CellUniqueId.cxx

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#include "Geometry/CellUniqueId.h"
#include <iostream>
#include "TGeoNode.h"

namespace geo {

  //....................................................................
  
  CellUniqueId NodesToUniqueId(const std::vector<const TGeoNode*>& n, 
                               unsigned int depth) 
  {
    static std::vector<int> ids;
    ids.clear();
    for (unsigned int i=0; i<=depth; ++i) {
      GetNodeNumbers(n[i]->GetName(), ids);
    }
    return IdsToUniqueId(ids);
  }
  
  //....................................................................
  
  CellUniqueId PathToUniqueId(const char* path) 
  {
    static std::vector<int> ids;
    ids.clear();
    GetNodeNumbers(path, ids);
    return IdsToUniqueId(ids);
  }
  
  //....................................................................
 
  CellUniqueId IdsToUniqueId(const std::vector<int>& ids)
  {
    // Experience has shown that only depths below this "depth0"
    // contribute to a cell's 'uniqueness'.
    static const unsigned int depth0 = 3;
    
    // Now construct the id
    CellUniqueId id = 0ULL;
    for (unsigned int i=depth0; i<ids.size(); ++i) {
      // The following check is useful, although not really
      // required. The code in Geometry.cxx checks that the ID's are
      // unique which is all that really matters. Even if we happen to
      // overflow the storage limits of the CellUniqueId, the result
      // will always be the same for the same cell. So, as long as the
      // overflow is unique, all is OK. BTW, I've checked that as of
      // at least v1.6 2008/08/17 the CellUniqueID's do not overflow
      //
      // if (id>0 && ULLONG_MAX/id < 1000) abort();
      id = 1000*id + ids[i];
    }
    return id;
  }
  
  //....................................................................

  void GetNodeNumbers(const char* nm, std::vector<int>& id) 
  {
    char buff[8];
    const char* c;
    const char* start = nm;
    const char* end;
    int indx;
    while (1) {
      start = strchr(start, '_');
      if (start == NULL) break;
      ++start;
      end = strchr(start, '/');
      if (end==NULL) end = strchr(start, '\0');
      if (end==NULL) abort();
      
      for (indx=0, c=start; c<end; ++indx, ++c) buff[indx] = *c;
      buff[indx] = '\0';
      id.push_back(atoi(buff));
    }
  }
}

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