Function from_chars

Common/Core/vtkStringScanner.h:58–80

namespace vtk
{
VTK_ABI_NAMESPACE_BEGIN
///@{
/**
 * Given a char* first and char* last, convert it to a number, and return a from_chars_result;
 *
 * @note The standard library provides these functions as of C++17, but they aren't as fast,
 * or fully implemented.
 */
template <typename T, typename = FASTFLOAT_ENABLE_IF(fast_float::is_supported_float_type<T>::value)>
VTK_ALWAYS_INLINE auto from_chars(const char* first, const char* last, T& value,
  std::chars_format format = std::chars_format::general) -> std::from_chars_result
{
  static constexpr std::array<fast_float::chars_format, 5> std_to_fast_float_chars_format = { {
    fast_float::chars_format::general,    // 0: Default general
    fast_float::chars_format::scientific, // 1: scientific
    fast_float::chars_format::fixed,      // 2: fixed
    fast_float::chars_format::general,    // 3: general
    fast_float::chars_format::hex,        // 4: hex
  } };
  auto result = fast_float::from_chars<T>(first, last, value,
    std_to_fast_float_chars_format[static_cast<std::underlying_type_t<std::chars_format>>(format)]);
  return { result.ptr, result.ec };
}
template <typename T,
  typename = FASTFLOAT_ENABLE_IF(fast_float::is_supported_integer_type<T>::value)>
VTK_ALWAYS_INLINE auto from_chars(const char* first, const char* last, T& value, int base = 10)