Re: [Boost-users] [multi_key] problems using modify_key with a composite_key index

From: Jeffrey Holle (jeffreyholle_at_[hidden])
Date: 2007-10-01 18:06:07

Joaquín Mª López Muñoz wrote:
> 
> So, instead of using modify_key resort to plain modify instead:
> 
>   c.get<1>().modify(c.get<1>().find(make_tuple(y,UINT_MAX)),&ll::_1->*&entry::m_x=startIter2->m_x);
> 
> Is your problem solved now?

This solved my compilation problem, but I ended up with an app than 
wants to runs forever.

To be clear, I'm including my entire function.  What it is supposed to 
do is reorder the x values of the composite_key index of the multi_index 
container based on the ordering of a vector<float> container.  It is a 
swap_sort algorithm because its the only way that I've imagined how to 
do this.  A better solution would definitely be entertained.

void sortByBaryCenterValue(Positioner& p, BaryCenterVals& bcv,size_t y)
{
   Positioner::XYIterator iter,iter_end;
   tie(iter,iter_end)=p.getXYIndex().equal_range(make_tuple(y));
   for (size_t nStartIndex=0;nStartIndex<bcv.size();++nStartIndex) {
     size_t nSmallestIndex=nStartIndex;
     for (size_t 
nCurrentIndex=nStartIndex+1;nCurrentIndex<bcv.size();++nCurrentIndex)
       if (bcv[nCurrentIndex]<bcv[nSmallestIndex])
         nSmallestIndex=nCurrentIndex;
       swap(bcv[nStartIndex],bcv[nSmallestIndex]);
       Positioner::XYIterator startIter(iter),smallestIter(iter);
       advance(startIter,nStartIndex);
       size_t x1=startIter->m_x;
       advance(smallestIter,nSmallestIndex);
       size_t x2=smallestIter->m_x;
 
p.getXYIndex().modify(p.getXYIndex().find(make_tuple(y,x1)),&ll::_1->*&Positioner::entry::m_x=UINT_MAX);
// 
p.getXYIndex().modify(p.getXYIndex().find(make_tuple(y,x2)),&ll::_1->*&Positioner::entry::m_x=x1);
 
p.getXYIndex().modify(p.getXYIndex().find(make_tuple(y,UINT_MAX)),&ll::_1->*&Positioner::entry::m_x=x2);
   }
}

If I uncomment the middle line of the sort attempt, the application runs 
forever.

Do you know what is wrong?
Thanks in advance.