Update chat template for qwen and yi-1.5.

python/sglang/lang/chat_template.py

@@ -16,6 +16,7 @@ class ChatTemplate:
     stop_str: List[str] = ()
     image_token: str = "<image>"
     style: ChatTemplateStyle = ChatTemplateStyle.PLAIN
+    use_default_system: bool = False
 
     def get_prefix_and_suffix(
         self, role: str, hist_messages: List[Dict]
@@ -42,7 +43,8 @@ def get_prompt(self, messages: List[Dict]) -> str:
         prompt = ""
         for i, message in enumerate(messages):
             role, content = message["role"], message["content"]
-            if role == "system" and content is None:
+            # if use default system like qwen
+            if role == "system" and (content is None or self.use_default_system):
                 content = self.default_system_prompt
                 if content is None:
                     continue
@@ -84,7 +86,7 @@ def get_chat_template_by_model_path(model_path):
             "system": ("SYSTEM:", "\n"),
             "user": ("USER:", "\n"),
             "assistant": ("ASSISTANT:", "\n"),
-        },
+        }
     )
 )
 
@@ -116,6 +118,24 @@ def get_chat_template_by_model_path(model_path):
     )
 )
 
+# There is default system prompt for qwen
+# reference: https://modelscope.cn/models/qwen/Qwen2-72B-Instruct/file/view/master?fileName=tokenizer_config.json&status=1
+# The chat template is: "{% for message in messages %}{% if loop.first and messages[0]['role'] != 'system' %}{{ '<|im_start|>system\nYou are a helpful assistant.<|im_end|>\n' }}{% endif %}{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% endif %}"
+register_chat_template(
+    ChatTemplate(
+        name="qwen",
+        default_system_prompt="You are a helpful assistant.",
+        role_prefix_and_suffix={
+            "system": ("<|im_start|>system\n", "<|im_end|>\n"),
+            "user": ("<|im_start|>user\n", "<|im_end|>\n"),
+            "assistant": ("<|im_start|>assistant\n", "<|im_end|>\n"),
+        },
+        style=ChatTemplateStyle.PLAIN,
+        stop_str=("<|im_end|>",),
+        use_default_system=True
+    )
+)
+
 
 register_chat_template(
     ChatTemplate(
@@ -148,6 +168,20 @@ def get_chat_template_by_model_path(model_path):
     )
 )
 
+# Reference: https://modelscope.cn/models/01ai/Yi-1.5-34B-Chat/file/view/master?fileName=tokenizer_config.json&status=1
+register_chat_template(
+    ChatTemplate(
+        name="yi-1.5",
+        default_system_prompt=None,
+        role_prefix_and_suffix={
+            "system": ("", ""),
+            "user": ("<|im_start|>user\n", "<|im_end|>\n<|im_start|>assistant\n"),
+            "assistant": ("", "<|im_end|>\n"),
+        },
+        style=ChatTemplateStyle.PLAIN,
+        stop_str=("<|im_end|>",)
+    )
+)
 
 register_chat_template(
     ChatTemplate(
@@ -187,7 +221,7 @@ def get_chat_template_by_model_path(model_path):
 # Reference: https://github.com/01-ai/Yi/tree/main/VL#major-difference-with-llava
 register_chat_template(
     ChatTemplate(
-        name="yi",
+        name="yi-vl",
         default_system_prompt=(
             "This is a chat between an inquisitive human and an AI assistant. Assume the role of the AI assistant. Read all the images carefully, and respond to the human's questions with informative, helpful, detailed and polite answers."
             "这是一个好奇的人类和一个人工智能助手之间的对话。假设你扮演这个AI助手的角色。仔细阅读所有的图像，并对人类的问题做出信息丰富、有帮助、详细的和礼貌的回答。"
@@ -289,8 +323,9 @@ def match_chat_ml(model_path: str):
     model_path = model_path.lower()
     if "tinyllama" in model_path:
         return get_chat_template("chatml")
-    if "qwen" in model_path and "chat" in model_path:
-        return get_chat_template("chatml")
+    # Now the suffix for qwen2 chat model is "instruct"
+    if "qwen" in model_path and ("chat" in model_path or "instruct" in model_path):
+        return get_chat_template("qwen")
     if (
         "llava-v1.6-34b" in model_path
         or "llava-v1.6-yi-34b" in model_path
@@ -302,8 +337,10 @@ def match_chat_ml(model_path: str):
 @register_chat_template_matching_function
 def match_chat_yi(model_path: str):
     model_path = model_path.lower()
-    if "yi" in model_path and "llava" not in model_path:
-        return get_chat_template("yi")
+    if "yi-vl" in model_path and "llava" not in model_path:
+        return get_chat_template("yi-vl")
+    elif "yi-1.5" in model_path and "chat" in model_path:
+        return get_chat_template("yi-1.5")
 
 
 @register_chat_template_matching_function