fix: sentences as a str

Signed-off-by: Meow <ongjackm@gmail.com>

modeling_lora.py

@@ -393,17 +393,20 @@ class XLMRobertaLoRA(XLMRobertaPreTrainedModel):
                 f"Alternatively, don't pass the `task_type` argument to disable LoRA."
             )
         adapter_mask = None
-        sentences = list(sentences) if isinstance(sentences, str) else sentences
         if task_type:
             task_id = self._adaptation_map[task_type]
+            num_examples = 1 if isinstance(sentences, str) else len(sentences)
             adapter_mask = torch.full(
-                (len(sentences),), task_id, dtype=torch.int32, device=self.device
+                (num_examples,), task_id, dtype=torch.int32, device=self.device
             )
         if task_type in ["query", "passage"]:
-            sentences = [
-                self._task_instructions[task_type] + " " + sentence
-                for sentence in sentences
-            ]
+            if isinstance(sentences, str):
+                sentences = self._task_instructions[task_type] + " " + sentences
+            else:
+                sentences = [
+                    self._task_instructions[task_type] + " " + sentence
+                    for sentence in sentences
+                ]
         return self.roberta.encode(
             sentences, *args, adapter_mask=adapter_mask, **kwargs
         )