inspect

VALUE
rb_str_inspect(VALUE str)
{
 int encidx = ENCODING_GET(str);
 rb_encoding *enc = rb_enc_from_index(encidx), *actenc;
 const char *p, *pend, *prev;
 char buf[CHAR_ESC_LEN + 1];
 VALUE result = rb_str_buf_new(0);
 rb_encoding *resenc = rb_default_internal_encoding();
 int unicode_p = rb_enc_unicode_p(enc);
 int asciicompat = rb_enc_asciicompat(enc);

 if (resenc == NULL) resenc = rb_default_external_encoding();
 if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
 rb_enc_associate(result, resenc);
 str_buf_cat2(result, "\"");

 p = RSTRING_PTR(str); pend = RSTRING_END(str);
 prev = p;
 actenc = get_actual_encoding(encidx, str);
 if (actenc != enc) {
 enc = actenc;
 if (unicode_p) unicode_p = rb_enc_unicode_p(enc);
 }
 while (p < pend) {
 unsigned int c, cc;
 int n;

 n = rb_enc_precise_mbclen(p, pend, enc);
 if (!MBCLEN_CHARFOUND_P(n)) {
 if (p > prev) str_buf_cat(result, prev, p - prev);
 n = rb_enc_mbminlen(enc);
 if (pend < p + n)
 n = (int)(pend - p);
 while (n--) {
 snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
 str_buf_cat(result, buf, strlen(buf));
 prev = ++p;
 }
 continue;
 }
 n = MBCLEN_CHARFOUND_LEN(n);
 c = rb_enc_mbc_to_codepoint(p, pend, enc);
 p += n;
 if ((asciicompat || unicode_p) &&
 (c == '"'|| c == '\\' ||
 (c == '#' &&
 p < pend &&
 MBCLEN_CHARFOUND_P(rb_enc_precise_mbclen(p,pend,enc)) &&
 (cc = rb_enc_codepoint(p,pend,enc),
 (cc == '$' || cc == '@' || cc == '{'))))) {
 if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
 str_buf_cat2(result, "\\");
 if (asciicompat || enc == resenc) {
 prev = p - n;
 continue;
 }
 }
 switch (c) {
 case '\n': cc = 'n'; break;
 case '\r': cc = 'r'; break;
 case '\t': cc = 't'; break;
 case '\f': cc = 'f'; break;
 case '\013': cc = 'v'; break;
 case '\010': cc = 'b'; break;
 case '\007': cc = 'a'; break;
 case 033: cc = 'e'; break;
 default: cc = 0; break;
 }
 if (cc) {
 if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
 buf[0] = '\\';
 buf[1] = (char)cc;
 str_buf_cat(result, buf, 2);
 prev = p;
 continue;
 }
 if ((enc == resenc && rb_enc_isprint(c, enc)) ||
 (asciicompat && rb_enc_isascii(c, enc) && ISPRINT(c))) {
 continue;
 }
 else {
 if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
 rb_str_buf_cat_escaped_char(result, c, unicode_p);
 prev = p;
 continue;
 }
 }
 if (p > prev) str_buf_cat(result, prev, p - prev);
 str_buf_cat2(result, "\"");

 OBJ_INFECT_RAW(result, str);
 return result;
}