https://stackoverflow.com/a/3926546/4867982
| Lookaround | Name | What it Does |
|---|---|---|
(?=foo) |
Lookahead | Asserts that what immediately follows the current position in the string is foo |
(?<=foo) |
Lookbehind | Asserts that what immediately precedes the current position in the string is foo |
(?!foo) |
Negative Lookahead | Asserts that what immediately follows the current position in the string is not foo |
(?<!foo) |
Negative Lookbehind | Asserts that what immediately precedes the current position in the string is not foo |