boost::regex_replace strange behaviour

[piotr.pydych@…]

Dear Boost Representative,

I have encountered a strange boost::reges_replace behaviour.

There is a complete (as small as possible, I think) project to reproduce that error in the attachement.

Generally, when the 'in' variable (std::string) exceedes a critical (indefinite) length boost::regex_replace throws an exception: _STL::runtime_error with message: "Exception Object Address...".

Some further info on my environment: BOOST VERSION: 1.33.1. Borland C++ Builder 6.0 Professional (Build 10.166). Update Pack 4 applied. Windows XP. SP2 applied.

Thank you in advance for any help in this strange matter.

Yours sincerely, Piotr.

[John Maddock]

I can't reproduce this as I don't have access to Borland C++ at present.

However, I believe this is caused by the regular expression used: match a regular expression is in general an NP-complete problem so Boost.Regex will throw a std::runtime_error if the complexity of matching grows to much.

The problem appears to be the:

(.|
s)*?

part, the issue is that "." will match all the same characters that "
s" will, so the number of possible alternative ways to find a match grows exponentially large - hence the exception thrown. Changing to:

.*?

will likely solve the problem I believe.

HTH, John Maddock.