PrecisionWrapper.h

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// --------------------------------------------------------------------------
//                   OpenMS -- Open-Source Mass Spectrometry
// --------------------------------------------------------------------------
// Copyright The OpenMS Team -- Eberhard Karls University Tuebingen,
// ETH Zurich, and Freie Universitaet Berlin 2002-2018.
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// $Maintainer: Timo Sachsenberg $
// $Authors: Marc Sturm, Clemens Groepl $
// --------------------------------------------------------------------------

#pragma once

#include <OpenMS/config.h>
#include <OpenMS/CONCEPT/Types.h>

#include <iostream>
#include <iomanip>

namespace OpenMS
{

  template <typename FloatingPointType>
  struct PrecisionWrapper
  {
    explicit PrecisionWrapper(const FloatingPointType rhs) :
      ref_(rhs) {}
    PrecisionWrapper(const PrecisionWrapper & rhs) :
      ref_(rhs.ref_) {}
    FloatingPointType const ref_;
private:
    PrecisionWrapper();     // intentionally not implemented
  };

  template <typename FloatingPointType>
  inline const PrecisionWrapper<FloatingPointType> precisionWrapper(const FloatingPointType rhs)
  {
    return PrecisionWrapper<FloatingPointType>(rhs);
  }

  template <typename FloatingPointType>
  inline std::ostream & operator<<(std::ostream & os, const PrecisionWrapper<FloatingPointType> & rhs)
  {
    // Same test as used by isnan(), spelled out here to avoid issues during overload resolution.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wfloat-equal"
    if (rhs.ref_ != rhs.ref_)
#pragma clang diagnostic pop
    {
      // That's what Linux GCC uses, and gnuplot understands.
      // Windows would print stuff like 1.#QNAN which makes testing hard.
      return os << "nan";
    }
    else
    {
      const std::streamsize prec_save = os.precision();
      os.precision(writtenDigits(FloatingPointType()));
      os << rhs.ref_;
      os.precision(prec_save);
      return os;
    }
  }
} // namespace OpenMS