| # Copyright 2016 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| |
| class _OptionalContextManager(object): |
| |
| def __init__(self, manager, condition): |
| self._manager = manager |
| self._condition = condition |
| |
| def __enter__(self): |
| if self._condition: |
| return self._manager.__enter__() |
| return None |
| |
| def __exit__(self, exc_type, exc_val, exc_tb): |
| if self._condition: |
| return self._manager.__exit__(exc_type, exc_val, exc_tb) |
| return None |
| |
| |
| def Optional(manager, condition): |
| """Wraps the provided context manager and runs it if condition is True. |
| |
| Args: |
| manager: A context manager to conditionally run. |
| condition: If true, runs the given context manager. |
| Returns: |
| A context manager that conditionally executes the given manager. |
| """ |
| return _OptionalContextManager(manager, condition) |
| |
