Implemented char_traits for SEXP octet_t

include/sexpp/sexp.h

@@ -99,14 +99,80 @@ class sexp_input_stream_t;
  * SEXP simple string
  */
 
-typedef uint8_t octet_t;
+//typedef uint8_t octet_t;
 
-class SEXP_PUBLIC_SYMBOL sexp_simple_string_t : public std::basic_string<octet_t>,
+using octet_t = uint8_t;
+
+struct octet_traits : std::char_traits<octet_t> {
+    static void assign(char_type& r, const char_type& a) {
+        r = a;
+    }
+
+    static bool eq(const char_type& c1, const char_type& c2) {
+        return c1 == c2;
+    }
+
+    static bool lt(const char_type& c1, const char_type& c2) {
+        return c1 < c2;
+    }
+
+    static int compare(const char_type* s1, const char_type* s2, std::size_t n) {
+        while ( n-- != 0 ) {
+            if ( *s1 < *s2 ) return -1;
+            if ( *s2++ < *s1++ ) return 1;
+        }
+        return 0;
+    }
+
+    static const char_type* find(const char_type* s, std::size_t n, const char_type& a) {
+        while ( n-- != 0 ) {
+            if ( *s == a ) return s;
+            s++;
+        }
+        return nullptr;
+    }
+
+    static char_type* move(char_type* s1, const char_type* s2, std::size_t n) {
+        return (char_type*)std::memmove(s1, s2, n);
+    }
+
+    static char_type* copy(char_type* s1, const char_type* s2, std::size_t n) {
+        return (char_type*)std::memcpy(s1, s2, n);
+    }
+
+    static char_type* assign(char_type* s, std::size_t n, char_type a) {
+        return (char_type*)std::memset(s, a, n);
+    }
+
+    static char_type to_char_type(const int_type& c) {
+        return char_type(c);
+    }
+
+    static int_type to_int_type(const char_type& c) {
+        return int_type(c);
+    }
+
+    static bool eq_int_type(const int_type& c1, const int_type& c2) {
+        return c1 == c2;
+    }
+
+    static int_type eof() {
+        return static_cast<int_type>(EOF);
+    }
+
+    static int_type not_eof(const int_type& c) {
+        return eq_int_type(c, eof()) ? 0 : c;
+    }
+};
+
+using octet_string = std::basic_string<octet_t, octet_traits>;
+
+class SEXP_PUBLIC_SYMBOL sexp_simple_string_t : public octet_string,
                                                 private sexp_char_defs_t {
   public:
     sexp_simple_string_t(void) = default;
-    sexp_simple_string_t(const octet_t *dt) : std::basic_string<octet_t>{dt} {}
-    sexp_simple_string_t(const octet_t *bt, size_t ln) : std::basic_string<octet_t>{bt, ln} {}
+    sexp_simple_string_t(const octet_t *dt) : octet_string{dt} {}
+    sexp_simple_string_t(const octet_t *bt, size_t ln) : octet_string{bt, ln} {}
     sexp_simple_string_t &append(int c)
     {
         (*this) += (octet_t)(c & 0xFF);