refactor build_model_input to not modify its parameters

evoprompt/models.py

@@ -80,7 +80,9 @@ class LLMModel(ABC):
         # create prompt
         prompt = prompt_prefix + prompt + prompt_suffix + prompt_appendix
         messages = [self._get_user_message(prompt)]
-        model_input = self.build_model_input(prompt, system_message, messages, history)
+        model_input, messages = self.build_model_input(
+            prompt, system_message, messages, history
+        )
 
         reponse, usage = self._create_completion(
             **model_input,
@@ -206,7 +208,7 @@ class Llama(LLMModel):
     ):
         if system_message is not None:
             prompt = system_message + prompt
-        return {"prompt": prompt}
+        return {"prompt": prompt}, messages
 
     def _create_completion(
         self,
@@ -290,13 +292,12 @@ class LlamaChat(Llama):
         # a history is prepended to the messages, and we assume that it also includes a system message, i.e., we never add a system message in this case
         # TODO is it better to check for a system message in the history?
         if history is not None:
+            messages = history + messages
             [messages.insert(index, entry) for index, entry in enumerate(history)]
         elif system_message:
-            messages.insert(
-                0,
-                self._get_system_message(system_message),
-            )
-        return {"messages": messages}
+            messages = [self._get_system_message(system_message)] + messages
+
+        return {"messages": messages}, messages
 
 
 class OpenAI(LLMModel):
@@ -341,7 +342,7 @@ class OpenAI(LLMModel):
             "system_message": system_message,
             "messages": messages,
             "history": history,
-        }
+        }, messages
 
     @classmethod
     def register_arguments(cls, parser: ArgumentParser):