tokenization_emu3.py

# coding=utf-8
# Copyright 2024 The Emu team, BAAI and The HuggingFace Inc. team. All rights reserved.
#
# 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.
#
# Adapted from https://github.com/huggingface/transformers/blob/52daf4ec768fb9ffe84a0c373834172a7c54aecc/src/transformers/models/qwen2/tokenization_qwen2.py
#
"""Tokenization classes for Emu3."""

import base64
import logging
import os
import unicodedata
from typing import Collection, Dict, List, Optional, Set, Tuple, Union

import tiktoken
from transformers import PreTrainedTokenizer, AddedToken

logger = logging.getLogger(__name__)


VOCAB_FILES_NAMES = {
    "vocab_file": "emu3.tiktoken",
    "special_tokens_file": "emu3_vision_tokens.txt",
}

PAT_STR = r"""(?i:'s|'t|'re|'ve|'m|'ll|'d)|[^\r\n\p{L}\p{N}]?\p{L}+|\p{N}| ?[^\s\p{L}\p{N}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+"""
ENDOFTEXT = "<|endoftext|>"
IMSTART = "<|im_start|>"
IMEND = "<|im_end|>"
# as the default behavior is changed to allow special tokens in
# regular texts, the surface forms of special tokens need to be
# as different as possible to minimize the impact
EXTRAS = tuple((f"<|extra_{i}|>" for i in range(205)))
# changed to use actual index to avoid misconfiguration with vocabulary expansion
SPECIAL_START_ID = 151643


def _load_tiktoken_bpe(tiktoken_bpe_file: str) -> Dict[bytes, int]:
    with open(tiktoken_bpe_file, "rb") as f:
        contents = f.read()
    return {
        base64.b64decode(token): int(rank)
        for token, rank in (line.split() for line in contents.splitlines() if line)
    }


class Emu3Tokenizer(PreTrainedTokenizer):
    """Emu3 tokenizer."""

    vocab_files_names = VOCAB_FILES_NAMES

    def __init__(
        self,
        vocab_file,
        special_tokens_file,
        errors="replace",
        bos_token = "<|extra_203|>",
        eos_token = "<|extra_204|>",
        pad_token = "<|endoftext|>",
        img_token = "<|image token|>",
        boi_token = "<|image start|>",
        eoi_token = "<|image end|>",
        eol_token = "<|extra_200|>",
        eof_token = "<|extra_201|>",
        **kwargs,
    ):
        super().__init__(**kwargs)

        # how to handle errors in decoding UTF-8 byte sequences
        # use ignore if you are in streaming inference
        self.errors = errors  

        self.mergeable_ranks = _load_tiktoken_bpe(vocab_file)

        vision_tokens = [t.strip() for t in open(special_tokens_file).readlines() if len(t.strip()) > 0]
        SPECIAL_TOKENS = tuple(
            enumerate(
                (
                    (
                        ENDOFTEXT,
                        IMSTART,
                        IMEND,
                    )
                    + EXTRAS
                    + tuple(vision_tokens)
                ),
                start=SPECIAL_START_ID,
            )
        )
        self.special_tokens = {token: index for index, token in SPECIAL_TOKENS}
        self.special_tokens_set = set(t for _, t in SPECIAL_TOKENS)

        enc = tiktoken.Encoding(
            "Emu3",
            pat_str=PAT_STR,
            mergeable_ranks=self.mergeable_ranks,
            special_tokens=self.special_tokens,
        )

        assert (
            len(self.mergeable_ranks) + len(self.special_tokens) == enc.n_vocab
        ), f"{len(self.mergeable_ranks) + len(self.special_tokens)} != {enc.n_vocab} in encoding"

        self.decoder = {
            v: k for k, v in self.mergeable_ranks.items()
        }
        self.decoder.update({v: k for k, v in self.special_tokens.items()})

        self.tokenizer = enc

        self.eod_id = self.tokenizer.eot_token
        self.bos_token = bos_token
        self.eos_token = eos_token
        self.pad_token = pad_token
        self.img_token = img_token
        self.boi_token = boi_token
        self.eoi_token = eoi_token
        self.eol_token = eol_token
        self.eof_token = eof_token

    def __getstate__(self):
        # for pickle lovers
        state = self.__dict__.copy()
        del state["tokenizer"]
        return state

    def __setstate__(self, state):
        # tokenizer is not python native; don't pass it; rebuild it
        self.__dict__.update(state)
        enc = tiktoken.Encoding(
            "Emu3",
            pat_str=PAT_STR,
            mergeable_ranks=self.mergeable_ranks,
            special_tokens=self.special_tokens,
        )
        self.tokenizer = enc

