Basic characteristics of regular expressions
Following are notable characteristics of regular expressions as defined on the Citrix ADC appliance:
A regular expression always begins with the string “re” followed by a pair of delimiting characters (called delimiters) that enclose the regular expression that you want to use.
For example, re#<regex_pattern># uses the number sign (#) as a delimiter.
A regular expression cannot exceed 1499 characters.
Digit matching can be done by using the string \d (a backslash followed by d).
White space can be represented by using \s (a backslash followed by s).
A regular expression can contain white spaces.
Following are the differences between the Citrix ADC syntax and the PCRE syntax:
- The Citrix ADC does not allow back references in regular expressions.
- You should not use recursive regular expressions.
- The dot meta-character also matches the newline character.
- Unicode is not supported.
- The operation SET_TEXT_MODE(IGNORECASE) overrides the (?i) internal option in the regular expression.