+/*!
+ * \b WARNING this method is a \b non \a const \b method. This method works tuple by tuple. Each tuple is expected to be pairs (number of components must be equal to 2).
+ * This method rearrange each pair in \a this so that, tuple with id \b tid will be after the call \c this->getIJ(tid,0)==this->getIJ(tid-1,1) and \c this->getIJ(tid,1)==this->getIJ(tid+1,0).
+ * If it is impossible to reach such condition an exception will be thrown ! \b WARNING In case of throw \a this can be partially modified !
+ * If this method has correctly worked, \a this will be able to be considered as a linked list.
+ * This method does nothing if number of tuples is lower of equal to 1.
+ *
+ * This method is useful for users having an unstructured mesh having only SEG2 to rearrange internaly the connectibity without any coordinates consideration.
+ *
+ * \sa MEDCouplingUMesh::orderConsecutiveCells1D
+ */
+void DataArrayInt::sortEachPairToMakeALinkedList()
+{
+ checkAllocated();
+ if(getNumberOfComponents()!=2)
+ throw INTERP_KERNEL::Exception("DataArrayInt::sortEachPairToMakeALinkedList : Only works on DataArrayInt instance with nb of components equal to 2 !");
+ int nbOfTuples(getNumberOfTuples());
+ if(nbOfTuples<=1)
+ return ;
+ int *conn(getPointer());
+ for(int i=1;i<nbOfTuples;i++,conn+=2)
+ {
+ if(i>1)
+ {
+ if(conn[2]==conn[3])
+ {
+ std::ostringstream oss; oss << "DataArrayInt::sortEachPairToMakeALinkedList : In the tuple #" << i << " presence of a pair filled with same ids !";
+ throw INTERP_KERNEL::Exception(oss.str().c_str());
+ }
+ if(conn[2]!=conn[1] && conn[3]==conn[1] && conn[2]!=conn[0])
+ std::swap(conn[2],conn[3]);
+ //not(conn[2]==conn[1] && conn[3]!=conn[1] && conn[3]!=conn[0])
+ if(conn[2]!=conn[1] || conn[3]==conn[1] || conn[3]==conn[0])
+ {
+ std::ostringstream oss; oss << "DataArrayInt::sortEachPairToMakeALinkedList : In the tuple #" << i << " something is invalid !";
+ throw INTERP_KERNEL::Exception(oss.str().c_str());
+ }
+ }
+ else
+ {
+ if(conn[0]==conn[1] || conn[2]==conn[3])
+ throw INTERP_KERNEL::Exception("DataArrayInt::sortEachPairToMakeALinkedList : In the 2 first tuples presence of a pair filled with same ids !");
+ int tmp[4];
+ std::set<int> s;
+ s.insert(conn,conn+4);
+ if(s.size()!=3)
+ throw INTERP_KERNEL::Exception("DataArrayInt::sortEachPairToMakeALinkedList : This can't be considered as a linked list regarding 2 first tuples !");
+ if(std::count(conn,conn+4,conn[0])==2)
+ {
+ tmp[0]=conn[1];
+ tmp[1]=conn[0];
+ tmp[2]=conn[0];
+ if(conn[2]==conn[0])
+ { tmp[3]=conn[3]; }
+ else
+ { tmp[3]=conn[2];}
+ std::copy(tmp,tmp+4,conn);
+ }
+ }
+ }
+}
+