refactor(utils/decorators): rewrite remove task decorator to use ast

Author: josix

airflow/utils/decorators.py

@@ -17,55 +17,50 @@
 # under the License.
 from __future__ import annotations
 
+import ast
 import sys
-from collections import deque
 from typing import Callable, TypeVar
 
 T = TypeVar("T", bound=Callable)
 
 
+class _TaskDecoratorRemover(ast.NodeTransformer):
+    def __init__(self, task_decorator_name):
+        self.decorators_to_remove = {
+            "setup",
+            "teardown",
+            "task.skip_if",
+            "task.run_if",
+            task_decorator_name,
+        }
+
+    def visit_FunctionDef(self, node):
+        node.decorator_list = [
+            decorator for decorator in node.decorator_list if not self._is_task_decorator(decorator)
+        ]
+        return self.generic_visit(node)
+
+    def _is_task_decorator(self, decorator):
+        if isinstance(decorator, ast.Name):
+            return decorator.id in self.decorators_to_remove
+        elif isinstance(decorator, ast.Attribute):
+            return f"{decorator.value.id}.{decorator.attr}" in self.decorators_to_remove
+        elif isinstance(decorator, ast.Call):
+            return self._is_task_decorator(decorator.func)
+        return False
+
+
 def remove_task_decorator(python_source: str, task_decorator_name: str) -> str:
     """
     Remove @task or similar decorators as well as @setup and @teardown.
 
     :param python_source: The python source code
     :param task_decorator_name: the decorator name
-
-    TODO: Python 3.9+: Rewrite this to use ast.parse and ast.unparse
     """
-
-    def _remove_task_decorator(py_source, decorator_name):
-        # if no line starts with @decorator_name, we can early exit
-        for line in py_source.split("\n"):
-            if line.startswith(decorator_name):
-                break
-        else:
-            return python_source
-        split = python_source.split(decorator_name, 1)
-        before_decorator, after_decorator = split[0], split[1]
-        if after_decorator[0] == "(":
-            after_decorator = _balance_parens(after_decorator)
-        if after_decorator[0] == "\n":
-            after_decorator = after_decorator[1:]
-        return before_decorator + after_decorator
-
-    decorators = ["@setup", "@teardown", "@task.skip_if", "@task.run_if", task_decorator_name]
-    for decorator in decorators:
-        python_source = _remove_task_decorator(python_source, decorator)
-    return python_source
-
-
-def _balance_parens(after_decorator):
-    num_paren = 1
-    after_decorator = deque(after_decorator)
-    after_decorator.popleft()
-    while num_paren:
-        current = after_decorator.popleft()
-        if current == "(":
-            num_paren = num_paren + 1
-        elif current == ")":
-            num_paren = num_paren - 1
-    return "".join(after_decorator)
+    tree = ast.parse(python_source)
+    remover = _TaskDecoratorRemover(task_decorator_name.strip("@"))
+    mutated_tree = remover.visit(tree)
+    return ast.unparse(mutated_tree)
 
 
 class _autostacklevel_warn: