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@mohitmanuja
Created May 4, 2016 00:31
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> Regular Expressions Cheat Sheet
> A regular expression specifies a set of strings that matches it. This cheat sheet is based off Python 3's Regular Expressions (http://docs.python.org/3/library/re.html) but is designed for searches within Sublime Text.
> Special Characters
\ Escapes special characters or signals a special sequence.
. Matches any single character except a newline.
^ Matches the start of the string.
$ Matches the end of the string.
* Greedily matches 0 or more repetitions of the preceding RE.
*? Matches 0 or more repetitions of the preceding RE.
+ Greedily matches 1 or more repetitions of the preceding RE.
+? Matches 1 or more repetitions of the preceding RE.
? Greedily matches 0 or 1 repetitions of the preceding RE.
?? Matches 0 or 1 repetitions of the preceding RE.
A|B Matches A, if A is unmatched then matches B, where A and B are arbitrary REs.
{m} Matches exactly m many repetitions of the previous RE.
{m,n} Greedily matches from m many to n many repetitions of the previous RE.
{m,n}? Matches m many to n many repetitions of the previous RE.
[...] Indicates a set of characters to match.
[amk] Matches 'a', 'm', or 'k'.
[a-z] Matches 'a' through 'z'.
[a-f0-7] Matches 'a' through 'f' or '0' through '7'.
[a\-z] Matches 'a', '-', or 'z'.
[a-] Matches 'a' or '-'.
[-a] Matches 'a' or '-'.
[(+*)] Matches '(', '+', '*', or ')'. [] matches special characters literally.
[\w] Matches the character class for '\w'. See character classes.
[^5] Matches anything other than '5'. '^' forms the complementary set only as the first character in a set.
[]()] Matches ']', '(', and ')'. ']' is taken literally only as the first character in a set.
[()\]] Matches ']', '(', and ')'.
(...) Matches the RE inside the parenthesis and assigns a new group.
(?P<name>...) The RE matched is accessible by the group indicated by name.
(?...) Extension notation which changes a RE's behavior. These do not assign a new group.
(?aiLmsux) Sets the corresponding flag to each letter. Does not work within Sublime Text.
(?:...) A non-capturing version of parenthesis. The matched substring cannot be retrieved later.
(?P=name) Matches the substring matched by the group named name.
(?#...) A comment, the contents are ignored.
(?=...) Lookahead assertion, the preceding RE only matches if this matches.
(?!...) Negative lookahead assertion, the preceding RE only matches if this doesn't match.
(?<=...) Positive lookbehind assertion, the following RE will only match if preceded with this fixed length RE.
(?<!...) Negative lookbehind assertion, the following RE will only match if not preceded with this fixed length RE.
(?(id)true|false) If group id exists then uses the true RE, else use the false RE.
> Character classes
\1 Matches the contents of the group labelled by the same number. Acceptable numbers are 1-99.
\A Matches at the start of the current string.
\b Matches the empty string at the beginning or end of a word. \b matches the boundary between \w and \W.
\B Matches the empty string not at the beginning or end of a word.
\d Matches any Unicode decimal digit, including 0-9.
\D Matches any Unicode non-decimal digit.
\s Matches any Unicode whitespace character, including ' ', \t, \n, \r, \f and \v.
\S Matches any Unicode non-whitespace character.
\w Matches any Unicode word character, including a-z, A-Z, and 0-9.
\W Matches any Unicode non-word character.
\Z Matches at the end of the string.
\a Matches the ASCII Bell ().
\f Matches the ASCII Formfeed ( ).
\n Matches the ASCII Linefeed.
\r Matches the ASCII Carriage Return (
).
\t Matches the ASCII Horizontal Tab.
\v Matches the ASCII Vertical Tab ( ).
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