: (optional) Integer if set will pad the sequence to a multiple of the provided value.
                This is especially useful to enable the use of Tensor Core on NVIDIA hardware with compute capability
                `>= 7.5` (Volta).
            return_attention_mask:
                (optional) Set to False to avoid returning attention mask (default: set to model specifics)
        """
        # Load from model defaults
        if return_attention_mask is None:
            return_attention_mask = "attention_mask" in self.model_input_names

        required_input = encoded_inputs[self.model_input_names[0]]

        if padding_strategy == PaddingStrategy.LONGEST:
            max_length = len(required_input)

        if max_length is not None and pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
            max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of

        needs_to_be_padded = padding_strategy != PaddingStrategy.DO_NOT_PAD and len(required_input) != max_length

        # Initialize attention mask if not present.
        if return_attention_mask and "attention_mask" not in encoded_inputs:
            encoded_inputs["attention_mask"] = [1] * len(required_input)

        if needs_to_be_padded:
            difference = max_length - len(required_input)

            if self.padding_side == "right":
                if return_attention_mask:
                    encoded_inputs["attention_mask"] = encoded_inputs["attention_mask"] + [0] * difference
                if "token_type_ids" in encoded_inputs:
                    encoded_inputs["token_type_ids"] = (
                        encoded_inputs["token_type_ids"] + [self.pad_token_type_id] * difference
                    )
                if "special_tokens_mask" in encoded_inputs:
                    encoded_inputs["special_tokens_mask"] = encoded_inputs["special_tokens_mask"] + [1] * difference
                encoded_inputs[self.model_input_names[0]] = required_input + [self.pad_token_id] * difference
            elif self.padding_side == "left":
                if return_attention_mask:
                    encoded_inputs["attention_mask"] = [0] * difference + encoded_inputs["attention_mask"]
                if "token_type_ids" in encoded_inputs:
                    encoded_inputs["token_type_ids"] = [self.pad_token_type_id] * difference + encoded_inputs[
                        "token_type_ids"
                    ]
                if "special_tokens_mask" in encoded_inputs:
                    encoded_inputs["special_tokens_mask"] = [1] * difference + encoded_inputs["special_tokens_mask"]
                encoded_inputs[self.model_input_names[0]] = [self.pad_token_id] * difference + required_input
            else:
                raise ValueError("Invalid padding strategy:" + str(self.padding_side))

        return encoded_inputs

    def convert_tokens_to_string(self, tokens: List[str]) -> str:
        """
        Converts a sequence of tokens in a single string. The most simple way to do it is `" ".join(tokens)` but we
        often want to remove sub-word tokenization artifacts at the same time.

        Args:
            tokens (`List[str]`): The token to join in a string.

        Returns:
            `str`: The joined tokens.
        """
        raise NotImplementedError

    def batch_decode(
        self,
        sequences: Union[List[int], List[List[int]], "np.ndarray", "torch.Tensor", "tf.Tensor"],
        skip_special_tokens: bool = False,
        clean_up_tokenization_spaces: bool = None,
        **kwargs,
    ) -> List[str]:
        """
        Convert a list of lists of token ids into a list of strings by calling decode.

        Args:
            sequences (`Union[List[int], List[List[int]], np.ndarray, torch.Tensor, tf.Tensor]`):
                List of tokenized input ids. Can be obtained using the `__call__` method.
            skip_special_tokens (`bool`, *optional*, defaults to `False`):
                Whether or not to remove special tokens in the decoding.
            clean_up_tokenization_spaces (`bool`, *optional*):
                Whether or not to clean up the tokenization spaces. If `None`, will default to
                `self.clean_up_tokenization_spaces`.
            kwargs (additional keyword arguments, *optional*):
                Will be passed to the underlying model specific decode method.

        Returns:
            `List[str]`: The list of decoded sentences.
        """
        return [
            self.decode(
                seq,
                skip_special_tokens=skip_special_tokens,
                clean_up_tokenization_spaces=clean_up_tokenization_spaces,
                **kwargs,
            )
            for seq in sequences
        ]

    def decode(
        self,
        token_ids: Union[int, List[int], "np.ndarray", "torch.Tensor", "tf.Tensor"],
        skip_special_tokens: bool = False,
        clean_up_tokenization_spaces: bool = None,
        **kwargs,
    ) -> str:
        """
        Converts a sequence of ids in a string, using the tokenizer and vocabulary with options to remove special
        tokens and clean up tokenization spaces.