    def __len__(self) -> int:
        return self.tokenizer.n_vocab

    def get_vocab(self) -> Dict[bytes, int]:
        return self.mergeable_ranks

    def convert_tokens_to_ids(
        self, tokens: Union[bytes, str, List[Union[bytes, str]]]
    ) -> List[int]:
        if isinstance(tokens, (str, bytes)):
            if tokens in self.special_tokens:
                return self.special_tokens[tokens]
            else:
                return self.mergeable_ranks.get(tokens)

        ids = []
        for token in tokens:
            if token in self.special_tokens:
                ids.append(self.special_tokens[token])
            else:
                ids.append(self.mergeable_ranks.get(token))
        return ids

    def _add_tokens(
        self,
        new_tokens: Union[List[str], List[AddedToken]],
        special_tokens: bool = False,
    ) -> int:
        if not special_tokens and new_tokens:
            raise ValueError("Adding regular tokens is not supported")

        for token in new_tokens:
            surface_form = token.content if isinstance(token, AddedToken) else token
            if surface_form not in self.special_tokens_set:
                raise ValueError("Adding unknown special tokens is not supported")

        return 0

    def save_vocabulary(self, save_directory: str, **kwargs) -> Tuple[str]:
        """
        Save only the vocabulary of the tokenizer (vocabulary).

        Returns:
            `Tuple(str)`: Paths to the files saved.
        """
        regular_file_path = os.path.join(save_directory, self.vocab_files_names["vocab_file"])
        with open(regular_file_path,'w', encoding="utf8") as w:
            for k, v in self.mergeable_ranks.items():
                line = base64.b64encode(k).decode("utf8") + " " + str(v) + "\n"
                w.write(line)

        excluded_special_tokens = set((ENDOFTEXT, IMSTART, IMEND,) + EXTRAS)
        special_file_path = os.path.join(save_directory, self.vocab_files_names["special_tokens_file"])
        with open(special_file_path, 'w', encoding="utf8") as w:
            for k in self.special_tokens:
                if k not in excluded_special_tokens:
                    print(k, file=w)

        return (regular_file_path, special_file_path)

    def tokenize(
        self,
        text: str,
        allowed_special: Union[Set, str] = "all",
        disallowed_special: Union[Collection, str] = (),
        **kwargs,
    ) -> List[Union[bytes, str]]:
        """
        Converts a string in a sequence of tokens.

        Args:
            text (`str`):
                The sequence to be encoded.
            allowed_special (`Literal["all"]` or `set`):
                The surface forms of the tokens to be encoded as special tokens in regular texts.
                Default to "all".
            disallowed_special (`Literal["all"]` or `Collection`):
                The surface forms of the tokens that should not be in regular texts and trigger errors.
                Default to an empty tuple.

            kwargs (additional keyword arguments, *optional*):
                Will be passed to the underlying model specific encode method.

        Returns:
            `List[bytes|str]`: The list of tokens.
        """
        tokens = []
        text = unicodedata.normalize("NFC", text)

        # this implementation takes a detour: text -> token id -> token surface forms
        for t in self.tokenizer.encode(
            text, allowed_special=allowed_special, disallowed_special=disallowed_special
        ):
            tokens.append(self.decoder[t])

        return tokens

    def convert_tokens_to_string(self, tokens: List[Union[bytes, str]]) -> str:
        """
        Converts a sequence of tokens in a single string.
        """
        text = ""
        temp = b""
        for t in tokens:
            if isinstance(t, str):
                if temp:
                    text += temp.decode("utf-8", errors=self.errors)
                    temp = b""
                text += t
            elif isinstance(t, bytes):
                temp += t
            else:
                raise TypeError("token should only be of type types or str")
        if temp:
            text += temp.decode("utf-8", errors=self.errors)
        return text

    @property
    def vocab_size(self):
        return self.tokenizer.n_vocab

    def _convert_id_to_token(self, index: int) -> Union[bytes, str]:
        """Converts an id to a token, special tokens included"""
        if index in self.decoder:
            return self.decoder[index]
        raise ValueError("unknown ids")

    def _convert_token_to_id(self, token: Union[bytes, str]) -> int:
        """Converts a token to an id using the vocab, special tokens included"""
        if token in self.special_tokens:
            return self.special_tokens[token]
        if token in self.mergeable_ranks:
            return self.mergeable_ranks[token]
        raise ValueError("unknown token")

    def _decode(
        self,
        token_ids: Union[int, List[int]],
        skip_special_tokens: bool = False,
        errors: Optional[str] = None,
        **kwargs,
    ) -> str:
        if isinstance(token_ids, int):
            token_ids = [token_ids]

        if skip_special_tokens:
            token_ids = [i for i in token_ids if i < self.eod_id]

        return self.tokenizer.decode(token_ids, errors=errors or self.errors)