inspect

/*
 * call-seq:
 *   str.inspect   => string
 *
 * Returns a printable version of _str_, with special characters
 * escaped.
 *
 *    str = "hello"
 *    str[3] = 8
 *    str.inspect       #=> "hel\010o"
 */

VALUE
rb_str_inspect(str)
    VALUE str;
{
    char *p, *pend;
    VALUE result = rb_str_buf_new2("\"");
    char s[5];

    p = RSTRING(str)->ptr; pend = p + RSTRING(str)->len;
    while (p < pend) {
        char c = *p++;
        int len;
        if (ismbchar(c) && p - 1 + (len = mbclen(c)) <= pend) {
            rb_str_buf_cat(result, p - 1, len);
            p += len - 1;
        }
        else if (c == '"'|| c == '\\' || (c == '#' && IS_EVSTR(p, pend))) {
            s[0] = '\\'; s[1] = c;
            rb_str_buf_cat(result, s, 2);
        }
        else if (ISPRINT(c)) {
            s[0] = c;
            rb_str_buf_cat(result, s, 1);
        }
        else if (c == '\n') {
            s[0] = '\\'; s[1] = 'n';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\r') {
            s[0] = '\\'; s[1] = 'r';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\t') {
            s[0] = '\\'; s[1] = 't';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\f') {
            s[0] = '\\'; s[1] = 'f';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\013') {
            s[0] = '\\'; s[1] = 'v';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\010') {
            s[0] = '\\'; s[1] = 'b';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == '\007') {
            s[0] = '\\'; s[1] = 'a';
            rb_str_buf_cat(result, s, 2);
        }
        else if (c == 033) {
            s[0] = '\\'; s[1] = 'e';
            rb_str_buf_cat(result, s, 2);
        }
        else {
            sprintf(s, "\\%03o", c & 0377);
            rb_str_buf_cat2(result, s);
        }
    }
    rb_str_buf_cat2(result, "\"");

    OBJ_INFECT(result, str);
    return result;
}