[Boost-users] [intrusive] slist: strange behaviour when using cache_last

From: Christian Rössel (christian.roessel_at_[hidden])
Date: 2008-05-19 06:57:54

Hi,

I have two slists and transfer items between them via splice() methods.
Without cache_last everything works as expected. With cache_last the third
call to splice does not transfer the list element. Am I using something
wrong or is this a bug in intrusive?

Thanks,
Christian

#include <boost/intrusive/slist.hpp>
#include <boost/intrusive/slist_hook.hpp>
#include <cassert>
using namespace boost::intrusive;

class MyClass : public slist_base_hook<>
{
   int int_;
public:
   MyClass(int i) : int_(i) {}
};

typedef slist<MyClass, cache_last<true> > MyList;

int main ()
{
  MyList freeList;
  for (int j = 0; j < 5; ++j) {
    freeList.push_front (*(new MyClass (j)));
  }

  MyList listInUse;

  // transfer first element of freeList to listInUse
  size_t free  = freeList.size ();
  size_t inUse = listInUse.size ();
  listInUse.splice (listInUse.begin (), freeList, freeList.begin ());
  assert (freeList.size () == free - 1);
  assert (listInUse.size () == inUse + 1);

  // transfer all elements of listInuse to freeList
  free  = freeList.size ();
  inUse = listInUse.size ();
  freeList.splice (freeList.begin (), listInUse);
  assert (listInUse.empty ());
  assert (freeList.size () == free + inUse);

  // again, transfer first element of freeList to listInUse
  free  = freeList.size ();
  inUse = listInUse.size ();
  listInUse.splice (listInUse.begin (), freeList, freeList.begin ());
  assert (freeList.size () == free - 1); // fails, sizes are 5 and 0
  assert (listInUse.size () == inUse + 1);

  // release memory omitted

  return 0;
}