# Regular Expression Metacharacters

Note that in addition to the standard metacharacters described in the table, Yate supports \V# sequences via a prescan to insert the contents of a Variable. The contents of the variable are escaped to ensure that they do not interfere with any of the standard sequences.

Character | Description
--- | ---
\a | Match a BELL, \u0007
\A | Match at the beginning of the input. Differs from ^ in that \A will not match after a new line within the input.
\b | Match if the current position is a word boundary. Boundaries occur at the transitions between word (\w) and non-word (\W) characters, with combining marks ignored..
\B | Match if the current position is not a word boundary.
\cX | Match a control-X character.
\d | Match any character with the Unicode General Category of Nd (Number, Decimal Digit.)
\D | Match any character that is not a decimal digit.
\e | Match an ESCAPE, \u001B.
\E | Terminates a \Q ... \E quoted sequence.
\f | Match a FORM FEED, \u000C.
\G | Match if the current position is at the end of the previous match.
\n | Match a LINE FEED, \u000A.
\N{UNICODE CHARACTER NAME} | Match the named character.
\p{UNICODE PROPERTY NAME} | Match any character with the specified Unicode Property.
\P{UNICODE PROPERTY NAME} | Match any character not having the specified Unicode Property.
\Q | Quotes all following characters until \E.
\r | Match a CARRIAGE RETURN, \u000D.
\s | Match a white space character. White space is defined as [\t\n\f\r\p{Z}].
\S | Match a non-white space character.
\t | Match a HORIZONTAL TABULATION, \u0009.
\uhhhh | Match the character with the hex value hhhh.
\Uhhhhhhhh | Match the character with the hex value hhhhhhhh. Exactly eight hex digits must be provided, even though the largest Unicode code point is \U0010ffff.
\w | Match a word character. Word characters are [\p{Alphabetic}\p{Mark}\p{Decimal_Number}\p{Connector_Punctuation}\u200c\u200d].
\W | Match a non-word character.
\x{hhhh} | Match the character with hex value hhhh. From one to six hex digits may be supplied.
\xhh | Match the character with two digit hex value hh
\X | Match a Grapheme Cluster.
\Z | Match if the current position is at the end of input, but before the final line terminator, if one exists.
\z | Match if the current position is at the end of input.
\n | Back Reference. Match whatever the nth capturing group matched. n must be a number > 1 and < total number of capture groups in the pattern.
\0ooo | Match an Octal character. 'ooo' is from one to three octal digits. 0377 is the largest allowed Octal character. The leading zero is required; it distinguishes Octal constants from back references.
[pattern] | Match any one character from the set.
. | Match any character.
^ | Match at the beginning of a line.
$ | Match at the end of a line.
\ | Quotes the following character. Characters that must be quoted to be treated as literals are * ? + [ ( ) { } ^ $ | \ .
\ | Quotes the following character. Characters that must be quoted to be treated as literals are [ ] \ Characters that may need to be quoted, depending on the context are - &