KorAP: Regular Expressions

Regular expressions are patterns describing a set of strings.

In the KorAP backend a wide range of operators is supported, but only the following are guaranteed to be stable throughout the system:

Operators

. - Any: Any symbol
() - Group: Create a group of operands
| - Alternation: Create alternative operands
[] - Character Class: Group alternative characters
\ - Escape symbol: Mark the following character to be interpreted as verbatim, when the character is special (i.e. an operator or quantifier)

".eine" Frau

"Fr..de"

"Fr(ie|eu)de" []{,3} Eierkuchen

"Fre[um]de"

"b.w\."

Quantifiers

Operands in regular expressions can be quantified, meaning they are allowed to occur consecutively a specified number of times. The following quantifieres are supported:

?: Match 0 or 1 times
*: Match 0 or more times
+: Match 1 or more times
{n}: Match n times
{n,}: Match at least n times
{n,m}: Match at least n times but no more than m times

"Schif+ahrt"

"kl?eine" Kinder

"Schlos{2,3}traße"

"Rha(bar){2}"