Cool string definition

gistfile1.txt

     /*
      *  String constants (C syntax)
      *  Escape sequence \c is accepted for all characters c. Except for
      *  \n \t \b \f, the result is c.
      *
      */

\"              {
                    string_buf_ptr = string_buf;
                    BEGIN(STRING);
                }
<STRING>{
    "\b"        STR_APPEND_CHAR('\b');      /* backspace */
    "\f"        STR_APPEND_CHAR('\f');      /* formfeed */
    "\t"        STR_APPEND_CHAR('\t');      /* tab */
    "\n"        STR_APPEND_CHAR('\n');      /* newline */
    \\\n        {                           /* escaped newline */
                    ++curr_lineno;
                    STR_APPEND_CHAR('\n');
                }
    \\.         STR_APPEND_CHAR(yytext[1]);
    [^\\\n\"]+  {
                    if (string_buf_ptr + yyleng >
                            &string_buf[MAX_STR_CONST - 1]) {
                        BEGIN(INVALID_STRING);
                        RETURN_ERROR("String constant too long");
                    }
                    strncpy(string_buf_ptr, yytext, yyleng);
                    string_buf_ptr += yyleng;
                }
    \"          {
                    BEGIN(INITIAL);
                    cool_yylval.symbol = stringtable.add_string(string_buf);
                    return STR_CONST;
                }
    \0          {
                    BEGIN(INVALID_STRING);
                    RETURN_ERROR("String contains null character");
                }
    \n          {
                    ++curr_lineno;
                    BEGIN(INITIAL);
                    RETURN_ERROR("Unterminated string constant");
                }
    <<EOF>>     {
                    BEGIN(INITIAL);     /* Prevent EOF loop */
                    RETURN_ERROR("EOF in string constant");
                }
}
<INVALID_STRING>{
    \\\n        ++curr_lineno;
    \\.         ;
    [^\\\n\"]+  ;
    \"          BEGIN(INITIAL);
    \n          {
                    ++curr_lineno;
                    BEGIN(INITIAL);
                }
}