f1131623_sion_Reference__Special_Groups__Description
[Feature] Lookbehind [Syntax] (?<=regex|longer regex) [Example] (?<=is|e)t matches the second and fourth t in twisty streets. [JGsoft] YES [.NET] YES [Java] YES [Perl] no [PCRE] YES [PCRE2] YES [PHP] YES [Delphi] YES [R] YES [JavaScript] n/a [VBScript] n/a [XRegExp] n/a [Python] no [Ruby] 1.9 [std::regex] n/a [Tcl ARE] n/a [POSIX BRE] n/a [POSIX ERE] n/a [GNU BRE] n/a [GNU ERE] n/a [Oracle] n/a [XML] n/a [XPath] n/a [Description] 
Alternatives inside lookbehind can differ in length.
Regular Expression Reference: Special Groups