NumberParsing.cc

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#include "NumberParsing.hh"
#include <cmath>
#include <sstream>

namespace Utils
{

  float getFloat(QTextStream &_source)
  {
    QString rawNumber;
    _source >> rawNumber;
    //decimal part > 0
    float highPart = 0.0f;
    //decimal part < 0
    float lowPart = 0.0f;
    //sign of the decimal
    float sign = 1.0;
    //counter to concatenate high and lowaprt
    int n = 0;

    QString::Iterator it = rawNumber.begin();
    QString::Iterator end = rawNumber.end();
    if(*it == QLatin1Char('-'))
    {
      //we have a negative float
      sign = sign * -1.0;
      ++it;
    }

    for (;it != end;++it)
    {
      //we have read a digit
      if(it->isDigit())
      {
        highPart *=10;
        highPart += it->digitValue();
      }
      else
      {
        //stop counting the highPart if its not a digit
        ++it;
        break;
      }
    }

    for (;it != end;++it)
    {
      //we assume to have read a digit
      if(it->isDigit())
      {
        lowPart *=10;
        lowPart += it->digitValue();
        ++n;
      }
      else
      {
        //stop counting the highPart dont increment here!
        // otherwise we cant detect if we successful converted
        break;
      }
    }
    // if something went wrong during decoding use the standard decoding
    if(it != end)
    {
      return rawNumber.toFloat();
    }
    return sign * (highPart + lowPart / std::pow(10.0,n));
  }

  float getFloat(std::istream &_source)
  {
    std::string rawNumber;
    _source >> rawNumber;

    //decimal part > 0
    float highPart = 0.0f;
    //decimal part < 0
    float lowPart = 0.0f;
    //sign of the decimal
    float sign = 1.0;
    //counter to concatenate high and lowaprt
    int n = 0;

    std::string::iterator it = rawNumber.begin();
    std::string::iterator end = rawNumber.end();
    if(*it == '-')
    {
      //we have a negative float
      sign = sign * -1.0;
      ++it;
    }

    for (;it != end;++it)
    {
      //we have read a digit
      if(isdigit(*it))
      {
        highPart *=10;
        highPart += (int)(*it - '0');
      }
      else
      {
        //stop counting the highPart if its not a digit
        ++it;
        break;
      }
    }

    for (;it != end;++it)
    {
      //we assume to have read a digit
      if(isdigit(*it))
      {
        lowPart *=10;
        lowPart += (int)(*it - '0');
        ++n;
      }
      else
      {
        //stop counting the highPart dont increment here!
        // otherwise we cant detect if we successful converted
        break;
      }
    }
    // if something went wrong during decoding use the standard decoding
    if(it != end)
    {
      float fallback;
      std::stringstream converter;
      converter<<rawNumber;
      converter>>fallback;
      return fallback;
    }
    return sign * (highPart + lowPart / std::pow(10.0,n));
  }

  double getDouble(QTextStream &_source)
  {
    QString rawNumber;
    _source >> rawNumber;
    //decimal part > 0
    double highPart = 0.0f;
    //decimal part < 0
    double lowPart = 0.0f;
    //sign of the decimal
    double sign = 1.0;
    //counter to concatenate high and lowaprt
    int n = 0;

    QString::Iterator it = rawNumber.begin();
    QString::Iterator end = rawNumber.end();
    if(*it == QLatin1Char('-'))
    {
      //we have a negative float
      sign = sign * -1.0;
      ++it;
    }

    for (;it != end;++it)
    {
      //we have read a digit
      if(it->isDigit())
      {
        highPart *=10;
        highPart += it->digitValue();
      }
      else
      {
        //stop counting the highPart if its not a digit
        ++it;
        break;
      }
    }

    for (;it != end;++it)
    {
      //we assume to have read a digit
      if(it->isDigit())
      {
        lowPart *=10;
        lowPart += it->digitValue();
        ++n;
      }
      else
      {
        //stop counting the highPart dont increment here!
        // otherwise we cant detect if we successful converted
        break;
      }
    }
    // if something went wrong during decoding use the standard decoding
    if(it != end)
    {
      return rawNumber.toDouble();
    }
    return sign * (highPart + lowPart / std::pow(10.0,n));
  }
}