Summary of Supported Constructs

Predefined Character Classes

.	Any character
\d	Numeric [0-9]
\D	Nonnumeric [^0-9]
\w	Alphanumeric [a-zA-Z0-9_]
\W	Nonalphanumeric [^a-zA-Z0-9_]
\s	Whitespace [ \t\n\r\f\v]
\S	Nonwhitespace [^ \t\n\r\f\v]

Character Classes

[abc]	a, b, or c
[^abc]	Any character except a, b, or c
[a-z]	a through z

Greedy Quantifiers

Greedy quantifiers match as much data as possible.

X?	One or zero
X*	At least zero
X+	At least one
X{n,m}	At least n, at most m
X{n,}	At least n
X{n}	Exactly n

Reluctant Quantifiers

Reluctant quantifiers match as little data as possible.

X??	One or zero
X*?	At least zero
X+?	At least one
X{n,m}?	At least n, at most m
X{n,}?	At least n

Possessive Quantifiers

Possessive quantifiers are greedy, but they don't "go back" if they have already matched data, even if doing so would cause a string to match the expression.

X?+	One or zero
X*+	At least zero
X++	At least one
X{n,m}+	At least n, at most m
X{n,}+	At least n

Logical Operators

(X)	Makes X a capturing group whose content can later be back referenced
X|Y	X or Y (this operator splits up the whole expression/group)
XY	X followed by Y

Other

\n	Back reference; subgroup n's content will be matched
$	End of string

Quotation

\	Quotes the following character
\Q	Quotes all characters until \E
\E	Ends a quotation started by \Q

Special Constructs (Non-capturing)

Non capturing groups don't capture data, so they can't be back referenced. They also don't update the parenthesis ID.

(?:X)	Non-capturing group
(?=X)	Zero-width positive look-ahead assertion
(?!X)	Zero-width negative look-ahead assertion
(?<=X)	Zero-width positive look-behind assertion (X is processed in reverse order, so for example, if there are any greedy quantifiers, the last ones get the text first - the same goes for the negative look-behind assertion).
(?<!X)	Zero-width negative look-behind assertion