mergeDuplicateEntries.h

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/*
  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef mergeDuplicateEntries_H
#define mergeDuplicateEntries_H
 
#include <vector>
 
namespace LArBadChanImpl {
 
  template <class C1, class CMP, class MERGER> 
  std::vector<typename C1::value_type> 
  mergeDuplicateEntries( const C1& c1, const CMP& cmp, const MERGER& merger)
  {
    typename C1::const_iterator first = c1.begin();
    typename C1::const_iterator current = first;
    typename C1::const_iterator last = c1.end();
    std::vector<typename C1::value_type> result;
 
    // protection against empty container
    if (first == last) return result;
 
    while (++first != last) {
      if (cmp( *current, *first)) { // elements differ, no need to merge
    result.push_back(*current);
    ++current;
      }
      else { // elemens are equivalent, need to merge
    typename C1::value_type merged = merger( *current, *first);
    while (++first != last && !cmp( *current, *first)) {
      merged = merger( merged, *first); // keep merging while elements don't differ
    }
    result.push_back(merged);
    if (first == last) return result;
    current = first; // keep track of the element after the last merged
      }
    }
    result.push_back( *current);
    return result;
  }
 
  struct DummyMerger {
    int operator()(const int & a, const int& /*b*/) const { return a;}
  };
 
}
 
#endif