narrow.h

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/*******************************************************************\
 
Module: Narrowing conversion functions
 
Author: Diffblue Ltd.
 
\*******************************************************************/
 
#ifndef CPROVER_UTIL_NARROW_H
#define CPROVER_UTIL_NARROW_H
 
#include <type_traits>
 
#include "invariant.h"
 
template <typename output_type, typename input_type>
output_type narrow_cast(input_type value)
{
  static_assert(
    std::is_arithmetic<input_type>::value &&
      std::is_arithmetic<output_type>::value,
    "narrow_cast is intended only for numeric conversions");
  return static_cast<output_type>(value);
}
 
template <typename output_type, typename input_type>
output_type narrow(input_type input)
{
  const auto output = static_cast<output_type>(input);
  INVARIANT(static_cast<input_type>(output) == input, "Data loss detected");
  return output;
}
 
template <typename output_type, typename input_type>
output_type narrow_or_throw_out_of_range(input_type input)
{
  auto const result = narrow_cast<input_type>(input);
  if(result != input)
  {
    throw std::out_of_range{"narrowing gave a different value than expected"};
  }
  return result;
}
 
#endif // CPROVER_UTIL_NARROW_H