is_ascii.hpp

   1 #include <algorithm>
   2 #include <string_view>
   3
   4 constexpr bool isascii(auto c) noexcept
   5 {
   6   return (static_cast<unsigned char>(c) & 0x80) == 0;
   7 }
   8
   9 constexpr bool is_ascii(std::string_view str) noexcept
  10 {
  11   return !std::any_of(std::begin(str), std::end(str),
  12                       [](auto ch) { return !isascii(ch); });
  13 }