[Boost-users] [iostreams] State of a filtering stream

9 Mar 2010

      Hi,
I have implemented a filtering stream for decompressing bzipped files, 
which looks as shown at the end of the message. I have tried to use it 
like this:

bz2istream bzippedfile("myfile.bz2");
while (bzippedfile >> data) {
   // process data
}

but the program enters an endless loop. The only way I can test for the 
end of file is with:

while (bzippedfile.peek() != EOF) {
   bzippedfile >> data;
   // process data
}

Isn't the first method supposed to work? Is my class missing something?

Regards
Nicola

   class bz2istream :
   public boost::iostreams::filtering_streamboost::iostreams::input
   {
   public:
      bz2istream(std::string const& path) : ff_(path.c_str(), 
std::ios_base::in | std::ios_base::binary)
      {
         if (ff_.fail())
         {
            // Here we are not distinguishing failbit from badbit...
            setstate(std::ios_base::failbit);
         }
         else
         {
            push(boost::iostreams::bzip2_decompressor());
            push(ff_);   

         }
      }

   private:
      std::ifstream ff_;
   };