[fix] hymba template more consistent with jinja

src/lmflow/utils/conversation_template/hymba.py

@@ -6,12 +6,12 @@
 
 from transformers import PreTrainedTokenizer
 
-
+# NOTE: 'contexts' are not used in sft
 # {{'<extra_id_0>System'}}
 # {% for message in messages %}
 #   {% if message['role'] == 'system' %}
 #       {{'\n' + message['content'].strip()}}
-#       {% if tools or contexts %}
+#       {% if tools %}
 #           {{'\n'}}
 #       {% endif %}
 #   {% endif %}
@@ -21,14 +21,6 @@
 #       {{ '\n<tool> ' + tool|tojson + ' </tool>' }}
 #   {% endfor %}
 # {% endif %}
-# {% if contexts %}
-#   {% if tools %}
-#       {{'\n'}}
-#   {% endif %}
-#   {% for context in contexts %}
-#       {{ '\n<context> ' + context.strip() + ' </context>' }}
-#   {% endfor %}
-# {% endif %}
 # {{'\n\n'}}
 # {% for message in messages %}
 #   {% if message['role'] == 'user' %}
@@ -45,18 +37,56 @@
 
 
 class HymbaConversationTemplate(ConversationTemplateForTool):
-    def _encode(
+    def encode_conversation(
         self,
         tokenizer: PreTrainedTokenizer,
         messages: List[Dict[str, str]],
         system: Optional[str] = None,
-        tools: Optional[str] = None,
+        tools: Optional[List[str]] = None,
         **kwargs
     ) -> Sequence[Tuple[List[int], List[int]]]:
-        if tools:
-            system = system + "<tool> " + tools + " </tool>\n"
-        return super()._encode(tokenizer=tokenizer,messages=messages, system=system, tools='')
-
+        r'''
+        Messages here should be guaranteed to be in pairs, with the first message being the user message and the second message being the system message.
+        Data example: 
+        ```json
+        {
+            "conversation_id": 2,
+            "system": "sysinfo1",
+            "tools": ["tool_1_desc"],
+            "messages": [
+                {
+                    "role": "user",
+                    "content": "hi"
+                },
+                {
+                    "role": "assistant",
+                    "content": "Hello!"
+                }
+            ]
+        }
+        ```
+        '''
+        assert isinstance(messages, list), "Messages must be a list."
+
+        tools_out = ''
+        if tools is not None:
+            for tool in tools:
+                tools_out += "\n<tool> " + tool + " </tool>"
+
+        if system is None:
+            system = ""
+        else:
+            if system.replace(" ",""): # has actual content
+                if not self.system_formatter:
+                    raise ValueError("Your dataset contains system message but no system formatter is provided. "
+                                     "Consider either providing a system formatter or removing system prompt from your dataset.")
+                system = '\n' + system
+            else:
+                system = ""
+        encoded_pairs = self._encode(tokenizer, messages, system, tools_out, **kwargs)
+        encoded_pairs = self.post_process_pairs(encoded_pairs=encoded_pairs, tokenizer=tokenizer)
+
+        return encoded_pairs    
 
 
 HYMBA_TEMPLATE = HymbaConversationTemplate(
@@ -83,7 +113,7 @@ def _encode(
     ),
     system_formatter=StringFormatter(
         template=[
-            TemplateComponent(type='string', content='<extra_id_0>System\n{{content}}\n')
+            TemplateComponent(type='string', content='<extra_id_0>System{{content}}\n\n')
         ]
     ),
     separator=TemplateComponent(type='token_id', content=13),