range_with_at.h

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
 * Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration.
 */
#ifndef CXXUTILS_RANGE_WITH_AT_H
#define CXXUTILS_RANGE_WITH_AT_H
 
 
#include <ranges>
#include <stdexcept>
 
 
namespace CxxUtils {
 
 
template <class RANGE>
class range_with_at
  : public RANGE
{
public:
  using RANGE::RANGE;
 
 
  decltype(auto) at (size_t i)
  {
    if (i >= std::size(*this))
      throw std::out_of_range ("CxxUtils::range_with_at");
    return this->operator[] (i);
  }
 
 
  decltype(auto) at (size_t i) const
  {
    if (i >= std::size(*this))
      throw std::out_of_range ("CxxUtils::range_with_at");
    return this->operator[] (i);
  }
};
 
 
template <std::ranges::input_range SPAN, class XFORM>
using transform_view_with_at =
  range_with_at<std::ranges::transform_view<SPAN, XFORM> >;
 
 
// Stand-alone begin/end functions, findable by ADL.
// Needed to work around issues seen when root 6.30.04 is used with gcc14.
template <class T>
auto begin (range_with_at<T>& s) { return s.begin(); }
template <class T>
auto begin (const range_with_at<T>& s) { return s.begin(); }
template <class T>
auto end (range_with_at<T>& s) { return s.end(); }
template <class T>
auto end (const range_with_at<T>& s) { return s.end(); }
 
 
} // namespace CxxUtils
 
 
#endif // not CXXUTILS_RANGE_WITH_AT_H