Class is_zero_int

extlibs/fmt/include/fmt/printf.h:54–65

An argument visitor that returns true iff arg is a zero integer.

// An argument visitor that returns true iff arg is a zero integer.
class is_zero_int {
 public:
  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  bool operator()(T value) {
    return value == 0;
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  bool operator()(T) {
    return false;
  }
};

template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};