        Similar to doing `self.convert_tokens_to_string(self.convert_ids_to_tokens(token_ids))`.

        Args:
            token_ids (`Union[int, List[int], np.ndarray, torch.Tensor, tf.Tensor]`):
                List of tokenized input ids. Can be obtained using the `__call__` method.
            skip_special_tokens (`bool`, *optional*, defaults to `False`):
                Whether or not to remove special tokens in the decoding.
            clean_up_tokenization_spaces (`bool`, *optional*):
                Whether or not to clean up the tokenization spaces. If `None`, will default to
                `self.clean_up_tokenization_spaces`.
            kwargs (additional keyword arguments, *optional*):
                Will be passed to the underlying model specific decode method.

        Returns:
            `str`: The decoded sentence.
        """
        # Convert inputs to python lists
        token_ids = to_py_obj(token_ids)

        return self._decode(
            token_ids=token_ids,
            skip_special_tokens=skip_special_tokens,
            clean_up_tokenization_spaces=clean_up_tokenization_spaces,
            **kwargs,
        )

    def _decode(
        self,
        token_ids: Union[int, List[int]],
        skip_special_tokens: bool = False,
        clean_up_tokenization_spaces: bool = None,
        **kwargs,
    ) -> str:
        raise NotImplementedError

    def get_special_tokens_mask(
        self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None, already_has_special_tokens: bool = False
    ) -> List[int]:
        """
        Retrieves sequence ids from a token list that has no special tokens added. This method is called when adding
        special tokens using the tokenizer `prepare_for_model` or `encode_plus` methods.

        Args:
            token_ids_0 (`List[int]`):
                List of ids of the first sequence.
            token_ids_1 (`List[int]`, *optional*):
                List of ids of the second sequence.
            already_has_special_tokens (`bool`, *optional*, defaults to `False`):
                Whether or not the token list is already formatted with special tokens for the model.

        Returns:
            A list of integers in the range [0, 1]: 1 for a special token, 0 for a sequence token.
        """
        assert already_has_special_tokens and token_ids_1 is None, (
            "You cannot use ``already_has_special_tokens=False`` with this tokenizer. "
            "Please use a slow (full python) tokenizer to activate this argument. "
            "Or set `return_special_tokens_mask=True` when calling the encoding method "
            "to get the special tokens mask in any tokenizer. "
        )

        all_special_ids = self.all_special_ids  # cache the property

        special_tokens_mask = [1 if token in all_special_ids else 0 for token in token_ids_0]

        return special_tokens_mask

    @staticmethod
    def clean_up_tokenization(out_string: str) -> str:
        """
        Clean up a list of simple English tokenization artifacts like spaces before punctuations and abbreviated forms.

        Args:
            out_string (`str`): The text to clean up.

        Returns:
            `str`: The cleaned-up string.
        """
        out_string = (
            out_string.replace(" .", ".")
            .replace(" ?", "?")
            .replace(" !", "!")
            .replace(" ,", ",")
            .replace(" ' ", "'")
            .replace(" n't", "n't")
            .replace(" 'm", "'m")
            .replace(" 's", "'s")
            .replace(" 've", "'ve")
            .replace(" 're", "'re")
        )
        return out_string

    def _eventual_warn_about_too_long_sequence(self, ids: List[int], max_length: Optional[int], verbose: bool):
        """
        Depending on the input and internal state we might trigger a warning about a sequence that is too long for its
        corresponding model

        Args:
            ids (`List[str]`): The ids produced by the tokenization
            max_length (`int`, *optional*): The max_length desired (does not trigger a warning if it is set)
            verbose (`bool`): Whether or not to print more information and warnings.

