关于Basic程序解释器及编译原理的简单化(1)--词法分析和代数式求值

关于Basic程序解释器及编译原理的简单化(1)--词法分析和代数式求值(6)     longjmp(e_buf,1);  /* return to save point */
}

/* get a token */
get_token()
{
    register char *temp;

    token_type = 0;tok = 0;
    temp = token;
   
    if (*prog == '\0')  {   /* end of file */
        *token = 0;
        tok = FINISHED;
        return (token_type = DELIMITER);
    }
   
    while (iswhite(*prog))  ++prog;  /* skip over white space */

    if (*prog == '\r')  {   /* CR LF */
        ++prog;++prog;
        tok = EOL;*token = '\r';
        token[1] = '\n';token[2] = 0;
        return (token_type = DELIMITER);
    }
   
    if (strchr("+-*^/%=;(),><",*prog))  {  /* delimiter */
        *temp = *prog;
        prog++;  /* advance to next position */
        temp++;
        *temp=0;
        return (token_type = DELIMITER);
    }
   
    if (*prog == '"')  {   /* quote string */
        prog++;
        while (*prog!='"'&&*prog!='\r')  *temp++=*prog++;
        if (*prog=='\r')  serror(1);
        prog++;*temp=0;
        return (token_type = QUOTE);