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Operations for regular expressions

September 14, 2021
Contributed by:
S C S

The following table describes the operators that work with regular expressions. The operation performed by a regular expression operator in a given default syntax expression depends on whether the expression prefix identifies text or HTTP headers. Operations that evaluate headers override any text-based operations for all instances of the specified header type. When you use an operator, replace with the default syntax expression prefix that you want to configure for identifying text.

Regular Expression Operation Description
.BEFORE_REGEX() Selects the text that precedes the string that matches the argument. If the regular expression does not match any data in the target, the expression returns a text object of length 0. The following expression selects the string “text” from “text/plain”. http.res.header(“content-type”).before_regex(re#/#)
.AFTER_REGEX() Selects the text that follows the string that matches the argument. If the regular expression does not match any text in the target, the expression returns a text object of length 0. The following expression extracts “Example” from “myExample”: http.req.header(“etag”).after_regex(re/my/)
.REGEX_SELECT() Selects a string that matches the argument. If the regular expression does not match the target, a text object of length 0 is returned. The following example extracts the string “NS-CACHE-9.0: 90” from a Via header: http.req.header(“via”).regex_select(re!NS-CACHE-\d.\d:\s*\d{1,3}!)
.REGEX_MATCH() Returns TRUE if the target matches a argument of up to 1499 characters. The regular expression must be of the following format: reregular expression< delimiter> Both delimiters must be the same. Additionally, the regular expression must conform to the Perl-compatible (PCRE) regular expression library syntax. For more information, go tohttp://www.pcre.org/pcre.txt. In particular, see the pcrepattern man page. However, note the following: Back-references are not allowed. Recursive regular expressions are not recommended. The dot metacharacter also matches the newline character. The Unicode character set is not supported. SET_TEXT_MODE(IGNORECASE) overrides the (?i) internal option specified in the regular expression. The following are examples: http.req.hostname.regex_match(re/[[:alpha:]]+(abc){2,3}/) and http.req.url.set_text_mode(urlencoded).regex_match(re#(ab+c)#) The following example matches ab and aB: http.req.url.regex_match(re/a(?i)b/) The following example matches ab, aB, Ab and AB: http.req.url.set_text_mode(ignorecase).regex_match(re/ab/) The following example performs a case-insensitive, multiline match in which the dot meta-character also matches a newline character: http.req.body.regex_match(re/(?ixm) (^ab (.*) cd$) /)
Operations for regular expressions
September 14, 2021
Contributed by:
S C S
September 14, 2021
Contributed by:
S C S

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