280 lines
9.4 KiB
Python
280 lines
9.4 KiB
Python
"""
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Tokenizer module with implementation and auto-loading support.
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"""
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import json
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from pathlib import Path
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from typing import Dict, List, Optional, Union
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from tokenizers import Tokenizer, decoders, normalizers, pre_tokenizers, processors
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from tokenizers.models import BPE
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from astrai.tokenize.chat_template import ChatTemplate
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class AutoTokenizer:
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"""Base tokenizer class with automatic loading support"""
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TOKENIZER_CLASSES = {} # Registry for auto-loading
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def __init__(
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self,
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path: Optional[Union[str, Path]] = None,
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special_token_map: Optional[Dict[str, str]] = None,
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chat_template: Optional[str] = None,
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):
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self._tokenizer: Tokenizer = None
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self._chat_template: Optional[ChatTemplate] = None
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self._special_token_map: Optional[Dict] = special_token_map or {}
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if chat_template:
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self.set_chat_template(chat_template)
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if path:
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self.load(path)
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def load(self, path: Union[str, Path]):
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"""Load tokenizer from directory."""
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path = Path(path)
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tokenizer_file = path / "tokenizer.json"
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config_file = path / "tokenizer_config.json"
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self._tokenizer = Tokenizer.from_file(str(tokenizer_file))
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if config_file.exists():
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with open(config_file, "r", encoding="utf-8") as f:
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config = json.load(f)
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if "special_tokens" in config:
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self._special_token_map.update(config["special_tokens"])
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# Load chat template from config
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if "chat_template" in config:
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self.set_chat_template(config["chat_template"])
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@classmethod
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def from_pretrained(cls, path: Union[str, Path], **kwargs) -> "AutoTokenizer":
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"""Load tokenizer from pretrained directory."""
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instance = cls(path)
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return instance
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def save_pretrained(self, save_path: str):
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"""
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Save tokenizer to pretrained directory.
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Args:
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save_path: Path to save the tokenizer
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"""
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save_path = Path(save_path)
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save_path.mkdir(parents=True, exist_ok=True)
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# Save tokenizer
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self._tokenizer.save(str(save_path / "tokenizer.json"))
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# Save tokenizer config
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config = {}
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if self._special_token_map is not None:
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config["special_tokens"] = self._special_token_map
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if self._chat_template is not None:
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config["chat_template"] = self._chat_template.template_str
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with open(save_path / "tokenizer_config.json", "w", encoding="utf-8") as f:
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json.dump(config, f, ensure_ascii=False, indent=2)
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@classmethod
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def register_tokenizer(cls, name: str, tokenizer_class: type):
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"""
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Register a new tokenizer class.
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Args:
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name: Name to register the tokenizer class under
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tokenizer_class: The tokenizer class to register
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"""
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cls.TOKENIZER_CLASSES[name] = tokenizer_class
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def encode(
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self,
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tokens: Union[str, List[str]],
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out_ids: bool = True,
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is_pretokenized: bool = False,
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add_special_tokens: bool = True,
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) -> List:
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"""Encode text to tokens or token IDs."""
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if self._tokenizer is None:
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raise RuntimeError(
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"Tokenizer not initialized. Load or create a tokenizer first."
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)
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if isinstance(tokens, str):
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encoded = self._tokenizer.encode(
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tokens,
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is_pretokenized=is_pretokenized,
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add_special_tokens=add_special_tokens,
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)
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return encoded.ids if out_ids else encoded.tokens
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else:
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encoded_list = self._tokenizer.encode_batch(
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tokens,
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is_pretokenized=is_pretokenized,
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add_special_tokens=add_special_tokens,
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)
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return [
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encoded.ids if out_ids else encoded.tokens for encoded in encoded_list
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]
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def decode(self, tokens: List[int], skip_special_tokens: bool = True) -> str:
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"""Decode token IDs to text."""
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if self._tokenizer is None:
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raise RuntimeError(
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"Tokenizer not initialized. Load or create a tokenizer first."
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)
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return self._tokenizer.decode(tokens, skip_special_tokens=skip_special_tokens)
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def __len__(self) -> int:
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if self._tokenizer is None:
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return 0
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return self._tokenizer.get_vocab_size()
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def __getattr__(self, key: str):
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"""
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Dynamically intercept special token attribute access.
