charconv_compat.hpp

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#ifndef OPENSWMM_CHARCONV_COMPAT_HPP
#define OPENSWMM_CHARCONV_COMPAT_HPP
 
#include <charconv>
#include <cstdlib>
#include <system_error>
#include <string>
 
namespace openswmm {
 
inline std::from_chars_result from_chars_double(const char* first,
                                                const char* last,
                                                double& value) noexcept {
#if defined(__cpp_lib_to_chars) && __cpp_lib_to_chars >= 201611L
    return std::from_chars(first, last, value);
#else
    if (first == last) {
        return {first, std::errc::invalid_argument};
    }
    // std::strtod needs a null-terminated string
    std::string tmp(first, last);
    char* end = nullptr;
    double v = std::strtod(tmp.c_str(), &end);
    if (end == tmp.c_str()) {
        return {first, std::errc::invalid_argument};
    }
    value = v;
    return {first + (end - tmp.c_str()), std::errc{}};
#endif
}
 
} // namespace openswmm
 
#endif // OPENSWMM_CHARCONV_COMPAT_HPP