VectorHolder.h

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#ifndef DataFormats_Common_VectorHolder_h
#define DataFormats_Common_VectorHolder_h
#include "DataFormats/Common/interface/CMS_CLASS_VERSION.h"
#include "DataFormats/Common/interface/BaseVectorHolder.h"
#include "DataFormats/Common/interface/Holder.h"
#include <memory>
#include "FWCore/Utilities/interface/GCC11Compatibility.h"

namespace edm {
  namespace reftobase {
    
    class RefVectorHolderBase;
    
    template <class T, class REFV>
    class VectorHolder : public BaseVectorHolder<T> {
    public:
      typedef BaseVectorHolder<T>                base_type;
      typedef typename base_type::size_type      size_type;
      typedef typename base_type::element_type   element_type;
      typedef typename base_type::base_ref_type  base_ref_type;
      typedef typename base_type::const_iterator const_iterator;
      typedef REFV                               ref_vector_type;
      
      VectorHolder() : base_type() {}
      VectorHolder(VectorHolder const & rh) :  base_type(rh),  refVector_(rh.refVector_){}
#if defined(__GXX_EXPERIMENTAL_CXX0X__)
      VectorHolder(VectorHolder && rh)  noexcept :  base_type(std::forward(rh)),  refVector_(std::move(rh.refVector_)){}
 #endif

      explicit VectorHolder(const ref_vector_type& iRefVector) : base_type(), refVector_(iRefVector) {}
      explicit VectorHolder(const ProductID& iId) : base_type(), refVector_(iId) {}
      ~VectorHolder()  noexcept override {}
      base_type* clone() const override { return new VectorHolder(*this); }
      base_type* cloneEmpty() const override { return new VectorHolder(refVector_.id()); }
      base_ref_type const at(size_type idx) const override { return base_ref_type( refVector_.at( idx ) ); }
      bool empty() const override { return refVector_.empty(); }
      size_type size() const override { return refVector_.size(); }
      //size_type capacity() const { return refVector_.capacity(); }
      //void reserve(size_type n) { refVector_.reserve(n); }
      void clear() override { refVector_.clear(); }
      ProductID id() const override { return refVector_.id(); }
      EDProductGetter const* productGetter() const override { return refVector_.productGetter(); }
      void swap(VectorHolder& other)  noexcept {
        this->BaseVectorHolder<T>::swap(other);
        refVector_.swap(other.refVector_);
      }
      VectorHolder& operator=(VectorHolder const& rhs) {
        VectorHolder temp(rhs);
        this->swap(temp);
        return *this;
      }
#if defined(__GXX_EXPERIMENTAL_CXX0X__)
     VectorHolder& operator=(VectorHolder && rhs)  noexcept {
       base_type::operator=(std::forward(rhs));
       refVector_ = std::move(rhs.refVector_);
       return *this;
     }
#endif
      
      const_iterator begin() const override {
        return const_iterator( new const_iterator_imp_specific( refVector_.begin() ) );
      }
      const_iterator end() const override {
        return const_iterator( new const_iterator_imp_specific( refVector_.end() ) );
      }
      void push_back( const BaseHolder<T> * r ) override {
        typedef Holder<T, typename REFV::value_type > holder_type;
        const holder_type * h = dynamic_cast<const holder_type *>( r );
        if( h == nullptr )
          Exception::throwThis( errors::InvalidReference,
                               "In VectorHolder<T, REFV> trying to push_back wrong reference type");
        refVector_.push_back( h->getRef() );
      }
      std::unique_ptr<RefVectorHolderBase> vectorHolder() const override {
        return std::unique_ptr<RefVectorHolderBase>( new RefVectorHolder<REFV>( refVector_ ) );
      }
      
      bool isAvailable() const override { return refVector_.isAvailable(); }
      
      //Used by ROOT storage
      CMS_CLASS_VERSION(10)

    private:
      typedef typename base_type::const_iterator_imp const_iterator_imp;
      
      ref_vector_type refVector_;
      
      // the following structure is public
      // to allow dictionary to compile
    public:
      struct const_iterator_imp_specific : public const_iterator_imp {
        typedef ptrdiff_t difference_type;
        const_iterator_imp_specific() { }
        explicit const_iterator_imp_specific( const typename REFV::const_iterator & it ) : i ( it ) { }
        ~const_iterator_imp_specific() override { }
        const_iterator_imp_specific * clone() const override { return new const_iterator_imp_specific( i ); }
        void increase() override { ++i; }
        void decrease() override { --i; }
        void increase( difference_type d ) override { i += d; }
        void decrease( difference_type d ) override { i -= d; }
        bool equal_to( const const_iterator_imp * o ) const override { return i == dc( o ); }
        bool less_than( const const_iterator_imp * o ) const override { return i < dc( o ); }
        void assign( const const_iterator_imp * o ) override { i = dc( o ); }
        base_ref_type deref() const override { return base_ref_type( * i ); }
        difference_type difference( const const_iterator_imp * o ) const override { return i - dc( o ); }
      private:
        const typename ref_vector_type::const_iterator & dc( const const_iterator_imp * o ) const {
          if ( o == nullptr )
            Exception::throwThis( errors::InvalidReference,
                                 "In RefToBaseVector<T> trying to dereference a null pointer");
          const const_iterator_imp_specific * oo = dynamic_cast<const const_iterator_imp_specific *>( o );
          if ( oo == nullptr )
            Exception::throwThis( errors::InvalidReference,
                                 "In RefToBaseVector<T> trying to cast iterator to wrong type ");
          return oo->i;
        }
        typename ref_vector_type::const_iterator i;
      };
    };
    
    // Free swap function
    template <typename T, typename REFV>
    inline
    void
    swap(VectorHolder<T, REFV>& lhs, VectorHolder<T, REFV>& rhs)  noexcept {
      lhs.swap(rhs);
    }
  }
}

#endif