add prompter from alpaca-lora

llama_lora/utils/prompter.py

@@ -0,0 +1,52 @@
+"""
+A dedicated helper to manage templates and prompt building.
+From https://github.com/tloen/alpaca-lora/blob/main/utils/prompter.py
+"""
+
+import json
+import os.path as osp
+from typing import Union
+
+
+class Prompter(object):
+    __slots__ = ("template", "_verbose")
+
+    def __init__(self, template_name: str = "", verbose: bool = False):
+        self._verbose = verbose
+        if not template_name:
+            # Enforce the default here, so the constructor can be called with '' and will not break.
+            template_name = "alpaca"
+        file_name = osp.join("templates", f"{template_name}.json")
+        if not osp.exists(file_name):
+            raise ValueError(f"Can't read {file_name}")
+        with open(file_name) as fp:
+            self.template = json.load(fp)
+        if self._verbose:
+            print(
+                f"Using prompt template {template_name}: {self.template['description']}"
+            )
+
+    def generate_prompt(
+        self,
+        instruction: str,
+        input: Union[None, str] = None,
+        label: Union[None, str] = None,
+    ) -> str:
+        # returns the full prompt from instruction and optional input
+        # if a label (=response, =output) is provided, it's also appended.
+        if input:
+            res = self.template["prompt_input"].format(
+                instruction=instruction, input=input
+            )
+        else:
+            res = self.template["prompt_no_input"].format(
+                instruction=instruction
+            )
+        if label:
+            res = f"{res}{label}"
+        if self._verbose:
+            print(res)
+        return res
+
+    def get_response(self, output: str) -> str:
+        return output.split(self.template["response_split"])[1].strip()