VectorConvertView.h

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/

 
 
#ifndef COLUMNAR_CORE_VECTOR_CONVERT_VIEW_H
#define COLUMNAR_CORE_VECTOR_CONVERT_VIEW_H
 
#include <cstddef> //std::size_t
#include <stdexcept> //std::out_of_range
#include <utility> //for std::move
 
namespace columnar
{
  namespace detail
  {
 

    template<typename FunctionType,typename IteratorType>
    class VectorConvertIterator final
    {
    public:
 
      VectorConvertIterator (const FunctionType& val_function, IteratorType&& val_iterator)
        : m_function (val_function), m_iterator (std::move (val_iterator))
      {}
 
      [[nodiscard]] bool operator == (const VectorConvertIterator& that) const noexcept {
        return m_iterator == that.m_iterator;}
      [[nodiscard]] bool operator != (const VectorConvertIterator& that) const noexcept {
        return m_iterator != that.m_iterator;}
      
      VectorConvertIterator& operator ++ () noexcept {
        ++ m_iterator; return *this;}
 
      [[nodiscard]] decltype(auto) operator * () const noexcept {
        return m_function (*m_iterator);}

    private:
 
      [[no_unique_address]] FunctionType m_function;
      IteratorType m_iterator;
    };
    template<typename FunctionType,typename IteratorType> VectorConvertIterator (FunctionType&&,IteratorType&&) -> VectorConvertIterator<std::decay_t<FunctionType>,std::decay_t<IteratorType>>;
 
 

    template<typename FunctionType,typename ViewType>
    class VectorConvertView final
    {
    public:
 
      explicit VectorConvertView (const FunctionType& val_function, const ViewType& val_view) noexcept
        : m_function (val_function), m_view (val_view)
      {}
 
      [[nodiscard]] std::size_t size () const noexcept
      {
        return m_view.size();
      }
 
      [[nodiscard]] decltype(auto) operator[] (std::size_t index) const
      {
        if (index >= m_view.size()) [[unlikely]]
          throw std::out_of_range ("VectorConvertView::operator[]: index out of range");
        return m_function (m_view[index]);
      }
 
      [[nodiscard]] auto begin () const noexcept
      {
        return VectorConvertIterator (m_function, m_view.begin());
      }
 
      [[nodiscard]] auto end () const noexcept
      {
        return VectorConvertIterator (m_function, m_view.end());
      }

    private:
 
      [[no_unique_address]] FunctionType m_function;
      ViewType m_view;
    };
    template<typename FunctionType,typename ViewType> VectorConvertView (FunctionType&&,ViewType&&) -> VectorConvertView<std::decay_t<FunctionType>,std::decay_t<ViewType>>;
  }
}
 
#endif