Regex quick overview
Parsing group contains blocks intended to process input data. Input data are processed using blocks, which work with regular expressions. More information about the regular expressions is available on: https://en.wikipedia.org/wiki/Regular_expression
Regular expressions basics:
| regular expression | description |
|---|---|
. |
Any character except newline |
a |
The character a |
ab |
The string ab |
a|b |
a or b |
a* |
0 or more a’s |
\ |
Escapes a special character |
Regular Expression Quantifiers:
| regular expression | description |
|---|---|
* |
0 or more |
+ |
1 or more |
? |
0 or 1 |
{2} |
Exactly 2 |
{2, 5} |
Between 2 and 5 |
{2,} |
2 or more |
{,5} |
Up to 5 |
Regular Expression Groups:
| regular expression | description |
|---|---|
(...) |
Capturing group |
(?P<Y>...) |
Capturing group named Y |
(?:...) |
Non-capturing group |
\Y |
Match the Y’th captured group |
(?P=Y) |
Match the named group Y |
(?#...) |
Comment |
Regular Expression Character Classes:
| regular expression | description |
|---|---|
[ab-d] |
One character of: a, b, c, d |
[^ab-d] |
One character except: a, b, c, d |
[\b] |
Backspace character |
\d |
One digit |
\D |
One non-digit |
\s |
One whitespace |
\S |
One non-whitespace |
\w |
One word character |
\W |
One non-word character |
Regular Expression Assertions:
| regular expression | description |
|---|---|
^ |
Start of string |
\A |
Start of string, ignores m flag |
$ |
End of string |
\Z |
End of string, ignores m flag |
\b |
Word boundary |
\B |
Non-word boundary |
(?=...) |
Positive lookahead |
(?!...) |
Negative lookahead |
(?<=...) |
Positive lookbehind |
(?<!...) |
Negative lookbehind |
(?()|) |
Conditional |