        """
        if max_length is None and len(ids) > self.model_max_length and verbose:
            if not self.deprecation_warnings.get("sequence-length-is-longer-than-the-specified-maximum", False):
                logger.warning(
                    "Token indices sequence length is longer than the specified maximum sequence length "
                    f"for this model ({len(ids)} > {self.model_max_length}). Running this sequence through the model "
                    "will result in indexing errors"
                )
            self.deprecation_warnings["sequence-length-is-longer-than-the-specified-maximum"] = True

    def _switch_to_input_mode(self):
        """
        Private method to put the tokenizer in input mode (when it has different modes for input/outputs)
        """
        pass

    def _switch_to_target_mode(self):
        """
        Private method to put the tokenizer in target mode (when it has different modes for input/outputs)
        """
        pass

    @contextmanager
    def as_target_tokenizer(self):
        """
        Temporarily sets the tokenizer for encoding the targets. Useful for tokenizer associated to
        sequence-to-sequence models that need a slightly different processing for the labels.
        """
        warnings.warn(
            "`as_target_tokenizer` is deprecated and will be removed in v5 of Transformers. You can tokenize your "
            "labels by using the argument `text_target` of the regular `__call__` method (either in the same call as "
            "your input texts if you use the same keyword arguments, or in a separate call."
        )
        self._switch_to_target_mode()
        self._in_target_context_manager = True
        yield
        self._in_target_context_manager = False
        self._switch_to_input_mode()

    @classmethod
    def register_for_auto_class(cls, auto_class="AutoTokenizer"):
        """
        Register this class with a given auto class. This should only be used for custom tokenizers as the ones in the
        library are already mapped with `AutoTokenizer`.

        <Tip warning={true}>

        This API is experimental and may have some slight breaking changes in the next releases.

        </Tip>

        Args:
            auto_class (`str` or `type`, *optional*, defaults to `"AutoTokenizer"`):
                The auto class to register this new tokenizer with.
        """
        if not isinstance(auto_class, str):
            auto_class = auto_class.__name__

        import transformers.models.auto as auto_module

        if not hasattr(auto_module, auto_class):
            raise ValueError(f"{auto_class} is not a valid auto class.")

        cls._auto_class = auto_class

    def prepare_seq2seq_batch(
        self,
        src_texts: List[str],
        tgt_texts: Optional[List[str]] = None,
        max_length: Optional[int] = None,
        max_target_length: Optional[int] = None,
        padding: str = "longest",
        return_tensors: str = None,
        truncation: bool = True,
        **kwargs,
    ) -> BatchEncoding:
        """
        Prepare model inputs for translation. For best performance, translate one sentence at a time.

        Arguments:
            src_texts (`List[str]`):
                List of documents to summarize or source language texts.
            tgt_texts (`list`, *optional*):
                List of summaries or target language texts.
            max_length (`int`, *optional*):
                Controls the maximum length for encoder inputs (documents to summarize or source language texts) If
                left unset or set to `None`, this will use the predefined model maximum length if a maximum length is
                required by one of the truncation/padding parameters. If the model has no specific maximum input length
                (like XLNet) truncation/padding to a maximum length will be deactivated.
            max_target_length (`int`, *optional*):
                Controls the maximum length of decoder inputs (target language texts or summaries) If left unset or set
                to `None`, this will use the max_length value.
            padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `False`):
                Activates and controls padding. Accepts the following values:

                - `True` or `'longest'`: Pad to the longest sequence in the batch (or no padding if only a single
                  sequence if provided).
                - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
                  acceptable input length for the model if that argument is not provided.
                - `False` or `'do_not_pad'` (default): No padding (i.e., can output a batch with sequences of different
                  lengths).
            return_tensors (`str` or [`~utils.TensorType`], *optional*):
                If set, will return tensors instead of list of python integers. Acceptable values are:

                - `'tf'`: Return TensorFlow `tf.constant` objects.
                - `'pt'`: Return PyTorch `torch.Tensor` objects.
                - `'np'`: Return Numpy `np.ndarray` objects.
            truncation (`bool`, `str` or [`~tokenization_utils_base.TruncationStrategy`], *optional*, defaults to `True`):
                Activates and controls truncation. Accepts the following values:

                - `True` or `'longest_first'`: Truncate to a maximum length specified with the argument `max_length` or
                  to the maximum acceptable input length for the model if that argument is not provided. This will
                  truncate token by token, removing a token from the longest sequence in the pair if a pair of
                  sequences (or a batch of pairs) is provided.
                - `'only_first'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the first sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `'only_second'`: Truncate to a maximum length specified with the argument `max_length` or to the
                  maximum acceptable input length for the model if that argument is not provided. This will only
                  truncate the second sequence of a pair if a pair of sequences (or a batch of pairs) is provided.
                - `False` or `'do_not_truncate'` (default): No truncation (i.e., can output batch with sequence lengths
                  greater than the model maximum admissible input size).
            **kwargs:
                Additional keyword arguments passed along to `self.__call__`.

