Extend copyright checker to allow for doxygen-style copyright

[jpsamper2009]

Description

This MR extends the copyright checker's regex to allow doxygen-style copyright:

• Add an optional, non-matching group for \copyright => (?:\\\copyright\s*)?
  • (?:<stuff>) -> Non-capturing group which means that later on in the code, the indexes for the matching groups won't have to change
  • \\\copyright -> \copyright with the \ escaped
  • \s* -> Any whitespace (or none) after \copyright
  • (<stuff>)? -> Optional match
• Allow \\\ in comment blocks

For example, it allows you to (optionally) use:

/// \copyright Copyright 2015 Open Source Robotics Foundation, Inc.
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.

How to test

1. Copy paste the copyright header above into a file (test_copyright.c)

$ ament_copyright test_copyright.c
No errors, checked 1 files

2. Files with the non-doxygen style copyright header should continue to pass the checks

[wjwwood]

Seems reasonable to me, though regex are not my strong suite, does anyone else on the ROS team have an issue with the changes to the regular expressions?

[dirk-thomas]

lgtm

[wjwwood]

CI:

• Linux
• Linux-aarch64
• macOS
• Windows

[jpsamper2009]

@wjwwood Re: regex are not my strong suite

I added a breakdown in the description for future reference

[wjwwood]

Thanks that's really helpful. Looks like the test failures on Linux are unrelated.