int compare(const charT* low1, const charT* high1,
const charT* low2, const charT* high2) const;
string_type transform(const charT* low, const charT* high) const;
long hash(const charT* low, const charT* high) const;
int do_compare(const charT* low1, const charT* high1,
const charT* low2, const charT* high2) const;
string_type do_transform(const charT* low, const charT* high) const;
long do_hash(const charT* low, const charT* high) const;