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[Feature]Add Parser for Qwen3 think model #258

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[Feature]Add Parser for Qwen3 think model #258

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[Feature]Add Parser for Qwen3 think model
zyksir Oct 21, 2025
33b228a
Merge branch 'main' into yikai/add_qwen_thinking_parser
zyksir Oct 21, 2025
be27c17
use lint
zyksir Oct 21, 2025
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26 changes: 26 additions & 0 deletions specforge/data/parse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,9 @@ def parse(
messages, tokenize=False, add_generation_prompt=False, **kwargs
)

if self.chat_template.ignored_token:
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medium

Consider adding a check to ensure self.chat_template.ignored_token is not None or empty before calling replace. This prevents potential errors if the token is not defined.

if self.chat_template.ignored_token and self.chat_template.ignored_token != "":
    conversation = conversation.replace(self.chat_template.ignored_token, "")
Suggested change
if self.chat_template.ignored_token:
if self.chat_template.ignored_token and self.chat_template.ignored_token != "":
conversation = conversation.replace(self.chat_template.ignored_token, "")

conversation = conversation.replace(self.chat_template.ignored_token, "")

if not self.tokenizer.pad_token_id:
self.tokenizer.pad_token_id = self.tokenizer.unk_token_id

Expand Down Expand Up @@ -122,6 +125,29 @@ def parse(
return input_ids, loss_mask


class Qwen3ThinkingParser(GeneralParser):
def __init__(self, tokenizer: PreTrainedTokenizer, chat_template: ChatTemplate):
super().__init__(tokenizer, chat_template)

def parse(
self,
conversation: "Conversation",
max_length: int,
preformatted: bool = False,
**kwargs,
) -> Dict[str, List[torch.Tensor]]:
if kwargs.get("enable_thinking", False):
self.assistant_message_separator = (
f"{self.chat_template.end_of_turn_token}<|im_start|>assistant\n<think>\n"
)
self.chat_template.ignored_token = None
else:
self.assistant_message_separator = (
f"{self.chat_template.end_of_turn_token}<|im_start|>assistant\n"
)
self.chat_template.ignored_token = "<think>\n\n</think>\n\n"
return super().parse(conversation, max_length, preformatted, **kwargs)
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high

The super().parse method returns input_ids and loss_mask. However, the return type annotation Dict[str, List[torch.Tensor]] suggests a dictionary is expected. This discrepancy could lead to confusion or errors if the caller expects a dictionary. Consider updating the return type annotation or modifying the return statement to return a dictionary.

Suggestion:

return {"input_ids": input_ids, "loss_mask": loss_mask}

Alternatively, update the return type annotation to Tuple[torch.Tensor, torch.Tensor] to match the actual return type.

Suggested change
return super().parse(conversation, max_length, preformatted, **kwargs)
return {"input_ids": input_ids, "loss_mask": loss_mask}


class HarmonyParser(Parser):

def build_single_turn_prompt(
Expand Down
4 changes: 3 additions & 1 deletion specforge/data/preprocessing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@

from specforge.utils import padding

from .parse import GeneralParser, HarmonyParser
from .parse import GeneralParser, HarmonyParser, Qwen3ThinkingParser
from .template import TEMPLATE_REGISTRY, ChatTemplate

# define a type called conversation
Expand Down Expand Up @@ -141,6 +141,8 @@ def preprocess_conversations(

if chat_template.parser_type == "general":
parser = GeneralParser(tokenizer, chat_template)
elif chat_template.parser_type == "qwen3-thinking":
parser = Qwen3ThinkingParser(tokenizer, chat_template)
elif chat_template.parser_type == "openai-harmony":
parser = HarmonyParser(tokenizer, chat_template)
else:
Expand Down
13 changes: 13 additions & 0 deletions specforge/data/template.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ class ChatTemplate(BaseModel):
system_prompt: str | None
end_of_turn_token: str | None
parser_type: str = "general"
ignored_token: str | None = None


class TemplateRegistry:
Expand Down Expand Up @@ -115,6 +116,18 @@ def get_all_template_names(self) -> List[str]:
),
)

TEMPLATE_REGISTRY.register(
name="qwen3-thinking",
template=ChatTemplate(
assistant_header="<|im_start|>assistant\n",
user_header="<|im_start|>user\n",
system_prompt="You are a helpful assistant.",
end_of_turn_token="<|im_end|>\n",
parser_type="qwen3-thinking",
ignored_token="<think>\n\n</think>\n\n",
),
)

TEMPLATE_REGISTRY.register(
name="qwen2-vl",
template=ChatTemplate(
Expand Down
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