        Return:
            [`BatchEncoding`]: A [`BatchEncoding`] with the following fields:

            - **input_ids** -- List of token ids to be fed to the encoder.
            - **attention_mask** -- List of indices specifying which tokens should be attended to by the model.
            - **labels** -- List of token ids for tgt_texts.

            The full set of keys `[input_ids, attention_mask, labels]`, will only be returned if tgt_texts is passed.
            Otherwise, input_ids, attention_mask will be the only keys.
        """
        # docstyle-ignore
        formatted_warning = """
`prepare_seq2seq_batch` is deprecated and will be removed in version 5 of HuggingFace Transformers. Use the regular
`__call__` method to prepare your inputs and targets.

Here is a short example:

model_inputs = tokenizer(src_texts, text_target=tgt_texts, ...)

If you either need to use different keyword arguments for the source and target texts, you should do two calls like
this:

model_inputs = tokenizer(src_texts, ...)
labels = tokenizer(text_target=tgt_texts, ...)
model_inputs["labels"] = labels["input_ids"]

See the documentation of your specific tokenizer for more details on the specific arguments to the tokenizer of choice.
For a more complete example, see the implementation of `prepare_seq2seq_batch`.
"""
        warnings.warn(formatted_warning, FutureWarning)
        # mBART-specific kwargs that should be ignored by other models.
        kwargs.pop("src_lang", None)
        kwargs.pop("tgt_lang", None)
        if max_length is None:
            max_length = self.model_max_length
        model_inputs = self(
            src_texts,
            add_special_tokens=True,
            return_tensors=return_tensors,
            max_length=max_length,
            padding=padding,
            truncation=truncation,
            **kwargs,
        )
        if tgt_texts is None:
            return model_inputs
        # Process tgt_texts
        if max_target_length is None:
            max_target_length = max_length
        with self.as_target_tokenizer():
            labels = self(
                tgt_texts,
                add_special_tokens=True,
                return_tensors=return_tensors,
                padding=padding,
                max_length=max_target_length,
                truncation=truncation,
                **kwargs,
            )
        model_inputs["labels"] = labels["input_ids"]
        return model_inputs


def get_fast_tokenizer_file(tokenization_files: List[str]) -> str:
    """
    Get the tokenization file to use for this version of transformers.

    Args:
        tokenization_files (`List[str]`): The list of available configuration files.

    Returns:
        `str`: The tokenization file to use.
    """
    tokenizer_files_map = {}
    for file_name in tokenization_files:
        search = _re_tokenizer_file.search(file_name)
        if search is not None:
            v = search.groups()[0]
            tokenizer_files_map[v] = file_name
    available_versions = sorted(tokenizer_files_map.keys())

    # Defaults to FULL_TOKENIZER_FILE and then try to look at some newer versions.
    tokenizer_file = FULL_TOKENIZER_FILE
    transformers_version = version.parse(__version__)
    for v in available_versions:
        if version.parse(v) <= transformers_version:
            tokenizer_file = tokenizer_files_map[v]
        else:
            # No point going further since the versions are sorted.
            break

    return tokenizer_file


# To update the docstring, we need to copy the method, otherwise we change the original docstring.
PreTrainedTokenizerBase.push_to_hub = copy_func(PreTrainedTokenizerBase.push_to_hub)
if PreTrainedTokenizerBase.push_to_hub.__doc__ is not None:
    PreTrainedTokenizerBase.push_to_hub.__doc__ = PreTrainedTokenizerBase.push_to_hub.__doc__.format(
        object="tokenizer", object_class="AutoTokenizer", object_files="tokenizer files"
    )