Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/libcst/_flatten_sentinel.py: 69%

1# Copyright (c) Meta Platforms, Inc. and affiliates. 

2# 

3# This source code is licensed under the MIT license found in the 

4# LICENSE file in the root directory of this source tree. 

5 

6import sys 

7 

8# PEP 585 

9if sys.version_info < (3, 9): 

10 from typing import Iterable, Sequence 

11else: 

12 from collections.abc import Iterable, Sequence 

13 

14from libcst._types import CSTNodeT_co 

15 

16 

17class FlattenSentinel(Sequence[CSTNodeT_co]): 

18 """ 

19 A :class:`FlattenSentinel` may be returned by a :meth:`CSTTransformer.on_leave` 

20 method when one wants to replace a node with multiple nodes. The replaced 

21 node must be contained in a `Sequence` attribute such as 

22 :attr:`~libcst.Module.body`. This is generally the case for 

23 :class:`~libcst.BaseStatement` and :class:`~libcst.BaseSmallStatement`. 

24 For example to insert a print before every return:: 

25 

26 def leave_Return( 

27 self, original_node: cst.Return, updated_node: cst.Return 

28 ) -> Union[cst.Return, cst.RemovalSentinel, cst.FlattenSentinel[cst.BaseSmallStatement]]: 

29 log_stmt = cst.Expr(cst.parse_expression("print('returning')")) 

30 return cst.FlattenSentinel([log_stmt, updated_node]) 

31 

32 Returning an empty :class:`FlattenSentinel` is equivalent to returning 

33 :attr:`cst.RemovalSentinel.REMOVE` and is subject to its requirements. 

34 """ 

35 

36 nodes: Sequence[CSTNodeT_co] 

37 

38 def __init__(self, nodes: Iterable[CSTNodeT_co]) -> None: 

39 self.nodes = tuple(nodes) 

40 

41 def __getitem__(self, idx: int) -> CSTNodeT_co: 

42 return self.nodes[idx] 

43 

44 def __len__(self) -> int: 

45 return len(self.nodes)