ContainerMeta.h

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#ifndef LARCOREALG_COREUTILS_CONTAINERMETA_H
#define LARCOREALG_COREUTILS_CONTAINERMETA_H

// LArSoft 
#include "larcorealg/CoreUtils/MetaUtils.h" // for Doxygen documentation

// C/C++ standard libraries
#include <iterator> // std::begin(), std::cbegin()
#include <utility> // std::declval()


namespace util {
  
  
  //--- BEGIN ContainerMetaprogramming -----------------------------------------
  
  
  //----------------------------------------------------------------------------
  template <typename Coll>
  struct collection_value_type {
    using type = typename Coll::value_type;
    using value_type = type;
  }; // struct collection_value_type
  
  template <typename Coll>
  using collection_value_t = typename collection_value_type<Coll>::type;
  
  
  //----------------------------------------------------------------------------
  template <typename Coll>
  struct collection_value_access_type {
      private:
    static auto getBegin(Coll&& coll) { using std::begin; return begin(coll); }
    
      public:
    using type = decltype(*getBegin(std::declval<Coll>()));
    using value_type = collection_value_t<Coll>;
    
  }; // struct collection_value_access_type
  
  template <typename Coll>
  using collection_value_access_t
    = typename collection_value_access_type<Coll>::type;
  
  
  //----------------------------------------------------------------------------
  template <typename Coll>
  struct collection_value_constant_access_type {
      private:
    static auto getCBegin(Coll&& coll)
      { using std::cbegin; return cbegin(coll); }
    
      public:
    using type = decltype(*getCBegin(std::declval<Coll>()));
    using value_type = collection_value_t<Coll>;
    
  }; // struct collection_value_constant_access_type
  
  template <typename Coll>
  using collection_value_constant_access_t
    = typename collection_value_constant_access_type<Coll>::type;
  
  
  //--- END ContainerMetaprogramming -------------------------------------------
  
  
} // namespace util


//------------------------------------------------------------------------------

#endif // LARCOREALG_COREUTILS_CONTAINERMETA_H