Pretty.hpp

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#ifndef ORG_EEROS_LOGGER_PRETTY_HPP_
#define ORG_EEROS_LOGGER_PRETTY_HPP_

#include <sstream>
#include <string>
#include <math.h>

namespace eeros
{
    namespace logger
    {
        std::string pretty(double x)
        {
            std::stringstream out;

            bool npositive = (x >= 0);
            if (!npositive) x = -x;

            if (x < 1e-12)
            {
                return "   0.000 ";
            }

            double l = log10(x);
            bool positive = (l >= 0);
            if (!positive) l = -l;

            int r = (((int)l)/3)*3;
            if (!positive) r += 3;

            double b = pow(10,r);

            if (positive)
                x /= b;
            else
                x *= b;

            int left = (int)x;
            int right = (int)((x - left)*1000);


            if (left < 10)
                out << "  ";
            else if (left < 100)
                out << " ";

            if (npositive)
                out << ' ';
            else
                out << '-';

            out << left;
            out << ".";

            if (right < 10)
                out << "00";
            else if (right < 100)
                out << "0";

            out << right;

            if (positive)
            {
                switch(r)
                {
                    case 0:
                        out << " ";
                        break;

                    case 3:
                        out << "k";
                        break;

                    case 6:
                        out << "M";
                        break;

                    case 9:
                        out << "G";
                        break;

                    case 12:
                        out << "T";
                        break;

                    default:
                        out << "e";
                        if (positive) out << '+'; else out << '-';
                        out << r;
                    break;
                }
            }
            else
            {
                switch(r)
                {
                    case 0:
                        out << " ";
                        break;

                    case 3:
                        out << "m";
                        break;

                    case 6:
                        out << "u";
                        break;

                    case 9:
                        out << "n";
                        break;

                    case 12:
                        out << "p";
                        break;

                    default:
                        out << "e";
                        if (positive) out << '+'; else out << '-';
                        out << r;
                    break;
                }
            }

            return out.str();
        }
    }
}

#endif /* ORG_EEROS_LOGGER_PRETTY_HPP_ */