Method rd_string

include/boost/multiprecision/cpp_dec_float.hpp:2080–3530

template <unsigned Digits10, class ExponentType, class Allocator>
bool cpp_dec_float<Digits10, ExponentType, Allocator>::rd_string(const char* const s)
{
#ifndef BOOST_NO_EXCEPTIONS
   try
   {
#endif

      std::string str(s);
      static const std::string valid_characters{"0123456789"};

      // TBD: Using several regular expressions may significantly reduce
      // the code complexity (and perhaps the run-time) of rd_string().

      // Get a possible exponent and remove it.
      exp = static_cast<exponent_type>(0);

      std::size_t pos;

      if (((pos = str.find('e')) != std::string::npos) || ((pos = str.find('E')) != std::string::npos))
      {
         // Remove the exponent part from the string.
#ifndef BOOST_MP_STANDALONE
         exp = boost::lexical_cast<exponent_type>(static_cast<const char*>(str.c_str() + (pos + 1u)));
#else
         if (str.find_first_not_of(valid_characters, ((str[pos + 1] == '+') || (str[pos + 1] == '-')) ? pos + 2 : pos + 1) != std::string::npos)
            BOOST_MP_THROW_EXCEPTION(std::runtime_error("Can not construct a floating point with non-numeric content"));
         exp = static_cast<exponent_type>(std::atoll(static_cast<const char*>(str.c_str() + (pos + 1u))));
#endif
         
         str = str.substr(static_cast<std::size_t>(0u), pos);
      }

      // Get a possible +/- sign and remove it.
      neg = false;

      if (str.size())
      {
         if (str[0] == '-')
         {
            neg = true;
            str.erase(0, 1);
         }
         else if (str[0] == '+')
         {
            str.erase(0, 1);
         }
      }
      //
      // Special cases for infinities and NaN's:
      //
      if ((str == "inf") || (str == "INF") || (str == "infinity") || (str == "INFINITY"))
      {
         if (neg)
         {
            *this = this->inf();
            this->negate();
         }
         else