reverse()
public
Returns a new string with the
characters from str in reverse
order.
"stressed".reverse
Show source
static VALUE
rb_str_reverse(VALUE str)
{
rb_encoding *enc;
VALUE rev;
char *s, *e, *p;
int single = 1;
if (RSTRING_LEN(str) <= 1) return rb_str_dup(str);
enc = STR_ENC_GET(str);
rev = rb_str_new5(str, 0, RSTRING_LEN(str));
s = RSTRING_PTR(str); e = RSTRING_END(str);
p = RSTRING_END(rev);
if (RSTRING_LEN(str) > 1) {
if (single_byte_optimizable(str)) {
while (s < e) {
*--p = *s++;
}
}
else {
while (s < e) {
int clen = rb_enc_mbclen(s, e, enc);
if (clen > 1 || (*s & 0x80)) single = 0;
p -= clen;
memcpy(p, s, clen);
s += clen;
}
}
}
STR_SET_LEN(rev, RSTRING_LEN(str));
OBJ_INFECT(rev, str);
if (ENC_CODERANGE(str) == ENC_CODERANGE_UNKNOWN) {
if (single) {
ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
}
else {
ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
}
}
rb_enc_cr_str_copy_for_substr(rev, str);
return rev;
}