When looking at the online help for the Match Regular Expression function, I noted the following copyright notice:
Match Regular Expression Details
Use regular expressions in this function to refine searches.
Certain regular expressions that use alternation (such as (.|\s)*) require significant resources to process when applied to large input strings. In some cases a stack overflow will occur and you will get an error dialog. If this occurs try to simplify your regular expression, or reduce the size of the string that you are parsing.
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So, it looks like NI is using the Pearl Compatible Regular Epression (PCRE) library.
Makes me wonder… why is there no copyright notice on the ZIP VIs which use the zlib and zip libraries. I guess that NI doesn’t have to put such notices for the zlib/zip libraries (based on the zlib and zip license terms, but it would be nice). I guess that’s just the way that NI likes to keep LabVIEW… don’t let anyone know what’s under the hood.