// ----------------------------------------------------------------------
//
// HBookColumnLess.cc -- define the comparator class to order columns
//                       withing a block for HBook.

#include "HepTuple/Column.h"
#include "HepTuple/HBookColumnLess.h"


ZM_BEGIN_NAMESPACE( zmht )	/*  namespace zmht  {  */

// First the index columns (in theory there could be several but in
//      the actual hbook implementation it seems limited to one)
// Then all the other columns ordered by size of it elements.
//      This is to insure that all the column are going to be properly
//      aligned.  We also need to verify that the first byte of the
//      array allocated for the data will give us this alignement.
//      It means that if there is no index, it should be aligned for
//      a double and if not we should make sure that the first non index
//      column is aligned for double.

bool HBookColumnLess::operator()(const Column* x, const Column* y) const {
  if ( x->isIndex() ) {
    if ( y->isIndex() ) {
      // we assume all index are the same size
      return ( x->name() < y->name() );
    }
    return true;
  }
  if ( y->isIndex() ) {
    // x is NOT an index (cf above)
    return false;
  }
  if ( x->sizeofSingleElem() > y->sizeofSingleElem() ) {
    return true;
  }
  if ( x->sizeofSingleElem() == y->sizeofSingleElem() ) {
    return( x->name() < y->name() );
  }
  return false;
}


ZM_END_NAMESPACE( zmht )	/*  }  // namespace zmht  */