converter.hpp

#pragma once
 
#include "fly/fly.hpp"
 
#include <charconv>
#include <cstdint>
#include <optional>
#include <string>
 
namespace fly::detail {
 
template <typename T>
struct Converter
{
    static std::optional<T> convert(const std::string &value)
    {
        const char *begin = value.data();
        const char *end = begin + value.size();
 
        T converted {};
        auto result = std::from_chars(begin, end, converted);
 
        if ((result.ptr != end) || (result.ec != std::errc {}))
        {
            return std::nullopt;
        }
 
        return converted;
    }
};
 
#if !defined(FLY_COMPILER_SUPPORTS_FP_CHARCONV)
 
//==================================================================================================
template <>
struct Converter<float>
{
    static std::optional<float> convert(const std::string &value)
    {
        std::size_t index = 0;
        float result {};
 
        try
        {
            result = std::stof(value, &index);
        }
        catch (...)
        {
            return std::nullopt;
        }
 
        if (index != value.length())
        {
            return std::nullopt;
        }
 
        return result;
    }
};
 
//==================================================================================================
template <>
struct Converter<double>
{
    static std::optional<double> convert(const std::string &value)
    {
        std::size_t index = 0;
        double result {};
 
        try
        {
            result = std::stod(value, &index);
        }
        catch (...)
        {
            return std::nullopt;
        }
 
        if (index != value.length())
        {
            return std::nullopt;
        }
 
        return result;
    }
};
 
//==================================================================================================
template <>
struct Converter<long double>
{
    static std::optional<long double> convert(const std::string &value)
    {
        std::size_t index = 0;
        long double result {};
 
        try
        {
            result = std::stold(value, &index);
        }
        catch (...)
        {
            return std::nullopt;
        }
 
        if (index != value.length())
        {
            return std::nullopt;
        }
 
        return result;
    }
};
 
#endif
 
} // namespace fly::detail