my_char_traits.h

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#ifndef MY_CHAR_TRAITS_INCLUDED
#define MY_CHAR_TRAITS_INCLUDED
 
#include <cstring>
 
template <class CharT>
struct my_char_traits;
 
/*
  This is a standards-compliant, drop-in replacement for
    std::char_traits<unsigned char>
  We need this because clang libc++ is removing support for it in clang 19.
  It is not a complete implementation. Rather we implement just enough to
  compile any usage of char_traits<uchar> we have in our codebase.
 */
template <>
struct my_char_traits<unsigned char> {
  using char_type = unsigned char;
  using int_type = unsigned int;
 
  static void assign(char_type &c1, const char_type &c2) { c1 = c2; }
 
  static char_type *assign(char_type *s, std::size_t n, char_type a) {
    return static_cast<char_type *>(memset(s, a, n));
  }
 
  static int compare(const char_type *s1, const char_type *s2, std::size_t n) {
    return memcmp(s1, s2, n);
  }
 
  static char_type *move(char_type *s1, const char_type *s2, std::size_t n) {
    if (n == 0) return s1;
    return static_cast<char_type *>(memmove(s1, s2, n));
  }
 
  static char_type *copy(char_type *s1, const char_type *s2, std::size_t n) {
    if (n == 0) return s1;
    return static_cast<char_type *>(memcpy(s1, s2, n));
  }
};
 
#endif  // MY_CHAR_TRAITS_INCLUDED