Why do I need this? We are developing a fairly robust chemical reaction network module where users can simply enter in large equations of chemical reactions with lots of species containing plues, minuses mixed with coefficients and other characters like parenthesis. While I could go about parsing these with the standard string tokenizing utilities, it'll be a lot of nasty code to handle all of the various cases. I'm just exploring the pain of moving to a much more powerful system, but don't want to give up portability.
Bottom line: Do any of you have any experience with how widespread and reliable the standard regex library is on a wide range of compilers? Would it be worth detecting the presence of this capability inside of libMesh?