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Supports three forms:
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- tokenizer.bos_token → returns string
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- tokenizer.bos_token_id → returns corresponding integer ID
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- tokenizer.stop_ids → returns list of corresponding integer IDs for all special tokens
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"""
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# Handle stop_ids - return IDs for all special tokens
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if key == "stop_ids":
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stop_ids = []
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if self._tokenizer is None:
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return stop_ids
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for val in self._special_token_map.values():
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token_id = self._tokenizer.token_to_id(val)
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if token_id is not None:
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stop_ids.append(token_id)
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return stop_ids
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# Handle _id suffix (e.g., bos_token_id -> bos_token)
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if key.endswith("_id"):
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base_attr = key[:-3] # Remove "_id"
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token_str = self._special_token_map.get(base_attr)
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if token_str is None:
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return None
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if self._tokenizer is None:
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raise RuntimeError("Tokenizer not loaded, cannot convert token to id.")
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return self._tokenizer.token_to_id(token_str)
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# Handle regular string attributes
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if key in self._special_token_map:
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return self._special_token_map.get(key)
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# Other attributes trigger default AttributeError
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raise AttributeError(f"'{type(self).__name__}' object has no attribute '{key}'")
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@property
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def vocab_size(self) -> int:
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return len(self)
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def set_chat_template(self, template: Union[str, ChatTemplate]):
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"""
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Set the chat template for the tokenizer.
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Args:
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template: Either a template name (str) registered in the global registry,
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or a ChatTemplate instance, or a Jinja2 template string.
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Raises:
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KeyError: If template name is not registered.
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"""
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if isinstance(template, str):
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self._chat_template = ChatTemplate.from_string(template)
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elif isinstance(template, ChatTemplate):
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self._chat_template = template
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else:
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raise ValueError("Invalid template type, must be str or ChatTemplate.")
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def apply_chat_template(
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self,
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messages: List[Dict[str, str]],
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system_prompt: Optional[str] = None,
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tokenize: bool = True,
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add_generation_prompt: bool = True,
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**kwargs,
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) -> Union[str, List[int]]:
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"""
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Apply the chat template to messages and optionally tokenize the result.
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Args:
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messages: List of message dicts with 'role' and 'content'.
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system_prompt: Optional system prompt string.
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tokenize: Whether to return token IDs (True) or raw string (False).
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add_generation_prompt: Whether to add the generation prompt (default: False).
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**kwargs: Additional variables to pass to the template.
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Returns:
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Either the rendered string or list of token IDs.
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Raises:
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RuntimeError: If chat template is not set.
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"""
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if self._chat_template is None:
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raise RuntimeError(
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"Chat template not set. Use set_chat_template() to set a template first."
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)
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# Render the template
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rendered = self._chat_template.render(
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messages=messages,
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system_prompt=system_prompt,
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add_generation_prompt=add_generation_prompt,
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**kwargs,
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)
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if tokenize:
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return self.encode(rendered)
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return rendered
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class BpeTokenizer(AutoTokenizer):
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"""BPE tokenizer implementation."""
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def __init__(
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self,
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special_token_map: Dict[str, str] = None,
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path: Optional[str] = None,
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chat_template: Optional[str] = None,
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):
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special_token_map = special_token_map or {
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"bos": "<｜begin▁of▁sentence｜>",
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"eos": "<｜end▁of▁sentence｜>",
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"pad": "<｜▁pad▁｜>",
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"im_start": "<｜im▁start｜>",
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"im_end": "<｜im▁end｜>",
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}
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self._tokenizer = None
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self._init_tokenizer()
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super().__init__(
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path, special_token_map=special_token_map, chat_template=chat_template
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)
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def _init_tokenizer(self):
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"""Initialize a new BPE tokenizer with default settings."""
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model = BPE()
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self._tokenizer = Tokenizer(model)
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self._tokenizer.normalizer = normalizers.Sequence(
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[normalizers.NFC(), normalizers.Strip()]
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)
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self._tokenizer.pre_tokenizer = pre_tokenizers.Sequence(
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[
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pre_tokenizers.UnicodeScripts(),
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pre_tokenizers.ByteLevel(add_prefix_space=False, use_regex=True),
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]
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)
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self._tokenizer.decoder = decoders.ByteLevel()
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self._tokenizer.post_processor = processors.ByteLevel(trim_offsets=True)
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