Improve Tokenizer New Type Onboarding

[zhenyan-zhang-meta]

🚀 The feature, motivation and pitch

---

As a sequel to #1518 where we added an enum for tokenizer types to simplify TokenizerArgs __post_init__, we need to further improve it to simplify new tokenizer type onboarding:

Tasks

---

• Move TokenizerType to a centralized place
  • We now have two of them:

    torchchat/dist_run.py

    Lines 67 to 69 in 0299a37

    	class TokenizerType(Enum):
    	Tiktoken = auto()
    	SentencePiece = auto()

    torchchat/torchchat/cli/builder.py

    Lines 241 to 245 in 0299a37

    	class TokenizerType(Enum):
    	NONE = 0
    	TIKTOKEN = 1
    	SENTENCEPIECE = 2
    	HF_TOKENIZER = 3

• Check all getters of tokenizer types
  • It may be able to be simplified as inline

    torchchat/torchchat/generate.py

    Line 368 in 0299a37

    self.is_llama3_model = self.tokenizer_args.is_tiktoken()

• Add documentation for future tokenizer onboard.
  • We may need to point people to update the model validation logic:

    torchchat/torchchat/cli/builder.py

    Lines 290 to 322 in 0299a37

    	def validate_model(
    	self,
    	model: Optional[Model],
    	model_description: str = "model",
    	) -> None:
    	if model is None:
    	return
    	if self.tokenizer_type == TokenizerType.NONE:
    	raise RuntimeError(f"no tokenizer was found at {self.tokenizer_path}")
    	is_tiktoken = self.is_tiktoken()
    	is_sentencepiece = self.is_sentencepiece()
    	is_hf_tokenizer = self.is_hf_tokenizer()
    	use_tiktoken = model.config.use_tiktoken
    	use_hf_tokenizer = model.config.use_hf_tokenizer
    	use_sentencepiece = not (use_tiktoken or use_hf_tokenizer)
    	if (
    	(is_tiktoken and not use_tiktoken) or
    	(is_hf_tokenizer and not use_hf_tokenizer) or
    	(is_sentencepiece and not use_sentencepiece)
    	):
    	raise RuntimeError(
    	"model-specified tokenizer ({}) does not match provided tokenizer ({}) for {}".format(
    	tokenizer_setting_to_name(use_tiktoken, use_hf_tokenizer),
    	tokenizer_setting_to_name(is_tiktoken, is_hf_tokenizer),
    	model_description,
    	)
    	)
    	return

---

To test, run a model with each tokenizer type:

• python torchchat.py generate llama2
• python torchchat.py generate llama3
• python torchchat.py generate granite-code

cc @Jack-Khuu @byjlw

[srikary12]

Would like to take this up.

[zhenyan-zhang-meta]

@srikary12 Nice, thanks for taking this up. I've just assigned you to this issue. Let us know when there's any PR to review, and chat in #torchchat-contributors if there's any questions.

[srikary12]

@zhenyan-zhang-meta I've made changes. Documentation changes are pending. If the PR looks looks okay, I'll add documentation changes.