multiprecision/test/test_cpp_double_float_io.cpp

///////////////////////////////////////////////////////////////////////////////
//  Copyright 2021 Fahad Syed.
//  Copyright 2021 Christopher Kormanyos.
//  Copyright 2021 Janek Kozicki.
//  Distributed under the Boost
//  Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Basic I/O tests for cpp_double_float<>
// Note that the I/O of cpp_double_float<> is currently extremely underdeveloped


#include <boost/config.hpp>
#include <boost/multiprecision/cpp_double_float.hpp>
#ifdef BOOST_MATH_USE_FLOAT128
#include <boost/multiprecision/float128.hpp>
#endif
#include <boost/random/uniform_real_distribution.hpp>
#include <iostream>
#include <cstdlib>
#include <random>

namespace test_cpp_double_float_io {

// TODO: this looks like a duplicate from test_cpp_double_float_comparision.cpp file.
template<typename FloatingPointType> constexpr bool is_floating_point = std::is_floating_point<FloatingPointType>::value
#ifdef BOOST_MATH_USE_FLOAT128
or std::is_same<FloatingPointType,boost::multiprecision::float128>::value
#endif
;

template <typename FloatingPointType,
          typename std::enable_if<is_floating_point<FloatingPointType>, bool>::type = true>
FloatingPointType uniform_real()
{
   //static std::random_device                                rd;
   static std::mt19937                                      gen /*(rd())*/;
   static boost::random::uniform_real_distribution<FloatingPointType> dis(0.0, 1.0);

   return dis(gen);
}

template <typename FloatingPointType>
boost::multiprecision::backends::cpp_double_float<typename FloatingPointType::float_type> uniform_rand()
{
   using float_type = typename FloatingPointType::float_type;
   return boost::multiprecision::backends::cpp_double_float<float_type>(uniform_real<float_type>()) * boost::multiprecision::backends::cpp_double_float<float_type>(uniform_real<float_type>());
}

int rand_in_range(int a, int b)
{
   return a + int(float(b - a) * uniform_real<float>());
}

template <typename FloatingPointType, typename std::enable_if<is_floating_point<FloatingPointType>>::type const* = nullptr>
FloatingPointType log_rand()
{
   if (uniform_real<float>() < (1. / 100.))
      return 0; // throw in a few zeroes
   using std::ldexp;
   return ldexp(uniform_real<FloatingPointType>(), rand_in_range(std::numeric_limits<boost::multiprecision::backends::cpp_double_float<FloatingPointType> >::min_exponent, std::numeric_limits<boost::multiprecision::backends::cpp_double_float<FloatingPointType> >::max_exponent));
}

template <typename FloatingPointType>
void test()
{
   using double_float_t = boost::multiprecision::backends::cpp_double_float<FloatingPointType>;

   bool passed = true;
   int  i;
   for (i = 0; i < 10000; ++i)
   {
      std::stringstream ss1, ss2;
      FloatingPointType d = log_rand<FloatingPointType>();
      double_float_t d_ = d;

      using std::log10;
      if (uniform_real<float>() > 0.66 && log10(d) + 1 < std::numeric_limits<FloatingPointType>::digits10)
         ss1.setf(std::ios::fixed);
      else if (uniform_real<float>() > 0.33)
         ss1.setf(std::ios::scientific);
      else
         ss1.unsetf(std::ios::floatfield);

      auto conditionally_set = [&](std::stringstream& sstream, std::ios::fmtflags flags) {
         if (uniform_real<float>() > 0.5)
            sstream.setf(flags);
         else
            sstream.unsetf(flags);
      };

      conditionally_set(ss1, std::ios::showpoint);
      conditionally_set(ss1, std::ios::showpos);
      conditionally_set(ss1, std::ios::uppercase);

      ss2.flags(ss1.flags());

      int p = static_cast<int>(uniform_real<float>() * std::numeric_limits<FloatingPointType>::digits10);
      if ((ss1.flags() & std::ios::fixed) && d > 0)
      {
         p = (std::min)(p, std::numeric_limits<FloatingPointType>::digits10 - (int)log10(d) - 1);
      }

      ss1.precision(p);
      ss2.precision(p);

      ss1 << d;
      ss2 << d_;

      if (ss1.str() != ss2.str())
      {
        // Skip known false negatives that arise at zero values
         if (d == 0)
         {
           // Some implementations do not count the leading zero as a digit
           // included in precision, while printing with specific precision
           // using ios::showpoint flags
            if (!(ss1.flags() & std::ios::fixed) && !(ss1.flags() & std::ios::scientific) && (ss1.flags() & std::ios::showpoint))
               continue;
         }

         std::cerr.precision(16);
         std::cerr << "FAIL | d=" << std::scientific << d << " (" << std::hexfloat << d << "), p=" << p << ", ";
         std::cerr << "scientific=" << bool(ss1.flags() & std::ios::scientific) << ", ";
         std::cerr << "fixed=" << bool(ss1.flags() & std::ios::fixed) << ", ";
         std::cerr << "showpoint=" << bool(ss1.flags() & std::ios::showpoint) << ", ";
         std::cerr << "showpos=" << bool(ss1.flags() & std::ios::showpos) << ", ";
         std::cerr << "uppercase=" << bool(ss1.flags() & std::ios::uppercase);
         std::cerr << std::endl;
         std::cerr << "expected: '" << ss1.str() << "'\nactual  : '" << ss2.str() << "'\n" << std::endl;

         std::stringstream ss;
         ss.flags(ss2.flags());
         ss.precision(ss2.precision());
         ss << d_;

         passed = false;
      }
   }

   std::cout << "cpp_double_float<" << typeid(FloatingPointType).name() << ">: "
     << (passed ? "PASS" : "FAIL") << " (" << i << " tests)" << std::endl;
}
} // namespace test_cpp_double_float_io

int main()
{
   test_cpp_double_float_io::test<float>();
   test_cpp_double_float_io::test<double>();
   test_cpp_double_float_io::test<long double>();
#ifdef BOOST_MATH_USE_FLOAT128
// FIXME:
// test_cpp_double_float_io::test<boost::multiprecision::float128>();
#endif

   std::cin.get();
   std::cin.get();
}