Simplify TokenizerArgs.__post_init__ with Enum Tokenizer Type

Summary:
Simplify `TokenizerArgs.__post_init__` with enum tokenizer type, since
only one of the tokenizer type can be true.

We want to touch as less code outside of `__post_init__` as possible at
the moment.

Test Plan:
python torchchat.py generate llama2|llama3|granite-code

Reviewers:
@Jack-Khuu

Subscribers:

Issue:
#1518

Author: zhenyanzhang

torchchat/cli/builder.py

@@ -8,6 +8,7 @@
 import os
 import sys
 from dataclasses import dataclass
+from enum import Enum
 from pathlib import Path
 from typing import Any, Dict, Optional, Tuple, Union
 
@@ -237,23 +238,24 @@ def from_speculative_args(cls, args: argparse.Namespace) -> "BuilderArgs":
         speculative_builder_args.pte_path = None
         return speculative_builder_args
 
+class TokenizerType(Enum):
+    NONE = 0
+    TIKTOKEN = 1
+    SENTENCEPIECE = 2
+    HF_TOKENIZER = 3
 
 @dataclass
 class TokenizerArgs:
     tokenizer_path: Optional[Union[Path, str]] = None
-    is_sentencepiece: bool = False
-    is_tiktoken: bool = False
-    is_hf_tokenizer: bool = False
+    tokenizer_type: TokenizerType = TokenizerType.NONE
     t: Optional[Any] = None
 
     def __post_init__(self):
         try:
             from tokenizer.tiktoken import Tokenizer as TiktokenTokenizer
 
             self.t = TiktokenTokenizer(model_path=str(self.tokenizer_path))
-            self.is_tiktoken = True
-            self.is_sentencepiece = False
-            self.is_hf_tokenizer = False
+            self.tokenizer_type = TokenizerType.TIKTOKEN
             return
         except:
             pass
@@ -262,9 +264,7 @@ def __post_init__(self):
             from sentencepiece import SentencePieceProcessor
 
             self.t = SentencePieceProcessor(model_file=str(self.tokenizer_path))
-            self.is_tiktoken = False
-            self.is_sentencepiece = True
-            self.is_hf_tokenizer = False
+            self.tokenizer_type = TokenizerType.SENTENCEPIECE
             return
         except:
             pass
@@ -273,19 +273,24 @@ def __post_init__(self):
             from tokenizer.hf_tokenizer import HFTokenizer
 
             self.t = HFTokenizer(str(self.tokenizer_path))
-            self.is_tiktoken = False
-            self.is_sentencepiece = False
-            self.is_hf_tokenizer = True
+            self.tokenizer_type = TokenizerType.HF_TOKENIZER
             return
         except:
             pass
 
-        self.is_tiktoken = False
-        self.is_sentencepiece = False
-        self.is_hf_tokenizer = False
+        self.tokenizer_type = TokenizerType.NONE
         self.t = None
         return
 
+    def is_tiktoken(self) -> bool:
+        return self.tokenizer_type == TokenizerType.TIKTOKEN
+
+    def is_sentencepiece(self) -> bool:
+        return self.tokenizer_type == TokenizerType.SENTENCEPIECE
+
+    def is_hf_tokenizer(self) -> bool:
+        return self.tokenizer_type == TokenizerType.HF_TOKENIZER
+
     def validate_model(
         self,
         model: Optional[Model],
@@ -294,12 +299,14 @@ def validate_model(
         if model is None:
             return
 
-        if sum([self.is_tiktoken, self.is_hf_tokenizer, self.is_sentencepiece]) != 1:
+
+        is_tiktoken = self.is_tiktoken()
+        is_sentencepiece = self.is_sentencepiece()
+        is_hf_tokenizer = self.is_hf_tokenizer()
+
+        if sum([is_tiktoken, is_hf_tokenizer, is_sentencepiece]) != 1:
             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)
@@ -651,13 +658,13 @@ def do_nothing(max_batch_size, max_seq_length):
             model = torch.load(builder_args.snapshot_path, weights_only=False)
         except Exception:
             raise RuntimeError(f"Failed to load torchchat snapshot {builder_args.snapshot_path}")
-        # _active_backend() does not allow DSO & AOTI to be true. 
+        # _active_backend() does not allow DSO & AOTI to be true.
         # Choose either.
         from torchchat.utils.build_utils import set_backend
         set_backend (dso=True, pte=False, aoti_package=False)
         if (model.config != config):
             raise RuntimeError("loaded model architecture mismatch")
-        ##        
+        ##
         ## import all libraries with custom kernels ans custom operators
         ## that quantize may be pulling in
         ##
@@ -792,4 +799,4 @@ def tokenizer_setting_to_name(tiktoken: bool, tokenizers: bool) -> str:
         return "TikToken"
     if tokenizers:
         return "Tokenizers"
-    return "SentencePiece"
+    return "SentencePiece"

torchchat/export.py

@@ -482,7 +482,7 @@ def main(args):
 
     if tokenizer_args is None:
         tokenizer_type = "0"
-    elif tokenizer_args.is_sentencepiece:
+    elif tokenizer_args.is_sentencepiece():
         tokenizer_type = "2"  # Corresponding to llama2
     else:
         tokenizer_type = "3"  # Corresponding to llama3

torchchat/generate.py

@@ -365,14 +365,14 @@ def __init__(
         # must use tiktokenizer.
         # Piggy backing off of this flag then for now to identify llama3
         # without prompting user.
-        self.is_llama3_model = self.tokenizer_args.is_tiktoken
+        self.is_llama3_model = self.tokenizer_args.is_tiktoken()
         if self.is_llama3_model:
             self.chat_formatter = Llama3ChatFormatter(self.tokenizer)
             if generator_args.chat_mode:
                 logger.debug(
                     "Llama3 model detected in chat mode. Using updated sentence schemas"
                 )
-        elif self.tokenizer_args.is_hf_tokenizer:
+        elif self.tokenizer_args.is_hf_tokenizer():
             if not self.tokenizer.has_chat_template():
                 raise ValueError("Tokenizer must have a chat template")
             self.chat_formatter = HFTokenizerChatFormatter(self.tokenizer)