Model: Fix prompt template initialization

The previous commit iterated through multiple try conditions which
made it so the user has to provide a dummy prompt template. Now,
template loading is fallback based.

Run through a loop of functions and return if one of them succeeds.

Signed-off-by: kingbri <[email protected]>

backends/exllamav2/model.py

@@ -158,32 +158,10 @@ def progress(loaded_modules: int, total_modules: int,
             self.config.set_low_mem()
         """
 
-        # Set prompt template override if provided
-        prompt_template_name = kwargs.get("prompt_template")
-        if prompt_template_name:
-            logger.info("Loading prompt template with name " f"{prompt_template_name}")
-            # Read the template
-            try:
-                self.prompt_template = get_template_from_file(prompt_template_name)
-            except FileNotFoundError:
-                self.prompt_template = None
-
-            # Then try finding the template from the tokenizer_config.json
-            try:
-                self.prompt_template = get_template_from_model_json(
-                    pathlib.Path(self.config.model_dir) / "tokenizer_config.json",
-                    "chat_template",
-                    "from_tokenizer_config",
-                )
-            except FileNotFoundError:
-                self.prompt_template = None
-
-            # If that fails, attempt fetching from model name
-            try:
-                template_match = find_template_from_model(model_directory)
-                self.prompt_template = get_template_from_file(template_match)
-            except (LookupError, FileNotFoundError):
-                self.prompt_template = None
+        # Try to set prompt template
+        self.prompt_template = self.find_prompt_template(
+            kwargs.get("prompt_template"), model_directory
+        )
 
         # Catch all for template lookup errors
         if self.prompt_template:
@@ -250,6 +228,34 @@ def progress(loaded_modules: int, total_modules: int,
                 self.draft_config.max_input_len = kwargs["chunk_size"]
                 self.draft_config.max_attn_size = kwargs["chunk_size"] ** 2
 
+    def find_prompt_template(self, prompt_template_name, model_directory):
+        """Tries to find a prompt template using various methods"""
+
+        logger.info("Loading prompt template with name " f"{prompt_template_name}")
+
+        find_template_functions = [
+            lambda: get_template_from_model_json(
+                pathlib.Path(self.config.model_dir) / "tokenizer_config.json",
+                "chat_template",
+                "from_tokenizer_config",
+            ),
+            lambda: get_template_from_file(find_template_from_model(model_directory)),
+        ]
+
+        # Add lookup from prompt template name if provided
+        if prompt_template_name:
+            find_template_functions.insert(
+                0, lambda: get_template_from_file(prompt_template_name)
+            )
+
+        for func in find_template_functions:
+            try:
+                prompt_template = func()
+                if prompt_template is not None:
+                    return prompt_template
+            except (FileNotFoundError, LookupError):
+                continue
+
     def calculate_rope_alpha(self, base_seq_len):
         """Calculate the rope alpha value for a given sequence length."""
         ratio = self.config.max_seq_len / base_seq_len