lib/expression: refactor expression compilation

Signed-off-by: Marc 'risson' Schmitt <marc.schmitt@risson.space>

authentik/lib/expression/evaluator.py

@@ -180,6 +180,11 @@ class BaseEvaluator:
         full_expression += f"\nresult = handler({handler_signature})"
         return full_expression
 
+    def compile(self, expression: str) -> Any:
+        """Parse expression. Raises SyntaxError or ValueError if the syntax is incorrect."""
+        param_keys = self._context.keys()
+        return compile(self.wrap_expression(expression, param_keys), self._filename, "exec")
+
     def evaluate(self, expression_source: str) -> Any:
         """Parse and evaluate expression. If the syntax is incorrect, a SyntaxError is raised.
         If any exception is raised during execution, it is raised.
@@ -188,13 +193,8 @@ class BaseEvaluator:
             span: Span
             span.description = self._filename
             span.set_data("expression", expression_source)
-            param_keys = self._context.keys()
             try:
-                ast_obj = compile(
-                    self.wrap_expression(expression_source, param_keys),
-                    self._filename,
-                    "exec",
-                )
+                ast_obj = self.compile(expression_source)
             except (SyntaxError, ValueError) as exc:
                 self.handle_error(exc, expression_source)
                 raise exc
@@ -221,13 +221,8 @@ class BaseEvaluator:
 
     def validate(self, expression: str) -> bool:
         """Validate expression's syntax, raise ValidationError if Syntax is invalid"""
-        param_keys = self._context.keys()
         try:
-            compile(
-                self.wrap_expression(expression, param_keys),
-                self._filename,
-                "exec",
-            )
+            self.compile(expression)
             return True
         except (ValueError, SyntaxError) as exc:
             raise ValidationError(f"Expression Syntax Error: {str(exc)}") from exc