adding back get_fixed_answer_choices_list - revert 07688e5

Author: VictorSanh

promptsource/templates.py

@@ -9,7 +9,7 @@
 import pandas as pd
 import pkg_resources
 import yaml
-from jinja2 import BaseLoader, Environment
+from jinja2 import BaseLoader, Environment, meta
 
 
 # Truncation of jinja template variables
@@ -135,6 +135,24 @@ def get_answer_choices_list(self, example):
         rendered_choices = rtemplate.render(**protected_example)
         return [self._unescape_pipe(answer_choice.strip()) for answer_choice in rendered_choices.split("|||")]
 
+    def get_fixed_answer_choices_list(self):
+        """
+        Returns a list of answer choices that is static across examples, if possible
+        :return: list of strings, or None if no static list exists
+        """
+        jinja = self.get_answer_choices_expr()
+        if jinja is None:
+            return None
+
+        parse = env.parse(jinja)
+        variables = meta.find_undeclared_variables(parse)
+        if len(variables) == 0:
+            rtemplate = env.from_string(jinja)
+            rendered_choices = rtemplate.render()
+            return [answer_choice.strip() for answer_choice in rendered_choices.split("|||")]
+        else:
+            return None
+
     def apply(self, example, truncate=True, highlight_variables=False):
         """
         Creates a prompt by applying this template to an example