robot/include/rttr/detail/conversion/number_conversion.h

/************************************************************************************
*                                                                                   *
*   Copyright (c) 2014 - 2018 Axel Menzel <info@rttr.org>                           *
*                                                                                   *
*   This file is part of RTTR (Run Time Type Reflection)                            *
*   License: MIT License                                                            *
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*   Permission is hereby granted, free of charge, to any person obtaining           *
*   a copy of this software and associated documentation files (the "Software"),    *
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*   Software is furnished to do so, subject to the following conditions:            *
*                                                                                   *
*   The above copyright notice and this permission notice shall be included in      *
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#ifndef RTTR_NUMBER_CONVERSION_H_
#define RTTR_NUMBER_CONVERSION_H_

#include "rttr/detail/base/core_prerequisites.h"
#include <limits>

namespace rttr
{
namespace detail
{

/////////////////////////////////////////////////////////////////////////////////////////

/*!
 * \brief Identity function
 *
 */
template<typename F, typename T>
typename std::enable_if<std::is_same<F, T>::value, bool>::type
convert_to(const F& from, T& to)
{
    to = from;
    return true;
}

template<typename F, typename T>
using is_integer = std::integral_constant<bool, !std::is_same<F, T>::value &&
                                                std::is_integral<F>::value && std::is_integral<T>::value>;

/////////////////////////////////////////////////////////////////////////////////////////

template<typename F, typename T>
typename std::enable_if<is_integer<F, T>::value &&
                        std::numeric_limits<F>::is_signed &&
                        !std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from < 0)
        return false; // value too small

    if (static_cast<typename std::make_unsigned<F>::type>(from) > (std::numeric_limits<T>::max)())
        return false; // value too large

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

template<typename F, typename T>
typename std::enable_if<is_integer<F, T>::value &&
                        !std::numeric_limits<F>::is_signed &&
                        std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from > static_cast<typename std::make_unsigned<T>::type>((std::numeric_limits<T>::max)()))
        return false; // value too large

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

template<typename F, typename T>
typename std::enable_if<is_integer<F, T>::value &&
                        std::numeric_limits<F>::is_signed &&
                        std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from > (std::numeric_limits<T>::max)())
        return false; // value too large
    else if (from < (std::numeric_limits<T>::min)())
        return false; // value too small

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

template<typename F, typename T>
typename std::enable_if<is_integer<F, T>::value &&
                        !std::numeric_limits<F>::is_signed &&
                        !std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from > (std::numeric_limits<T>::max)())
        return false; // value too large

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
// floating point conversion

template<typename F, typename T>
typename std::enable_if<std::is_floating_point<F>::value &&
                        std::is_integral<T>::value && std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from > (std::numeric_limits<T>::max)())
        return false; // value too large
    else if (from < - (std::numeric_limits<T>::max)())
        return false; // value to small

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

template<typename F, typename T>
typename std::enable_if<std::is_floating_point<F>::value &&
                        std::is_integral<T>::value && !std::numeric_limits<T>::is_signed,
                        bool>::type
convert_to(const F& from, T& to)
{
    if (from < 0 || from > (std::numeric_limits<T>::max)())
        return false; // value too large

    to = static_cast<T>(from);
    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
// string conversion

template<typename F, typename T>
typename std::enable_if<std::is_same<T, std::string>::value,
                        bool>::type
convert_to(const F& from, T& to)
{
    bool ok = false;
    to = to_string(from, &ok);
    return ok;
}

/////////////////////////////////////////////////////////////////////////////////////////

} // end namespace detail
} // end namespace rttr

#endif // RTTR_NUMBER_CONVERSION_H_