\b | word boundary |
\B | non-word boundary |
(?:...) | non-capturing group |
(?<foo>...) | named capture |
(?=abc) | positive lookahead: ensures that the following characters match abc, but doesn't include those characters in the matched text |
(?!abc) | negative lookahead: ensures that the following characters do not match abc, but doesn't include those characters in the matched text |
(?<=abc) | positive lookbehind: ensures that the preceding characters match abc, but doesn't include those characters in the matched text |
(?<!abc) | negative lookbehind: ensures that the preceding characters do not match abc, but doesn't include those characters in the matched text |
\1 | use the result of group capture 1 |
\k<foo> | use the result of named group capture foo |
(?1) | indexed subroutine (repeat the pattern of group 1) |
(?&foo) | named subroutine (repeat the pattern of group named foo) |
(?(DEFINE)...) | predefined subroutines |
(?#...) | comment |