[Boost-users] [multi_index] - duplicates_iterator.hpp issue?

From: Bogdan M. (bogdan_at_[hidden])
Date: 2006-07-23 11:59:34

Hi,

 

I am trying to serialize a multi-indexed container defined as below ( I am
using boost 1.33.1 ):

 

 

____________________________________________________________________________
___

 

/**

Shorter id of namespaces.

*/

namespace bmi = boost::multi_index;

 

/**

Tags for accessing several indices defined below

*/

struct name_tag {};

 

class

  string_node

{

public:

 

   std::string   m_name;

  friend class boost::serialization::access;

 

  void

    serialize      ( boost::archive::polymorphic_iarchive & ar, const
unsigned int file_version);

  void

    serialize      ( boost::archive::polymorphic_oarchive & ar, const
unsigned int file_version);

};

 

/**

Container of children of a node in the string tree

*/

typedef boost::multi_index_container<

string_node*,

bmi::indexed_by<

bmi::sequenced<>,           // sequenced type

bmi::ordered_non_unique<

bmi::tag<name_tag>,  BOOST_MULTI_INDEX_MEMBER( string_node, const
std::string, m_name)> > >

node_set;

____________________________________________________________________________
___

 

 

 

While serializing this container containing ===> several nodes with the same
key <===, 

I get an access violation exception somewhere deep in the multi_index
library.

 

Tracing a little bit back the stack I noticed something unusual in 

 

boost_1_33_1\install\include\boost\multi_index\detail\duplicates_iterator.hp
p 

 

in the duplicates_iterator::sync() member function (around line 80):

            

____________________________________________________________________________
___

 

  void sync()

  {

    if(pred(begin_chunk->value,node->value))advance();

  }

 

____________________________________________________________________________
___

 

 

This function seems to advance the iterator within a chunk of equal keys. 

However, the if clause does not consider the case where node == end. These
are exactly the 

circumstances under which my program crashes in 'pred(begin_chunk...)'.

Changing the if condition into

 

____________________________________________________________________________
___

 

  void sync()

  {

    if( (node != end) && pred(begin_chunk->value,node->value))

      advance();

  }

 

____________________________________________________________________________
___

 

seems to fix the problem. However, I am not familiar with the overall
implementation and 

therefore I cannot tell whether this is indeed the cause or whether there
are side-effects 

to my patch.

 

Has anyone else experienced a situation similar to this one? Is there
something wrong with

 my container definition, to begin with?

 

I really appreciate any feedback.

 

Thanks,

 

Bogdan